1,4-sulfoxonium salt and preparation method therefor, and preparation method for acid-generating cationic photoinitiator

Abstract

The present invention relates to a 1,4-sulfoxonium salt and a preparation method therefor, and a method for preparing an acid-generating cationic photoinitiator from the 1,4-sulfoxonium salt.

Description

1,4-oxysulphonium salts, processes for their preparation and processes for the preparation of onium photoinitiators of the acid generator type TECHNICAL FIELD

[0001] The present invention relates to 1,4-oxysulphonium salts, processes for their preparation and processes for the preparation of onium photoinitiators of the acid generator type from said 1,4-oxysulphonium salts. TECHNICAL BACKGROUND

[0002] Photoresists are generally composed of 4 parts: resin type polymer, solvent, photo acid generator, additives. The photo acid generator (also known as photoinitiator) controls the photosensitivity of the photoresist to a certain specific wavelength of light / electron beam / ion beam / X-ray, etc., and causes a corresponding chemical reaction. The photoactive component of the photoresist is the photo acid generator, which generates acid under irradiation. Among the existing photo acid generators, sulphonium salt photo acid generators occupy a dominant position. In recent years, the shortening of the wavelength of energy has been developing, and in the pursuit of fine patterns today, environmentally friendly photo acid generators with good acid generation efficiency and excellent development performance have become the focus of research.

[0003] At present, the main varieties of sulphonium salt photo acid generators reported are

[0004] (1) Triphenyl series of sulphonium salts, the synthesis method is mostly based on Grignard method. In the presence of trimethylsilyl chloride, phenylmagnesium bromide reacts with diphenyl sulfoxide to prepare the target product. The main varieties are:

[0005] (2) Tetrahydrothiophenium salt, the synthesis method is mostly based on the cyclization of thiophenol and 1,4-dibromobutane. The main varieties are:

[0006] (3) 1,4-oxysulphonium salt, the main varieties are:

[0007] The 1,4-oxysulphonium salt photo acid generator has two less benzene rings compared to the triphenyl sulphonium salt, and the small molecules generated under ultraviolet light irradiation have the characteristics of low toxicity and low mobility. It has received extensive attention. The preparation methods are reported in documents US2016052860, US9274421, US2016052859, JP2017021342A, which are all prepared by reacting iodonium chloride salt and 1,4-thioxanthane. The reaction formula is as follows:

[0008] This method uses expensive bis-tert-butyl phenyliodonium chloride as a raw material, and there is more waste acid and waste water, which is difficult to industrialize.

[0009] The application designs a new synthetic route and takes 1,4-oxysulfonium salt as an intermediate compound, has the characteristics of low cost, less waste acid and waste water, and easy industrial production. SUMMARY

[0010] The application aims to provide a suitable intermediate for synthesizing acid-producing cationic photoinitiator and a preparation method thereof, and a method for synthesizing acid-producing cationic photoinitiator, the method and the intermediate compound have the characteristics of low cost, less waste acid and waste water, and easy industrial production.

[0011] The technical solutions of the application can be summarized as follows:

[0012] 1. A 1,4-oxysulfonium salt of general formula (I)

[0013] wherein

[0014] each R is independently selected from the group consisting of C1-C 12 alkyl and nitro;

[0015] X is halogen; and

[0016] m is an integer from 0 to 5.

[0017] 2. The 1,4-oxysulfonium salt of general formula (I) according to embodiment 1, wherein

[0018] each R is independently C1-C 12 alkyl, preferably C1-C8 alkyl;

[0019] X is halogen, preferably bromine; and

[0020] m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2.

[0021] 3. The 1,4-oxysulfonium salt of general formula (I) according to embodiment 1 or 2, wherein

[0022] R is C1-C6 alkyl, preferably tert-butyl;

[0023] X is bromine; and

[0024] m is 1;

[0025] Preferably, R is located in the para position relative to the position of the connection of the phenyl ring to the 1,4-oxysulfonium ring.

[0026] 4. A method for preparing a 1,4-oxysulfonium salt of general formula (I) according to any one of embodiments 1 to 3, comprising reacting a bis(2-halogenoethyl) ether of formula (II) with a thiophenol of formula (III) to obtain a 1,4-oxysulfonium salt of general formula (I):

[0027] wherein R, X and m are defined as in any one of embodiments 1 to 3.

[0028] 5. The process according to embodiment 4, wherein the molar ratio of the bis(2-haloethyl) ether of the formula (II) to the thiophenol of the formula (III) is from 0.8:1 to 1 :0.8, preferably from 1 :1 to 1 :0.8.

