GB1572291A

GB1572291A - Production of aromatic polycarbonates

Info

Publication number: GB1572291A
Application number: GB41324/77A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1976-10-12
Filing date: 1977-10-05
Publication date: 1980-07-30
Also published as: BR7706238A; MX145820A; PL201469A1; DD132780A5; GB1578713A; NL7711176A; AU518531B2; IN148600B; JPS5638145B2; BE859576A; DE2738437A1; FR2367732B1; AU2826677A; JPS5368746A; FR2367732A1

Description

(54) PRODUCTION OF AROMATIC POLYCARBONATES (71) We, GENERAL ELECTRIC COMPANY, a corporation organized and existing under the laws of the laws of the State of New York, United States of America, of 1 River Road, Schenectady 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to aromatic carbonates and in particular to a process for making aromatic polycarbonates.

Similar processes are described in our co-pending British Patent Applications No.

41325/77 Serial No. 1572292; 41326/77 Serial No. 1572293; 41327/77 Serial No. 1572294-and 41328/77 Serial No. 1572295.

As broadly disclosed in the above-mentioned British Patent Application No. 41327/77, aromatic carbonates can be prepared by contacting a phenol, carbon monoxide, an oxidant, a base and a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum.

Unexpectedly, it has been found that good aromatic carbonate process yields result when a phenol, carbon monoxide, an oxidant other than and in addition to oxygen, a base and a Group VIIIB element are contacted in the presence of a dehydrating agent, especially when molecular sieves are used to promote substantially anhydrous reaction conditions. Further, unexpectedly it has been found that even better aromatic carbonate process yields results when the process is carried out in the presence of a manganese or cobalt complex redox cocatalyst compound.

This invention, relates to a process for making aromatic carbonates which comprises contacting in the presence of a dehydrating agent a phenol, oxygen, carbon monoxide, an oxidant other than and in addition to oxygen, a base, and a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum.

The reactants and the resulting reaction products can be illustrated by the following general equations which are furnished for illustrative purposes only, since the reaction mechanisms involved in the preparation of aromatic monocarbonates (Eq. 1) and polycarbonates (Eq. 2) may be much more complex:

wherein R' is an aryl radical, R" is an arene radical, and n is a number at least equal to 1.

Any of the phenols, solvents, bases, ligands, the Group VIIIB elements, oxidants, including oxygen, redox agents, or reaction parameters relative to time, temperature and pressure disclosed in British Patent Application No. 41327/77 Serial No. 1572294 can be employed in the process. Also. any of the amounts disclosed in British Patent Application No. 41327/77 Serial No. 1572294 relative to the aforementioned phenols, solvents, etc., can also be employed in a like manner in the process. In general, the preferred reactants and reaction conditions disclosed in British Patent Application No. 41327/77 Serial No. 1572294 are also preferred in the present process.

Among the preferred embodiments of the invention are processes in which the Group VIIIB element is present in an ionic form; or associated with a carbonyl group; or associated with a halide; or associated with a ligand selected from an arsine, a stibine, a phosphine, a nitrile or a halide; or associated with an ionic halide compound. The base can, for example, be a tertiary amine or a sterically-hindered amine.

The reaction can if desired be carried out in the presence of an inert solvent.

The phenol which is employed can be a compound of the formula Ra-OH wherein Ra represents an aromatic radical e.g. a carbo- or hetero- monocyclic, polycyclic or fused polycyclic aromatic radical, and the OH radical is attached directly to an aromatic ring carbon atom. Phenol itself is an example of a compound of this formula.

Alternatively, the phenol can be a polyphenol, e.g. having the formula

where independently each Rl and R2 is hydrogen, C1 4 alkyl or phenyol, and independently each R3 and R4 is hydrogen or C1.4 alkyl. Preferably R1 and R are methyl and at least one of R3 and R4 is hydrogen. The most preferred polyphenol of this formula is bisphenol-A.

