EPOXYDATION CATALYST SYSTEMS AND PROCESS FOR PREPARING EPOXIDES

Abstract

The invention relates to a first epoxydation catalyst system comprising a mixture of a metal salt of the metals chromium, manganese, molybdenum, lead and/or bismuth and a hydroxide as well as of a redox-active compound. The invention also relates to an additional second epoxydation catalyst system comprising a mixture of an additional metal salt, iodine and a hydroxide. Furthermore, the invention relates to a process for preparing epoxides comprising the oxidative reaction of an alkene in a reactor in the presence of the first epoxydation catalyst system or the second epoxydation catalyst system.

Claims

1. An epoxidation catalyst system comprising: a) a mixture or a reaction product of: a-1) a metal salt of the metals chromium (Cr), manganese (Mn), molybdenum (Mo), lead (Pb) and/or bismuth (Bi); and a-2) a hydroxide; and b) a redox-active compound.

2. The epoxidation catalyst system as claimed in claim 1, wherein the metal salt is one or more compounds and comprises MoCl.sub.5, MoOCl.sub.3, MnCl.sub.2, K.sub.2MnCl.sub.6, CrOCl.sub.2, PbCl.sub.4, BiCl.sub.3, or a combination thereof.

3. The epoxidation catalyst system as claimed in claim 1, wherein the hydroxide is one or more compound(s) and comprises (trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylphosphonium hydroxide, choline hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium hydroxide, or a combination thereof.

4. The epoxidation catalyst system (1) as claimed in claim 1, wherein the redox-active compound is one or more compound(s) and comprises CuCl.sub.2, Cu(BF.sub.4).sub.2, CuCl, VCl.sub.3, VOCl.sub.3, NH.sub.4VO.sub.3, 1,4-benzoquinone, 1,4-naphthoquinone, Se.sub.2O.sub.5, TeO.sub.2, TeO.sub.2, Sb.sub.2O.sub.3, Sb.sub.2O.sub.5, CeCl.sub.3, Co(salen), Co(OAc).sub.2, SnSO.sub.4, Fe(acac).sub.3, Mo(acac).sub.3, K.sub.2Cr.sub.2O.sub.7, Mn(OAc).sub.3, Ni(CF.sub.3CO.sub.2H).sub.2, BiCl.sub.3, or a combination thereof.

5. The oxidation catalyst system as claimed in claim 1, wherein the epoxidation catalyst system comprises the reaction product, and the reaction product has a structure of formula (I), (II) and/or (III): TABLE-US-00008 Q R.sub.1R.sub.2R.sub.3R.sub.4).sup.+.sub.n+om[M(A).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p].sup.mno (I) if m < n + o [M(A).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p] (II) if m = n + o [M(A).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p].sup.(mno) [X].sup..sub.n+om (III) if m > n + o wherein Q=nitrogen or phosphorus; R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each independently; (i) a linear or branched alkyl group containing 1 to 22 carbon atoms, optionally substituted by heteroatoms and/or heteroatom-containing substituents; (ii) a cycloaliphatic group containing 3 to 22 carbon atoms with 1 to 3 bridging carbon atoms, optionally substituted by heteroatoms and/or heteroatom-containing substituents; and/or (iii) an aryl group containing 6 to 18 carbon atoms, optionally substituted by 1 to 10 carbon atoms and/or optionally substituted by heteroatoms and/or heteroatom-containing substituents; M(A).sup.m+=Mo.sup.5+, Mn.sup.4+, Cr.sup.4+, Pb.sup.4+, or Bi.sup.5+; Hal=Cl.sup., Br.sup. or I.sup.; S=H.sub.2O, THF (tetrahydrofuran), dioxane, bis(2-methoxyethyl) ether (diglyme), methoxyethanol, a polyethylene glycol, pyridine, lutidine, 2,2-bipyridine, acetonitrile, dimethyl sulfoxide, sulfolane, or thiophene; n+o+p=6; n1; o1; X=OTf.sup., BF4.sup., or Hal.sup..

6. An epoxidation catalyst system comprising: a) a mixture or a reaction product of: c-1) a metal salt, c-2) iodine (I.sub.2), and c-3) a hydroxide; and b) optionally a redox-active compound.

7. The epoxidation catalyst system as claimed in claim 6, wherein the metal salt is one or more compounds and comprises NiCl.sub.2, MnCl.sub.2, PbCl.sub.2, SnCl.sub.2, CrCl.sub.3, VCl.sub.3, MoCl.sub.4, FeCl.sub.2, RuCl.sub.3, or a combination thereof.

