GB2069486A

GB2069486A - A Method for Making Triarylsulphonium Salts

Info

Publication number: GB2069486A
Application number: GB8101092A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1980-02-19
Filing date: 1981-01-14
Publication date: 1981-08-26
Also published as: JPH0139423B2; GB2069486B; FR2476078B1; DE3104744A1; JPS56138167A; FR2476078A1; DE3104744C2

Abstract

A method is provided for making certain arylthiotriarylsulfonium salts. A diarylsulfide is self-condensed in the presence of elemental halogen and a Lewis acid and the product is reacted with a metal salt. The resulting triarylsulfonium salts are useful as photoinitiators for a variety of cationically polymerizable materials.

Description

SPECIFICATION A Method for Making Photoinitiators Cross Reference to Related Applications Reference is made to our copending application for Photocurable Compositions, Photoinitiators and Methods for Making Such Materials, Serial No. 079,692, filed September 28,1979 and assigned to the same assignee as the present invention.

Prior to the present invention as shown by Smith Patent 4,1 73,476, various complex triphenylsulfonium salts were prepared by heating a mixture of diphenylsulfide, diphenylsulfoxide and phosphorus pentoxide. Another procedure as shown in our copending application Serial No. 079,692 based on the use of a diarylthioether and a diaryliodonium salt in the presence of a copper II catalyst.

An additional method is based on the use of aluminum chloride as shown by H. M. Pitts, U.S. Patent 2,807,648. Although the aforementioned procedures can be used for thioaryloxytriarylsulfonium salts, the yield provided by such methods rarely exceeds 50%. It would be desirable therefore to provide a method for making thioaryloxytriarylsulfonium salts at substantially improved yields.

There is provided by the present invention, a method for making triarylsulfonium salts of the formula,

which comprises (A) effecting the self-condensation of diarylsulfide of the formula, RSR in the presence of elemental halogen and a Lewis acid, (B) effecting reaction at temperatures up to 1000C between the resulting diarylsulfide selfcondensation reaction product of (A) and a metal salt of the formula, (2) YMXm and (C) recovering the triarylsulfonium salt of formula (1), where R is a C16~,3) monovalent aromatic organic radical, R1 is a C18~,31 divalent aromatic organic radical, Y is an alkali metal or alkaline earth metal ion, M is a metal or metalloid, X is a halogen radical, and n has a value of 4-6 inclusive.

Radicals included within R of formula (1) can be the same or different and are, for example, phenyl, tolyl, xylyl, naphthyl, anthryl, etc. Radicals included by R1 of formula (1) are, for example, phenylene, tolyiene, xylylene, naphthylene, etc. The aforementioned R and R' radicals also can be substituted with from 1-4 C(19 alkyl, or alkoxy radicals such as the corresponding methyl, methoxy, ethyl, propyl, butoxy, etc.; halogen radicals, for example, chlorine, bromine, or fluorine, etc., as well as nitro carbonyl and carboxy. Some of the radicals included by MXn are, for example, Puff, SbF8 Ass6, Bur4, SbF50H-, and SbCl-8.

Some of the triarylsulfonium salts of formula (1) are compounds having the formula,

Suitable metal salts of formula (2) are for example sodium or potassium tetrafluoroborate, NaPF6, NaAsF0, KSbF " KAsF8, Ca(PF0)2, Mg(AsFe)2, HPF8, HAsF6, HSbF6, Ba(AsF)2, Pb(PF6)2, Zn(AsFe)2, etc.

In the practice of the invention, a diarylsulfide, for example, diphenylsulfide, dinaphthylsulfide, etc., is reacted with an elemental halogen and a Lewis acid to produce a triarylsulfonium halide complex. Although the order of addition of the reactants is not critical, it is preferred to introduce the halogen in the presence of the Lewis acid catalyst. Accordingly, a mixture of the diarylsulfide and the Lewis acid can be prepared initially. Suitable Lewis acid catalysts which can be utilized include, for example, aluminum chloride (AICI3), SnCI4, BF3, BCI3, PF5, SbF5, Asps, etc.There can be used from about 0.5 to 2.0 moles of elemental halogen, for example, chlorine, bromine, etc., per mole of the diarylsulfide and 10 to 90% by weight of the Lewis acid catalyst, based on the mixture of diarylsulfide, elemental halogen and Lewis acid catalyst. Temperatures in the range of between -10 to 1000C and preferably 0 to 250C can be employed along with agitation of the mixture, such as stirring.

After the triarylsulfonium halide has been formed on the mixture as the result of the complete introduction of halogen, the resulting mixture can then be poured into ice water to destroy the Lewis acid complex. The triarylsulfonium halide can then be recovered from the mixture by standard techniques and further reacted with an alkali metal or alkaline earth metal, polyhalometalloid to effect a metathesis with the triarylsulfonium halide. If desired, the polyhalometalloid can be added directly to the mixture without isolation of the triarylsulfonium halide.

The resulting mixture can be heated at a temperature of 0 to 1000C and stirred for .1 to 24 hours.