The reaction parameters essential to the practice of the process of the present invention comprise any of the process parameters of British Patent Application No. 41327/77 Serial No. 1572294 and in addition, the presence of a dehydrating agent is essential. The process is preferably carried out under reaction conditions wherein no measurable amount of water can be detected during the course of the reaction. Substantially anhydrous reaction conditions are defined herein and in the appended claims as the practice of the process carried out in the presence of any dehydrating agent which will take up a measurable amount of any water formed as described hereinbefore by Equations 1 and 2. The dehydrating agents are preferably inert and can be any of those known to those of ordinary skill in the art. They can be classified by any means, e.g. regenerative or nonregenerative; liquid or solid; chemical reaction, i.e. the formation of a new compound or a hydrate; physical absorption at constant or variable relative humidity; or adsorption. Preferably, the dehydrating agent(s) employed in the present process have high capacity and/or efficiency and preferably both in removing moisture from the reaction medium. As employed herein, the term "capacity" refers to the mount of water that can be removed from a given weight of the reaction medium and the efficiency refers to the degree of dryness that can be produced by the dehydrating agent. Among the many dehydrating agents that can be employed are activated alumina, barium oxide, calcium chloride, calcium oxide, calcium sulfate, lithium chloride, and molecular sieves, e.g. dehydrating agents, made from natural or synthetic crystalline alkali metal aluminosilicates of the zeolite type. Preferred dehydrating agents used in the practice of the present invention are natural and synthetic zeolites well known to the art, such as those described in detail in the publication Molecular Sieves, Charles K. Hersh, Reinhold Publishing Company, New York (1961). Representative natural zeolites which may be used include those in Table 3-1, page 21 of the Hersh reference. Additional useful zeolite dehydrating agents are set forth in Organic Catalysis over Crystalline Aluminosilicates, P.B. Venuto and P.S. Landis, Advances in Catalysis, Vol. 18, pp. 259-371 (1968). Particularly useful molecular sieves are those designated by the Linde Division of the Union Carbide Corporation as zeolite types A, X and Y, described in U.S. Patents 2,882,243, 3,130,007 and 3,529,033. Other zeolites are, of course, included within the scope of this invention.

In another embodiment of the process, preferably manganese or cobalt redox co-catalyst complexes are employed in addition to dehydrating agent. Illustrative of manganese complexes which are preferred oxidants are those commonly referred to as manganese chelates and includes those represented by the general formula LMn, wherein L is a ligand derived from an omega-hydroxyoxime or an orthohydroxyareneoxime, including mixtures thereof, and Mn is the transition metal manganese. Illustratively, the manganese can be employed in any of its oxidation states, e.g. from -1 to +7.

An omega-hydroxyoxime ligand, represented as "L" in the general formula LMn, can be described by the following formula:

wherein independently each Rb, Rc, Rd and Re is selected from hydrogen, acyclic and cyclic hydrocarbon radicals, and n is 0 or 1.

An ortho-hydroxyareneoxime ligand, represented as "L" in the general formula LMn, can be described by the following formula:

wherein Rf is independently selected from hydrogen and acyclic hydrocarbon radicals, Ar is at least a divalent arene radical having at least one - OH radical and at least one

radical attached directly to an ortho position arene ring carbon atom. Methods for the preparation of manganese chelate complexes including mixtures thereof are described in U.S. Patents 3,956,242, 3,965,069 and 3,972,851.

Illustrative of generally preferred manganese chelate complexes are compounds having the following formulae:

Illustrative of cobalt complexes which are preferred oxidants are those commonly referred to as cobalt chelates and includes those represented by the general formula:

wherein Ar represents a divalent arene radical and Rg represents a divalent arene radical andRg represents a divalent organic radical containing at least 2 carbon atoms. Methods for the preparation of cobalt chelate complexes including mixtures thereof are described in U.S. Patents 3,455,880, 3,444,133 and 3,781,382.

Generally presently preferred cobalt chelate complexes are described by the following formulae:

Since manganese and cobalt complexes can coordinate with water, oxygen, alcohol, or amines, such coordination compounds are included within the context as oxidants in the practice of the present invention.

In the process, any amount of dehyrating agent can be employed. Those skilled in the art can determine, by means of routine experimentation, the optimum amounts of any particular dehydrating agent which is selected and used in the practice of the present invention. For example, those skilled in the art can readily estimate the optimum amounts of molecular sieve required for selective absorption of water by routine reference to Linde (Registered Trade Mark) Company, molecular Types 3A and 4A "Water Data Sheets" published and distributed by Union Carbide Corporation.

In order that those skilled in the art may better understand the invention, the following Examples are given which are illustrative of the best mode of this invention, however, these Examples are not intended to limit the invention in any manner whatsoever. In the examples, unless otherwise specified, all parts are by weight and the reaction products were verified by infrared spectrum, C-13 nuclear magnetic resonance and mass spectrometry.

Reference Example A control procedure was carried out for the preparation of 4,4'-(a,a- dimethylbenzyl)diphenylcarbonate under carbon monoxide and oxygen pressure, in the absence of a drying agent.

A reaction medium containing p-cumylphenol, bis-(benzonitrile)palladium(II) dichloride, disopropylmonoethyl-amine and copper dibromide was formulated. The mole proportions of the ingredients were as follows 100:2:15:8, respectively. The reaction medium was charged with sufficient carbon monoxide to raise the pressure to 31 psi and sufficient oxygen to raise the pressure from 31 psi to 62 psi. Subsequent workup and analysis of the reaction identified a product yield of 8% of 4,4'-(a,adimethylbenzyl)diphenylcarbonate of the formula:

lhe number ot carbonate moieties, i.e.

formed per mole of palladium metal was 4. Hereafter this number is referred to as the Group VIIIB "turnover value" of the reaction.