8. The epoxidation catalyst system as claimed in claim 6, wherein the hydroxide is one or more compound(s) and comprises 3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylphosphonium hydroxide, choline hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium hydroxide, or a combination thereof.

9. The oxidation catalyst system as claimed in claim 6, wherein the epoxidation catalyst system comprises the reaction product, and the reaction product has a structure of formula (IV), (V) and/or (VI): TABLE-US-00009 (Q R.sub.1R.sub.2R.sub.3R.sub.4).sup.+.sub.ImopI [M(E).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p].sup.mno .Math. q .Math. I.sub.2 (IV) if m < n + o, [M(E).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p] .Math. q .Math. I.sub.2 (V) if m = n + o [M(E).sup.m+(Hal).sub.n(OH).sub.o(S).sub.p].sup.mno .Math. q .Math. I.sub.2 [X].sup..sub.n+om (VI) if m > n + o wherein Q=nitrogen or phosphorus, R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each independently: (i) a linear or branched alkyl group containing 1 to 22 carbon atoms, optionally substituted by heteroatoms and/or heteroatom-containing substituents; (ii) a cycloaliphatic group containing 3 to 22 carbon atoms with 1 to 3 bridging carbon atoms, optionally substituted by heteroatoms and/or heteroatom-containing substituents; and/or (iii) an aryl group containing 6 to 18 carbon atoms, optionally substituted by 1 to 10 carbon atoms and/or optionally substituted by heteroatoms and/or heteroatom-containing substituents; M(E).sup.m+=Ni.sup.2+, Mn.sup.2+, Pb.sup.2+, Sn.sup.2+, Cr.sup.3+, V.sup.3+, Mo.sup.4+, Fe.sup.2+ or Ru.sup.3+; Hal=Cl.sup., Br.sup. or I.sup.; n+o+p=6; S=H.sub.2O, THF (tetrahydrofuran), dioxane, bis(2-methoxyethyl) ether (diglyme), methoxyethanol, a polyethylene glycol, pyridine, lutidine, 2,2-bipyridine, acetonitrile, dimethyl sulfoxide, sulfolane, or thiophene; n1; o1; X=OTf.sup., BF.sub.4.sup., or Hal.sup.; and q1.

10. A process for producing an epoxide, comprising oxidatively converting an alkene in a reactor in the presence of the epoxidation catalyst system as claimed in claim 1.

11. The process as claimed in claim 10, wherein the oxidative conversion in the reactor is effected in the presence of oxygen or an oxygen-containing gas mixture.

12. The process as claimed in claim 10, wherein the alkene is one or more compound(s) and comprises ethene, propene, butene, 1-octene, butadiene, butane-1,4-diol diallyl ether, allyl chloride, allyl alcohol, styrene, cyclopentene, cyclohexene, phenyl allyl ether, diallyl ether, n-butyl allyl ether, tert-butyl allyl ether, bisphenol A diallyl ether, resorcinol diallyl ether, triphenylolmethane triallyl ether, cyclohexane-1,2-dicarboxylic acid bis(allyl ester), isocyanuric acid tris(prop-2,3-ene) ester, or a mixture thereof.

13. The process as claimed in claim 10, wherein the preparation is effected in the presence of a solvent.

14. The process as claimed in claim 10, wherein the preparation is effected in the absence of a solvent.

15. The process as claimed in claim 10, wherein the alkene and the oxygen-containing gas mixture are metered into the reactor continuously or stepwise.

16. A process for producing an epoxide, comprising oxidatively converting an alkene in a reactor in the presence of the epoxidation catalyst system as claimed in claim 6.

17. The process as claimed in claim 16, wherein the oxidative conversion in the reactor is effected in the presence of oxygen or an oxygen-containing gas mixture.

18. The process as claimed in claim 16, wherein the alkene is one or more compound(s) and comprises ethene, propene, butene, 1-octene, butadiene, butane-1,4-diol diallyl ether, allyl chloride, allyl alcohol, styrene, cyclopentene, cyclohexene, phenyl allyl ether, diallyl ether, n-butyl allyl ether, tert-butyl allyl ether, bisphenol A diallyl ether, resorcinol diallyl ether, triphenylolmethane triallyl ether, cyclohexane-1,2-dicarboxylic acid bis(allyl ester), isocyanuric acid tris(prop-2,3-ene) ester, or a mixture thereof.

