RU2549897C1 - Catalytic system of ethylene in 1-hexene trimerisation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: catalytic system of ethylene in 1-hexene trimerisation includes a chromium (III) complex with a diphosphoric ligand of the general formula [CrCl₃[(Ph₂P(1,2-C₆H₄)P(Ph)(1,2-C₆H₄)(R)](THF)], where R is a hydrocarbon radical or a heteroatom-containing hydrocarbon group, which is in a phenyl substituent in the ortho-position relative to one of the phosphorus atoms. A source of chromium (III) is represented by tris(tetrahydrofuran)chromium chloride, and an activator, representing a mixture of solutions of trimethylaluminium and partially hydrolysed trimethylaluminium in toluene or methylcyclohexane. The molar ratio of the catalytic system components [Cr] : partially hydrolysed trimethylaluminium : trimethylaluminium constitutes 0.03-1.09%:6.95-31.92%:67.39-92.81%.

EFFECT: obtaining high selectivity by 1-hexene with the simultaneous reduction of the quantity of ethylene polymerisation byproducts in the process of trimerisation.

2 cl, 2 tbl, 19 ex

Description

The invention relates to organic chemistry, and in particular to a technology for the selective production of 1-hexene by ethylene trimerization.

A significant number of technologies for the trimerization of ethylene into 1-hexene are known. US 5856257 A, 11/05/1999, US 6900152 B2, 05/31/2005, US 5811618 A, 09/22/1998, US 7141633 B2, 11/28/2006, US 7361623 B2, 11/28/2006, US 7554001 B2, 06/30/2009. In all these examples, the process is carried out using a catalytic system consisting of a chromium compound, a ligand (or a finished complex of chromium with a ligand), an activator and, if necessary, a coactivator at pressures of 20 to 50 bar and elevated temperatures in the range of 80-105 ° C . In the vast majority of technologies, the catalyst system activator is a commercially available solution of methylaluminoxane (MAO) or a solution of modified methylaluminoxane (MMAO). The structures of MAO and MMAO have not been established, their solutions have a complex set of equilibria between different organoaluminum compounds, however, ¹ H NMR spectroscopy methods allow us to see that residual trimethylaluminium (TMA) is always present in the MAO solution in an amount depending on the method of producing methylaluminoxane [F. Ghiotto, C. Patraki, J. Tanskanen, JR Severn, N. Luehmann, A. Kusmin, J. Stellbrink, M. Linnolahti, M. Bochmann. Probing the Structure of Methylalumoxane (MAO) by a Combined Chemical, Spectroscopic, Neutron Scattering, and Computional Approach. Organomet. 2013, 32, 3354; JN Pedeutour, K. Radhakrishnan, H. Cramail, A. Deffieux. Reactivity of Metallocene Catalysts for Olefin Polymerization: Influence of Activator Nature and Structure. Macromol. Rapid Commun. 2001, 22, 1095]. The uncertainty of the MAO composition, which affects the efficiency of the catalytic system, which consists in the high selectivity of the process for 1-hexene, high productivity and a minimum amount of polymer, as well as the need to use a significant excess of MAO, contribute to the search for a more specific activator composition and properties to improve the technology for producing 1- hexene by trimerization of ethylene.

Closest to the claimed technology is a two-stage activation of a mixture of a compound of chromium and PNP ligands or complexes of chromium with SNS ligands, where the catalytic system is first activated using methylaluminoxane and then trialkylaluminum is added. The trimerization process is characterized by selectivity for 1-octene, and not for 1-hexene, and not a ready-made chromium complex is used, but a mixture of the ligand and the “precursor” (chromium – tris (tetrahydrofuran) chromium (III) trichloride, tris (acetylacetonate) complex chromium (III), chromium (III) 2-ethylhexanoate). The activator in this case is not trimethylaluminum, but MAO, taken in molar excess with respect to chromium compounds of at least 300: 1. US 8367786 B2, 02/05/2013.

An object of the present invention is to develop a catalytic system for the selective trimerization of ethylene into 1-hexene based on chromium diphosphine complexes with high selectivity.

