WO2000069867A1

WO2000069867A1 - Manufacture of olefin/carbon monoxide polymers

Info

Publication number: WO2000069867A1
Application number: PCT/US2000/013318
Authority: WO
Inventors: Lin Wang; Geraldine Marie Lenges
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1999-05-13
Filing date: 2000-05-12
Publication date: 2000-11-23
Also published as: JP2002544334A; AU4850900A; EP1178995A1

Abstract

Olefin/carbon monoxide copolymers are prepared by contacting these monomers with nickel complexes of selected diphosphine ligands. The copolymers are useful as molding resins.

Description

TITLE MANUFACTURE OF OLEFIN/CARBON MONOXIDE POLYMERS

FIELD OF THE INVENTION Olefin/carbon monoxide copolymers are prepared by contacting these monomers with nickel complexes of selected diphosphine ligands. Also disclosed is a novel phosphorous containing ligand.

TECHNICAL BACKGROUND

Olefin/carbon monoxide copolymers are items of commerce, being useful for injection molded parts for various industrial uses. Usually these copolymers are alternating (to a great extent) copolymers. The most common method of making these polymers is catalyzing the copolymerization with various complexes of palladium. While these complexes are satisfactory from a reaction viewpoint, economically they have the great disadvantage of using palladium, a very expensive metal . Thus cheaper catalysts that would make these polymers are being sought .

One method of reducing the catalyst cost is to find a catalyst which uses a cheaper transition metal. WO97/00127 and W097/23492 describe nickel complexes of specified ligands which copolymerize ethylene and carbon monoxide. Neither of these references describes the diphosphine ligands discussed herein.

SUMMARY OF THE INVENTION

This invention concerns a first process for producing olefin/carbon monoxide copolymers, comprising the step of contacting one or more olefins of the formula H₂C=CHR , carbon monoxide, a Bronsted acid and a nickel complex of a ligand of the formula

. PAr¹ ₂

Ar¹ ₉P'

( i i :

R⁶ ₃SiCH₂ P P CH₂SiR⁶ ₃ (_V) wherein: each Ar is aryl or substituted aryl; each R is independently hydrogen, hydrocarbyl or substituted hydrocarbyl; Cy is cyclohexyl; each R⁴ is independently alkyl containing 1 to 20 carbon atoms ;

R is hydrogen or n-alkyl containing 1 to 20 carbon atoms; and each R⁶ is independently hydrocarbyl or substituted hydrocarbyl .

This invention also concerns a second process for producing olefin/carbon monoxide copolymers, comprising the step of contacting one or more olefins of the formula H₂C=CHR⁵, carbon monoxide, a Bronsted acid, a nickel [II] compound, and a ligand of the formula

R⁶ ₃SiCH₂ P Λ P CH₂SiR⁶ ₃ (V)

wherein: each Ar is independently aryl or substituted aryl; each R is independently hydrogen, hydrocarbyl or substituted hydrocarbyl;

Cy is cyclohexyl; each R is independently alkyl containing 1 to 20 carbon atoms; R is hydrogen or n-alkyl containing 1 to 20 carbon atoms ; and each R is hydrocarbyl or substituted hydrocarbyl .

Also disclosed herein is a compound of the formula

CH₂SiR ₃

wherein R , Cy and R are as defined above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Herein, certain terms are used. Some of them are: A "hydrocarbyl group" is a univalent group containing only carbon and hydrogen. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.