19. The process as claimed in claim 16, wherein the preparation is effected in the presence of a solvent.

20. The process as claimed in claim 16, wherein the preparation is effected in the absence of a solvent.

Description

EXAMPLES

Starting Materials Used:

[0177] Metal chlorides and metal oxides: All metal salts used are sourced directly from commercial sources and used in the corresponding reactions without further processing as precursors for the active catalysts: [0178] molybdenum(V) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 95%; [0179] manganese(II) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 99%; [0180] chromium(VI) oxychloride from the manufacturer Sigma Aldrich Corporation in a purity of 99%; [0181] lead(II) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 98%; [0182] bismuth(III) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 98%; [0183] copper(II) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 97%; [0184] nickel(II) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 98%; [0185] tin(II) chloride from the manufacturer Sigma Aldrich Corporation in a purity of 98%.

[0186] Molybdenum(VI) oxychloride was produced in accordance with Vitzthumecker et al. in Monatsh. Chem. 148, 629-633 (2017).

[0187] Elemental iodine, Triton B and all solvents used were likewise introduced into the reaction without further processing: [0188] iodine from the manufacturer Sigma Aldrich Corporation in a purity of 99.8%; [0189] tetrahydrofuran (THF) from the manufacturer Sigma Aldrich Corporation in a purity of 99.9% (inhibitor-free); [0190] benzyltrimethylammonium hydroxide (Triton B) from the manufacturer Sigma Aldrich Corporation as a 40% solution in methanol.

[0191] Propylene was sourced from the manufacturer Sigma Aldrich Corporation in a purity of 99.9% and used as obtainable.

[0192] The chemicals are used for the synthesis without further purification.

Gas Chromatography Analysis

[0193] The gas chromatography analysis (GC for short) of liquid and gas samples was performed in accordance with Determine Impurities in High-Purity Propylene Oxide with Agilent J&W PoraBOND U by Dianli Ma, Ningbo ZRCC Lyondell Chemical Co., Ltd Zhejiang, China, and Yun Zou, Hua Wu, Agilent Technologies, Inc. On the basis of GC, conversions of propene, yields of propylene oxides and selectivities were ascertained.

Simulation Method

[0194] All quantum mechanical calculations were carried out using the software package TURBOMOLE version 7.4.1 from Cosmologic GmbH & Co. KG. The density functional theory method used was the TPSS density functional, implemented as unrestricted DFT for spin contamination of open-shell systems, with a def2-SVP basis set, as implemented as standard in the Turbomole software package. The energies obtained were refined by the DFT method described and with a basis set of def2-TZVP quality.

[0195] Transition states were calculated by gradient-based Monte Carlo, as described in application WO 2020/079094A2.

Production of the Epoxidation Catalyst System (1)

[0196] The epoxidation catalyst systems listed in tables 1 and 2 were produced and used as described in the general test methods.

General Procedure for the In Situ Synthesis of the Epoxidation Catalyst System (1)

[0197] A reaction vessel with stirrer apparatus and protective gas sparging was initially charged with 200 ml tetrahydrofuran under inert conditions. Added to the solvent in each experiment were 0.020 mol of the metal (oxy)chloride of the appropriate oxidation state (see table 1, 1-5) and 0.020 mol of CuCl.sub.2 as redox-active compound (C) under an opposing protective gas flow. While stirring vigorously, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was in each case stirred in until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11.

[0198] The suspension thus produced was used without further purification for the oxidation of propene.

TABLE-US-00003 TABLE 1 Overview of the epoxidation catalyst systems (1) used for oxidative conversion of propene Epoxidation catalyst system (1) Reaction Metal salt Hydroxide Redox-active No. product (1) (A) (B) compound (C) 1 [Mo(V)Cl.sub.2(OH).sub.2(THF).sub.2] MoCl.sub.5, Benzyltrimethyl- CuCl.sub.2 Cl MoOCl.sub.3 ammonium hydroxide 2 [Mn(IV)Cl(OH).sub.3(THF).sub.2] MnCl.sub.2, Benzyltrimethyl- CuCl.sub.2 K.sub.2MnCl.sub.6 ammonium hydroxide 3 [Cr(VI)Cl.sub.2(OH).sub.2(THF).sub.2] CrOCl.sub.2 Benzyltrimethyl- CuCl.sub.2 Cl.sub.2 ammonium hydroxide 4 [Pb(IV)Cl.sub.2(OH).sub.2(THF).sub.2] PbCl.sub.4 Benzyltrimethyl- CuCl.sub.2 ammonium hydroxide 5 [Bi(V)Cl.sub.2(OH).sub.3THF] BiCl.sub.3 Benzyltrimethyl- CuCl.sub.2 ammonium hydroxide 6 (comp.) Cu(II)(OH).sub.2 CuCl.sub.2 Benzyltrimethyl- CuCl.sub.2 ammonium hydroxide 7 (comp.) [Ti(IV)Cl.sub.2(OH).sub.2(THF).sub.2] TiCl.sub.4 Benzyltrimethyl- CuCl.sub.2 ammonium hydroxide (comp.) comparative example