The technical result from the implementation of the present invention is to achieve in the process of trimerization of high selectivity for 1-hexene while reducing the number of by-products of ethylene polymerization less than 0.15%.

The technical result is achieved by the fact that the catalytic system for the trimerization of ethylene into 1-hexene includes a chromium (III) complex with a diphosphine ligand of the general formula [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1, 2-C ₆ H ₄ ) (R)] (THF)], where R is a hydrocarbon radical or a heteroatom containing hydrocarbon group located in the phenyl substituent in the opmo position with respect to one of the phosphorus atoms, where the source of chromium (III) is tris chloride (tetrahydrofuran) chromium, and an activator, which is a mixture of a solution of trimethylaluminum and partially hydrolyzed trimethyl aluminum in toluene or methylcyclohexane, wherein the molar ratio of the components of the catalyst system [Cr]: partially hydrolyzed trimethylaluminum: 0,03-1,09% of trimethylaluminum: 6,95-31,92%: 67,39-92,81%.

According to the claimed invention, the diphosphine ligand is selected from [2- (diphenylphosphino) phenyl] [2- (ethoxymethyl) phenyl] phenylphosphine, [2- (diphenylphosphino) phenyl] [2- (vinyl) phenyl] phenylphosphine, [2- (diphenylphosphino) phenyl ] [2- (N, N-diethylaminomethyl) phenyl] phenylphosphine and [2- (diphenylphosphino) phenyl] [2- (octylthiomethyl) phenyl] phenylphosphine.

Examples of chromium (III) diphosphine complexes used are the following compounds:

The technical task and technical result are achieved with the following methods for obtaining complexes and the conditions of the trimerization process.

Diphosphines for the preparation of complexes 1-4 were synthesized using methods similar to those described in the examples of US patent 8404915 B2, 03/26/2013.

Examples of the preparation of diphosphine complexes of chromium.

Example 1 (synthesis of complex 1 - [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1,2-C ₆ H ₄ ) (CH ₂ OCH ₂ CH ₃ )] (THF )], (([2- (diphenylphosphino) phenyl] [2- (ethoxymethyl) phenyl] phenylphosphine) -P, P) - (tetrahydrofuran) trichlorochromium (III)).

To 0.15 g (0.4 mmol) of Tris (tetrahydrofuran) chromium (III) chloride, a solution of 0.22 g (0.44 mmol) of [2- (diphenylphosphino) phenyl] [2- (ethoxymethyl) phenyl] phenylphosphine 6 ml of dry toluene, the mixture is stirred for 16 hours. The precipitate is filtered off, washed with toluene, dried in vacuo.

Example 2 (synthesis of complex 2 - [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1,2-C ₆ H ₄ ) (CHCH ₂ )] (THF)], ( ([2- (diphenylphosphino) phenyl] [2- (vinyl) phenyl] phenylphosphine) -P, P) - (tetrahydrofuran) trichlorochromium (III)).

The example is similar to example 1, but 0.21 g (0.44 mmol) [2- (diphenylphosphino) phenyl] [2- (vinyl) phenyl] phenylphosphine is used as diphosphine.

Example 3 (synthesis of complex 3 - [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1,2-C ₆ H ₄ ) (CH ₂ N (CH ₂ CH ₃ ) 2 )] (THF)], (([2- (diphenylphosphino) phenyl] [2- (N, N-diethylaminomethyl) phenyl] phenylphosphine) -P, P) - (tetrahydrofuran) trichlorochromium (III)).

The example is similar to example 1, but 0.23 g (0.44 mmol) of [2- (diphenylphosphino) phenyl] [2- (N, N [diethylaminomethyl) phenyl] phenylphosphine is used as diphosphine.

Example 4 (synthesis of complex 4 - [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1,2-C ₆ H ₄ ) (CH ₂ SC ₈ H ₁₇ ) (THF) ],

(([2- (diphenylphosphino) phenyl] [2- (octylthiomethyl) phenyl] phenylphosphine) -P, P) - (tetrahydrofuran) trichlorochromium (III)).

The example is similar to example 1, but 0.27 g (0.44 mmol) of [2- (diphenylphosphino) phenyl] [2- (octylthiomethyl) phenyl] phenylphosphine is used as diphosphine.

