Dehydrogenation catalyst, and carbonyl compound and hydrogen production method using said catalyst

Abstract

Objects of the present invention are to provide a novel dehydrogenation reaction catalyst, to provide a method that can produce a ketone, an aldehyde, and a carboxylic acid with high efficiency from an alcohol, and to provide a method for efficiently producing hydrogen from an alcohol, formic acid, or a formate, and they are accomplished by a catalyst containing an organometallic compound of Formula (1). ##STR00001##

Claims

1. An organometallic compound of Formula (1): ##STR00067## wherein: Ar is a substituted cyclopentadienyl group, M is iridium, R.sup.1 to R.sup.6 are independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-C10 sulfenyl group, or C1-C10 silyl group in which one or more hydrogen atoms are optionally substituted, and R.sup.3 and R.sup.4 are optionally bonded to each other to form CH, the hydrogens in the CCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted.

2. The organometallic compound according to claim 1, wherein Ar is a 1,2,3,4,5-pentamethylcyclopentadienyl group.

3. A method for continuously producing hydrogen (H.sub.2), the method comprising adding an alkaline compound to a mixture containing an alcohol and water, carrying out a dehydrogenation reaction in the presence of an organometallic compound of Formula (1) according to claim 1 and adding said mixture and said alkaline compound one or more times in the course of progress of dehydrogenation, to produce hydrogen (H.sub.2).

4. The method according to claim 3, wherein the dehydrogenation reaction is carried out in a reaction vessel containing a supply section and a recovery section wherein the mixture and the alkaline compound are added to the supply section and the hydrogen (H.sub.2) is collected in the recovery section.

5. A method for producing hydrogen (H.sub.2), the method comprising reacting an alcohol, a mixture containing an alcohol and water, formic acid, or a formate with a catalyst of Formula (I) containing the organometallic compound according to claim 1 to produce hydrogen (H.sub.2).

6. A method for dehydrogenating an oxygen-containing compound by the use of a catalyst comprising an organometallic compound of Formula (1) according to claim 1, the method comprising reacting the catalyst with an oxygen-containing compound to produce a carbonyl compound or an unsaturated bond-containing compound, and hydrogen (H.sub.2).

7. The method according to claim 6, wherein the oxygen-containing compound is an alcohol.

8. The method according to claim 6, wherein the oxygen-containing compound is formic acid or a formate.

9. The method according to claim 6, wherein the oxygen-containing compound is an alcohol, and the alcohol is dehydrogenated to produce a corresponding carbonyl compound and hydrogen (H.sub.2).

10. The method according to claim 9, wherein the carbonyl compound is a ketone or an aldehyde.

11. The method according to claim 9, wherein the alcohol is a primary alcohol, the carbonyl compound is a carboxylic acid, and a solvent comprising water is used.

12. A dehydrogenation catalyst comprising an organometallic compound of Formula (1) according to claim 1.

13. A system for continuously producing hydrogen by use of the method according to claim 3, the system comprising a reaction vessel for carrying out a dehydrogenation reaction, a supply section for supplying the mixture and the alkaline compound, and a recovery section for recovering hydrogen (H.sub.2) produced.

Description

MODES FOR CARRYING OUT THE INVENTION

(1) That is, the present invention relates to the following.

(2) [1] A method for dehydrogenating an oxygen-containing compound by the use of a catalyst containing an organometallic compound of Formula (1)

(3) ##STR00003##
wherein

(4) Ar is an optionally substituted benzene or an optionally substituted cyclopentadienyl group,

(5) M is ruthenium, rhodium, or iridium,

(6) R.sup.1 to R.sup.6 are mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted,

(7) R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, the Hs in the CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, and

(8) L is selected from the group consisting of a sulfoxide ligand, a nitrogen-containing aromatic ring ligand, an amine ligand, a phosphine ligand, an ether ligand, and an aquo ligand.

(9) [2] The method according to [1], wherein the oxygen-containing compound is an alcohol.

(10) [3] The method according to [1], wherein the oxygen-containing compound is formic acid or a formate.

(11) [4] The method according to any one of [1] to [3], wherein L is an aquo ligand.

(12) [5] The method according to any one of [1] to [4], wherein Ar is an optionally substituted cyclopentadienyl group, and M is iridium.

(13) [6] A dehydrogenation catalyst containing an organometallic compound of Formula (1), wherein it is for use in the method according to any one of [1] to [5].

(14) [7] A method for producing a carbonyl compound, wherein an alcohol is dehydrogenated by use of the dehydrogenation method according to any one of [1] to [5] to produce a corresponding carbonyl compound.

(15) [8] The method according to [7], wherein the carbonyl compound is a ketone or an aldehyde.

(16) [9] The method according to [7], wherein the alcohol is a primary alcohol, the carbonyl compound is a carboxylic acid, and a solvent containing water is used.

(17) [10] A method for producing hydrogen, wherein hydrogen is prepared by dehydrogenation of an alcohol, a mixture containing an alcohol and water, formic acid, or a formate using the dehydrogenation method according to any one of [1] to [5].

(18) [11] An organometallic compound of Formula (1)

(19) ##STR00004##
wherein,

(20) Ar is an optionally substituted benzene or an optionally substituted cyclopentadienyl group,

(21) M is ruthenium, rhodium, or iridium,

(22) R.sup.1 to R.sup.6 are mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted,

(23) R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, the Hs in the CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, and

(24) L is an aquo ligand.

(25) [12] The organometallic compound according to [11], wherein Ar is an optionally substituted cyclopentadienyl group, and M is iridium.

(26) [13] An organometallic compound of Formula (2)

(27) ##STR00005##
wherein

(28) Ar is an optionally substituted benzene or an optionally substituted cyclopentadienyl group,

(29) M is ruthenium, rhodium, or iridium,

(30) R.sup.1 to R.sup.6 are mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted,

(31) R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, the Hs in the CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, and

(32) Z is Na, Li, K, or Cs.

(33) [14] The organometallic compound according to [13], wherein Ar is an optionally substituted cyclopentadienyl group, and M is iridium.

(34) [15] A method for dehydrogenating an oxygen-containing compound by the use of a catalyst containing the organometallic compound according to [13] or [14].

(35) [16] The method according to [15], wherein the oxygen-containing compound is an alcohol, formic acid, or a formate.

(36) [17] A dehydrogenation catalyst containing the organometallic compound according to [13] or [14].

(37) [18] A method for producing a carbonyl compound, wherein an alcohol is dehydrogenated by use of the dehydrogenation method according to [15] or [16] to produce a corresponding carbonyl compound.

(38) [19] The method according to [18], wherein the carbonyl compound is a ketone or an aldehyde.

(39) [20] The method according to [18], wherein the alcohol is a primary alcohol, the carbonyl compound is a carboxylic acid, and a solvent containing water is used.

(40) [21] A method for producing hydrogen, wherein hydrogen is prepared by dehydrogenation of an alcohol, a mixture of an alcohol and water, formic acid, or a formate by use of the dehydrogenation method according to [16].

(41) [22] A method for continuously producing hydrogen, the method including adding an alkaline compound to a mixture containing an alcohol and water, carrying out a dehydrogenation reaction in the presence of an organometallic compound of Formula (1) according to [1] and/or Formula (2) according to [13], and adding said mixture and said alkaline compound one or more times in the course of progress of dehydrogenation.
[23] A system for continuously producing hydrogen by use of the method according to [22], the system including a reaction vessel for carrying out a dehydrogenation reaction, a supply section for supplying the mixture and the alkaline compound, and a recovery section for recovering hydrogen produced.