By "substituted hydrocarbyl" herein is meant a hydrocarbyl group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of "substituted" are heteroaromatic rings. All of the hydrogen atoms in a substituted hydrocarbyl group may be substituted, as in perfluoroalkyl . Other groups may be "substituted" in an analogous manner. By "(inert) functional group" herein is meant a group other than hydrocarbyl or substituted hydrocarbyl which is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially interfere with any process described herein that the compound in which they are present may take part in. Examples of functional groups include halo (fluoro, chloro, bromo and iodo) , ether such as -OR wherein R is hydrocarbyl or substituted hydrocarbyl. By "relatively noncoordinating anions" (or "weakly coordinating anions") are meant those anions as are generally referred to in the art in this manner, and the coordinating ability of such anions is known and has been discussed in the literature, see for instance W. Beck., et al . , Chem . Rev . , vol. 88 p. 1405-1421 (1988), and S. H. Stares, Chem. Rev. , vol. 93, p. 927-942 (1993), both of which are hereby included by reference. Among such anions are those formed from the aluminum compounds in the immediately preceding paragraph and X^", including R ₃A1X , R⁹ ₂A1C1X^", R⁹A1C1₂X^", and "R⁹A10X^"" , wherein R⁹ is alkyl. Other useful noncoordinating anions include BAF^" {BAF = tetrakis [3 , 5-bis (trifluoromethyl) phenyl] borate} , SbF₆ ^~, PF₆ and BF₄ ^", trifluoromethanesulfonate, p-toluenesulfonate, (R_fS0₂)₂N^~, and (C_SF₅)₄B\ Included within the meaning of adding a specified complex of nickel is the addition of ingredients which are known in the art to form such a complex under the process conditions .

In (II) it is preferred that every Ar is phenyl or substituted phenyl, more preferably phenyl.

In (III) it is preferred that every R is hydrogen. In (IV) it is preferred that each R⁴ is independently an alkyl containing 1 to 4 carbon atoms, more preferably each R⁴ is independently methyl or ethyl, and especially every R is ethyl.

In (V) it is preferred that each R is independently alkyl, more preferably each R is independently an alkyl containing 1 to 4 carbon atoms, and especially every R is methyl . The amount of compound (I), (II), (III), and/or (IV) supplied to the polymerization process may vary, but is conveniently selected in the range of from about 0.1 to about 2 moles of compound per gram atom of nickel . Preferably, the amount is in the range of from about 0.5 to about 1.5 moles of compound per mole nickel compound.

Preferred Bronsted acids are strong acids, i.e. those which have a pKa of less than about 6, in particular less than about 4, more in particular less than about 2, when measured in aqueous solution at 18°C. Examples of suitable Bronstead acids are protic acids that may also participate in the nickel salts, e.g. trifluoroacetic acid. Examples of protic acids which may be used are sulfonic acids and hydrohalogenic acids, in particular hydrogen fluoride, tetrafluoroboric acid and hexafluoroboric acid (HBF₄ and HBF₅) .

The activity of the catalyst composition may be such that amounts in the range from 10^' to 10^" gram atom of nickel per mole of olefinically unsaturated compound to be copolymerized are adequate. Preferably, the amount will be from 10^" to 10^" , on the same basis.

In preferred olefins, R is hydrogen or an alkyl containing 1 to 4 carbon atoms, more preferably R is hydrogen (ethylene) or methyl (propylene) , and especially preferably R is hydrogen. In one preferred polymer ethylene and another olefin, preferably propylene or 1-butene, more preferably propylene, are used. Generally, the molar ratio of on the one hand carbon monoxide to on the other hand the olefinically unsaturated compound (s) may be selected within a wide range, for example in the range of from about 1:50 to about 20:1. However, it is preferred to employ a molar ratio in the range of from about 1:20 to about 2:1.

The process of the invention is conveniently carried out in the presence of a diluent . Preferably a diluent is used in which the copolymers are insoluble or virtually insoluble so that they form a suspension upon their formation. Recommended diluents are polar organic liquids, such as ketones, ethers, esters or amides. Preferably, protic liquids are used, such as monohydric and dihydric alcohols, in particular the lower alcohols having at most 4 carbon atoms per molecule, such as methanol and ethanol . The process of this invention may also be carried out as a gas phase process, in which case the catalyst is typically deposited on a solid particulate material or chemically bound thereto .

When a diluent is used in which the formed copolymer forms a suspension it is preferred to have a solid particulate material suspended in the diluent before the monomers are contacted with the catalyst composition. Suitable solid particulate materials are silica, polyethylene and a copolymer of carbon monoxide and an olefinically unsaturated compound, preferably a copolymer which is based on the same monomers as the copolymer to be prepared. The quantity of the solid particulate material is preferably in the range of from about 0.1 to about 20 g, particularly from about 0.5 to about 10 g, per 100 g diluent .

