WO1994023836A1

WO1994023836A1 - Catalyst composition and process for the production of unsaturated diesters

Info

Publication number: WO1994023836A1
Application number: PCT/US1994/003636
Authority: WO
Inventors: Jerald Feldman; Stephan James Mclain
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1993-04-08
Filing date: 1994-04-04
Publication date: 1994-10-27

Abstract

A tungsten-based catalyst composition for the self-metathesis of unsaturated esters to form unsaturated diesters, especially useful in the process of synthesizing dihydromuconic acid esters from 3-pentenoic acid esters.

Description

TITLE

CATALYST COMPOSITION AND PROCESS FOR THE

PRODUCTION OF UNSATURATED DIESTERS

FIELD OF THE INVENTION This invention relates to tungsten-based catalyst compositions which are useful for the production of unsaturated diesters by metathesis of unsaturated esters.

BACKGROUND OF THE INVENTION Traditional commercial synthesis of Nylon 66 has involved utilization of benzene feedstocks to produce adipic acid, which is a key intermediate in the synthesis of Nylon 66. One important aspect of the present invention presents an alternative route to production of adipic acid, whereby butadiene may be used as the feedstock to produce methyl-3-pentenoate (M3P) , which is then metathesized to give dimethyldihydro- muconate using the catalyst system of the invention. Dimethyldihydromuconate may then be readily converted to adipic acid, en route finally to Nylon 66.

The present invention provides a tungsten based catalyst composition effective for the self-metathesis of unsaturated esters to produce unsaturated diesters. In a preferred embodiment, the catalyst provides for the effective self metathesis of a 3-pentenoic acid ester to yield the dihydromuconic acid ester. Examples of catalysts for self-metathesis of 3-pentenoic acid esters are very rare, and this type of reaction appears to be more difficult than metathesis of fatty acid esters. For example, conventional catalysts for methyl oleate metathesis (e.g., WClβ/SnMe-i) are poor catalysts for M3P metathesis (E. Verkuijlen, et al.. Reel. Trav. Chim. Pays-Bas, 96: 8 (1977) .

Patents which specifically disclose 3-pentenoic acid ester metathesis include JP 57 (1982) -140657 and JP 57 (1982) -110, 536, but these catalysts are molybdenum based, (e.g., MoCls/SnMe-i, MoOCl-i/SnMe-i) .

Other references to 3-pentenoic acid ester metathesis include cross-metathesis with other olefins, Otton et al., J. Mol. Catal. , 8:313 (1980); European

Patent Application No. 83300162.1 (BP Chemicals) . Also, a patent to Consortium fur Eleckrochemische Industrie employs Re2θ₇/Al₂θ3/tetraethyllead for both cross- and self-metathesis of methyl-3-pentenoate, Federal Republic of Germany, Patent No. 3,229,419 C2.

Olefin metathesis catalysts containing electron- withdrawing phenoxide ligands are disclosed by Basset et al., J. Chem. Soc, Che . Commun., 1816 (1985); J. Mol. Catal., 36:13 (1986); U.S. 4,550,216. The Basset complexes were demonstrated to be olefin metathesis catalysts and are active for methyl oleate metathesis. No results are reported for 3-pentenoic acid ester metathesis and a solvent was always employed, contrary to the instant system. Also, in the Basset system, Cl4(0-2, 6-C6H3-X2-)2 MR , two equivalents of the cocatalyst MR₄ are preferred for the catalyst to achieve maximum activity; in the preferred catalyst composition embodiment of the instant system, WOCI2 (0-2, 6-C_δH3-Br2) ₂/ PbEt4, only one equivalent of tetraethyllead is needed for maximum activity in methyl-3-pentenoate metathesis. U.S. 5,082,909 and a presentation by Andrew Bell entitled "Dicyclopentadiene Polymerization Utilizing Well-Characterized Tungsten Complexes" which was given at the Ninth International Symposium on Olefin Metathesis and Polymerization, Ursinius College,

Collegeville, PA, July 21-26, 1991 describe the system WOCl₄-χ(OAr)_x/MR_n (OAr = electron withdrawing phenoxide and MR_n = alkylaluminum, tin, silicon, or zinc compound) which was shown to be a catalyst for metathesis of strained cyclic olefins such as dicyclopentadiene. However, no results are reported for acyclic olefins or esters.