(42) One aspect of the present invention relates to a method for dehydrogenating an oxygen-containing compound using a catalyst containing a nitrogen-containing organometallic compound (organometallic complex) of Formula (1) below. The organometallic complex used in the present invention is not particularly limited as long as it is a metal complex containing a ligand containing carbonyl oxygen and nitrogen on bipyridine or phenanthroline, and is typically of Formula (1).

(43) ##STR00006##

(44) In Formula (1), Ar is typically a benzene or cyclopentadienyl group in which one or more hydrogen atoms are optionally substituted.

(45) Specific examples of aromatic compounds in which one or more hydrogen atoms are optionally substituted include, but are not limited to, benzene, benzenes having an alkyl group such as toluene, o-, m- and p-xylene, o-, m- and p-cymene, 1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene, 1,2,4,5-tetramethylbenzene, 1,2,3,4-tetramethylbenzene, 1,3,4,5-tetramethylbenzene, pentamethylbenzene, and hexamethylbenzene, benzenes having an unsaturated hydrocarbon group such as benzyl, vinyl, or allyl, and benzenes having a heteroatom such as a halogen atom, a hydroxy group, an alkoxy group, an ester group, or an amino group. The number of substituents on the benzene ring may be any of 1 to 6, and the position of substitution can be selected from any position. In terms of ease of synthesis of a complex, p-cymene, 1,3,5-trimethylbenzene, or hexamethylbenzene is preferable.

(46) In the present invention, being optionally substituted means optionally having any substituent; typical substituents include, but are not limited to, a C1-10 saturated or unsaturated hydrocarbon group, an aryl group, a heterocyclyl group, an alkoxy group, a fluoroalkyl group, an acyl group, an ester group, a hydroxy group, an amino group, an amide group, a carboxyl group, a sulfonyl group, a nitro group, a cyano group, a sulfenyl group, a sulfo group, a mercapto group, a silyl group, and a halogen group and, in particular, a C1-10 saturated or unsaturated hydrocarbon group, an aryl group, a heterocyclyl group, an alkoxy group, an acyl group, an ester group, a hydroxy group, an amino group, a sulfonyl group, a silyl group, and a halogen group.

(47) Specific examples of the substituent include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexylene group, an ethenyl group, a propenyl group, a butenyl group, a phenyl group, a toluyl group, a naphthyl group, a pyridyl group, a furanyl group, a methoxy group, an ethoxy group, a propoxy group, an acetyl group, a propanoyl group, a cyclohexanecarbonyl group, a benzoyl group, a methoxycarbonyl group, an ethoxycarbonyl group, a hydroxy group, a methylamino group, an ethylamino group, a dimethylamino group, a methylsulfonyl group, an ethylsulfonyl group, a methylsilyl group, a dimethylsilyl group, a fluoro group, a chloro group, and a trifluoromethyl group. In terms of ease of synthesis of a complex, a saturated or unsaturated hydrocarbon group is preferable, and a methyl group or an i-propyl group is more preferable.

(48) Specific examples of the cyclopentadienyl group in which one or more hydrogen atoms are optionally substituted include, but are not limited to, a cyclopentadienyl group, a methylcyclopentadienyl group, an ethylcyclopentadienyl group, an isopropylcyclopentadienyl group, a phenylcyclopentadienyl group, a benzylcyclopentadienyl group, a 1,2-dimethylcyclopentadienyl group, a 1,3-dimethylcyclopentadienyl group, a 1,2,3-trimethylcyclopentadienyl group, a 1,2,4-trimethylcyclopentadienyl group, a 1,2,3,4-tetramethylcyclopentadienyl group, and a 1,2,3,4,5-pentamethylcyclopentadienyl group (Cp*). In terms of ease of synthesis of a complex, a 1,2,3,4,5-pentamethylcyclopentadienyl group (Cp*) is preferable.

(49) M in Formula (1) is any of ruthenium, rhodium, and iridium. In terms of high catalytic activity, iridium is preferable.

(50) R.sup.1 to R.sup.6 in Formula (1) are typically mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, and the Hs in CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted.

(51) Specific examples of R.sup.1 to R.sup.6 include, but are not limited to, a hydrogen atom, a fluoro group, a chloro group, a bromo group, an iodo group, a trifluoromethyl group, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, a tert-butoxy group, a dimethylamino group, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a tert-butyl group, an isobutyl group, a benzyl group, a cyclohexyl group, a phenyl group, a vinyl group, a pyridyl group, an ethynyl group, an ester bond-containing group, an acetyl group, a methanesulfonyl group, an ethanesulfonyl group, a p-toluenesulfonyl group, a trifluoromethanesulfonyl group, a methylsilyl group, a dimethylsilyl group, and a trimethylsilyl group and so on. In terms of high catalytic activity and reaction yield, a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an isobutyl group, a benzyl group, a phenyl group, a 4-methoxyphenyl group, or a 4-(dimethylamino)phenyl group is preferable.

(52) L in Formula (1) is typically selected from the group consisting of a sulfoxide ligand, a nitrogen-containing aromatic ring ligand, an amine ligand, a phosphine ligand, an ether ligand, and an aquo ligand.

(53) Specific examples thereof include, but are not limited to, DMSO, diphenylsulfoxide, and methylphenylsulfoxide as the sulfoxide ligand, pyridine, picoline, lutidine, 3-chloropyridine, and 4-chloropyridine as the nitrogen-containing aromatic ring ligand, aniline, toluidine, and anisidine as the amine ligand, triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine, and triethoxyphosphine as the phosphine ligand, and dimethyl ether, diethyl ether, diisopropyl ether, cyclopentyl methyl ether, methyl tert-butyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and anisole as the ether ligand.

(54) L is preferably a dimethylsulfoxide ligand (dmso), a pyridine ligand (pyridine), an aniline ligand (aniline), or an aquo ligand, and is particularly preferably an aquo ligand in terms of very high catalytic efficiency and reaction yield.

(55) In the present invention, a preferred organometallic complex is a complex of Formula (1), wherein Ar being an optionally substituted cyclopentadienyl group, M being iridium, and L being a dimethylsulfoxide ligand (dmso), a pyridine ligand (pyridine), an aniline ligand (aniline), or an aquo ligand. Since the organometallic complex of the present invention is a neutral complex, it exhibits high solubility in most of the usual organic solvents, and solvents having various boiling points may be freely selected and used. It is also possible to select and use a solvent that easily dissolves a substrate.

(56) From the viewpoint of catalytic efficiency and reaction yield, in particular, an organometallic complex of Formula (1), wherein Ar is an optionally substituted cyclopentadienyl group, M is iridium, and L is an aquo ligand, that is, an aquo complex, is preferable. Although the reason why this aquo complex exhibits very high catalytic efficiency and reaction yield is not necessarily clear, it is surmised that an aquo ligand easily dissociates and a coordinatively-unsaturated active species is easily generated.

(57) In the present invention, the oxygen-containing compound may be a compound containing oxygen and hydrogen, and examples thereof include, but are not limited to, an alcohol, formic acid, and a formate.

(58) The alcohol may be a primary alcohol or a secondary alcohol but is not limited thereto.

(59) The primary alcohol is a compound typically of Formula (3)
[Chem. 5]
R.sup.7CH.sub.2OH(3)

(60) wherein R.sup.7 denotes a hydrogen atom or an optionally substituted C5 to C15 aromatic monocyclic or polycyclic hydrocarbon group, C1 to C15 heteroatom-containing heteromonocyclic or polycyclic group, or C1 to C25 saturated or unsaturated chain-form or cyclic hydrocarbon group.

(61) The substituent in this case may be selected as appropriate from for example a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C5 to 15 aryl group, C1-15 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted.