[0029] 6. The process according to embodiment 4 or 5, wherein the reaction of the bis(2-haloethyl) ether of the formula (II) with the thiophenol of the formula (III) is carried out in the presence of a base, preferably the base is selected from the group consisting of inorganic bases and organic bases such as organic nitrogen-containing bases, preferably the molar ratio of the base to the thiophenol of the formula (III) is from 5:1 to 1 :2, preferably from 3:1 to 1 :1.

[0030] 7. The process according to embodiment 6, wherein the base is added to the bis(2-haloethyl) ether of the formula (II) and the thiophenol of the formula (III) at a temperature of not more than 15 °C, preferably not more than 10 °C, in particular not more than 5 °C.

[0031] 8. The process according to any one of embodiments 4 to 7, wherein the reaction of the bis(2-haloethyl) ether of the formula (II) with the thiophenol of the formula (III) is carried out in a solvent.

[0032] 9. The process according to any one of embodiments 4 to 8, wherein the reaction of the bis(2-haloethyl) ether of the formula (II) with the thiophenol of the formula (III) is carried out at a temperature of from 0 to 50 °C, preferably from 10 to 50 °C, in particular from 20 to 30 °C.

[0033] 10. The process according to any one of embodiments 4 to 9, wherein the bis(2-haloethyl) ether of the formula (II) is prepared by reacting a diethylene glycol with a sulfonating agent to obtain the corresponding sulfonate compound, and then reacting the sulfonate compound with a halogenating agent to obtain the bis(2-haloethyl) ether of the formula (II).

[0034] 11. The process according to any one of embodiments 4 to 10, wherein the thiophenol of the formula (III) is prepared by:

[0035] reacting a compound of the formula (III-1)

[0036] wherein R and m are defined as in any one of embodiments 1 to 3,

[0037] and then reducing the resulting compound of the formula (III-2) to obtain the thiophenol of the formula (III).

[0038] 12. A process for preparing an acid generator type cationic photoinitiator, comprising preparing by anion exchange of a 1,4-oxysulphonium salt of general formula (I) according to any one of embodiments 1 to 3 with a corresponding anion salt suitable for obtaining said acid generator type cationic photoinitiator; or

[0039] comprising preparing a 1,4-oxysulphonium salt of general formula (I) by a process according to any one of embodiments 4 to 11, and then preparing by anion exchange of the resulting 1,4-oxysulphonium salt of general formula (I) with a corresponding anion salt suitable for obtaining said acid generator type cationic photoinitiator.

[0040] 13. The process according to embodiment 12, wherein the corresponding anion salt is hexafluorophosphate, hexafluoroantimonate or 2-(adamantan-1-methoxy)-1,1-difluoro-2-oxoethanesulfonate.

[0041] 14. The process according to embodiment 12 or 13, wherein the anion exchange fulfils at least one, two or all of the following conditions:

[0042] a) is carried out in a solvent;

[0043] b) is carried out at 10 to 80 °C;

[0044] c) the molar ratio of the 1,4-oxysulphonium salt of general formula (I) to the corresponding anion salt is 1:1 to 1:2.

[0045] The advantageous effects of the present application are as follows:

[0046] (1) The process route of the present application avoids the high cost, high waste acid and waste water problems caused by using expensive iodonium salt as raw material;

[0047] (2) The present application successfully prepared the 4-(4-tert-butylphenyl)-1,4-oxysulphonium bromide intermediate, which can be exchanged with any anion compound to obtain the corresponding acid generator, creating a convenient synthesis method for preparing acid generators;

[0048] (3) The raw materials selected in the present application are widely available and inexpensive; the reaction conditions of the method of the present application are mild, the reaction yield is high, and it has good industrial application prospect. DETAILED DESCRIPTION

[0049] One aspect of the present application relates to a 1,4-oxysulphonium salt of general formula (I)

[0050] wherein

[0051] each R is independently selected from the group consisting of C1-C 12 alkyl and nitro;

[0052] X is halogen; and

[0053] m is an integer from 0 to 5.

[0054] "Halogen" means fluorine, chlorine, bromine and iodine.

[0055] In the present application, the prefix "C n -C m " in each case denotes the number of carbon atoms comprised in the group as n-m.

[0056] The term "C n -C m alkyl" as used herein means a straight-chain or branched saturated hydrocarbon group having n-m, such as 1-12, 1-10, 1-8, 1-6, 1-4 or 1, 2, 3, 4, 5, 6, 8, 10 or 12 carbon atoms, for example methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, t-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl and n-dodecyl and the like.

[0057] In one embodiment, each R is independently of the others C1-C 12 alkyl, preferably C1-C8 alkyl, C1-C6 alkyl, in particular t-butyl.

[0058] In a preferred embodiment, R is located in the para position to the position of attachment of the phenyl ring to the 1,4-oxathi- ium ring.