Tungsten oxo-alkoxide complexes have been reported to be olefin metathesis catalyst precursors: FR 2 499 083 (Rhone-Poulenc) ; Kress et al., J. Chem.

Soc, Chem. Coraraun., 514 (1982); Aguero et al., J. Chem. Soc, Chem. Commun., 793 (1985); Kress et al., J. Mol. Catal., 36:1 (1986) .

SUMMARY OF THE INVENTION The present invention provides a novel catalyst composition which is useful for the self-metathesis of unsaturated esters, comprising a catalyst composition of formula IA

OX2(OR)2 / PbR^R^⁴ IA

wherein X is F, Cl, Br or I;

R is Ci to C₂₀ hydrocarbyl optionally substituted with NO₂, CN, CO₂R⁷/ SR⁷, F, Cl, Br, or I; R¹, R², R³, and R⁴ are independently H, Ci to C₂₀ hydrocarbyl, F, Cl, Br, or I; and R⁷ is a Ci to C₂₀ hydrocarbyl optionally substituted with F or Cl. The present invention also provides a process for the metathesis of unsaturated esters comprising reacting compounds of formula II

R⁶CH=CH(CH₂)π-C02*R⁵

II in the presence of the catalyst composition of formula IB

OX2(OR)2 / MR¹R²R³R⁴ IB

to yield compounds of formula III and IV

R⁵0₂C(CH2)_mCH=CH (CH₂)_mC0₂R⁵ III

R⁶CH=CHR⁶ IV

wherein R is Ci to C20 hydrocarbyl optionally substituted with SR⁷, NO2, CN, CO₂R⁷, F, Cl, Br, or I; R¹, R², R³, and R⁴ are independently H, Ci to C₂0 hydrocarbyl, F, Cl, Br, or I; R⁵ is Ci to C₂0 hydrocarbyl; R⁶ is H or CH3(CH₂)_n;

R⁷ is a Ci to C20 hydrocarbyl optionally substituted with F or Cl; X is F, Cl, Br or I; n is an integer from 0 to 20; m is an integer from 1 to 20; and M is a Main Group element.

DETAILED DESCRIPTION

This invention provides a useful synthetic route for the production of unsaturated diesters by the self metathesis of unsaturated esters; and especially provides a key step in an efficient route to adipic acid, which, together with hexamethylenediamine, is used commercially to make Nylon 66®. In describing the catalyst composition and process of the invention. Applicants intend to convey the following meanings to the terms employed throughout this application. By hydrocarbyl, Applicants include straight chain, branched or cyclic carbon atoms connected by single, double or triple bonds, and substituted accordingly with hydrogen atoms. As used herein, hydrocarbyl groups may be aliphatic and/or aromatic. By metathesis Applicants mean "the interchange of carbon atoms between a pair of double bonds" (K. J. Ivin Olefin Metathesis, Academic Press, 1983) . Self metathesis specifically refers to the reaction of two structurally identical olefins to produce two new and structurally different olefins.

By "Main Group" elements Applicants include the metallic and metalloid elements in groups 1, 2, 12, 13, 14, and 15 which are described as the "new notation" in the Periodic Table appearing in the CRC Handbook of Chemistry and Physics, 67th Edition, 1986-1987, CRC Press. Preferred elements are lithium, sodium, magnesium, zinc, boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead, antimony, and bismuth. Most preferred are lead and tin. An example of the catalyst composition of the invention is comprised of a tungsten-based catalyst and lead based cocatalyst as shown below.

catalyst cocatalyst The formula of the catalyst composition is shown in formula IA

WOX2(OR)2 / PbR¹R²R³R⁴ IA

wherein R is Ci to C₂0 hydrocarbyl optionally substituted with SR⁷, NO2, CN, CO₂R⁷, F, Cl, Br, or I; R¹, R², R³, and R⁴ are independently H, Ci to C₂0 hydrocarbyl, F, Cl, Br, or I; R⁵ is Ci to C20 hydrocarbyl; R⁶ is H or CH3(CH2)_n;

R⁷ is Ci to C₂0 hydrocarbyl optionally substituted with F or Cl; and X is F, Cl, Br, or I.