(62) Specific examples of R.sup.7 include a hydrogen atom, an aromatic monocyclic or polycyclic group such as a phenyl group, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-tert-butylphenyl, 2-methoxyphenyl, 2-chlorophenyl, 2-vinylphenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 3-methoxyphenyl, 3-chlorophenyl, 3-vinylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-vinylphenyl, cumenyl, mesityl, xylyl, 1-naphthyl, 2-naphthyl, anthryl, phenanthryl, or indenyl group, a heteromonocyclic or polycyclic group such as thienyl, furyl, pyranyl, xanthenyl, pyridyl, pyrrolyl, imidazolinyl, indolyl, carbazoyl, or Phenanthrolinyl, an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, or heptyl, a cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or 2-adamantyl, an unsaturated hydrocarbon group such as benzyl, vinyl, or aryl, and a ferrocenyl group.

(63) The secondary alcohol is typically of Formula (4)

(64) ##STR00007##

(65) wherein R.sup.8 and R.sup.9 denote identical or different optionally substituted C5 to C15 aromatic monocyclic or polycyclic hydrocarbon groups, C1 to C15 heteroatom-containing heteromonocyclic or polycyclic groups, or C1 to C25 saturated or unsaturated chain-form or cyclic hydrocarbon groups. Here, R.sup.8 and R.sup.9 may be bonded to each other to form a ring.

(66) The substituent in this case may be selected as appropriate from for example a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, and a C1-10 alkyl group, C3-15 cycloalkyl group, C5 to 15 aryl group, C1-15 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted.

(67) Specific examples of R.sup.8 and R.sup.9 include an aromatic monocyclic or polycyclic group such as a phenyl group, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-tert-butylphenyl, 2-methoxyphenyl, 2-chlorophenyl, 2-vinylphenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 3-methoxyphenyl, 3-chlorophenyl, 3-vinylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-vinylphenyl, cumenyl, mesityl, xylyl, 1-naphthyl, 2-naphthyl, anthryl, phenanthryl, or indenyl group, a heteromonocyclic or polycyclic group such as thienyl, furyl, pyranyl, xanthenyl, pyridyl, pyrrolyl, imidazolinyl, indolyl, carbazoyl, or Phenanthrolinyl, an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, or heptyl, a cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or 2-adamantyl, an unsaturated hydrocarbon group such as benzyl, vinyl, or aryl, and a ferrocenyl group.

(68) When R.sup.8 and R.sup.9 are bonded to form a ring, examples include saturated and unsaturated alicyclic groups that give a cyclic alcohol such as cyclopentanol, cyclohexanol, cycloheptanol, cyclopentenol, cyclohexenol, or cycloheptenol, and saturated and unsaturated alicyclic groups having on each carbon an alkyl group, an aryl group, an unsaturated alkyl group, or a hetero element-containing chain-form or cyclic hydrocarbon group-containing substituent.

(69) Examples of the formate include, but are not limited to, a metal formate such as sodium formate or potassium formate and a formate such as ammonium formate.

(70) In the present specification, a dehydrogenation reaction means a reaction in which a hydrogen molecule is removed, and examples include an oxidative dehydrogenation reaction and a decomposition reaction. The dehydrogenation method of the present specification is carried out by a dehydrogenation reaction.

(71) One aspect of the present invention relates to a method for producing from the alcohol the corresponding carbonyl compound by means of the dehydrogenation method of the present invention. For example, when the alcohol is a primary alcohol, an aldehyde is obtained as the corresponding carbonyl compound, as shown by for example the following reaction formula.
[Formula 2]
R.sup.7CH.sub.2OH.fwdarw.R.sup.7CHO+H.sub.2

(72) R.sup.7 is as described above.

(73) When it is a secondary alcohol, a ketone is obtained, as shown by for example the following reaction formula.

(74) ##STR00008##

(75) R.sup.8 and R.sup.9 are as described above.

(76) One aspect of the present invention relates to a method for producing a carboxylic acid from a primary alcohol via an aldehyde using the dehydrogenation method of the present invention. It is thought that this conversion from an alcohol to a carboxylic acid progresses via three steps, that is, 1) formation of an aldehyde by dehydrogenation of the alcohol, 2) formation of a hemiacetal by hydration of the aldehyde, and 3) formation of a carboxylic acid by dehydrogenation of the hemiacetal. Therefore, when producing a carboxylic acid, it is preferable to use a solvent containing water in order to hydrate the aldehyde to form the hemiacetal. Specific examples of the production include, but are not limited to, production of acetic acid from ethanol.

(77) One aspect of the present invention relates to a method for producing hydrogen from an alcohol, preferably a primary alcohol, using the dehydrogenation method of the present invention. The alcohol is not particularly limited, but is preferably a primary alcohol from the viewpoint of hydrogen generation efficiency, and is preferably produced by dehydrogenation of a solution in which it is mixed with water. For example, when the primary alcohol is methanol, 3 moles of molecular hydrogen are formed by dehydrogenation of a mixed solution of 1 mole of methanol:water=1:1, and formally all the hydrogen atoms in a methanol molecule and all of the hydrogen atoms in a water molecule are converted into hydrogen molecules, which is very efficient as a hydrogen production method.

(78) In the production of hydrogen, a dehydrogenation reaction can progress at a pH of 1 to 14. From the viewpoint of hydrogen generation efficiency, the pH is preferably 5 to 14, and particularly preferably 10 to 14. Since carbon dioxide is generated accompanying progress of the reaction, and the reaction system gradually becomes acidic, efficient hydrogenation can be continued for a long period of time by setting the pH at the start of reaction at 13 or greater.

(79) In accordance with the present invention, a carboxylic acid and hydrogen can be obtained from a primary alcohol at the same time. This enables a carboxylic acid, which is important in organic industrial chemistry, and hydrogen, which is useful as clean energy, to be obtained at the same time using as a starting material an alcohol obtained by fermentation from a biomass resource.

(80) One aspect of the present invention relates to a method for producing hydrogen by a decomposition reaction of formic acid or a formate using the dehydrogenation method of the present invention. In accordance with the present invention, since it can be carried out at a reaction temperature of on the order of 60 C. to 90 C., it is excellent in terms of safety and economy and is very advantageous for industrial use.

(81) In the dehydrogenation method of the present invention, the amount of catalyst used can be expressed as S/C (S is the number of moles of alcohol, formic acid, or formate, and C is the number of moles of catalyst), which is the molar ratio of alcohol, formic acid, or formate relative to ruthenium, rhodium, or iridium complex. In this case, the degree to which S/C can be increased greatly depends on the structure of the substrate, the type of catalyst, the concentration, the reaction temperature, the type of reaction solvent, etc, but in practice it is desirable to set S/C equal to on the order of 50 to 500000.

(82) The dehydrogenation reaction of the present invention is carried out in the presence or absence of solvent. When a solvent is used, the reaction solvent may be selected as appropriate while taking into consideration the physical properties and the chemical properties of catalyst, substrate, and product. A protic solvent, an aprotic solvent, an ionic liquid, water, or a buffer may be used on their own or in a combination of a plurality thereof.

(83) Specific examples of the solvent include, but are not limited to, pentane, hexane, heptane, benzene, toluene, xylene, tetrahydrofuran, diisopropyl ether, dichloromethane, dimethylformamide, t-butanol, and water.

(84) The reaction temperature may preferably be on the order of 20 C. to 200 C., and more preferably 20 C. to 150 C., while taking into consideration solubility, reactivity, and economic efficiency of catalyst, substrate, and product.

