HIGHLY REACTIVE METAL HYDRIDES, PROCESS FOR THEIR PREPARATION AND USE

Abstract

The invention relates to powdery, highly reactive alkali and alkaline earth hydride compounds, and to mixtures with elements of the third main group of the periodic table of elements (PTE) and to the preparation thereof by reacting alkali or alkaline earth metals in the presence of finely dispersed metals or compounds of the third main group of the PTE, wherein the latter have one or more hydride ligands or said hydride ligands are converted in situ, under the prevailing reaction conditions, i.e., in the presence of hydrogen gas or another H source, into hydride species, and to the use thereof for the preparation of complex hydrides and organometallic compounds.

Claims

1. Highly reactive mixtures of alkali metal or alkaline earth metal hydrides MH.sub.n*, where n=1 or 2 corresponding to the valence of the metal M, and highly reactive metal M.sup.2* selected from the group consisting of B, Al, Ga, In, and optionally with another metal hydride M.sup.1H.sub.m* with M.sup.1 selected from an alkali metal, an alkaline earth metal or an element from the group of the rare earths, wherein the molar ratio between MH.sub.n*, M.sup.2* and M.sup.1H.sub.m* is 1:0.001 to q/6:0 to p/6, preferably 1:0.01 to q/6:0 to p/6.

2. The mixtures according to claim 1, characterized in that M and M.sup.1 are selected from Li, Na or Mg, and M.sup.2=Al.

3. A method for preparing highly reactive alkali metal or alkaline earth metal hydrides MH.sub.n* where n=1 or 2 corresponding to the valence of the metal M, characterized in that metals M of the first or second periods of the periodic table of elements are reacted with a compound of general formula M.sup.1.sub.x[M.sub.2H.sub.3+x].sub.b under inert conditions or under hydrogen atmosphere according to
M+o/6M.sup.1.sub.x[M.sub.2H.sub.3+x].sub.b>MH.sub.n*+p/6M.sup.1H.sub.m*+q/6 M.sup.2* , wherein M.sup.1=an alkali metal selected from the group consisting of Li, Na, K, Rb, Cs, an alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, Ba; x=0 or 1, M.sup.2=an element of the 3rd main group of the periodic table of elements selected from the group consisting of B, Al, Ga, In; b=the valence of M.sup.1; m=1 or 2, corresponding to the valence of the metal M.sup.1; n=1 or 2, corresponding to the valence of the metal M; and in the case in which x=0, p=0, and for M=alkali element, o and q=2; for M=alkaline earth element, o and q=4 and in the case in which x=1: for M and M.sup.1=alkali metals, o, p, q=2; for M and M.sup.1=alkaline earth metals, o, p=2, and q=4; for M=alkali metal and M.sup.1=alkaline earth metal, o, p=1, and q=2, and for M =alkaline earth metal and M.sup.1=alkali metal, o, p, q=4.

4. A method for preparing highly reactive alkali metal or alkaline metal hydrides MH.sub.n* where n=1or 2 corresponding to the valence of the metal M, characterized in that metals M of the first or second period of the periodic of table of elements are reacted with a compound of general formula M.sup.1.sub.x[M.sup.2(A.sup.1.sub.yA.sup.2.sub.z).sub.3+x].sub.b or in the presence of finely dispersed, highly reactive metal M.sup.2+ with a mean particle size D.sub.50 in the range from 0.01 to 100 m in the presence of hydrogen gas or another source of hydrogen according to ##STR00005## wherein M.sup.1=an alkali metal selected from the group consisting of Li, Na, K, Rb, Cs, an alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, or an element from the group of the rare earths selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; x=0 or 1; n=1 or 2, corresponding to the valence of the metal M; b=the valence of M.sup.1; M.sup.2=an element of the 3rd main group of the periodic table of elements, selected from the group consisting of B, Al, Ga, In; A.sup.1=H or an alkyl group, branched or unbranched, containing 1-18 C atoms, wherein the up to four A groups can be identical or different; A.sup.2=an alkoxy residue OR where R=alkyl with 1-8 C atoms, a dialkylamino residue NR.sub.2 where R=alkyl with 1-8 C atoms or a halogen from Cl, Br, I; y can assume the value 1, 2 or 3, and wherein y+z=3.

5. The method for producing highly reactive metal hydrides MH.sub.n* according to claim 3 or 4, characterized in that the reaction is carried out in an aprotic solvent or solvent mixture, wherein at least one of the solvent components is an open-chain or cyclic ether, a tertiary amine or a hydrocarbon, either in pure form or as any mixtures of at least two of the listed solvents.