"R" may be substituted with halogen atoms to yield halogenated or partially halogenated phenoxide or alkoxide ligands . Examples of such ligands include 2, 6-dichlorophenoxide, 2, 6-dibromophenoxide, 2,4, 6-tri- bromophenoxide, 2,3,4,5, 6-pentafluorophenoxide, and hexafluoro-2-methylisopropoxide. The preferred halogen substituent for phenoxide ligands is bromine, and in this invention the preferred phenoxide ligand is 2, 6-dibromophenoxide. Other substituents on the phenoxide or alkoxide ligands are possible; e.g., alkyl groups containing from 1 to 20 carbons, alkoxy groups, thiolate groups, amino groups, nitro groups, and carboxylic acid esters . The substituents need not all be identical.

"R¹, R², R³, and R⁴" may be independently hydrogen; a Ci to C₂0 straight chain or branched hydrocarbyl group, either aromatic or aliphatic, or a halogen.

The invention also comprises a process for the metathesis of unsaturated esters to yield unsaturated diesters, for example, as illustrated in the following reactions:

cis/trans methyl-3-pentenoate cis trans dimethyldihydromuconate cis/trans bute

The process comprises reacting compounds of formula

II

R⁶CH=CH (CH₂)_mCθ2R⁵ II

in the presence of the catalyst composition of formula IB

OX2(OR)2 / MR¹R²R³R⁴ IB

to yield compounds of formula III and IV

R⁵0₂C(CH₂)_mCH=CH(CH₂)_mC0₂R⁵ III

R⁶CH=CHR⁶ IV

wherein R is Ci to C₂₀ hydrocarbyl optionally substituted with SR⁷, NO₂, CN, CO₂R⁷, F, Cl, Br, or I; R¹, R², R³, and R⁴ are independently H, Ci to C₂₀ hydrocarbyl, F, Cl, Br, or I; R⁵ is Ci to C20 hydrocarbyl; R⁶ is H or CH₃(CH2)_n R⁷ is Ci to C20 hydrocarbyl optionally substituted with F or Cl;

X is F, Cl, Br or I; n is an integer from 0 to 20; m is an integer from 1 τ.o 20; and M is a Main Group element.

The reaction may be carried out between 20 and 180°C. The optimum temperature will depend on the structure of the ester. For methyl-3-pentenoate metathesis, the preferred temperature range is 80-150°C.

The reaction can be carried out under reduced pressure or at pressures between 1 and 200 atmospheres; pressures between 0.5 and 60 atmospheres are preferred. For methyl-3-pentenoate metathesis, the reaction is preferrably run at a pressure between 0.5 and 1 at , in order to remove 2-butene from the reaction mixture as it is formed and so drive the reaction equilibrium towards product. (1 Atmosphere is 1 x IO⁵ Pascal.) It is also preferred that the reaction be carried out under an inert atmosphere, such as nitrogen or argon, since the catalyst system is somewhat air sensitive.

The reaction can be carried out in an organic solvent; examples of suitable organic solvents include benzene, toluene, xylene, chlorobenzene, methylene chloride, diisopropylether, and methyl caproate. The reaction can also be carried out with no solvent.

The molar ratio of cocatalyst MR¹R²R³R⁴ to catalyst W0X2(0R)2 may range from about 1 to 2, to about 10 to 1.' When the preferred catalyst system, WOCI2 (0-2, 6-C6H3-Br )2 PbEt , is employed for methyl-S¬ pentenoate metathesis in the absence of solvent, only one equivalent of tetraethyllead is needed for maximum activity; thus, the preferred cocatalyst to catalyst ratio in this system is 1:1. However, for other cocata-lysts the optimum cocatalyst to catalyst ratio may be different; for example, when the system WOCI₂ (0-2, 6-C6H3~Br₂)2 SnBU₄ is employed for methyl-3- pentenoate metathesis in the absence of solvent, two equivalents of tetrabutyltin are needed for maximum activity.