(85) With regard to the reaction time, although it varies depending on reaction conditions such as substrate concentration and reaction temperature, the reaction is completed in a few minutes to 100 hours.

(86) Purification of a carbonyl compound prepared by the dehydrogenation reaction may be carried out by a known method such as acid-base extraction, column chromatography, distillation, or recrystallization, or by a combination thereof as appropriate.

(87) In accordance with the dehydrogenation method of the present invention, a reaction is possible over a wide range of pH. In the dehydrogenation reaction of an alcohol, the pH may be 1 to 14, and preferably 4 to 10, and from a synthetic chemistry viewpoint the pH is preferably 6 to 8.

(88) In the production of a carboxylic acid, the pH can change toward the acidic side accompanying formation of the carboxylic acid, but the reaction progresses in a pH region of to 14. From a synthetic chemistry viewpoint it is preferable to start at a pH of 6 to 8, which is the neutral region, and from the viewpoint of efficiency of formation of a carboxylic acid it is preferable for the pH of the reaction system to be in the range of 1 to 10 throughout the reaction; it is particularly preferable for the pH to be in the range of 1 to 8.

(89) One aspect of the present invention relates to an organometallic compound of Formula (1) below Formula (1)

(90) ##STR00009##

(91) wherein

(92) Ar is an optionally substituted benzene or an optionally substituted cyclopentadienyl group,

(93) M is ruthenium, rhodium, or iridium,

(94) R.sup.1 to R.sup.6 are mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted,

(95) R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, the Hs in the CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, and

(96) L is an aquo ligand.

(97) One aspect of the present invention relates to an organometallic compound of Formula (2) below

(98) ##STR00010##

(99) wherein

(100) Ar is an optionally substituted benzene or an optionally substituted cyclopentadienyl group,

(101) M is ruthenium, rhodium, or iridium,

(102) R.sup.1 to R.sup.6 are mutually independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-10 amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted,

(103) R.sup.3 and R.sup.4 may be bonded to each other to form CHCH, the Hs in the CHCH are optionally substituted mutually independently by a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfo group, a mercapto group, a carboxyl group, or a C1-10 alkyl group, C3-15 cycloalkyl group, C6-15 aryl group, C1-10 heterocyclyl group, C2-10 alkenyl group, C2-10 alkynyl group, C1-10 alkoxy group, C1-10 ester group, C1-10 fluoroalkyl group, C1-10 acyl group, C1-10 sulfonyl group, C1-amino group, C1-10 amide group, C1-10 sulfenyl group, or C1-10 silyl group in which one or more hydrogen atoms are optionally substituted, and

(104) Z is Na, Li, K, or Cs.

(105) A compound of Formula (2) may be produced by a reaction between an alkaline compound and an organometallic compound of Formula (1) where L is an aquo ligand. Examples of the alkaline compound include, but are not limited to, sodium hydroxide, lithium hydroxide, potassium hydroxide, and cesium hydroxide. Therefore, a compound of Formula (2) may be prepared in the reaction system by adding an alkaline compound in a dehydrogenation reaction using as a catalyst an organometallic compound of Formula (1) where L is an aquo ligand.

(106) A compound of Formula (2) may be used in the same way as for a compound of Formula (1) in the dehydrogenation method, the method for producing a carbonyl compound, the method for producing hydrogen, etc. described above for a compound of Formula (1). Therefore, the present invention relates to a dehydrogenation catalyst containing a compound of Formula (2).

(107) The method for producing hydrogen according to the present invention involves producing hydrogen continuously from a mixture of an alcohol and water. From the viewpoint of efficiency in particular, it is preferable to use a compound of Formula (2).

(108) As methods for continuously producing hydrogen there can be cited, for example, a consecutive addition method and a continuous addition method. The consecutive addition method involves adding to a mixture of an alcohol and water a compound of Formula (1) and/or Formula (2) and an alkaline compound, carrying out a reaction under reflux by heating to thus generate hydrogen, then adding amounts of alcohol and water corresponding to those consumed, and further adding an alkaline compound. It is preferable for the pH after each addition to be identical to the pH at the time of starting the reaction. In this way, by consecutively adding the amounts consumed, hydrogen can be produced continuously.

(109) The continuous addition method involves adding a compound of Formula (1) and/or Formula (2) and an alkaline compound to a mixture of an alcohol and water, starting the reaction system under reflux by heating, and continuing to add a premixed mixture of alcohol, water, and alkaline compound using for example a syringe pump, a micro-feeder, etc. in a state in which reflux is continued. In this way, hydrogen gas can be produced at a substantially constant rate for a long period of time by continuously carrying out a reaction while replenishing the amounts, corresponding to the rate at which they are consumed, of the starting materials (alcohol and water) and sodium hydroxide that are consumed continuously at a constant rate.

(110) In accordance with the method for producing hydrogen, in which hydrogen is produced continuously, according to the present invention, it is possible to achieve a catalytic turnover number of at least 2, at least 100, preferably at least 1000, and more preferably at least 3500, and it is possible to construct a new system having very high efficiency and high practicality.

(111) Examples of a system for continuously producing hydrogen include, but are not limited to, a system containing a reaction vessel, a supply section, and a recovery section. The reaction vessel is not particularly limited as long as it can subject a starting material to a dehydrogenation reaction in the presence of a catalyst, but is preferably one in which the reaction can be made continuous, and is typically equipped with devices that can carry out heating and refluxing. The supply section typically contains storage vessels for storing starting materials and alkaline compound for replenishment addition, and supply means such as a syringe pump or a micro-feeder. The recovery section is not particularly limited as long as it recovers the hydrogen generated, and examples include a gas burette, a gas bag, and a gas tank.

(112) One aspect of the present invention relates not only to the dehydrogenation reaction but also to hydrogenation and interconversion by reversible dehydrogenation-hydrogenation. For example, in a catalytic reaction of reaction formula (II)

(113) ##STR00011##
wherein
R.sup.8 and R.sup.9 are as described above,
(i) is a dehydrogenation reaction and (ii) is hydrogenation,

(114) the catalyst of the present invention can repeatedly carry out quantitative interconversion, that is, catalytic reactions in both directions (i) and (ii), accompanied by release and absorption of hydrogen.

(115) By reversibly and continuously carrying out a dehydrogenation reaction and hydrogenation using the same catalyst, it can be expected that the system will be developed as a hydrogen storage system.

EXAMPLES

(116) The present invention is explained below in further detail by reference to Examples, but the present invention should not be construed as being limited by these Examples.

(117) The reactions described in the Examples below were carried out under an atmosphere of an inert gas such as argon gas or nitrogen gas. As the alcohols used, commercial reagents were used as they were. Identification of complexes and reaction products was carried out using a nuclear magnetic resonance (NMR) machine with tetramethylsilane (TMS) as an internal reference substance, the signal thereof being =0 (: chemical shift). The conversion and yield of carbonyl compound and hydrogen were determined by gas chromatography (GC). For NMR, JOEL ECX-500 and JOEL ECS-400 machines (JEOL) were used, and for GC a GL-Sciences GC353B machine (G L Sciences Inc.) was used.

(118) <Synthesis of Novel Neutral Iridium Complex Catalyst>

Production Example 1

(119) Neutral iridium complex 1 was produced by the method shown in either production example 1-a or 1-b.

Production Example 1-a

(120) As shown in synthetic scheme 1-a, a dicationic Cp* iridium-aquo complex (407.8 mg, 0.60 mmol) was reacted with 6,6-dihydroxy-2,2-bipyridine ligand (113.8 mg, 0.60 mmol) in aqueous solvent (12 mL) to thus give complex A (yield 93%). Subsequently, complex A (915.0 mg, 1.1 mmol) was reacted with sodium t-butoxide (211.4 mg, 2.2 mmol) in aqueous solvent (30 mL) to give neutral iridium complex 1 (yield 84%).