The output and data of elemental analysis of complexes 1-4 are presented in table 1.

Table 1 Data of elemental analysis of complexes 1-4 Complex (yield,%) Gross formula MM Found,% Calculated,% FROM N R FROM N R 1 (75) C ₃₇ H ₃₈ P ₂ CrCl ₃ O ₂ 734.4 60.25 5.04 8.60 60.45 5.17 8.44 2 (64) C ₃₆ H ₃₄ P ₂ CrCl ₃ O 702.4 61.38 4.98 8.51 61.50 5.12 8.83 3 (70) C ₃₉ H ₄₁ P ₂ CrCl ₃ NO 761.4 61.29 4.95 8.24 61.46 5.12 8.14 4 (82) C ₄₃ H ₅₀ P ₂ CrCl ₃ SO 834.4 61.75 4.86 7.50 61.84 4.91 7.43

Examples of preparation of an activator solution.

Example 5

The preparation of the activator solution is carried out in 3 stages.

First, a 1.36 M solution of trimethylaluminum is prepared by dissolving 6 ml of TMA (97%, Sigma-Aldrich) in 40 ml of absolutized toluene in an inert gas atmosphere, the resulting mixture is stirred for 20 minutes, then 5 ml of the resulting solution is taken and added to 14 ml of absolute toluene in an inert gas atmosphere. The resulting 0.36 M solution is stirred in an inert gas stream for 20 minutes.

The activator is prepared by mixing 0.15 ml of a 0.36 M TMA solution and 0.3 ml of a 0.085 M partially hydrolyzed TMA solution (prepared by controlled hydrolysis of 0.08 ml TMA (97%, Sigma-Aldrich) with an equimolar amount of ice in a mixture of 0.6 ml toluene and 9.3 ml of methylcyclohexane according to a known method [N. Winter, W. Schnuchel, N. Sinn, The Preparation of Aluminoxane from Trimethylaluminium at a Defined Surface of Deeply Cooled Ice. Macromol. Symp. 1995, v. 97, p. 119]) at room temperature in an inert gas atmosphere.

Example 6

The example is similar to example 5, but instead of 0.15 ml, 0.25 ml of a 0.36 M TMA solution is taken.

Example 7

The example is similar to example 5, but instead of 0.15 ml, 0.45 ml of a 0.36 M TMA solution is taken.

Example 8

The example is similar to example 5, but for the preparation of 1.36 M and 0.36 M solutions of trimethylaluminum, methylcyclohexane is taken instead of toluene and 0.60 ml of a 0.36 M TMA solution is taken instead of 0.15 ml.

Example 9

The example is similar to example 5, but instead of 0.15 ml, 0.70 ml of a 0.36 M TMA solution is taken.

Example 10

The example is similar to example 5, but instead of 0.15 ml, 0.95 ml of a 0.36 M TMA solution is taken.

Carrying out trimerization using the inventive catalytic system, including the diphosphine complex of chromium (III) 1-4, is presented below.

Example 11

The preparation of the catalytic solution is carried out in a Schlenk vessel in an inert atmosphere of argon. A portion of complex 1 (0.56 mg) is loaded under a stream of argon, 5 ml of absolute methylcyclohexane are added. The catalytic solution of the process of obtaining 1-hexene is stirred for 15 min at room temperature. Then add 0.6 ml of the activator solution obtained in example 5, after which it is stirred for 5 minutes and introduced into the autoclave in a stream of argon. After loading the obtained catalyst system into the autoclave, the ethylene feed is switched on and is not interrupted during the entire process. The temperature and pressure in the autoclave during the experiment are kept constant (temperature 85 ° C, pressure 20 bar). After the reaction time (30 min), the ethylene supply is shut off, heating and stirring are turned off. After cooling and depressurization, methanol is introduced into the autoclave to decompose the catalyst system and the internal standard (n-decane; 0.2-0.8 g) is stirred for 10 minutes. After opening the autoclave, 10 ml of a 20% aqueous HCl solution and 5 ml of toluene are added to the reaction mass.

Example 12

The example is similar to example 11, but using the activator obtained in example 6.