[0059] According to the present application, X is halogen, for example fluorine, chlorine, bromine and iodine, preferably bromine. According to the present application, it is not only advantageous for the reaction to proceed when X is bromine, but it can also be advantageous to save costs, in particular compared to iodine.

[0060] According to the present application, m is an integer from 0 to 5, for example an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2, in particular 1.

[0061] In a preferred embodiment, each variable has the following definition:

[0062] each R independently of the others is C1-C8 alkyl, preferably C1-C8 alkyl; 12 alkyl, preferably C1-C8 alkyl;

[0063] X is halogen, preferably bromine; and

[0064] m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2.

[0065] In a preferred embodiment, each of the variables has the following definition:

[0066] R is C1-C6 alkyl, preferably tert-butyl;

[0067] X is bromine; and

[0068] m is 1.

[0069] In a preferred embodiment, each of the variables has the following definition:

[0070] each R independently of the others is C1-C8 alkyl, preferably C1-C8 alkyl; 12 alkyl, preferably C1-C8 alkyl;

[0071] X is halogen, preferably bromine;

[0072] m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2; and

[0073] R is located in the para position relative to the position of attachment of the phenyl ring to the 1,4-oxathi- ium ring.

[0074] In a preferred embodiment, each of the variables has the following definition:

[0075] R is C1-C6 alkyl, preferably tert-butyl;

[0076] X is bromine;

[0077] m is 1; and

[0078] R is located in the para position relative to the position of attachment of the phenyl ring to the 1,4-oxathi- ium ring.

[0079] In a preferred embodiment, each of the variables has the following definition:

[0080] R is tert-butyl;

[0081] X is bromine;

[0082] m is 1; and

[0083] R is located in the para position relative to the position of attachment of the phenyl ring to the 1,4-oxathi- ium ring.

[0084] For example, the 1,4-oxathiium salt of general formula (I) of the present application can have the following structure:

[0085] One aspect of the present application relates to a process for preparing a 1,4-oxysulfonium salt of general formula (I) according to the present application, comprising reacting a bis(2-halogenoethyl)ether of formula (II) with a thiophenol of formula (III) to obtain a 1,4-oxysulfonium salt of general formula (I):

[0086] wherein R, X and m are as defined above, in particular having the preferred definitions described above.

[0087] For example, in one embodiment, the variables have the following definitions:

[0088] each R is independently of the others C1-C8alkyl, preferably C1-C4alkyl; 12 C8alkyl, preferably C1-C4alkyl;

[0089] X is halogen, preferably bromine; and

[0090] m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2.

[0091] In one preferred embodiment, the variables have the following definitions:

[0092] R is tert-butyl;

[0093] X is bromine;

[0094] m is 1; and

[0095] R is located in the para position to the SH group.

[0096] In one embodiment, the molar ratio of the bis(2-halogenoethyl)ether of formula (II) to the thiophenol of formula (III) is from 0.8:1 to 1:0.8 (e.g. 0.85:1, 0.9:1, 0.95:1, 1:1, 1:0.95, 1:0.9, 1:0.85, 1:8), preferably from 1:1 to 1:0.8.

[0097] In one embodiment, the reaction of bis(2-halogenethyl)ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base. The base can be selected from inorganic bases and organic bases. Inorganic bases are for example alkali and alkaline earth metal hydroxides such as LiOH, NaOH, KOH, or Ca(OH)2, alkali and alkaline earth metal carbonates such as Na2CO3, K2CO3, or Cs2CO3, alkali metal bicarbonates such as NaHCO3. Organic bases are preferably organic nitrogen bases, which can be tertiary amines (such as trialkylamines, such as tri-Ci-C6-alkylamines, such as triethylamine, diisopropylethylamine; N-methylpiperidine) or nitrogen-containing basic aromatic rings such as pyridine, 2,4,6-trimethylpyridine, 2,6-dimethylpyridine, or 4-(dimethylamino)pyridine, or bicyclic amines such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), or 1,4-diazabicyclo[2.2.2]octane (DABCO).

[0098] The base can be selected from alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal bicarbonates, tertiary amines, nitrogen-containing basic aromatic rings and bicyclic amines. In one embodiment, the base can be selected from alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, tertiary amines, nitrogen-containing basic aromatic rings and bicyclic amines. Preferably, the base is selected from tertiary amines (such as trialkylamines such as triethylamine), pyridine, potassium carbonate, sodium carbonate, sodium hydroxide and potassium hydroxide.

[0099] The molar ratio of the base to thiophenol of formula (III) can be in the range of 5:1 to 1 :2 (e.g. 5:1, 4:1, 3:1, 2:1, 1 :1, 1 :2), preferably in the range of 3:1 to 1 :1.