(121) ##STR00012##

Production Example 1-b

(122) As shown in scheme 1-b, [Cp*IrCl.sub.2].sub.2 (458.4 mg, 0.570 mmol) was reacted with 6,6-dihydroxy-2,2-bipyridine ligand (250.0 mg, 1.33 mmol) in methanol solvent (8 mL), a reaction was carried out at 60 C. for 3 hours, and filtration using a glass filter was then carried out to thus give cationic complex A (yield 74%). Subsequently, cationic complex A (100.0 mg, 0.170 mmol) was reacted with potassium t-butoxide (38.3 mg, 0.340 mmol) in water (5 mL) at room temperature for 30 minutes while stirring, and a solid thus precipitated was filtered to thus give complex 1 (yield 64%).

(123) ##STR00013##

(124) .sup.1H NMR (400 MHz, CD.sub.3OD) 7.43 (t, J=8 Hz, 2H), 6.92 (d, J=8 Hz, 2H), 6.43 (d, J=8 Hz, 2H), 1.59 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, CD.sub.3OD) 170.9, 157.3, 139.9, 118.1, 106.9, 88.0, 9.83. Anal. Calcd for C.sub.20H.sub.23O.sub.3N.sub.2Ir: C, 45.18; H, 4.36; N, 5.27. Found: C, 45.47; H, 4.01; N, 5.62.

[Production Example 2] Synthesis of Neutral Iridium Complex 2

(125) As shown in scheme 2, [Cp*IrCl.sub.2].sub.2 (240.0 mg, 0.301 mmol) was reacted with 2,9-dihydroxy-1,10-phenanthroline ligand (150.1 mg, 0.707 mmol) in methanol solvent (5.4 mL), a reaction was carried out at 60 C. for 4 hours, and filtration using a glass filter was then carried out to thus give cationic complex T (yield 60%). Subsequently, cationic complex T (150 mg, 0.229 mmol) was reacted with potassium t-butoxide (51.4 mg, 0.421 mmol) in water (6.8 mL) at room temperature for 30 minutes while stirring, and the solvent was removed by distillation under vacuum. The residue was extracted by adding toluene (15 mL), the solvent was removed by distillation, and recrystallization was then carried out using ethanol (2 mL) and water (18 mL) to thus give complex 2 (yield 73%).

(126) ##STR00014##

(127) .sup.1H NMR (400 MHz, CDCl.sub.3) 7.78 (d, J=9 Hz, 2H), 7.16 (s, 2H), 6.81 (d, J=9 Hz, 2H), 1.86 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, CDCl.sub.3) 168.7, 146.1, 139.1, 123.5, 119.2, 118.8, 91.7, 10.8.

[Production Example 3] Synthesis of Neutral Iridium Complex B

(128) Cationic complex A (150.6 mg, 0.240 mmol) was reacted with potassium t-butoxide (80.5 mg, 0.718 mmol) and pyridine (101.1 mg, 1.278 mmol) in dichloromethane (10 mL) at room temperature while stirring overnight, and the solvent was removed by distillation under vacuum. The residue was extracted by adding toluene (15 mL), and the solvent was then removed by distillation to thus give complex B (yield 75%).

(129) .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) 9.87 (d, J=8 Hz, 2H), 7.58 (t, J=8 Hz, 1H), 7.16 (d, J=8 Hz, 2H), 6.22 (d, J=8 Hz, 2H) 1.50 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, CD.sub.2Cl.sub.2) 168.8, 158.4, 157.4, 136.9, 136.7, 125.7, 117.6, 103.4, 88.2, 9.4.

[Production Example 4] Synthesis of Neutral Iridium Complex C

(130) Cationic complex A (150.6 mg, 0.240 mmol) was reacted with potassium t-butoxide (80.5 mg, 0.718 mmol) and aniline (35.7 mg, 0.360 mmol) in dichloromethane (10 mL) at room temperature while stirring overnight, and the solvent was removed by distillation under vacuum. The residue was extracted by adding toluene (15 mL), and the solvent was then removed by distillation to thus give complex C (yield 70%).

(131) .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) 7.49 (bs, 1H), 7.27 (bs, 2H), 7.23 (t, J=8 Hz, 2H), 7.06 (bs, 1H), 6.52 (d, J=7 Hz, 2H), 6.22 (d, J=8 Hz, 2H), 5.79 (bs, 1H), 1.28 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, CD.sub.2Cl.sub.2) 169.1, 156.1, 141.5, 137.5, 128.6, 125.2, 122.5, 117.0, 103.4, 86.6, 8.4.

[Production Example 5] Synthesis of Neutral Iridium Complex D

(132) Cationic complex A (150.6 mg, 0.240 mmol) was reacted with potassium t-butoxide (80.5 mg, 0.718 mmol) and dimethylsulfoxide (18.3 mg, 0.234 mmol) in dichloromethane (10 mL) at room temperature while stirring overnight, and the solvent was removed by distillation under vacuum. The residue was extracted by adding toluene (15 mL), and the solvent was then removed by distillation to thus give complex D (yield 61%).

(133) .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) 7.15 (t, J=8 Hz, 2H), 6.46 (d, J=8 Hz, 2H), 6.13 (d, J=8 Hz, 2H), 2.89 (bs, 6H), 1.56 (s, 15H). .sup.13C{.sup.1H} NMR (100.5 MHz, CD.sub.2Cl.sub.2) 168.2, 156.6, 137.2, 117.2, 103.9, 95.1, 46.1, 9.0.

[Production Example 6] Synthesis of Neutral Iridium Complex E

(134) Cationic complex T (150.6 mg, 0.230 mmol) was reacted with potassium t-butoxide (79.2 mg, 0.706 mmol) and pyridine (90.5 mg, 1.144 mmol) in dichloromethane (10 mL) at room temperature while stirring overnight, and the solvent was removed by distillation under vacuum. The residue was extracted by adding toluene (15 mL), and the solvent was then removed by distillation to thus give complex E (yield 82%).

(135) .sup.1H NMR (500 MHz, CDCl.sub.3) 9.65 (d, J=5 Hz, 1H), 7.56 (d, J=8 Hz, 2H), 7.53 (t, J=8 Hz, 2H), 7.19 (t, J=7 Hz, 2H), 6.68 (d, J=8 Hz, 2H), 1.59 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, CD.sub.2Cl.sub.2) 168.2, 158.2, 147.4, 136.9, 136.8, 125.9, 122.6, 120.8, 118.7, 88.2, 10.0.

(136) Dehydrogenation reactions using the complexes thus synthesized as catalysts are now illustrated. The structural formulae of the complexes used in the Examples are shown below.

(137) Complexes Used in Examples

(138) ##STR00015## ##STR00016##

Example 1

(139) <Synthesis of Acetophenone by Dehydrogenation Reaction of Racemic 1-Phenylethanol>

(140) Under an inert gas atmosphere a 50 mL two-necked recovery flask was charged with 3 mL of anhydrous pentane, 122.2 mg (1.0 mmol) of racemic 1-phenylethanol, and 2.7 mg (0.005 mmol, 0.5 mol %) of complex 1, and stirring was carried out under reflux conditions for 5 hours. 10 mL of toluene was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding acetophenone was formed with a conversion factor of 100% and a yield of 100% as shown in Table 1.