The preferred catalyst WOCI2 (0-2, 6-C6H3~Br2)2 is easily prepared by the reaction described in Example 13 below. Other OX2(OR)2 complexes can be readily prepared by similar methods well known to those skilled in the art. The preparation of WOCI2 (0-2, 6-C6H3-CI2)2 and WOCI2 (0-2, 6-C6H3~i-Pr2)2 for example, have been disclosed previously, A. Bell, U.S. 5,082,909 which is hereby incorporated by reference. The cocatalysts MR^XR²R³R⁴ and catalyst ligand precursors ROH are readily available commercially, for example, from Aldrich Chemical Co., Milwaukee, WI, USA, or Johnson ALFA Products, Wand Hall, MA, USA.

This example demonstrates the use of

WOCI2 (0-2, 6-C_δH3-Br2)2/tetraethyllead as a catalyst composition for methyl-3-pentenoate metathesis, and isolation of the product dimethyldihydromuconate. The reaction was carried out in a nitrogen filled glove box. In an oven-dried 50 mL round bottom flask containing a teflon covered magnetic stirbar, WOCI2 (0-2, 6-CβH3-Br2)2 (2.03 g, 2.63 mmol) was dissolved in methyl-3-pentenoate (30.0 g, 263 mmol) . Tetraethyllead (0.850 g, 2.63 mmol) was then added to the solution. A reflux condenser was attached to the round bottom flask. The reaction mixture was heated to 138°C and stirred at this temperature for 2.5 h. During this time the reaction mixture was open to glove box atmosphere through the reflux condenser, in order to vent off 2-butene formed in the reaction. ' The reaction mixture was then cooled to room temperature and filtered through a glass frit. The insoluble material filtered off was washed with petroleum ether; the petroleum ether washings were combined with the filtrate and the resulting solution concentrated under vacuum to remove volatile organics, including unreacted methyl-3-pentenoate. The resulting oil was distilled under vacuum to afford 12.53 g of a clear oil identified as dimethyldihydromuconate, as identified by ¹H and ¹³NMR spectroscopy, and gas chromatography and mass spectrometry (GCMS) comparison with an authentic sample.

In Examples 2-10 and 14-18 below, ortho-dichloro- benzene was added to the reaction mixture as an internal standard, in order to accurately determine methyl-3- pentenoate conversion and selectivity to dimethyl¬ dihydromuconate. Results are reported in Table 1.

EXAMPLE 2 The reaction was carried out in a nitrogen-filled glovebox. In a round bottom flask containing a teflon stirbar, WOCI₂(0-2,6-C₆H₃~Br₂)₂ (1.35 g, 1.75 mmol) was dissolved in methyl-3-pentenoate (10.0 g, 87.6 mmol). Ortho-dichlorobenzene (3.23 g, 21.97 mmol) was then added, followed by tetraethyllead (0.567 g, 1.75 mmol) . A reflux condenser fitted with a teflon stopcock in its side arm was attached to the round bottom flask; the apparatus was taken outside the glove box and via the stopcock connected to a nitrogen filled vaccuum line and mercury bubbler. The reflux condenser was chilled with cold water, and the reaction mixture heated to reflux (138°C) . The reaction mixture was stirred under nitrogen for 2.0 h at reflux; it was then cooled to room temperature and analyzed by gas chromatography. The results are reported in Table 1.

EXAMPLE 3 The reaction was carried out in a nitrogen-filled glovebox. In a round bottom flask containing a teflon stirbar, WOCI₂(0-2, 6-C₆H₃-Br₂)₂ (0.897 g, 1.16 mmol) was dissolved in methyl-3-pentenoate (6.63 g, 58.1 mmol). Ortho-dichlorobenzene (2.13 g, 14.51 mmol) was then added, followed by tributyltinhydride (0.338 g,

1.16 mmol) . A reflux condenser fitted with a teflon stopcock in its side arm was attached to the round bottom flask; the apparatus was taken outside the glove box and via the stopcock connected to a nitrogen filled vaccuum line and mercury bubbler. The reflux condenser was chilled with cold water, and the reaction mixture heated to reflux (138°C) . The reaction mixture was stirred under nitrogen for 2.0 h at reflux; it was then cooled to room temperature and analyzed by gas chromatography. The results are reported in Table 1.