Example 13

The example is similar to example 11, but using the activator obtained in example 7.

Example 14

The example is similar to example 11, but using the activator obtained in example 8.

Example 15

The example is similar to example 11, but using the activator obtained in example 9.

Example 16

The example is similar to example 10, but using the activator obtained in example 10.

Example 17

The example is similar to example 16, but in the preparation of the catalytic solution is used 0.54 mg of complex 2.

Example 18

The example is similar to example 16, but in the preparation of the catalytic solution is used 0.60 mg of complex 3.

Example 19

The example is similar to example 13, but 0.17 mg of complex 4 is used in preparing the catalytic solution. The process is carried out at a pressure of 40 bar.

The results obtained in examples 11-19 are shown in table 2.

As can be seen from the data obtained, the use of the inventive catalytic system based on diphosphine chromium complexes allows one to selectively (with selectivity on average more than 90%) obtain 1-hexene by the method of catalytic trimerization of ethylene with a minimum amount (on average less than 0.15%) of side-forming polymer.

table 2 The performance of the catalyst and the composition of the reaction products of the trimerization of ethylene into 1-hexene, depending on the nature of the complex Complex example The concentration of activator in the reaction solution, · 10 ² mmol / ml The ratio of [Cr]: partially hydrolyzed trimethylaluminum: trimethylaluminum in the catalyst system, molar% Productivity, kg / g _Cr * h The amount of polymer, mass. % The selectivity for fractions of hydrocarbons, mass. % The content of 1-hexene in fraction C ₆ , mass. % C ₄ C ₆ C ₈ C ₁₀₊ 1,11 300,3 1.09: 31.52: 67.39 7.3 0.56 1,6 85.7 7.9 4.3 95.5 1.12 448.8 0.74: 21.89: 77.37 11.3 0.26 1,5 91.0 5,6 1.7 95.5 1.13 745.8 0.44: 13.22: 86.34 11.3 0.22 1.8 91.3 5.3 1,5 95.4 1.14 953.7 0.34: 10.34: 89.32 9.3 0.05 2.0 94.5 3,1 0.4 96.0 1.15 1095.6 0.30: 9.01: 90.69 9.7 0.15 1.9 87.3 7.4 3,1 95.6 1.16 1372.8 0.24: 6.95: 92.81 8.8 0.05 1.4 89.9 5.1 3,5 95.4 2.17 1372.8 0.24: 6.95: 92.81 8.3 1.38 1,6 86.0 3.6 7.5 96.2 3.18 1372.8 0.24: 6.95: 92.81 1,1 6.00 7.3 26.3 37.1 23,4 78.5 4.19 1372.8 0.03: 13.27: 86.70 124.0 6.90 0.6 79.6 9,4 3.6 97.2

Claims (2)

1. The catalytic system for the trimerization of ethylene in 1-hexene, including a complex of chromium (III) with a diphosphine ligand of the general formula [CrCl ₃ [(Ph ₂ P (1,2-C ₆ H ₄ ) P (Ph) (1,2-C ₆ H ₄ ) (R)] (THF)], where R is a hydrocarbon radical or a heteroatom containing hydrocarbon group located in the phenyl substituent in the optimal position with respect to one of the phosphorus atoms, where the source of chromium (III) is Tris chloride ( tetrahydrofuran) chromium, and an activator, which is a mixture of solutions of trimethylaluminum and partially hydrolyzed trimethylaluminum in toluene or methylcyclohec sane, the molar ratio of the components of the catalytic system [Cr]: partially hydrolyzed trimethylaluminum: trimethylaluminum is 0.03-1.09%: 6.95-31.92%: 67.39-92.81%. 2. The catalytic system according to claim 1, in which the diphosphine ligand is selected from [2- (diphenylphosphino) phenyl] [2- (ethoxymethyl) phenyl] phenylphosphine, [2- (diphenylphosphino) phenyl] [2- (vinyl) phenyl] phenylphosphine , [2- (diphenylphosphino) phenyl] [2- (N, N-diethylaminomethyl) phenyl] phenylphosphine and [2- (diphenylphosphino) phenyl] [2- (octylthiomethyl) phenyl] phenylphosphine.