[0100] According to one preferred embodiment, the base is added to the bis(2-halogenethyl)ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 15°C (e.g. 12°C, 10°C, 8°C, 5°C, 2°C, 0°C), preferably not more than 10°C, e.g. at a temperature in the range of 0 to 15°C, preferably in the range of 0 to 10°C, more preferably in the range of 0 to 5°C. After the base has been added, the reaction can be warmed to the reaction temperature, if necessary.

[0101] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out in a solvent. Suitable solvents are selected from the group consisting of halogenated hydrocarbons such as dichloromethane (DCM), dichloroethane or chloroform, ethers such as diethyl ether, diisopropyl ether, tert-butyl methyl ether, tetrahydrofuran (THF) or 1,4-dioxane, and esters such as n-propyl acetate, isopropyl acetate, ethyl acetate or butyl acetate. Preferably, the solvent is selected from the group consisting of dichloromethane, dichloroethane, diisopropyl ether, tert-butyl methyl ether and ethyl acetate.

[0102] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out at 0-50 °C (e.g. 0 °C, 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, or 50 °C), preferably at 10-50 °C or 15-40 °C, in particular at 20-30 °C. In one embodiment, the reaction is carried out at room temperature.

[0103] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out for 4-15 hours or 6-12 hours or 8-12 hours.

[0104] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out in the presence of a base, and wherein the reaction is carried out at 0-50 °C.

[0105] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out in the presence of a base, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at 0-50 °C.

[0106] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out in the presence of a base, wherein the molar ratio of the base to the thiophenol of the formula (III) is 5:1 to 1 :2, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at 0-50 °C.

[0107] In one embodiment, the reaction of the bis(2-halogenethyl)ether of the formula (II) with the thiophenol of the formula (III) is carried out in the presence of a base, wherein the molar ratio of the base to the thiophenol of the formula (III) is 5:1 to 1 :2, wherein the base is added to the bis(2-halogenethyl)ether of the formula (II) and the thiophenol of the formula (III) at a temperature of not more than 15 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at 0-50 °C.

[0108] In one embodiment, the reaction of bis(2-halogenethyl) ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base, wherein the molar ratio of bis(2-halogenethyl) ether of formula (II) to thiophenol of formula (III) is from 0.8:1 to 1 :0.8, wherein the molar ratio of the base to thiophenol of formula (III) is from 5:1 to 1 :2, wherein the base is added to bis(2-halogenethyl) ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 15 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at a temperature of from 0 to 50 °C.

[0109] In one embodiment, the reaction of bis(2-halogenethyl) ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base, wherein the molar ratio of bis(2-halogenethyl) ether of formula (II) to thiophenol of formula (III) is from 0.8:1 to 1 :0.8, wherein the molar ratio of the base to thiophenol of formula (III) is from 5:1 to 1 :2, wherein the base is added to bis(2-halogenethyl) ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 15 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at a temperature of from 0 to 50 °C, and the reaction is carried out for a period of from 4 to 15 hours.

[0110] In one embodiment, the reaction of bis(2-halogenethyl) ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base, wherein the molar ratio of bis(2-halogenethyl) ether of formula (II) to thiophenol of formula (III) is from 0.8:1 to 1 :0.8, wherein the molar ratio of the base to thiophenol of formula (III) is from 5:1 to 1 :2, wherein the base is added to bis(2-halogenethyl) ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 15 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at a temperature of from 0 to 50 °C, and the reaction is carried out for a period of from 4 to 15 hours.

[0111] In one embodiment, the reaction of bis(2-halogenethyl) ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base, wherein the molar ratio of bis(2-halogenethyl) ether of formula (II) to thiophenol of formula (III) is from 0.8:1 to 1 :0.8, wherein the molar ratio of the base to thiophenol of formula (III) is from 5:1 to 1 :2, wherein the base is added to bis(2-halogenethyl) ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 15 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at a temperature of from 0 to 50 °C, and the reaction is carried out for a period of from 4 to 15 hours.

[0112] In one embodiment, the reaction of bis(2-halogenethyl) ether of formula (II) with thiophenol of formula (III) is carried out in the presence of a base, wherein the base is selected from inorganic bases and organic bases such as organic nitrogen-containing bases, wherein the molar ratio of bis(2-halogenethyl) ether of formula (II) to thiophenol of formula (III) is in the range of 1 : 1 to 1 : 0.8, wherein the molar ratio of the base to thiophenol of formula (III) is in the range of 3: 1 to 1 : 1, wherein the base is added to bis(2-halogenethyl) ether of formula (II) and thiophenol of formula (III) at a temperature of not more than 5 °C, wherein the reaction is carried out in a solvent, and wherein the reaction is carried out at a temperature in the range of 20 to 30 °C, and the reaction is carried out for a time in the range of 8 to 12 hours.