Example 1 Preparation of 4,4'(a,a-dimethylbenzyl)diphenyl-carbonate under carbon monoxide and oxygen pressure and in the presence of a molecular sieve Type 4A -- a commercial product of Union Carbide Corporation of the general chemical formula 0.96 + 0.04 Na2O 1.00 Awl203 1.92 + 0.09 SiO2 x H2O.

The reaction medium contained p-cumylphenol, bis-(benzonitrile)palladium(II) dichloride, diisopropylmonoethyl-amine, and copper dibromide which were present in the following mole proportions 100:2:16:8, respectively. The reaction medium was charged with carbon monoxide to 31 psi and oxygen to 62 psi as in Example I. Subsequent analysis identified a product yield of 31% of 4,4'-(a,a-dimethylbenzyl)diphenylcarbonate. As illustrated by this Example, the inclusion of a dehydrating agent, e.g. a molecular sieve, significantly increases the yield of aromatic carbonate, e.g. by 400% when the yield of this example is compared with the yield of the procedure described in the reference Example.

Example 2 Preparation of 4,4'-(a, a-dimethylbenzyl)diphenyl-carbonate using p-cumylphenol, carbon monoxide, 2,2,6,6 ,N-pentamethylpiperidine, palladium(II) dibromide, bis(benzoinoxime)-manganese(II) and a molecular sieve.

A reaction vessel was charged with 2.12 g. (0.010 mole) of p-cumylphenol, 0.030 g.

(0.00010 moles) of palladium(II) di-bromide, 0.051 g. (0.00010 mole) of bis(benzoinoxime) manganese-(II), 0.155 g. (0.0010 mole) of 2,2,6,6,N-pentamethylpiperidine, 30 ml. of methyl chloride and 2.0 g. of a Linde Union Carbide 3A molecular sieve which had been activated by heating at 2000C. in vacuo. the Type 3A molecular sieve employed is a commercial product of Union Carbide Corporation produced from Type 4A molecular sieves through ionic exchange of about 75% of the sodium ions by potassium. Carbon monoxide and air were bubbled slowly through the reaction vessel mixture at room temperature for 18 hours. Gas chromatography indicated the presence of 0.495 g.

(22.2%yield) of 4,4'-(a, a-dimethylbenzyl)diphenylcarbonate. After 44 hours, reaction product contained 1.23 g. (55% yield) of the aromatic carbonate.

Examples 3 to 10 Following the General Procedure of Example 2 set out hereinbefore, a series of reactions were run employing various oxidants for the preparation of aromatic carbonates in the presence of molecular sieves. Summarized in Table I hereafter are the reaction parameters and products, i.e. the mole proportions of Group VIIIB element : redox component phenolic reactant : base, the percent conversion of the phenolic reactant to aromatic carbonate, the reaction time and the turnover value.

In all of the examples, the phenolic reactant was p-cumylphenol and the base was 2,2,6,6,N-pentnmethylpipen.dine. The Group VIIIB element in Examples 3, 4, 5 and 9 was palladium-(II) dibromide, and in Examples 6, 7 and 8 was palladium(I) monocarbonyl monobromide. The redox component oxidant employed in addition to oxygen in each example is tabulated in Table I. Example 10 was a control run analogous to Example 3 except that the Group VIII element was excluded from the reaction and the reaction time was extended.

TABLE I Turn Example Group Redox Phenolic Percent (%) Reaction Over No. Redox Component VIIIB : Component : Reactant Base Conversion Time (hr) Value 3 Mn(II)(benzoinoxime)2 1 3 100 20 96 44 95 4 Mn(II)(benzoinoxime)2 1 1 100 10 55 44 54 5 (C4H9N)2Mn(II)Br4 1 3.5 100 35 20 overnight 19 6 Mn(II)Br2.4H2O 1 10 100 100 20 165 19 7 Cu(I)Br 1 10 100 20 21 110 20 8 Co(salen)pyridine 1 3 100 15 90 192 89 9 VBr3 1 3 100 15 1.7 72 0.7 10 Mn(II)(benzoinoxime) 0 3 100 20 non- 168 0 detectable Example 11 Preparation of a polycarbonate of bisphenol-A by contacting bis(4hydroxyphenyl)propane-2,2, carbon monoxide, manganese(II)bis(benzoinoxime), 2,2,6,6,N-pentamethyIpiperidine, palladium(II)dibromide, oxygen, a molecular sieve Type 3A and alr.