[0199] Production of the Epoxidation Catalyst System (2)

General Procedure for the In Situ Synthesis of the Epoxidation Catalyst System (2)

[0200] A reaction vessel with stirrer apparatus and protective gas sparging was initially charged with a mixture of 180 ml tetrahydrofuran and 20 nil of water under inert conditions. Added to the solvent mixture were 0.020 mol of the metal (oxy)chloride of the appropriate oxidation state (see table 2, 9-12) and 0.040 mol (5.1 g) of elemental iodine under an opposing protective gas flow. While stirring vigorously, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was stirred in until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11.

[0201] The suspension thus produced was used without further purification for the oxidation of propene.

TABLE-US-00004 TABLE 2 Overview of the epoxidation catalyst systems (2) used for oxidative conversion of propene Epoxidation catalyst system (2) Metal Iodine Hydroxide No. Reaction product (2) salt (E) (I.sub.2) (F) 8 (comp.) Q(1)[Pt(II)Cl.sub.2(OH)(THF).sub.3] PtCl.sub.2 I.sub.2 Benzyltrimethyl- I.sub.2 ammonium hydroxide 9 Q(1)[Ni(II)Cl.sub.2(OH)(THF).sub.3] NiCl.sub.2 I.sub.2 Benzyltrimethyl- I.sub.2 ammonium hydroxide 10 Q(1)[Mn(II)Cl.sub.2(OH)(THF).sub.3] MnCl.sub.2 I.sub.2 Benzyltrimethyl- I.sub.2 ammonium hydroxide 11 Q(1)[Pb(II)Cl.sub.2(OH)(THF).sub.3] PbCl.sub.2 I.sub.2 Benzyltrimethyl- I.sub.2 ammonium hydroxide 12 Q(1)[Sn(II)Cl.sub.2(OH)(THF).sub.3] SnCl.sub.2 I.sub.2 Benzyltrimethyl- I.sub.2 ammonium hydroxide (comp.) comparative example; Q(1) = benzyltrimethylammonium with Q = N; R.sub.1 = benzyl, R.sub.2 = R.sub.3 = R.sub.4 = methyl

Simulation Results for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (1)

[0202] The activation energies for the catalytic reactions were calculated hereinafter by quantum-chemical simulations. For this purpose, a structure was drawn in each case according to the transition states A T1-B T2 (FIG. 1). The bonds drawn in bold were set at an atomic distance of in each case 1.90 (190 pm), and in the case of A T2 to 1.30 , and the structures thus obtained were converted to Cartesian coordinates. The atomic indices in the set of Cartesian coordinates of the bonds shown in bold in FIG. 3 were set as function space in the gradient-based Monte Carlo program, and the Monte Carlo procedure was executed until the corresponding transition states A T1-B T2 were obtained. Thereafter, the Cartesian coordinates of structures A T1-B T2 that were obtained in this way were manipulated in order to obtain the corresponding reactant catalyst complexes or the corresponding catalyst product complexes. For this purpose, one of the bonds drawn in bold in each case (FIG. 3) was i) extended and ii) shortened by X=0.20 (20 pm). The structures i) and ii) thus obtained were expressed in the form of Cartesian coordinates and subjected to optimization of geometry by the DFT method described, and the resultant geometries were used for the calculation of the activation energies. The bonds selected in each case are compiled in table 3.