[0113] After completion of the reaction, an acid such as hydrochloric acid can be added to the reaction mixture. The product can then be purified by extraction, such as extraction with ethyl acetate, washing, recrystallization.

[0114] In one embodiment, bis(2-halogenethyl) ether of formula (II) is prepared by reacting diethylene glycol with a sulfonating agent to obtain the corresponding sulfonate compound, and then reacting the sulfonate compound with a halogenating agent to obtain bis(2-halogenethyl) ether of formula (II).

[0115] The diethylene glycol is typically reacted with the sulfonating agent in stoichiometric amounts, or the sulfonating agent is used in an excess of up to 50% or in an excess of up to 30%. The sulfonating agent can be selected from the group consisting of methanesulfonyl chloride, toluenesulfonyl chloride, and thionyl chloride. The reaction of diethylene glycol with the sulfonating agent can be carried out in the presence of a base. The base is as described above. Preferably, the base is selected from the group consisting of tertiary amines (such as trialkylamines such as triethylamine), pyridine, potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide. The base is typically used in stoichiometric amounts or in excess.

[0116] The reaction of diethylene glycol with the sulfonating agent can be carried out in a solvent. Suitable solvents are as described above. For example, the solvent is selected from the group consisting of halogenated hydrocarbons such as dichloromethane (DCM), dichloroethane, or chloroform, esters such as n-propyl acetate, isopropyl acetate, ethyl acetate, or butyl acetate, and aromatic hydrocarbons such as toluene. Preferably, the solvent is selected from the group consisting of dichloromethane, dichloroethane, toluene, and ethyl acetate.

[0117] The reaction of diethylene glycol with the sulfonating agent can be carried out at a temperature in the range of 0 to 100 °C, preferably in the range of 10 to 50 °C, in particular in the range of 20 to 30 °C, or even at room temperature. The reaction time can be in the range of 2 to 20 hours or in the range of 5 to 15 hours.

[0118] The sulfonic acid ester compound is typically reacted with the halogenating agent in stoichiometric amounts, or the halogenating agent can be present in up to 20% excess. The halogenating agent can be selected from the group consisting of KBr, PBr3, and PCl3. The reaction of the sulfonic acid ester compound with the halogenating agent can be carried out in a solvent. Suitable solvents are described above. The reaction of the sulfonic acid ester compound with the halogenating agent can be carried out under reflux. The reaction time can be in the range of 5 to 24 hours, or 10 to 20 hours.

[0119] In one embodiment, the thiophenol of formula (III) is prepared as follows:

[0120] The compound of formula (III-1) is reacted with chlorosulfonic acid to give a compound of formula (III-2),

[0121] wherein R and m are as defined above,

[0122] The resulting compound of formula (III-2) is then reduced to give the thiophenol of formula (III).

[0123] For example, in one embodiment, each variable has the following definition: each R is independently C1-C8 alkyl, preferably C1-C8 alkyl; and m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1, or 2. In a preferred embodiment, each variable has the following definition: R is t-butyl; m is 1; and R is located in the para position to the SO2CI group. 12 alkyl, preferably C1-C8 alkyl; and m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1, or 2. In a preferred embodiment, each variable has the following definition: R is t-butyl; m is 1; and R is located in the para position to the SO2CI group.

[0124] The molar ratio of the compound of formula (III-1) to chlorosulfonic acid can be in the range of 1 : 1 to 1 : 1.5, preferably 1 : 1 to 1 : 1.2.

[0125] The reaction can be carried out in a solvent. Suitable solvents are described above. For example, the solvent is selected from the group consisting of halogenated hydrocarbons such as dichloromethane (DCM), dichloroethane, or chloroform, esters such as n-propyl acetate, isopropyl acetate, ethyl acetate, or butyl acetate, and aromatic hydrocarbons such as toluene. Preferably, the solvent is selected from the group consisting of dichloromethane, dichloroethane, toluene, and ethyl acetate.

[0126] The reaction temperature of the compound of formula (III-1) with chlorosulfonic acid can be in the range of -10 °C to 50 °C, for example, 0 °C to 40 °C. The reaction time of the compound of formula (III-1) with chlorosulfonic acid can be in the range of 2 to 16 hours, or 5 to 12 hours.

[0127] The reduction of the compound of formula (III-2) is carried out using a reducing agent. Suitable reducing agents can be selected from the group consisting of iron powder, zinc powder, red phosphorus, and / or iodine. The molar ratio of the compound of formula (III-2) to reducing agent is typically in the range of 1 : 4 to 1 : 8, or 1 : 5 to 1 : 7, such as 1 : 6.