EXAMPLE 4 This was done identically to Example 2, except WOCI2(0-2,6-C6H3-Cl2)2 (1.20 g, 1.75 mmol) was used in place of WOCI2 (0-2, 6-C6H3~Br2)2• The results are reported in Table 1.

EXAMPLE 5 This was done identically to Example 4, except the reaction was stirred at reflux for 18 h instead of 2 h. The results are reported in Table 1. EXAMPLE 6

This example demonstrates the use of an organic solvent for the reaction, in this case toluene. The reaction was carried out in a nitrogen filled glove box. In a round bottom flask containing a teflon covered stirbar, WOCI2(0-2,6-CδH3-Br2)2 (1.35 g, 1.75 mmol) was dissolved in methyl-3-pentenoate (10.0 g, 87.6 mmol) . Ortho-dichlorobenzene (3.22 g, 21.90 mmol) was then added, followed by tetraethyllead (0.567 g, 1.75 mmol), and finally toluene (40 mL) . A reflux condenser fitted with a teflon stopcock in its side arm was attached to the round bottom flask; the apparatus was taken outside the glove box and via the stopcock connected to a nitrogen filled vaccuum line and mercury bubbler. The reflux condenser was chilled with cold water, and the reaction mixture heated to reflux (110°C) . The reaction mixture was stirred under nitrogen for 18 h at reflux; it was then cooled to room temperature and analyzed by gas chromatography. The results are reported in Table 1. EXAMPLE 7

This was done identically to Example 2, except WOCI2 (0-2, 6-C6H3-i-Pr2)2 (1.10 g, 1.75 mmol) was used in place of WOCI2 (0-2, 6-C6H₃-Br2)2- The results are reported in Table 1. EXAMPLE 8

This was done identically to Example 2, except that tetrabutyltin (0.608 g, 1.75 mmol) was used in place of tetraethyllead. The results are reported in Table 1.

EXAMPLE 9 This was done identically to Example 8, except that that 1.216 g of tetrabutyltin (3.50 mmol) was used. The results are reported in Table 1.

EXAMPLE 10 This was done identically to Example 2, except that two equivalents of tetraethyllead were used (1.13 g, 3.50 mmol) . The results are reported in Table 1.

EXAMPLE 11

This example demonstrates methyl oleate metathesis. Under nitrogen, WOCI2(0-2, 6-CδH3-Br2)2 (12 mg, 0.016 mmol) was dissolved in methyl oleate (480 mg. 0.16 mmol) . Tetraethyllead (5 mg, 0.016 mmol) was then added. The resulting solution was heated to 80°C, and the progress of the reaction monitored by gas chromatography. The equilibrium mixture depicted below was attained between 1 and 2 hours at 80°C.

CH₃(CH₂)₇CH=CH(CH₂)₇CH₃ (25%)

CH₃(CH₂)₇CH=CH(CH₂)₇Cθ₂Me,^__--_ _ +

^50% Me0₂C(CH₂)₇CH*=CH(CH₂)₇C0₂Me (25

EXAMPLE 12 Under nitrogen, WOCI2 (0-2, 6-CδH3-Br2)2 (15 mg, 0.019 mmol) was dissolved in methyl oleate (288 mg,

0.97 mmol) . Tributyltinhydride (6 mg, 0.019 mmol) was then added. The resulting solution was stirred at room temperature, and the progress of the reaction monitored by gas chromatography. The equilibrium mixture depicted in Example 11 was attained within 3 hours at room temperature.