Example 2

(141) <Synthesis of Acetophenone by Dehydrogenation Reaction of Racemic 1-Phenylethanol>

(142) A reaction was carried out under the same conditions as those of Example 1 except that 2.8 mg (0.005 mmol, 0.5 mol %) of complex 2 was used as a catalyst. From the result of analysis by GC, it was confirmed that acetophenone was formed with a conversion factor of 37% and a yield of 36% as shown in Table 1.

Examples 3 to 6

(143) <Synthesis of Acetophenone by Dehydrogenation Reaction of Racemic 1-Phenylethanol>

(144) Reactions were carried out under the same conditions as those of Example 1 except that the various types of complex catalyst B to E (0.005 mmol) shown in Table 1 were used as catalyst. The results of analysis by GC are summarized in Table 1. It was confirmed that acetophenone was formed.

(145) TABLE-US-00001 TABLE 1 Example Catalyst Conversion Factor (%) Yield (%) Example 1 1 100 100 Example 2 2 37 36 Example 3 0 B 8 7 Example 4 C 11 10 Example 5 D 17 16 Example 6 E 9 8

Example 7

(146) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol>

(147) Under an inert gas atmosphere a 50 mL two-necked recovery flask was charged with 3 mL of anhydrous pentane, 122.2 mg (1.0 mmol) of racemic 1-phenylethanol, and 2.7 mg (0.005 mmol, 0.5 mol %) of complex 1, and stirring was carried out under reflux conditions for 5 hours. 10 mL of toluene was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding acetophenone was formed with a conversion factor of 100% and a yield of 100% as shown in Table 2.

Comparative Example 1

(148) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol>

(149) A reaction was carried out under the same conditions as those of Example 7 except that complex A (0.005 mmol) was used as a catalyst. From the result of analysis by GC, it was found that acetophenone was prepared with a conversion factor of 19% and a yield of 18% as shown in Table 2. Compared with Example 7, the yield was clearly low, showing the effectiveness of the present invention.

Comparative Example 2

(150) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol>

(151) A reaction was carried out under the same conditions as those of Example 7 except that complex A (0.005 mmol) was used as a catalyst and water was used as a reaction solvent. From the result of analysis by GC, it was found that acetophenone was prepared with a conversion factor of 6% and a yield of 4% as shown in Table 2. Compared with Example 7, the yield was clearly low, showing the effectiveness of the present invention.

Comparative Example 3

(152) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol>

(153) A reaction was carried out under the same conditions as those of Example 7 except that complex A (0.005 mmol) was used as a catalyst, water was used as a reaction solvent, and the reaction was carried out at 80 C. From the result of analysis by GC, it was found that acetophenone was prepared with a conversion factor of 12% and a yield of 11% as shown in Table 2. Compared with Example 7, the yield was clearly low, showing the effectiveness of the present invention.

(154) TABLE-US-00002 TABLE 2 Example and Conv. Comparative Example Catalyst Solvent Temp. ( C.) factor (%) Yield (%) Ex. 7 1 pentane 36 (reflux) 100 100 Comp. Ex. 1 A pentane 36 (reflux) 19 18 Comp. Ex. 2 A H.sub.2O 36 6 4 Comp. Ex. 3 A H.sub.2O 80 12 11

Examples 8 to 14

(155) <Synthesis of Ketone by Dehydrogenative Oxidation Reaction of Secondary Alcohol>

(156) Dehydrogenative oxidation reactions of various secondary alcohols were carried out using complex 1 as a catalyst under the reaction conditions shown in Table 3. After the reactions were completed, when the reaction solutions were analyzed by GC it was confirmed that ketones were formed with a high conversion factor and a high yield in all cases.

(157) TABLE-US-00003 TABLE 3 Conv. Example Alcohol Catalyst (mol %) Solvent Time (h) factor (%) Yield (%) Example 8 0 0.5 pentane 5 100 100 Example 9 0.5 pentane 5 100 100 Example 10 1.0 pentane 5 90 90 Example 11 2.0 pentane 20 86 85 Example 12 1.0 hexane 20 100 100 Example 13 1.0 hexane 20 95 94 Example 14 2.0 hexane 20 89 88

Example 15

(158) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol>

(159) A 1000 mL recovery flask was charged with 500 mL of anhydrous p-xylene, 61.06 g (500 mmol) of racemic 1-phenylethanol, and 0.53 mg (0.001 mmol, 0.0002 mol %) of complex 1, and stirring was carried out under reflux conditions for 48 hours. Dichloromethane was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding acetophenone was formed at a yield of 55%. Since a high catalytic turnover number (TON=275,000) was shown in this reaction, the effectiveness of the present invention was shown.

(160) ##STR00037##

Example 16

(161) <Synthesis of Estrone by Dehydrogenative Oxidation Reaction of -Estradiol>

(162) A 50 mL one-neck recovery flask was charged with 3 mL of tert-butyl alcohol, 272.4 mg (1.0 mmol) of -estradiol, and 2.7 mg (0.005 mmol, 0.5 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. The solvent of the reaction solution was removed by distillation, and when analysis by NMR was carried out it was confirmed that the corresponding estrone was formed at a yield of 100%.

(163) ##STR00038##

Example 17

(164) <Synthesis of Benzaldehyde by Dehydrogenative Oxidation Reaction of Benzyl Alcohol>

(165) A 50 mL recovery flask was charged with 10 mL of tert-butyl alcohol, 54.0 mg (0.5 mmol) of benzyl alcohol, and 4.0 mg (0.0075 mmol, 1.5 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. 10 mL of dichloromethane was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding benzaldehyde was formed with a conversion factor of 92% and a yield of 92% as shown in Table 4.

Examples 18 to 20

(166) <Synthesis of Aldehyde by Dehydrogenative Oxidation Reaction of Primary Alcohol>

(167) Reactions were carried out under the same conditions as those of Example 17 except that the various types of primary alcohols (0.5 mmol) shown in Table 4 were used as a substrate. The results of analysis by GC are summarized in Table 4.

Example 21

(168) <Synthesis of 4-(Trifluoromethyl)Benzaldehyde by Dehydrogenative Oxidation Reaction of 4-(Trifluoromethyl)Benzyl Alcohol>

(169) A 50 mL recovery flask was charged with 10 mL of anhydrous heptane, 88.5 mg (0.5 mmol) of 4-(trifluoromethyl)benzyl alcohol, and 7.9 mg (0.015 mmol, 3.0 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. 10 mL of dichloromethane was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding 4-(trifluoromethyl)benzaldehyde was formed with a conversion factor of 89% and a yield of 88% as shown in Table 4.

Example 22

(170) <Synthesis of Cyclohexanecarboxyaldehyde by Dehydrogenative Oxidation Reaction of Cyclohexanemethanol>

(171) A 50 mL recovery flask was charged with 10 mL of anhydrous toluene, 56.2 mg (0.5 mmol) of cyclohexanemethanol, and 6.5 mg (0.012 mmol, 2.5 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. 10 mL of toluene was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding cyclohexanecarboxyaldehyde was formed with a conversion factor of 82% and a yield of 81% as shown in Table 4.

Example 23

(172) <Synthesis of n-Octanal by Dehydrogenative Oxidation Reaction of 1-Octanol>

(173) A 50 mL recovery flask was charged with 10 mL of anhydrous toluene, 65.2 mg (0.5 mmol) of 1-octanol, and 13.2 mg (0.025 mmol, 5.0 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. 10 mL of toluene was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding n-octanal was formed with a conversion factor of 89% and a yield of 87% as shown in Table 4.