The conditions under which the process of the invention is performed, include the use of elevated temperatures and pressures, such as between about 0°C and about 200°C, in preferably between about 30°C and about 130°C, and pressures (of ethylene and CO combined) between about 0.1 MPa and about 200 MPa, in particular between about 0.5 MPa and about 10 MPa. The pressure of carbon monoxide is typically at least about 0.1 MPa. Preferably the partial pressure of the CO is approximately equal to the pressure of ethylene.

The copolymers can be recovered from the polymerization mixture by using conventional techniques. When a diluent is used the copolymers may be recovered by filtration or by evaporation of the diluent. The copolymer may be purified to some extent by washing.

Copolymers are suitably prepared in which the units originating from carbon monoxide on the one hand and the units originating from the olefinically unsaturated compound (s) on the other hand occur in an alternating or substantially alternating arrangement. The term "substantially alternating" will generally be understood by one skilled in the art as meaning that the molar ratio of the units originating from carbon monoxide to the units originating from the olefinically unsaturated compound is above about 35:65, in particular above about 40:60. When polymers are completely alternating this ratio equals 50:50.

It is preferred to prepare copolymers which have a melting point above 150 °C, as determined by Differential Scanning Calorimetry (DSC) . For example, linear copolymers of carbon monoxide and ethylene and linear copolymers of carbon monoxide, ethylene and an α-olefin which are alternating or substantially alternating fall into this category. It is particularly preferred to prepare linear alternating copolymers of carbon monoxide and ethylene or linear alternating copolymers of carbon monoxide, ethylene and an α-olefin in which the molar ratio of the other α-olefin (R is n-alkyl) to ethylene is typically above about 1:100, preferably in the range of from about 1:100 to about 1:3, more preferably in the range of about 1:50 to about 1:5.

It is preferred that the copolymers produced have a number average molecular weight (Mn) of at least about 10,000, more preferably more than about 20,000, and especially preferably more than about 30,000. The Mn may be measured by Gel Permeation Chromatography using hexafluoroisopropanol as a solvent .

Furthermore, for practical reasons the nickel content of the copolymers will typically be above about 0.01 ppm by weight, relative to the weight of the copolymer. It is preferred to prepare copolymers which have a nickel content in the range of from about 0.05 to about 300 ppm, in particular from about 0.1 to about 200 ppm, relative to the weight of the copolymer. The copolymers are substantially free, preferably free of palladium. "Substantially free of palladium" means to the skilled person that the palladium content is lower than the value normally achieved when a palladium based catalyst is employed in the copolymerization, for example less than 1 ppm by weight, in particular less than 0.1 ppm, relative to the weight of the copolymer. Alternatively it is preferred that, if palladium is present, the weight ratio of palladium to nickel is less than about 1:50, in particular less than about 1:100 or most in particular even less than about 1:200.

Methods for making compound (I) are found in WO97/00127, for making (III) in Example 4 [other compounds (III) can be made by analogous methods] , and for making (IV) in WO00/21970. Both of these references are incorporated by reference herein for all purposes as if fully set forth. Compound (II) is available commercially.

Examples 1-4 and Comparative Example A Ethylene/CO Copolymerization

This procedure is general for cationic nickel-catalyzed ethylene/carbon monoxide (E/CO) copolymerization.

A reactor was charged with nickel [II] acetate tetrahydrate (0.05 mmol) and the diphosphine (0.06 mmol) . A methanol solution of trifluoroacetic acid (0.2 mmol/5mL) was added, and the reactor was brought out of the drybox. The reactor was evacuated, charged with ethylene (350 kPa; all pressures are gauge pressures) and E/CO (1:1, 3.90 MPa) and the reaction was run for 16 h at 90 °C. Under these conditions, the final pressure was 5.17 MPa. Polymer was recovered from the shaker vials, washed with methanol and dried under high vacuum overnight . The samples were submitted for Differential Scanning Calorimetry (melting point Tm, determined at a heating rate of 10°C/min on the first heat, and taken as the peak of the endotherm) .