A flask was charged with 4.56 g. (20.0 mmol.) of bis(4-hydroxyphenyl)propane-2,2 also known as bisphenol-A, 0.62 g. (4.4 mmol.) of 2,2,6,6,N-pentamethylpiperidine, 0.06 g.

(0.20 mmol.) of palladium(II)dibromide, 0.30 g. (0.60 mmol.) to manganese(II)bis(benzoinoxime), 4 g. of molecular sieve Type 3A and 30 ml. of methylene chloride. Carbon monoxide and air were passed through the solution for 42 hours. Reverse phase liquid chromatography showed the presence of bisphenol-A and bisphenol-A dimers, trimers, pentamers and higher oligomers An additional 0.06. (0.20 mmol.) of palladium(II)dibromide was added and the reaction continued. The M number average molecular weight of the polycarbonate was estimated at 2,800 with about a 10% recovery. This Example demonstrates and utility of the catalytic process in the preparation of polycarbonates of bisphenol-A.

While not wishing to limit the invention to any theory, it is believed that the practice of the invention is significantly improved by the presence of molecular sieves because of the ability of the molecular sieves selectively to absorb carbon dioxide and water, as opposed to carbon monoxide, oxygen and hydrogen.

In the practice of the process, the Group VIIIB elements after separation from the resulting reaction products can be oxidized or reduced by any means to any oxidation state, and can be re-employed, that is recycled, in the aromatic process described herein.

Claims

WHAT WE CLAIM IS:

1. A process for preparing an aromatic carbonate which comprises contacting, in the presence of a dehydrating agent, a phenol, oxygen, carbon monoxide, a base, a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum, and an oxidant comprising an element, a compound or a complex having an oxidation potential greater than that of the said selected Group VIIIB element.

2. A process as claimed in claim 1, wherein said Group VIIIB element is present in an ionic form.

3. A process as claimed in claim 1 or claim 2, wherein said base is a sterically hindered amine.

4. A process as claimed in any one of claims 1 to 3, wherein said Group VIIIB element is associated with a carbonyl group.

5. A process as claimed in claim 1, wherein said Group VIIIB element is associated with a halide.

6. A process as claimed in claim 1, wherein said Group VIIIB element is coordinated with a ligand selected from an arsine, a stibine, a phosphine, a nitrile or a halide.

7. A process as claimed in claim 1, wherein said Group VIIIB element is associated with an inorganic halide compound.

8. A process as claimed in any one of the preceding claims wherein said dehydrating agent is a molecular sieve.

9. A process as claimed in any one of the preceding claims, wherein said oxidant is a manganese or a cobalt complex.

10. A process as claimed in any one of the preceding claims, wherein the Group VIIIB element is palladium.

11. A process as claimed in any one of the preceding claims, wherein the phenol is bis (4-hydroxyphenyl) propane-2,2; p-cumyl-phenol or phenol.

12. A process as claimed in claim 11, wherein the base is 2,2,6,6,N - pentamethylpiperidine, the oxidant is bis-(benzoinoxime) manganese (II) and oxygen, the Group VIIIB element is palladium (II) dibromide, and the drying agent is a molecular sieve.

13. A process as claimed in any one of claims 1 to 11, wherein the oxidant is a cobalt chelate complex of the formula:

14. A process as claimed in any preceding Claim, wherein said phenol is a polyphenol.

15. A process as claimed in claim 14, wherein said polyphenol is an aromatic bisphenol of the formula:

wherein independently each Rl and R' is hydrogen, C1 4 alkyl or phenyl and independently each R3 and R4 iS hydrogen or C14 alkyl.

16. A process as claimed in claim 15, wherein R1 and R2 are methyl and at least one of R3 and R4 is hydrogen.

17. A process, as claimed in claim 15 or claim 16 wherein the base is a tertiary amine.

18. A process as claimed in any one of claims 15 to 17 carried out in the presence of an inert solvent.

19. A process according to any one of claims 15 to 18, wherein said bis-phenol is bis-phenol - A.

20. A process according to any one of claims 1 to 13 wherein said phenol has the formula: Ra - OH wherein Ra represents an aromatic radical and the -OH radical is attached directly to an aromatic ring carbon atom.

21. A process as claimed in claim 20, wherein Ra is selected from carbo-or heteromonocyclic, polycyclic or fused polycyclic aromatic radicals.

22. A process as claimed in claim 20 or claim 21, wherein the base is a tertiary amine.

23. A process as claimed in any one of claims 20 to 22 carried out in the presence of an inert solvent.

24. A process according to any one of claims 20 to 23, wherein said phenol is phenol.

25. A process as claimed in claim 1 substantially as hereinbefore described in any one of Examples 1 to 9.

26. An aromatic carbonate when produced by a process as claimed in any one of the preceding claims.