(174) TABLE-US-00004 TABLE 4 Conv. Example Alcohol Catalyst (mol %) Solvent factor (%) Yield (%) Example 17 0 1.5 .sup.tBuOH 92 92 Example 18 1.5 .sup.tBuOH 98 97 Example 19 1.5 .sup.tBuOH 90 90 Example 20 1.5 .sup.tBuOH 89 87 Example 21 3.0 heptane 89 88 Example 22 2.5 toluene 82 81 Example 23 5.0 toluene 89 87

Example 24

(175) <Synthesis of Benzaldehyde by Dehydrogenative Oxidation Reaction of Benzyl Alcohol>

(176) A 500 mL recovery flask was charged with 270 mL of anhydrous toluene, 8.648 g (80 mmol) of benzyl alcohol, and 0.85 mg (0.0016 mmol, 0.002 mol %) of complex 1, and stirring was carried out under reflux conditions for 48 hours. Toluene was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding benzaldehyde was formed at a yield of 95%. Since in this reaction a high catalytic turnover number (TON=47,500) was shown, the effectiveness of the present invention was exhibited.

(177) ##STR00047##

Example 25

(178) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol (Under Solvent-Free Conditions)>

(179) A 50 mL two-necked recovery flask was charged with 610.4 mg (5.0 mmol) of racemic 1-phenylethanol and 79.7 mg (0.15 mmol, 3.0 mol %) of complex 1 and stirring was carried out at 60 C. for 20 hours. 100 mL of dichloromethane was added thereto and the mixture was made uniform, and when the reaction solution was then analyzed by GC it was confirmed that the corresponding acetophenone was formed with a conversion factor of 95% and a yield of 93% as shown in Table 5.

Examples 26 to 28

(180) <Synthesis of Aldehyde by Dehydrogenative Oxidation Reaction of Alcohol (Under Solvent-Free Conditions)>

(181) Reactions were carried out under the same conditions as those of Example 25 except that the various types of alcohols (5.0 mmol) shown in Table 5 were used as a substrate and the reaction temperature was 90 C. The results of analysis by GC are summarized in Table 5.

Comparative Example 4

(182) <Synthesis of Acetophenone by Dehydrogenative Oxidation Reaction of Racemic 1-Phenylethanol (Under Solvent-Free Conditions)>

(183) A reaction was carried out under the same conditions as those of Example 25 except that complex A (0.15 mmol) was used as a catalyst. From the result of analysis by GC, as shown in Table 5 the conversion factor was 93%, but the yield of acetophenone was 5%. Since, compared with example 25, the yield was clearly low, the effectiveness of the present invention was exhibited.

(184) TABLE-US-00005 TABLE 5 Example and Conv. Comparative Example Alcohol Catalyst Temp.( C.) factor (%) Yield (%) Example 25 1 60 95 93 Example 26 0 1 90 91 89 Example 27 1 90 83 81 Example 28 1 90 41 35 Comp. Ex. 4 A 60 93 5

Example 29

(185) <Synthesis of Acetic Acid Via Dehydrogenative Oxidation Reaction of Ethanol>

(186) A 10 mL test tube was charged with 460.7 mg (10 mmol) of ethanol, 360.4 mg (20 mmol) of water, and 159.7 mg (0.3 mmol, 3.0 mol %) of complex 1, and stirring was carried out under reflux conditions for 20 hours. When the reaction solution was analyzed by NMR, it was confirmed that acetic acid was formed at a yield of 75%. When the gas that was generated was analyzed, it was confirmed that hydrogen was formed at a yield of 84%. Since ethanol, which is obtained by fermentation from a biomass resource, was used as the starting material, and acetic acid, which is important in organic industrial chemistry, and hydrogen, which is useful as clean energy, could be obtained at the same time, the effectiveness of the present invention was exhibited.

(187) ##STR00054##

Example 30

(188) <Production of Hydrogen by Dehydrogenative Oxidation Reaction of 2-Propanol>

(189) A 10 mL test tube was charged with 901.6 mg (15 mmol) of 2-propanol and 159.5 mg (0.3 mmol, 2.0 mol %) of complex 1, and stirring was carried out under reflux conditions for 4 hours. When the reaction solution was analyzed by GC, it was confirmed that acetone was formed at a yield of 98%. When the gas that was generated was analyzed, it was confirmed that hydrogen was formed at a yield of 91%.

(190) ##STR00055##

Example 31

(191) <Hydrogenation of Acetone>

(192) Under an inert gas atmosphere, a 30 mL two-necked recovery flask was charged with 79.6 mg (0.15 mmol, 0.5 mol %) of complex 1, flushed with hydrogen, then charged with 1.7418 g (30.0 mmol) of acetone, equipped with a balloon filled with hydrogen, and stirred at 40 C. for 4 hours. When the reaction solution was analyzed by GC, it was confirmed that 2-propanol was formed at a yield of 95%.

(193) ##STR00056##

Example 32

(194) <Production of Hydrogen by Dehydrogenative Oxidation Reaction of Methanol>

(195) A 10 mL test tube was charged with 320.4 mg (10 mmol) of methanol, 180.2 mg (10 mmol) of water, and 159.5 mg (0.3 mmol, 3.0 mol %) of complex 1, an aqueous solution of sodium hydroxide was added until the pH, by pH meter, exceeded 13, and stirring was carried out under reflux conditions for 20 hours. When the gas that was generated was analyzed, it was confirmed that hydrogen was formed at a yield of 99%.

(196) ##STR00057##

Example 33

(197) <Production of Hydrogen by Dehydrogenative Oxidation Reaction of Formic Acid>

(198) A 10 mL test tube was charged with 460.6 mg (10 mmol) of formic acid and 2.6 mg (0.005 mmol, 0.05 mol %) of complex 1, and stirring was carried out at 60 C. for 21 minutes. When the gas that was generated was analyzed, it was confirmed that hydrogen was formed at a yield of 94%. Since formic acid could be decomposed with a small amount of catalyst in a short period of time to thus produce hydrogen, the effectiveness of the present invention was exhibited.

(199) ##STR00058##

Production Example 7

(200) <Synthesis of Anionic Iridium Complex Having Functional Bipyridonate Ligand>

(201) A flask was charged with neutral iridium complex 1 (1.0630 g, 2.0 mmol), a 1.0 M aqueous solution of sodium hydroxide (3.0 mL, 3.0 mmol) was added thereto, a reaction was carried out at room temperature, and a dark green uniform solution was obtained. The solution was subsequently transferred to a micro tube and crystallized by allowing it to stand while open to the air, thus giving the novel anionic complex 3 having sodium ion as the counterion at a yield of 72% (796.5 mg, 1.4 mmol).

(202) .sup.1H NMR (500 MHz, D.sub.2O) 7.46 (t, J=8.0 Hz, 2H), 7.03 (d, J=6.5 Hz, 2H), 6.42 (d, J=7.5 Hz, 2H), 1.49 (s, 15H). .sup.13C{.sup.1H} NMR (125.8 MHz, D.sub.2O) 170.6, 156.9, 139.3, 116.8, 107.4, 85.6, 9.39. Anal. Calcd for C.sub.20H.sub.22O.sub.3N.sub.2NaIr.H.sub.2O: C, 42.02; H, 4.23; N, 4.90. Found: C, 42.07; H, 4.64; N, 4.93.

(203) ##STR00059##

(204) Catalytic reactions using complex 3, dicationic complex A, and neutral iridium complex 1 as catalysts were examined, as follows.