Results of the polymerizations and the structure of the diphosphines ("Compound") are given in Table 1. In Example 3, determination of the molecular weight of the polymer by Differential Scanning Calorimetry in hexafluoroisopropanol gave a number average molecular weight of 81,800, and a weight average molecular weight of 129,000. In Comparative Example A the "Compound" used was

( I )

Table 1

Example 5 In a drybox, 1.20 g R-(+)-l, 1' -bi-2-naphthol (Aldrich Chemical Co., Milwaukee, WI, U.S.A.), 2.00 g dicyclohexylphosphorus chloride (Strem Chemical) and 1.70 g triethylamine were dissolved in 25 mL THF . The mixture was allowed to stir at room temperature for 35 h. The mixture was filtered through Celite^®, followed by 3X10mL tetrahydrofuran wash. The combined filtrate was evaporated under reduced pressure. The product was dried in vacuo overnight. White solid was obtained. The conversion was quantitative. H-NMR (CD₂C1₂, δ): 0.25-1.85 (44H) , 7.10- 8.10 (12H, Ar-H) . ³¹P-NMR (CD₂Cl₂ , δ): 114.33 (s) .

Example 6

A round bottom flask was charged with 1 , 3-bis (dichlorophosphino) benzene (1.0 g, 3.57 mmol). Diethyl ether (20 mL) was added and the solution was cooled to -30°C. Trimethylsilylmethylmagnesium chloride (1.0 M in diethylether , 17.9 mL, 17.9 mmol) was added slowly and the reaction was slowly warmed to room temperature. The next day, water (2.0 mL) was added and the reaction was stirred 30 min. The solvent was removed in vacuo . Toluene (35 mL) was added and the reaction was stirred an additional 30 min. The reaction mixture was filtered and the product was washed with toluene (2x5 mL) and dried in vacuo . A pale yellow oil (0.52 g, 30%), (Me₃SiCH₂)₂P(C₂H-₄)P(CH₂SiMe₃)₂, was recovered. ³¹P NMR (121.5 MHz, 20°C, C6D6) δ-44.8.

Claims

CLAIMSWhat is claimed is:

1. A process for producing olefin/carbon monoxide copolymers, comprising the step of contacting one or more olefins of the formula H₂C=CHR , carbon monoxide, a Bronsted acid and a nickel complex of a phosphorous-containing ligand, characterized in that said ligand is of the formula

wherein : each Ar is aryl or substituted aryl; each R is independently hydrogen, hydrocarbyl or substituted hydrocarbyl; Cy is cyclohexyl; each R is independently alkyl containing 1 to 20 carbon atoms; R is hydrogen or n-alkyl containing 1 to 20 carbon atoms ; and eeaacchh R is independently hydrocarbyl or substituted hydrocarbyl

2. A process for producing olefin/carbon monoxide copolymers, comprising the step of contacting one or more olefins of the formula H₂C=CHR , carbon monoxide, a Bronsted acid, a nickel [II] compound, and a phosphorous-containing ligand, characterized in that said ligand is of the formula

wherein : each Ar is independently aryl or substituted aryl; each R is independently hydrogen, hydrocarbyl or substituted hydrocarbyl; Cy is cyclohexyl; each R is independently alkyl containing 1 to 20 carbon atoms ;

R is hydrogen or n-alkyl containing 1 to 20 carbon atoms ; and each R is hydrocarbyl or substituted hydrocarbyl

3. The process as recited in claim 1 or 2 , characterized in that said contacting is carried out at a temperature of about 30°C to about 130°C.

4. The process as recited in claim 1 or 2, characterized in that: every Ar is phenyl or substituted phenyl; every R is hydrogen; each R⁴ is independently alkyl containing 1 to 4 carbon atoms; and each R is independently alkyl .

5. The process as recited in claim 4 characterized in that : every Ar is phenyl; and every R is methyl or ethyl; and every R is methyl.

6. The process as recited in claim 1 or 2 , cchhaarraacctteerriizzed in that R⁵ is hydrogen, or R is both hydrogen and methyl .

7. The process as recited in claim 1 or 2 , characterized in that an alternating polymer is produced.

8. The process as recited in claim 1 or 2 , characterized in that said Bronsted acid has a pKa of about 2 or less.

9. A compound of the formula

(III) (V) wherein: each R ,3 is independently hydrogen, hydrocarbyl or substituted hydrocarbyl;

Cy is cyclohexyl ; and each R is hydrocarbyl or substituted hydrocarbyl.

10. The compound as recited in claim 9, characterized in that every R is hydrogen, and every R is methyl.