The resulting triarylsulfonium poiyhalometalloid salt can be separated by standard techniques such as decantation, filtration, etc., and then washed first with water and dried in a vacuum oven at temperatures of about 40 to 1200C.

In order that those skilled in the art will be better able to practice the invention, the following examples are given by way of illustration and not by way of limitation. All parts are by weight.

Example 1 Elemental chlorine gas was slowly introduced into a vessel containing 37.2 parts of diphenylsulfide and 13.34 parts of aluminum chloride. After 9.5 parts of chlorine had been transferred, the mixture was poured into approximately 500 parts of ice water. There was obtained about a 95% yield of a white semi-solid. Based on the method of preparation, the white semi-solid was 4 thiophenoxyphenyl-S-diphenylsu Ifonium chloride.

There was added to the aforementioned substituted triphenylsulfonium chloride, 22.8 parts of potassium hexafluoroarsenate in 300 parts of hot water. The mixture was heated at a temperature of about 60 C and stirred for one hour. An orange oil was separated by decantation, washed first with water and then with anhydrous ethyl ether. Finally, the product was dried in a vacuum oven for about 8 hours at 6000. Based on method of preparation, its ultraviolet and 13C NMR spectra the product was

An 80% yield of the above sulfonium salt was obtained based on starting diphenylsulfide.

A 3% solution of the above salt in 4-vinylcyclohexene dioxide had a tack-free time of less than one second when irradiated using a GE H3T7 medium pressure mercury arc lamp mounted at a distance of 6 inches from the solution when applied onto a glass substrate as a 2 mil coating.

Example 2 There was added slowly 90 parts of bromine to a mixture of 50 parts of diphenylsulfide and about 300 parts of glacial acetic acid which was being stirred. The temperature of the reaction mixture rose to 300C and a yellow precipitate was formed. After all of the bromine had been added, the reaction mixture was warmed to 50--600C and held there for 2.5 hours. The mixture was then allowed to cool and a product was isolated by filtration and dried in vacuo. There was obtained a product yield of 82.4%. Based on method of preparation, the product was 4,4'-dibromo-diphenylsulfide.

Chlorine gas was introduced slowly into a mixture of 75.7 parts of the above 4,4'-dibromodiphenylsulfide dissolved in 435 parts of benzene while the solution was stirred. An organge crystalline product was obtained after 33 parts of chlorine gas was introduced. A solid was isolated by filtration and washed with cold benzene and hexane. There was obtained a 89% yield of 4,4'-dibromo diphenyichlorosulfonium chloride.

There was added 27.9 parts of the above 4,4'-dibromo-diphenylchlorosulfonium chloride in small portions over the course of 10 minutes to a mixture with stirring of 40 parts of anhydrous aluminum chloride in about 110 parts of diphenylsulfide. During the addition, the reaction mixture became dark brown and turned purple. The solution was allowed to stir for an additional 3 hours at room temperature and then poured into 1 50 parts of ice water. A yellow oil was obtained which was isolated by decantation. After washing twice with anhydrous ethyl ether, the oil was mixed with 100 parts of hot water and 1 5 parts of potassium hexafluoroarsenate. The mixture was vigorously stirred for one hour and the product obtained was a yellow oil which was removed by decantation and washed once again with ethyl ether. Based on method of preparation, the product was a salt having the following formula:

A 3% solution of the above salt and 4-vinylcyclohexene dioxide had a cure time of 3-5 seconds when irradiated using a GE H3T7 lamp as described in Example 1.

Although the above examples are directed to only a few of the very many variables of the present invention, it should be understood that the present invention is directed to a much broader method of making triarylsulfonium salts of formula (1), based on the reaction of diarylsulfide, and a Lewis acid catalyst.

Claims

1. A method for making a complex triarylsulfonium salt of the formula,

which comprises (1) effecting the self-condensation of diarylsulfide of the formula, R-S-R in the presence of elemental halogen and a Lewis acid, (2) effecting reaction at temperatures up to 1000C between the resulting diarylsulfide selfcondensation reaction product of (1) and a metal salt of the formula, YMXn and (3) recovering said triarylsulfonium salt from the mixture of (2), where R is a C(813) monovalent aromatic organic radical, R1 is a Cm6 13) divalent aromatic organic radical, Y is an alkali metal or alkali metal ion, M is a metal or metalloid, Xis a halogen radical and n has a value of 4-6 inclusive.

2. A method as claimed in Claim 1, where the diarylsulfide is diphenylsulfide.

3. A method as claimed in Claim 1 or Claim 2, where the diarylsulfide is diphenylsulfide.

4. A method as claimed in any one of the preceding claims, wherein the Lewis acid is aluminum chloride.

5. A method as claimed in any one of the preceding claims, wherein the metal salt is potassium hexafluoroarsenate.

6. A method as claimed in any one of Claims 1 to 4, where the metal salt is potassium hexafluoroantimonate.

7. A method as claimed in any one of Claims 1 to 4, where the metal salt is potassium hexafluorophosphate.

8. A method as claimed in Claim 1, substantially as hereinbefore described in any one of the Examples.

9. A triarylsulfonium salt when produced by a method as claimed in any one of the preceding claims.