(205) ##STR00060##

Example 34

(206) <Reaction Involving Generation of Hydrogen from Mixture of Methanol and Water>

(207) Dehydrogenation reactions from a mixture of methanol and water were carried out using complexes A, 1, and 3 described above as catalysts. The reactions were carried out using methanol and water as starting materials in the presence of catalyst while heating and refluxing, and the gas that was generated was collected in a gas burette and quantitatively measured. Of the volume of gas, 75% was considered to be hydrogen, and the volume and yield of hydrogen were calculated and are listed in the table. First, equal parts of methanol (20 mmol) and water (20 mmol) were used as starting materials, they were heated and refluxed in the presence of catalyst A, 1, and 3 (0.5 mol %) for 20 hours, and the activities of the catalysts were compared (entries 1-3). The reaction hardly progressed when catalyst A, which is dicationic, or catalyst 1, which is neutral, was used, and it was observed that only a very small amount of hydrogen was generated (entries 1 and 2), but the reaction progressed with the use of catalyst 3, which is anionic, and 120 mL (yield 8%) of hydrogen could be obtained (entry 3). Second, the number of equivalents of water relative to methanol was changed (entries 3-5), and when four equivalents of water were used a maximum amount of hydrogen was generated (150 mL, yield 10%, entry 4). Subsequently, since in this catalyst system carbon dioxide is generated accompanying the progress of the reaction, the system gradually becomes acidic, it can be expected that the catalyst molecule will be converted from anionic complex 3 to neutral complex 1 and further to dicationic complex A, and in order to prevent this the addition of a base (sodium hydroxide) as an additive was investigated (entries 6-9). This greatly improved the yield of hydrogen; the optimum conditions were obtained when 0.5 mol % of sodium hydroxide was added, and 1223 mL (yield 84%) of hydrogen was obtained (entry 7).

(208) TABLE-US-00006 TABLE 6 Volume of hydrogen Yield of H.sub.2O Additive generated hydrogen entry Catalyst (equiv.) (mol %) (mL) (%) 1 A 1.0 none 4 >1 2 1 1.0 none 11 >1 3 3 1.0 none 120 8 4 3 4.0 none 150 10 5 3 7.0 none 68 5 6 3 4.0 NaOH (0.3) 848 58 7 3 4.0 NaOH (0.5) 1223 84 8 3 4.0 NaOH (0.75) 1204 83 9 3 4.0 NaOH (1.0) 1170 80

Example 35

(209) <Method for Generating Hydrogen from Methanol and Water (Consecutive Addition Method)>

(210) ##STR00062##

(211) The construction of a catalyst system for continuously generating hydrogen from mixture of methanol and water was examined.

(212) First, catalyst 3 (0.1 mol %) and sodium hydroxide (0.5 mol %) were added to a mixture of methanol (20 mmol) and water (80 mmol). At this point, the pH of the system was 11.2. When a reaction of this mixture was carried out under reflux conditions for 20 hours, 607.5 mL (yield 41%) of hydrogen was generated. Here, amounts of methanol (8.2 mmol) and water (8.2 mmol) corresponding to those consumed were added to the reaction system, sodium hydroxide (0.5 mol %) was again added to thus adjust the pH of the system to 11.3, and a reaction was then carried out under reflux conditions for 20 hours, and 611.3 mL (yield 41%) of hydrogen was generated. By repeating the same procedure, 562.5 mL (yield 38%) of hydrogen could be obtained.

(213) By such a continuous method for generating hydrogen, a total of 1781.3 mL (71.5 mmol) of hydrogen could be obtained, and a catalytic turnover number of 1191 was achieved. In accordance with a procedure of continuously adding starting materials (mixture of methanol and water) that are safe and easy to handle and sodium hydroxide to the catalyst and heating, a new system that can continuously generate hydrogen gas can be developed.

Example 36

(214) <Method for Generating Hydrogen from Methanol and Water (Continuous Addition Method No. 1)>

(215) ##STR00063##

(216) In order to replenish the amounts of methanol and water that had been consumed accompanying catalytic generation of hydrogen, an experiment involving addition at a constant rate using a syringe pump was carried out.

(217) First, catalyst 3 (0.1 mol %) and sodium hydroxide (0.5 mol %) were added to a mixture of methanol (20 mmol) and water (80 mmol). At this point, the pH of the system was 11.2. Refluxing of the reaction system was started by heating, and a premixed solution [methanol (0.6 mmol/h), water (0.6 mmol/h), sodium hydroxide (0.001 mmol/h)] was added using a syringe pump. The generation of gas at a substantially constant rate was observed by continuing refluxing; after 50 hours 2385 mL of hydrogen (99.61 mmol) could be obtained, and a catalytic turnover number of 1660 was achieved.

(218) In accordance with such a continuous reaction by replenishing consumed starting materials (methanol and water) and sodium hydroxide at amounts corresponding to the consumption rates, hydrogen gas can be generated continuously at a substantially constant rate over a long period of time (50 hours).

Example 37

(219) <Method for Generating Hydrogen from Methanol and Water (Continuous Addition Method No. 2)>

(220) ##STR00064##

(221) In order to replenish the amounts of methanol and water that had been consumed accompanying catalytic generation of hydrogen, an experiment involving addition at a constant rate using a syringe pump was similarly carried out for an extended period of 150 hours.

(222) First, catalyst 3 (0.1 mol %) and sodium hydroxide (0.5 mol %) were added to a mixture of methanol (20 mmol) and water (80 mmol). At this point, the pH of the system was 11.2. Refluxing of the reaction system was started by heating, and a premixed solution [methanol (0.6 mmol/h), water (0.6 mmol/h), sodium hydroxide (0.001 mmol/h)] was added using a syringe pump. The generation of gas at a substantially constant rate was observed by continuing refluxing; after 150 hours 4946 mL of hydrogen (210.2 mmol) could be obtained, and a catalytic turnover number of 3502 was achieved.

(223) In accordance with such a continuous reaction by replenishing the consumed starting materials (methanol and water) and sodium hydroxide at amounts corresponding to the consumption rates, hydrogen gas can be generated continuously at a substantially constant rate over a long period of time (150 hours).

Example 38

(224) <Dehydrogenative Synthesis Reaction for Carboxylic Acid from Lower Alcohol and Water as Starting Materials>

(225) A catalytic reaction for obtaining hydrogen at the same time as obtaining, using a mixture of a lower alcohol (ethanol, 1-propanol, 1-butanol) and water as starting materials, a carboxylic acid having the corresponding number of carbons was examined. First, anionic catalyst 3 (3.0 mol %) and sodium hydroxide (3.0 mol %) were added to a mixture of ethanol (10 mmol) and water (20 mmol), and when a reaction was carried out under reflux conditions for 20 hours acetic acid was formed at a yield of 85%, and 445 mL (yield 92%) of hydrogen was also obtained (entry 1). When a similar reaction using a mixture of 1-propanol and water as starting materials was carried out over 40 hours, propionic acid was obtained at a yield of 68%, and 411 mL (yield 85%) of hydrogen was also generated. In this reaction, a small amount (18%) of an ester product (propyl propionate) was also observed (entry 2). Furthermore, when a reaction using a mixture of 1-butanol and water as starting materials was carried out, a similar carboxylic acid formation reaction progressed, and butyric acid could be obtained accompanied by the generation of hydrogen (entries 3 and 4).

(226) TABLE-US-00007 TABLE 7 Volume of Yield of hydrogen Yield of carboxylic Time generated hydrogen acid entry Alcohol (h) (mL) (%) (%) 1 Ethanol 20 445 92 85 2 1-Propanol 40 411 85 68.sup.a 3 1-Butanol 20 411 85 60.sup.b 4 1-Butanol 40 422 87 70.sup.c .sup.aEster (propyl propionate) also formed at a yield of 18%. .sup.bEster (butyl butyrate) also formed at a yield of 30%. .sup.cEster (butyl butyrate) also formed at a yield of 22%.