6. The method according to claim 5, characterized in that an open-chain or cyclic ether selected from the group consisting of diethyl ether, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, tetrahydropyrane, dioxane, dioxolane; a tertiary amine selected from the group consisting of triethylamine, tributylamine, morpholine, or a hydrocarbon selected from the group consisting of saturated C.sub.4-C.sub.18 hydrocarbons, preferably pentanes, hexanes, heptanes, octanes; aromatic compounds selected from the group consisting of benzene, toluene, ethylbenzene, xylenes, cumene.

7. The method according to claims 3 to 6, characterized in that the reaction temperature is in the range between 20 and 150 C., preferably 0 and 100 C., and particularly preferably between 25 and 70 C.

8. The method according to claim 4, characterized in that one operates under H.sub.2 atmosphere, wherein the H.sub.2 pressure is between 1 and 300 bar, particularly preferably 10-100 bar.

9. The method according to claim 4, characterized in that the compound M.sup.1.sub.x[M.sup.2(A.sup.1.sub.yA.sup.2.sub.z).sub.3+x].sub.b is used in catalytic quantities from 0.001 to 20 mol %, preferably from 0.01 to 10 mol %, with respect to the metal M.

10. The use of the metal hydrides MH.sub.n* according to claim 1 or 2 or obtained according to one of claims 3 to 8 for the reaction with Lewis acids of the 3rd main group of the periodic table of elements or for the hydrometalation of olefins.

11. The use according to claim 10 for the preparation of metal hydridoborates M[HBR.sub.3].sub.n or metal hydridoaluminates M[HAI(OR).sub.3].sub.n with R=unbranched, cyclic or branched alkyl groups containing 1 to 12 C atoms.

12. The use according to claim 10, characterized in that a Lewis acid is selected from the group consisting of tri-sec-butylborane, trisiamylborane, tricyclohexylborane, aluminum trimethylate, aluminum-tri(tert-butylate), aluminum tri(tert-pentylate).

13. The use according to claim 10 for the hydrometalation of an olefin R.sup.1R.sup.3CCR.sup.2R.sup.4 where R.sup.1, R.sup.2 and R.sup.3=H, wherein preferably an a-olefin from the group consisting of 1-propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene is selected.

14. The use according to claim 10 for the hydrometalation of an olefin R.sup.1R.sup.3CCR.sup.2R.sup.4 where R.sup.2 and R.sup.4=alkyl groups containing 1-12 C.

Description

EXAMPLE 1

Preparation of Active Lithium Hydride LiH* from LiAlH.SUB.4 .and Lithium Powder in THF

[0060] In a glass flask rendered inert (i.e., heated and filled with argon), 0.29 g (41.8 mmol) of lithium powder (D.sub.50=approximately 80 m) were suspended in 50 mL of dry tetrahydrofuran. Then, 13.9 mmol LiAlH.sub.4 in the form of an approximately 10% solution in tetrahydrofuran were added by means of a syringe. After a few minutes, the metal had already turned dark; after 20 hours of stirring, a black suspension had formed. The solid formed was isolated using a Schlenk frit under protective gas (argon).

[0061] Yield: 0.61 g

[0062] An X-ray diffractogram showed that the black solid contains the phases LiH and Al.

EXAMPLE 2

Preparation of Active Lithium Hydride LiH* from LiAlH.SUB.4 .and Lithium Powder in Et.SUB.2.O

[0063] In a glass flask rendered inert (i.e., heated and filled with argon), 0.29 g (41.8 mmol) of lithium powder (D.sub.50=approximately 80 m) were suspended in 45 mL of dry diethyl ether. Then, 13.9 mmol of LiAlH.sub.4 in the form of an approximately 12% solution in diethyl ether were added by means of a syringe. After a few minutes, the metal had already turned dark; after 20 hours of stirring, a black suspension had formed. The solvent was removed by condensation under a vacuum. A powdery, pyrophoric residue remained.

[0064] Yield: 0.65 g

[0065] An X-ray diffractogram showed that the black solid consists of the phases LiH and Al.

EXAMPLE 3

Preparation of Active Sodium Hydride NaH* from LiAlH.SUB.4 .and Sodium Powder in THF

[0066] In a glass flask rendered inert (i.e., heated and filled with argon), 0.96 g (42 mmol) of sodium powder were suspended in 43.7 g of dry tetrahydrofuran. Then, 14.5 mmol of LiAlH.sub.4 in the form of an approximately 10% solution in tetrahydrofuran were added by means of a syringe under magnetic stirring. After stirring for approximately 3 hours at RT, the metal turned dark. After a reaction time of 20 hours, the stirrer was turned off, a sample was removed from the upper liquid region, filtered until clear through a membrane syringe filter (0.45 m) and examined for dissolved hydride activity (by gas volumetry). In the case of decomposition in water, the clear filtered sample developed no significant gas volume, i.e., the soluble AlH4 had been converted largely completely to insoluble NaH* and Al.