TABLE-US-00005 TABLE 3 Selection of bonds for manipulation to obtain the equilibrium structures Manipulated bond (marked in bold Transition state in FIG. 3, X = 0.20 ) A T1 carbon-oxygen A T2 alcoholic oxygen-hydrogen A T3 carbon-oxygen B T1 carbon-oxygen B T2 carbon-iodine

[0203] FIG. 1: Three-stage reaction mechanism of the oxidative hydroxylation of propene with hydroxide under metal catalysis

##STR00001##

[0204] The three-stage mechanism described in FIG. 1 was calculated by quantum chemical simulation for various catalysts, and the activation energies from the respective reaction sequence were determined. The estimate of the activation energies thus obtained was used for assessment of various metal compounds as potential catalysts for oxidative hydroxylation. The results of the simulations are summarized in table 4.

TABLE-US-00006 TABLE 4 Comparison of the quantum-chemically simulated activation energies for the oxidative conversion of propene with various epoxidation catalyst systems (1). Epoxidation catalyst system (1) .sup.a E.sub.rel A T1 E.sub.rel A T2 E.sub.rel A T3 E.sub.a, es Example (Table 1, No.) [kcal/mol] [kcal/mol] [kcal/mol] [kcal/mol] 13 Q(1)[Ni(II)Cl(OH).sub.2(THF).sub.3] 24.1 34.5 too high (comp.) 14 [Cu(II)(OH).sub.2 (6) 17.7 49.0 too high (comp.) 15 Q(1)[Pt(II)Cl(OH).sub.2(THF).sub.2].sup. 45.9 too high (comp.) 16 Q(1)[Ni(0)(OH) (THF).sub.2] 35.2 15.5 too high (comp.) 17 Q(1)[Co(II)Cl(OH).sub.2(THF).sub.2].sup. 27.2 too high (comp.) 18 Q(1)[Mn(II)Cl(OH).sub.2(THF).sub.2] 20.2 28.0 too high (comp.) 19 [Mn(IV)Cl(OH).sub.3(THF).sub.2] (2) 2.1 5.4 15.8 28.0 20 [Nb(V)Cl(OH).sub.2(THF).sub.2]Cl.sub.2 19.9 28.9 60.6 (comp.) 21 [Cr(VI)Cl.sub.2(OH).sub.2(THF).sub.2]Cl.sub.2 Nc 24.6 10.0 24.6 (3) 22 [Bi(V)C.sub.1l.sub.2(OH).sub.3 THF] (5) 3.0 nc 13.6 (13.6) 23 [Sn(IV)Cl.sub.2(OH).sub.2(THF).sub.2] 10.3 1.7 41.9 too high (comp.) 24 [Pb(IV)Cl.sub.2(OH).sub.2(THF).sub.2] (4) 4.2 15.1 5.0 24.9 25 [Sb(V)Cl.sub.2(OH).sub.2(THF).sub.2]Cl 1.6 18.0 19.9 31.7 (comp.) 26 [As(V)Cl.sub.2(OH).sub.2(THF).sub.2]Cl 38.3 too high (comp.) 27 [Mo(V)Cl.sub.2(OH).sub.2(THF).sub.2]Cl 14.1 19.6 20.1 20.1 (1) 28 [V(V)Cl.sub.2(OH).sub.2(THF).sub.2]Cl deoxygenation (comp.) 29 [Ti(IV)Cl.sub.2(OH).sub.2(THF).sub.2] (7) deoxygenation (comp.) (comp.) comparative example; Q(1) = benzyltrimethylammonium with Q = N; R.sub.1 = benzyl, R.sub.2 = R.sub.3 = R.sub.4 = methyl .sup.a Assuming that the THF ligand is at least partly displaced by propene from the complex epoxidation catalyst systems (1) before the oxidative conversion.

[0205] The results compiled in table 4 show that, in particular, the activation energies of the hydroxylation of propene and the reductive elimination of the propylene oxide formed depend significantly on the particular metal that functions as catalyst. This limits the possible selection of the metal compounds examined as catalysts for the oxidative hydroxylation to particular metals. Suitable metals are, in particular, Mo(V), Mn(IV), Cr(VI), Bi(V) and Pb(IV).

Simulation Results for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (2)

[0206] In a further execution B of the process, the epoxidation catalyst system (2) consisting of the metal salt (E), elemental iodine and the hydroxide (F) is used. This mixture (2) is laden with propene, firstly with addition of the hydroxide onto the double bond of propene. In a second step, iodine is then inserted into the metal-carbon bond, releasing an iodohydrin. This breaks down in the slightly basic medium to give propylene oxide and iodide, which is oxidized back to elemental iodine by supply of oxygen. The metal catalyst ensures controlled addition of hydroxide and iodide to give intermediate iodohydrin, without formation of predominantly unusable 1,2-diiodoalkanes. Compared to the known chlorine hydroxylation, iodine can be used here in catalytic or substoichiometric amounts. Thus, oxidation can be effected directly with oxygen.