[0128] According to the present application, the reduction is carried out in the presence of an acid. The acid can be hydrochloric acid or sulfuric acid. The molar ratio of acid to compound of formula (III-2) is typically 2:1 to 1 :1 (e.g. 1.5:1).

[0129] The reduction can be carried out at 10 to 150°C, such as 20 to 130°C, preferably first at 10 to 50°C or 15 to 40°C and then at 80 to 150°C or 90 to 130°C or 80 to 110°C or 85 to 100°C. The time of the reduction can be 2 to 10 hours, or 3 to 8 hours; preferably 1 to 5 hours or 2 to 4 hours at 10 to 50°C or 15 to 40°C and then 2 to 6 hours or 3 to 5 hours at 80 to 150°C or 80 to 130°C or 80 to 110°C or 85 to 100°C.

[0130] According to the present application, the reduction is carried out under inert atmosphere, such as nitrogen.

[0131] One aspect of the present application relates to a process for the preparation of an acid generator type cationic photoinitiator, comprising preparing a 1,4-oxysulfoxonium salt of general formula (I) according to the present application and subjecting it to an anion exchange with a corresponding anion salt suitable to obtain said acid generator type cationic photoinitiator; or

[0132] comprising preparing a 1,4-oxysulfoxonium salt of general formula (I) according to the process of the present application and then subjecting the resulting 1,4-oxysulfoxonium salt of general formula (I) to an anion exchange with a corresponding anion salt suitable to obtain said acid generator type cationic photoinitiator.

[0133] In one embodiment, the salt of the corresponding anion is a salt of triflate, BF4 - , CIO4 - , PF6 - , AsF6 - , SbF6 - and 2-(adamantan-1 -methoxy)-1,1 -difluoro-2-oxoethanesulfonate, preferably the salt of the corresponding anion is hexafluorophosphate, hexafluoroantimonate or 2-(adamantan-1 -methoxy)-1,1 -difluoro-2-oxoethanesulfonate.

[0134] The cation of the salt of the corresponding anion is preferably an alkali metal cation.

[0135] In one embodiment, the anion exchange meets at least one, two or all of the following conditions:

[0136] a) it is carried out in a solvent;

[0137] b) it is carried out at 10 to 80°C (e.g. 20°C, 40°C or 60°C) or 15 to 75°C or 20 to 70°C;

[0138] c) the molar ratio of the 1,4-oxysulphonium salt of general formula (I) to the corresponding anion salt is 1:1 to 1:2 or 1:1 to 1:1.5.

[0139] The solvent can be selected from alcohols such as methanol or ethanol, ketones such as acetone, halogenated hydrocarbons such as dichloromethane (DCM), dichloroethane or chloroform, esters such as n-propyl acetate, isopropyl acetate, ethyl acetate or butyl acetate, and water. Preferably the solvent is selected from methanol, acetone, ethyl acetate, water, dichloromethane and combinations thereof, preferably combinations of water and methanol, acetone, ethyl acetate or dichloromethane, such as combinations of water and ethyl acetate, water and dichloromethane, water and acetone, and water and methanol.

[0140] The anion exchange can be carried out for 1 to 10 hours, or 1.5 to 8 hours, or 1.5 to 5 hours.

[0141] Example

[0142] Example 1:

[0143] 1. Preparation of ethylene glycol dimethane sulfonate

[0144] In a 500 ml reaction flask was taken ethylene glycol 42.4 g (0.4 mol), triethylamine 80.8 g (0.8 mol) and solvent dichloroethane 200 ml, cooled to 0 °C, added dropwise methylsulfonyl chloride 91.4 g (0.8 mol), after completion of addition, raised to room temperature and stirred overnight, then washed with 100 ml of 1 M hydrochloric acid, washed with 3 x 100 ml of water, concentrated under reduced pressure, cooled to crystallize the product 94.38 g, i.e. the title compound, yield 90.06 %. 1 H NMR (300 MHz, CDC13) δ ppm 3.07 (s, 6 H, CH3), 3.76-3.83 (m, 4 H,), 4.34-4.41 (m, 4 H,).

[0145] 2. Preparation of bis(2-bromoethyl)ether

[0146] In a 500 ml reaction flask fitted with a stirrer, reflux condenser, thermometer was taken 200 ml of isopropyl ether, 52.4 g (0.2 mol) of ethylene glycol dimethane sulfonate and 48.8 g (0.41 mol) of potassium bromide, heated to reflux for 18 h, cooled, filtered to remove potassium methanesulfonate salt, the filtrate was washed with 3 x 100 ml of water, concentrated, the crude was distilled under reduced pressure, collecting the fraction 74-74 °C / 4 Torr 39.9 g, yield 86 %.