[0067] The black solid formed was isolated and dried.

[0068] Yield: 1.32 g (87% of the theory)

[0069] Analysis (ICP): Na=27 mmol/g; Al=9.1 mmol/g; Li=9.1 mmol/g X-ray diffractometry:

[0070] Sodium hydride, aluminum metal (main products)

[0071] Sodium metal, Na.sub.2LiAlH.sub.6 (secondary components)

EXAMPLE 4

Preparation of Highly Active LiH* and Addition to B(sec-Bu).SUB.3

[0072] In a glass flask rendered inert (i.e., heated and filled with argon), 0.31 g (44.7 mmol) of lithium powder (D.sub.50=approximately 80 m) were suspended in 20 mL of dry tetrahydrofuran. Then, 13.9 mmol of LiAlH.sub.4 in the form of an approximately 10% solution in tetrahydrofuran were added by means of a syringe. After a few minutes, the metal had already turned dark; after stirring for 20 hours, a black suspension had formed.

[0073] Then, 43.6 g (55.7 mmol) of B(sec-Bu)3 in the form of a 1 M solution in THF were added within 15 minutes (min) at room temperature. A slight temperature increase (approximately 30-35 C.) was observed. At certain times, solution samples were collected, immediately filtered until clear by means of a membrane filter and examined by .sup.11B NMR spectroscopy:

TABLE-US-00002 Reaction time B species content, % 1 hour 5 hours 23 hours Li[HB(sec-Bu).sub.3], doublet 79 85 92 .sup.11B = 5.2 ppm B(sec-Bu).sub.3, 21 15 8 .sup.11B = 85 ppm

EXAMPLE 5

Preparation of Highly Reactive LiH* and Addition to R-13-isopinocampheyl-9-borabicyclo[3.3.1]Nonanes, R-Alpine-Borane

[0074] In a 100-mL ISO threaded bottle rendered inert (i.e., heated and filled with argon) with septum closure, 0.155 g (22.3 mmol) of lithium powder (D.sub.50=approximately 80 m) were suspended in 30 mL of dry tetrahydrofuran. Then, 7.1 mmol of LiAlH.sub.4 in the form of an approximately 10% solution in tetrahydrofuran were added by means of a syringe. Already after a few minutes, the metal had turned dark; after 20 hours of stirring, a black suspension had formed. Then 4.78 g (27 mmol) of R-Alpine-Borane in the form of a 0.5 molar solution in THF were added within 30 min by means of a syringe/syringe pump. Spontaneous heating (in the end approximately 40 C.) was observed. A sample of the reaction mixture was filtered until clear and examined by .sup.11B NMR.

[0075] Alpine-Borane (.sup.11B=85.3 ppm): not detectable, thus completely reacted

[0076] LiH addition product (.sup.11B=5.4 ppm, doublet): approximately 100%

EXAMPLE 6

Preparation of Highly Active LiH* with Catalytic LiAlH4 Quantities

[0077] 0.284 g (40.9 mmol) of lithium powder (D.sub.50=approximately 80 m) were filled into a glass flask which had been rendered inert (i.e., heated and filled with argon). The flask was evacuated twice and aerated with hydrogen gas. Via a hose, a connection to a graduated hydrogen reservoir was established. Then, 24.5 g of dry tetrahydrofuran and 2.20 mmol of LiAlH.sub.4 in the form of a THF solution were added. Slow magnetic stirring was carried out at RT. After approximately 2 h, the lithium powder had turned black, wherein the consumption of hydrogen gas had started. After 20 hours of stirring, 529 mL (20.2 mmol) of hydrogen had been absorbed from the suspension. This consumption corresponds to 99% of the theory.

[0078] The solid formed was isolated using a Schlenk frit.

[0079] Yield: 0.29 g

[0080] An X-ray diffractogram showed that the black pyrophoric solid contains the phases LiH and Al/Li alloy.

EXAMPLE 7

Preparation of Active Aluminum from Triethylaluminum and Lithium Metal

[0081] 0.97 g (140 mmol) of lithium powder (D.sub.50=approximately 80 m) were filled into a glass flask which had been rendered inert (i.e., heated and filled with argon). 20 mL of toluene were added, and subsequently, using the canula technique, 187 mmol of triethylaluminum in the form of a 25% solution in toluene were added within 30 min. Stirring was carried out for 5 hours at room temperature. In the process, a black dispersion formed. The reaction mixture was filtered, and the black filter residue was dried in a vacuum.

[0082] Yield: 0.87 g (69% of the theory, black powder)

[0083] An X-ray diffractometric examination showed that it was Al metal.

[0084] The filtrate was examined by .sup.27Al NMR:

[0085] =155.9 ppm, h.sub.1/2=300 Hz (characteristic for LiAlEt.sub.4)