[0207] For this purpose, quantum-chemical simulations were conducted in order to identify suitable metal catalysts.

TABLE-US-00007 TABLE 5 Comparison of the quantum-chemically simulated activation energies for the iodine hydroxylation of propene with various metal catalysts Epoxidation catalyst system (2).sup.a) E.sub.rel B T1 E.sub.rel B T2 E.sub.a, es Example (Table 1, No.) [kcal/mol] [kcal/mol] [kcal/mol] 30 (comp.) Q(1)[Pt(II)Cl.sub.2(OH)(THF)] I.sub.2 (8) 40.0 too high 31 Q(1)[Ni(II)Cl.sub.2(OH)(THF)] I.sub.2 (9) 0.0 18.1 25.5 32 Q(1)[Mn(II)Cl.sub.2(OH)(THF)] I.sub.2 0.0 7.7 7.7 (10) 33 Q(1)[Pb(II)Cl.sub.2(OH)(THF)] I.sub.2 (11) 0.0 17.9 17.9 34 Q(1)[Sn(II)Cl.sub.2(OH)(THF)] I.sub.2 (12) 0.0 14.1 14.1 (comp.) comparative example; Q(1) = benzyltrimethylammonium with Q = N; R.sub.1 = benzyl, R.sub.2 = R.sub.3 = R.sub.4 = methyl; .sup.a)Assuming that the THF ligand is at least partly displaced by propene and iodine from the complex epoxidation catalyst systems (1) before the oxidative conversion.

[0208] The simulation results compiled in table 5 show that the activation energy of

iodine insertion depends significantly on the metal catalysts used. Especially Mn(II), Sn(II) and Pb(II), but also Ni(II), are thereby identified as being suitable as catalysts for the reaction.

[0209] FIG. 2: Two-stage reaction mechanism for the metal-catalyzed iodine hydroxylation of propene

##STR00002##

[0210] FIG. 3: Input geometries for the quantum-chemical calculations of the transition states of the catalyzed oxidative hydroxylations A and iodine hydroxylations B.

##STR00003##

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (1) in a Batchwise Stirred Tank

[0211] A pressure-resistant 1 l reactor with stirrer system, pressure relief valve, pressure sensor, riser tube for removal of liquid, and sparging and degassing conduits was initially charged with 200 ml of tetrahydrofuran under inert conditions. Added to the solvent in each experiment were 0.020 mol of the metal chloride of the appropriate oxidation state (see table 1, 1-5) and 0.020 mol of CuCl2 under an opposing protective gas flow. While stirring vigorously, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was in each case stirred in until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. 0.400 mol of propene was then injected into the reaction vessel (about 11 bar). The internal reactor temperature was kept at 120 C. by closed-loop control, and oxygen was slowly injected until a molar amount of 0.200 mol of oxygen was attained. The addition of the oxygen was carried out such that the additional pressure rise was never more than 2 bar. The progress and endpoint of the reaction were ascertained from the pressure profile and/or by withdrawal of liquid and gas samples and analysis by GC analyzed. After the reaction had ended, the reactor was cooled down to 40 C., then expanded, and the propylene oxide reaction product was distilled off into a cooled receiver via the degassing conduit.

[0212] The yield of propylene oxide was 23.2 g for all five experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (2) in a Batchwise Stirred Tank

[0213] A pressure-resistant 11 reactor with stirrer system, pressure relief valve, pressure sensor, riser tube for removal of liquid, and sparging and degassing conduits was initially charged with a mixture of 180 ml of tetrahydrofuran and 20 ml of water under inert conditions. Added to the solvent mixture were 0.020 mol of the metal chloride of the appropriate oxidation state (see table 2, 9-12) and 0.040 mol (5.1 g) of elemental iodine under an opposing protective gas flow. While stirring vigorously, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was stirred in until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. 0.400 mol of propene was then injected into the reaction vessel (about 11 bar). The internal reactor temperature was kept at 120 C. by closed-loop control, and oxygen was slowly injected until a molar amount of 0.200 mol of oxygen was attained. The addition of the oxygen was carried out such that the additional pressure rise was never more than 2 bar. The progress and endpoint of the reaction were ascertained from the pressure profile and/or by withdrawal of liquid and gas samples and analysis by GC analyzed. After the reaction had ended, the reactor was cooled down to 40 C., then expanded, and the propylene oxide reaction product was distilled off into a cooled receiver via the degassing conduit.