[0147] 1H-NMR (CDC13, δ ppm): 1.21 (9H, s, C(CH3)3), 3.19 (1H, s, SH), 7.05 (4H, m, Har).

[0148] 3. Synthesis of 4-tert-butylbenzenesulfonyl chloride

[0149] Into a 500ml flask equipped with a stirrer, thermometer, 200ml of dichloroethane was added, 67.0g (0.5mol) of tert-butylbenzene, cooled to 0-5°C, and 69.9g (0.6mol) of chlorosulfonic acid was added dropwise. After the dropwise addition, the reaction was maintained at 0°C for 2 hours, and then the temperature was raised to 25-30°C and the reaction was continued for 8 hours. The reaction was poured into 200g of ice water and hydrolyzed, and the aqueous layer was extracted with 100ml of dichloroethane twice. The combined organic layer was washed with water, and concentrated to give 97.9g of 4-tert-butylbenzenesulfonyl chloride as a white solid, which was the title compound, in a yield of 84.4%.

[0150] 4. Synthesis of 4-tert-butylbenzenethiol

[0151] Into a 500ml flask equipped with a stirrer, reflux condenser, thermometer, 89.6g of 30% hydrochloric acid, 100g of water, and 116g (0.5mol) of 4-tert-butylbenzenesulfonyl chloride prepared according to the method of Step 3 above were added, and stirred rapidly under nitrogen for 10 minutes. Then, 168g (3.0mol) of reduced iron powder was added at 20-30°C, and the reaction was maintained at 90-95°C for 4 hours. After cooling, the reaction solution was extracted with dichloromethane, washed with water, concentrated, and distilled under reduced pressure to collect a fraction of 88-90°C / 2 Torr to give 66.4g of colorless oil as the title compound in a yield of 80%. 1 H-NMR (CDC13, δ ppm): 1.21 (9H, s, C(CH3)3), 3.19 (1H, s, SH), 7.05 (4H, m, Har).

[0152] 5. Synthesis of 4-(4-tert-butylphenyl)-l,4-oxathi- ium bromide

[0153] In a 500ml reaction flask equipped with a stirrer and a thermometer, 200ml of diisopropyl ether, 33.2g (0.2mol) of 4-tert-butylphenylthiol and 51.04g (0.22mol) of bis(2-bromoethyl)ether prepared according to the procedure described in Step 2 above were added. The reaction mixture was cooled to 0-5°C in an ice bath and 30.3g (0.3mol) of triethylamine was added dropwise over a period of 1h. The reaction mixture was allowed to warm to room temperature and the reaction was continued for 10h. The reaction was monitored by TLC. The reaction mixture was quenched with 100ml of 1.5M HCl and the organic layer was extracted with ethyl acetate. The combined organic layer was washed with saturated NaHCO3solution and concentrated. The residue was crystallized from n-hexane to give 49.6g of 4-(4-tert-butylphenyl)-1,4-oxathiium bromide as a white solid in 78.3% yield. Melting point: 240-242°C. 1 H-NMR (600 MHz, CDCl3) δ: 7.28 (d, 2H), 7.21 (d, 2H), 4.38 (m, 2H), 4.10 (m, 2H), 3.92 (m, 2H), 3.67 (m, 2H), 1.33 (s, 9H).

[0154] 6. Preparation of 4-(4-tert-butylphenyl)-1,4-oxathiium hexafluorophosphate

[0155] In a 500ml reaction flask equipped with a stirrer and a thermometer, 150ml of ethyl acetate and 30.2g (0.1mol) of 4-(4-tert-butylphenyl)-1,4-oxathiium bromide were added. 22.3g (0.12mol) of sodium hexafluorophosphate in 100ml of water was added dropwise at room temperature. The reaction was stirred at room temperature for 6h. The aqueous layer was separated and the organic layer was washed with water, concentrated and dried to give 36.3g of 4-(4-tert-butylphenyl)-1,4-oxathiium hexafluorophosphate as the desired product in 95% yield. 1 H-NMR (600 MHz, CDCl3) δ: 7.28 (d, 2H), 7.21 (d, 2H), 4.38 (m, 2H), 4.10 (m, 2H), 3.92 (m, 2H), 3.67 (m, 2H), 1.33 (s, 9H).

[0156] Example 2:

[0157] 1. Preparation of 4-(4-tert-butylphenyl)-1,4-oxathiium-2-(adamantan-1- methoxy)-1,1-difluoro-2-oxoethanesulfonate

[0158] Prepared 158 g (0.5 mol) of 4-(4-tert-butylphenyl)-l,4-oxathi- ium bromide salt according to the method of Example 1 and added to a 500 ml three-necked reaction flask equipped with a thermometer and an electric stirrer, added 300 ml of acetone, after dissolution, added 189 g (0.5 mol) of 2-(adamantan-l-methoxy)-l,l-difluoro-2-oxoethane sulfonate sodium and stirred to reflux for 2 h, cooled, washed with water, dried over anhydrous magnesium sulfate, concentrated to give 281 g of the desired product, yield 95%.

