Research For The Synthesis Of 2,4-diethylthiophenol And Thioxanthone Compounds

Alkyl-substituted thiophenols are an important class of organic synthesis intermediates and are widely used in the preparation and research of chemicals such as pharmaceuticals,pesticides and auxiliaries.At present,the research on the synthesis of alkyl substituted thiophenols is dominated by monosubstitution.However,2,4-diethylthiophenol which is an intermediate for high-end products such as photoinitiators is lacking related synthetic technology research.Therefore,the synthesis of 2,4-diethylthiophenol was systematically studied in this paper.Synthesis of 2,4-diethylthiophenol based on the previous research results of our group,2,4-diethylbenzene was prepared by the reaction of sulfonation,chloridization and reduction with diethylbenzene as raw material.The effects of reaction reagents,inhibitors,molar ratio,reaction temperature on the reaction were discussed in detail,screening out the optimal synthesis conditions,with higher yield obtained product 2,4-diethylthiophenol.And the bis-2,4-diethylphenyl sulfone was synthesized for the first time.In addition,the intermediates,products and by-products were characterized by IR,¹H NMR and GC-MS.Thioxanthone compounds with excellent optical properties,as a photoinitiator widely used in coatings,printing,ink,photoresist,optical fiber manufacturing and other fields.2,4-diethylthioxanthone?DETX?as one of the commercially available photoinitiators,The2,2'-dithiodibenzoic acid and 1,3-diethylbenzene dissolved in concentrated sulfuric acid condensation closed-loop reaction is the current industrial synthesis method.This method has the problem of large amount of waste acid discharged and low yield.Aiming at this problem,based on the above work,a new synthesis route was designed using 2,4-diethylthiophenol as raw material,and the process parameters such as reaction solvent,mass ratio of material and reaction temperature were optimized,The best synthetic process conditions were obtained and the product 2,4-diethylthioxanthone was obtained in higher yield.Besides,this method was successfully extended to the synthesis of other thioxanthone compounds,including the commercial thioxanthone photoinitiators 2-chloro thioxanthone and 2-isopropyl thioxanthone which were both obtained in higher yield.The effects of different substituents of thiophenol raw materials on the yield of the reaction were discussed and the main by-product of the cyclization reaction were isolated.The intermediates were characterized by IR,¹H NMR,¹³C NMR and GC-MS.This gives a deeper understanding of the reaction.