[0214] The yield of propylene oxide was 23.2 g for all four experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (1) in a Continuous One-Bubble Column Reactor

[0215] A pressure-resistant bubble column (diameter 15 cm) with sparging frit, pressure relief valve, pressure sensor, upper and lower liquid withdrawal ports, upper addition point for solids, and inlets and outlets for gases was initially charged with 3500 ml of tetrahydrofuran under inert conditions. Added to the solvent in each experiment were 0.350 mol of the metal chloride of the appropriate oxidation state (see table 1, 1-5) and 0.350 mol of CuCl2 under an opposing protective gas flow. While sparging with N2 at 10 l/min, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was added until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. The bubble column was then brought to reaction temperature, 120 C., and a mixture of propene, oxygen and nitrogen (molar ratio of propene to oxygen 2:1) was introduced, with establishment of a total volume flow rate of less than 10 l/min by closed-loop control. The progress of the reaction and its steady-state point were ascertained by withdrawing liquid and gas samples at the upper withdrawal points and analyzing them by GC. The continuously generated product gas mixture was freed of propylene oxide by cascaded cooling, and the resulting gas stream was slightly compressed again and, in a blend with propene, oxygen and nitrogen, fed to the sparging frit of the bubble column.

[0216] Selectivities for propylene oxide were between 95% and 100% in all five experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (2) in a Continuous One-Bubble Column Reactor

[0217] A pressure-resistant bubble column (diameter 15 cm) with sparging frit, pressure relief valve, pressure sensor, upper and lower liquid withdrawal ports, upper addition point for solids, and inlets and outlets for gases was initially charged with 3150 ml of tetrahydrofuran and 350 ml of water under inert conditions. Added to the solvent mixture in each experiment were 0.350 mol of the metal chloride of the appropriate oxidation state (see table 2, 9-12) and 0.700 mol (89.3 g) of elemental iodine under an opposing protective gas flow. While sparging with N2 at 10 l/min, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was added until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. The bubble column was then brought to reaction temperature, 120 C., and a gas mixture of propene, oxygen and nitrogen (molar ratio of propene to oxygen 2:1) was introduced, with establishment of a total volume flow rate of less than 10 l/min by closed-loop control. The progress of the reaction and its steady-state point were ascertained by withdrawing liquid and gas samples at the upper withdrawal points and analyzing them by GC. The continuously generated product gas mixture was freed of propylene oxide by cascaded cooling, and the resulting gas stream was slightly compressed again and, in a blend with propene, oxygen and nitrogen, fed to the sparging frit of the bubble column.

[0218] Selectivities for propylene oxide were between 95% and 100% in all four experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (1) in a Continuous Two-Bubble Column Reactor

[0219] Two pressure-resistant bubble columns (diameter 15 cm), each equipped with sparging frit, pressure relief valve, pressure sensor, upper and lower liquid withdrawal/addition ports, upper addition point for solids, and inlets and outlets for gases are connected via a pump via the upper and lower liquid withdrawal points. One bubble column was initially charged with 3500 ml of tetrahydrofuran under inert conditions. Added to the solvent in each experiment were 0.350 mol of the metal chloride of the appropriate oxidation state (see table 1, 1-5) and 0.350 mol of CuCl2 under an opposing protective gas flow. While sparging with nitrogen at 10 l/min, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was added until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. The second bubble column was prepared analogously. The bubble columns were then brought to reaction temperature, 120 C. A gas mixture of nitrogen and propene was fed into the first bubble column, and a gas mixture of nitrogen and oxygen was fed into the second bubble column, with establishment of a total volume flow rate of less than 10 l/min by closed-loop control in both cases. The molar ratio of propene to oxygen was 2:1. At the same time, the liquid phase was withdrawn continuously from the first bubble column at the upper point and added to the second bubble column at the lower point, and withdrawn continuously from the second bubble column at the upper point and added to the first bubble column at the lower point. The volume flows were adjusted by closed-loop control such that there was no change in the fill levels of the two bubble columns over the duration of the experiment. The progress of the reaction and its steady-state point were ascertained by withdrawing liquid and gas samples at the upper withdrawal points of the two bubble columns and analyzing them by GC. The continuously generated product gas mixture from the first bubble column was freed of propylene oxide by cascaded cooling, and the resulting gas stream was slightly compressed again and, in a blend with nitrogen and propene, fed to the sparging frit of the bubble column. The gas stream from the second bubble column was freed of propene by cascaded cryogenic cooling, and disposed of via the air output. The propene recovered was reused by addition at the lower sparging point of the first bubble column.