EXAMPLE 13 This example demonstrates synthesis of the preferred catalyst, WOCI2 (0-2, 6-C_δH₃-Br₂)₂ • Under nitrogen, WOCI₄ (4.38 g, 12.8 mmol) and 2,6-dibromo- phenol (6.46 g, 25.7 mmol) were dissolved in 50 rtiL of toluene. The resulting solution was stirred overnight at reflux. The reaction mixture was then concentrated to dryness, and the crude product washed with petroleum ether; recrystallization from methylene chloride/petroleum ether at -40°C afforded 9.09 g of WOCI2 (0-2, 6-C6H3-Br2)2 as black-green crystals. The mother liquor was concentrated under vacuum and again cooled to -40°C; this afforded an additional 0.54 g of crystals. Yield of WOCI2 (0-2, 6-C6H₃-Br2)2 = 9.63 g (97%) . EXAMPLE 14 In a nitrogen-filled glove box, a round bottom flask was charged with WOCI₂ (0-2, 6-C6H3~Br₂)₂ (1-35 g, 1.75 mmol) and toluene (40 mL) . Tetraethyllead (0.567 g, 1.75 mmol) was then added. A reflux condenser was attached, and the reaction mixture heated to reflux. The reaction mixture was stirred at reflux for 5 min, and then cooled. Ortho-dichlorobenzene (3.22 g, 21.9 mmol) and methyl-3-pentenoate (10.0 g, 87.6 mmol) were then added. The reflux condenser was fitted with a teflon stopcock in its side arm; the nitrogen-filled apparatus was then taken outside the glove box and via the stopcock connected to a nitrogen-filled vacuum line and mercury bubbler. The reflux condenser was chilled to approximately 0°C, and the reaction mixture heated at reflux (110°C) for 18 h; it was then cooled to room temperature and analyzed by gas chromatography. The results are reported in Table 1.

COMPARATIVE EXAMPLE 15 This was done identically to Example 2, except WCI4 (0-2, 6-CδH3-Br2)2 d-45 g, 1.75 mmol) was used in place of WOCI2 (0-2, 6-CgH3-Br2)2- ^Tne results are reported in Table 1.

COMPARATIVE EXAMPLE 16 This was done identically to Comparative

Example 15, except that 1.34 g (3.45 mmol) of tetra¬ ethyllead were used instead of 0.567 g of tetraethyl¬ lead. The results are reported in Table 1.

COMPARATIVE EXAMPLE 17 This was done identically to Comparative Example 15, except that tetrabutyltin (1.22 g, 3.50 mmol) was used in place of tetraethyllead. Results are in Table 1. COMPARATIVE EXAMPLE 18

This was done identically to Example 2, except that WOCI₄ (0.58 g, 1.75 mmol) was used in place of WOCI2 (0-2, 6-CeH3-Br2)2_' The results are reported in Table 1.

COMPARATIVE EXAMPLE 19

This was done identically to Example 2, except that WClε (0.70 g, 1.75 mmol) was used in place of WOCI2 (0-2, 6-C6H3-Br2)2, and tetramethyltin (0.31 g, 1.75 mmol) was used in place of tetraethyllead. Results are in Table 1.

TABLE 1 Catalysts for methyl-3-pentenoate metathesis^

Temp.

Ex. Catalyst Cocatalyst Ratio °C Conversion Selectivity* Yield*

2 C l2(0-2.6-C6H3-Br2)2 PbEt4 1:1 138 78% 91% 71%

3 WOCl2(0-2,6-C6H3-Bi2)2 SnHBu3 1:1 138 52 74 38

4 WOCl2(0-2,6-C6H3-Cl2)2 PbEt4 1:1 138 50 85 43

5± WOCl2(0-2,6-C6H₃-α2)2 PbEt4 1:1 138 53 83 44

6t WOCl2(0-2,6-C6H3-Br2)2 PbEt4 1:1 110 72 91 65

7 OCl2(0-2,6-C6H3-/-Pr2)2 PbEt4 1:1 138 3 67 2

8 OCl2(0-2,6-C6H3-Br2)2 SnBu4 1:1 138 43 77 33

9 0Cl2(0-2,6-C6H3-Br2)2 SnBu4 1:2 138 57 73 42

10 W0Cl2(0-2,6-C6H3-Br2)2 PbEt4 1:2 138 70 91 63

14t WOCl2(0-2,6-C6H3-Br2)2 PbEt4 1:1 110 65 88 57

15 WCl4(0-2,6-C6H3-Br2)2 PbEt4 1:1 138 60 87 53

16 WO4(0-2,6-C6H3-Br2)2 PbEt4 1:2 138 73 84 61

17 WC.4(0-2,6-C6H3-Bi2)2 SnBu4 1:2 138 51 81 42

18 WOCI4 PbEt4 1:1 138 3 0 0

19 WC16 SnMe4 1:1 138 34 40 14

§2% catalyst based on methyl-3-pentenoate; unless otherwise noted, reaction time at stated temperature was 2 h.