[0159] Finally, it should be noted that the above is merely to illustrate the technical solutions of the present application, and is not a limitation on the scope of protection of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those of ordinary skill in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A 1,4-oxosulfonium salt of general formula (I) wherein each R is independently selected from the group consisting of C1-C 12 alkyl and nitro; X is halogen; and m is an integer from 0 to 5.

2. The 1,4-oxysulphonium salt of general formula (I) according to claim 1, wherein Each R is independently C1-C 12 Alkyl groups, preferably C1-C8 alkyl groups; X is halogen, preferably bromine; and m is an integer from 0 to 4, preferably an integer from 0 to 3, more preferably 0, 1 or 2.

3. The 1,4-oxysulphonium salt of general formula (I) according to claim 1 or 2, wherein R is CrC6alkyl, preferably tert-butyl; X is bromine; and m is 1 ; preferably R is located in para position to the position of attachment of the phenyl ring to the 1,4-oxysulphonium ring.

4. A method for preparing a 1,4-oxosulfonium salt of general formula (I) according to any one of claims 1-3, comprising reacting a bis(2-haloethyl) ether of formula (II) with a thiophene of formula (III) to obtain a 1,4-oxosulfonium salt of general formula (I): wherein R, X and m are as defined in any one of claims 1 to 3.

5. The process according to claim 4, wherein the molar ratio of the bis(2-haloethyl)ether of formula (II) to the thiophenol of formula (III) is from 0.8:1 to 1 :0.8, preferably from 1 :1 to 1 :0.

8.

6. The process according to claim 4 or 5, wherein the reaction of the bis(2-haloethyl)ether of formula (II) with the thiophenol of formula (III) is carried out in the presence of a base, preferably the base is selected from the group consisting of inorganic bases and organic bases such as organic nitrogen-containing bases, preferably the molar ratio of the base to the thiophenol of formula (III) is from 5:1 to 1 :2, preferably from 3:1 to 1 :

1.

7. The process according to claim 6, wherein the base is added to the bis(2-haloethyl)ether of formula (II) and the thiophenol of formula (III) at a temperature of not more than 15 °C, preferably not more than 10 °C, in particular not more than 5 °C.

8. The process according to any one of claims 4 to 7, wherein the reaction of the bis(2-haloethyl)ether of formula (II) with the thiophenol of formula (III) is carried out in a solvent.

9. The process according to any one of claims 4 to 8, wherein the reaction of the bis(2-haloethyl)ether of formula (II) with the thiophenol of formula (III) is carried out at a temperature from 0 to 50 °C, preferably from 10 to 50 °C, in particular from 20 to 30 °C.

10. The process according to any one of claims 4 to 9, wherein the bis(2-haloethyl)ether of formula (II) is prepared by reacting a diethylene glycol with a sulfonating agent to obtain the corresponding sulfonate compound, and then reacting the sulfonate compound with a halogenating agent to obtain the bis(2-haloethyl)ether of formula (II).

11. The process according to any one of claims 4 to 10, wherein the thiophenol of formula (III) is prepared by: reacting a compound of formula (III-1) with chlorosulfonic acid to obtain a compound of formula (III-2), wherein R and m are as defined in any one of claims 1 to 3, then reducing the resulting compound of formula (III-2) to obtain the thiophenol of formula (III).

12. A process for the preparation of an acid generator type cationic photoinitiator, which comprises preparing a 1,4-oxysulphonium salt of general formula (I) according to any one of claims 1 to 3 by anion exchange with a corresponding anion salt suitable to obtain said acid generator type cationic photoinitiator; or which comprises preparing a 1,4-oxysulphonium salt of general formula (I) by a process according to any one of claims 4 to 11, and then preparing the resulting 1,4-oxysulphonium salt of general formula (I) by anion exchange with a corresponding anion salt suitable to obtain said acid generator type cationic photoinitiator.

13. The process according to claim 12, wherein the corresponding anion salt is hexafluorophosphate, hexafluoroantimonate or 2-(adamantan-1 -methoxy)-1,1 -difluoro-2-oxoethanesulfonate.

14. The process according to claim 12 or 13, wherein the anion exchange meets at least one, two or all of the following conditions: a) it is carried out in a solvent; b) it is carried out at 10-80 °C; c) the molar ratio of the 1,4-oxysulphonium salt of general formula (I) to the corresponding anion salt is 1 :1 - 1 :2.

Images