[0220] Selectivities for propylene oxide were between 95% and 100% in all five experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Epoxidation Catalyst System (2) in a Continuous Two-Bubble Column Reactor

[0221] Two pressure-resistant bubble columns (diameter 15 cm), each equipped with sparging frit, pressure relief valve, pressure sensor, upper and lower liquid withdrawal/addition ports, upper addition point for solids, and inlets and outlets for gases are connected via a pump via the upper and lower liquid withdrawal points. One bubble column was initially charged with 3500 ml of tetrahydrofuran under inert conditions. Added to the solvent in each experiment were 0.350 mol of the metal chloride of the appropriate oxidation state (see table 2, 9-12) and 0.700 mol (89.3 g) of elemental iodine under an opposing protective gas flow. While sparging with nitrogen at 10 l/min, N-benzyltrimethylammonium hydroxide (trade name: Triton B) was added until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. The second bubble column was prepared analogously. The bubble columns were then brought to reaction temperature, 120 C. A gas mixture of nitrogen and propene was fed into the first bubble column, and a gas mixture of nitrogen and oxygen was fed into the second bubble column, with establishment of a total volume flow rate of less than 10 l/min by closed-loop control in both cases. The molar ratio of propene to oxygen was 2:1. At the same time, the liquid phase was withdrawn continuously from the first bubble column at the upper point and added to the second bubble column at the lower point, and withdrawn continuously from the second bubble column at the upper point and added to the first bubble column at the lower point. The volume flows were adjusted by closed-loop control such that there was no change in the fill levels of the two bubble columns over the duration of the experiment. The progress of the reaction and its steady-state point were ascertained by withdrawing liquid and gas samples at the upper withdrawal points of the two bubble columns and analyzing them by GC. The continuously generated product gas mixture from the first bubble column was freed of propylene oxide by cascaded cooling, and the resulting gas stream was slightly compressed again and, in a blend with nitrogen and propene, fed to the sparging frit of the bubble column. The gas stream from the second bubble column was freed of propene by cascaded cryogenic cooling, and disposed of via the air output. The propene recovered was reused by addition at the lower sparging point of the first bubble column.

[0222] Selectivities for propylene oxide were between 95% and 100% in all four experiments.

General Experimental Procedure for the Process for Producing Propylene Oxide by Oxidation of Propene in the Presence of the Supported Epoxidation Catalyst System (1) in a Continuous Gas Phase Reactor

[0223] A pressure-resistant 1 l reactor with stirrer system, pressure relief valve, pressure sensor, riser tube for removal of liquid, and sparging and degassing conduits was initially charged with a mixture of 200 ml of tetrahydrofuran under inert conditions. Added to the solvent mixture in each experiment were 0.350 mol of the metal salt (A) of the appropriate oxidation state (see table 1, example 1-5) and 0.350 mol of CuCl2 under an opposing protective gas flow. While stirring vigorously, N-benzyltrimethylammonium hydroxide as hydroxide (F) (trade name: Triton B) was stirred in until a liquid sample taken, in contact with a water-moist pH test strip, gave a pH of 10-11. Subsequently, the mixture obtained was applied to silica as support material. The solids were then introduced into an inertized pressure-resistant and pressure-safeguarded flow reactor. Nitrogen and oxygen were then passed through the flow reactor, which was brought to reaction temperature 180 C. Subsequently, a certain amount of propene was added to the gas flow until a molar ratio of propene to oxygen of 2:1 was attained, and contacted continuously with the solids. The flow conditions and contact time were chosen here such that partial conversions were attained. The continuously produced product gas mixture was in each case freed of propylene oxide by cascaded cooling, and the resulting gas stream was heated again and enriched with oxygen and propene, and the resulting mixture was introduced again into the solids. The gas is analyzed by taking of gas samples and analysis thereof by GC.

[0224] Selectivities for propylene oxide were between 95% and 100% in all five experiments.