*Selectivity to, and yield of cis trans-dimethyldihydromuconate.

*In this example the reaction time was 18 h. tin this example toluene was used as a solvent and the reaction time was 18 h.

Claims

What is claimed is:

1. A catalyst composition comprising formula IA

WOX2(OR)2 / PbR¹R²R³R⁴ IA

wherein X is F, Cl, Br, or I;

R is Ci to C₂₀ hydrocarbyl optionally substituted with F, Cl, Br, I, NO2, CN, CO2R⁷, or SR⁷; R¹, R², R³, and R⁴ are independently H, Ci to C₂0 hydrocarbyl, F, Cl, Br, or I; and R⁷ is H or Ci to C20 hydrocarbyl optionally substituted with F or Cl.

2. The catalyst composition of Claim 1, wherein the composition comprises a molar ratio cocatalyst to catalyst from about 1:2 to about 10:1.

3. The catalyst composition of Claim 2, wherein the molar ratio of cocatalyst to catalyst is about 1:1.

4. The catalyst composition of Claim 1, wherein R is a phenyl substituted with 0 to 5 halides selected from F, Cl, Br, or I.

5. The catalyst composition of Claim 1, wherein each X is Cl, and R is 2, 6-C6H3-CI2.

6. The catalyst composition of Claim 1, wherein each X is Cl, and R is 2, 6-C6H3~Br2.

7. The catalyst composition of Claim 1 wherein R¹, R², R³ and R⁴ are each CH2CH3.

8. The catalyst composition of Claim 1 wherein each X is Cl; R is 2, 6-C6H3-CI₂; and R¹, R², R³ and R⁴ are each CH₂CH3.

9. The catalyst composition of Claim 1, wherein each X is Cl; R is 2, 6-C_δH3-Br2; and R¹, R², R³, R⁴ are each CH₂CH3.

10. A process for the metathesis of unsaturated esters comprising reacting compounds of formula II

R⁶CH=CH(CH₂)_mCθ2R⁵ II

in the presence of the catalyst composition of formula IB

WOX2(OR)2 / MR¹R²R³R⁴ IB

to yield compounds of formula III and IV

R⁵0 C(CH₂)_mCH=CH (CH₂)_mC0₂R⁵ III

R⁶CH=CHR⁶ IV

wherein

R is Ci to C20 hydrocarbyl optionally substituted with SR⁷, NO2, CN, CO₂R⁷, F, Cl, Br, or I; R¹, R², R³, and R⁴ are independently H, Ci to C20 hydrocarbyl, F, Cl, Br, or I;

R⁵ is Ci to C₂₀ hydrocarbyl; R6 is H or CH3(CH2)_n

R⁷ is a Ci to C20 hydrocarbyl optionally substituted with F or Cl; X is F, Cl, Br, or I; n is an integer from 0 to 20; m is an integer from 1 to 20; and

M is a Main Group element.

11. The process of Claim 10, wherein the meta¬ thesis reaction is carried out in the absence of solvent.

12. The process of Claim 10, wherein the meta- thesis reaction is carried out at about between 0.5 and 1 atmospheres pressure.

13. The process of Claim 10, wherein the reaction is carried out under an inert atmosphere.

14. The process of Claim 10, wherein the metathesis reaction is carried out at a temperature of from about 20°C to about 180°C.

15. The process of Claim 14, wherein the metathesis reaction is carried out at a temperature of from about 80°C to about 150°C.

16. The process of Claim 10, wherein the molar ratio of MR¹R²R³R⁴ to OX2 (OR)2 is from about 1 to 2 to about 10 to 1.

17. The process of Claim 16 wherein the ratio of

MR¹R²R³R⁴ to WOX2(OR)2 is about 1 to 1.

18. The process of Claim 10 wherein M is tin or lead.

19. The process of Claim 10 wherein the compound of Formula II is methyl-3-pentenoate.

20. The process of Claim 19, wherein each X is Cl; R is 2, 6-C6H₃-Br2; M is Pb; and R¹, R², R^3", and R⁴ are each methyl, ethyl, propyl or butyl.