Studies On Synthesis Of Fluorinated Intermediate Compounds

The fluorine-containing compounds are an important organic compounds, withthe development of the fluorinated drugs, the people have a more deep recognition forthe biological activity of fluorochemicals. Fluorinated intermediates are widely usedin the medicine, pesticide, dye, and so on. This paper aimed to study on the synthesisof organic intermediates fluorochemicals, the contents included the followinginformation:1. The synthesis of ethyl trifluoroacetoacetate: Ethyl trifluoroacetate and ethylacetate as raw materials, ethyl trifluoroacetoacetate is preparated in the catalyst bytwo methods. We have studied the influence factors for the yield of ethyltrifluoroacetoacetate, which are the ratio of raw materials, reaction time, reactiontemperature, the order of raw materials, and so on on. At the same time, we havesearched the optimun synthesis conditions.(1) Ethyltrifluoroacetate and ethyl acetateare condensed in the presence of sodium ethoxide in cyclothxane and the ethyltrifluoroacetoacetate is preparated. The optimum conditions for synthesis of ethyltrifluoroacetoacetate: n (sodium ethoxide): n (ethyl trifluoroacetate): n (ethyl acetate)=1.3:1.5:1, the yield of ethyl trifluoroacetoacetate is68.2％, after a reactiontemperature at about50℃and reaction time of7hours.(2) Ethyltrifluoroacetate andethyl acetate are condensed in the presence of sodium and the ethyltrifluoroacetoacetate is obtained. The optimum conditions for synthesis of ethyltrifluoroacetoacetate: n (sodium): n (ethyl trifluoroacetate): n (ethyl acetate)=1.1:1.4:1, the yield of ethyl trifluoroacetoacetate is86.7%, after a reaction temperatureat about50℃and reaction time of9hours. Sodium as alkaline reagent, it is not onlyinexpensive as raw materials, but all so ethyl trifluoroacetoacetate has high yield.2. The synthesis of ethyl bromo (chloro)-trifluoroacetoacetate: The organiccompounds are synthesized from ethyl trifluoroacetoacetate. We have studied the influence factors for the yield of products, which are the ratio of raw materials,reaction time, reaction temperature, the order of raw materials and so on on.(1)Bromine and N-bromosuccinimide as the bromine atoms of reagents, ethyl2-bromo-4,4,4-trifluoro-3-oxo-butanoate is preparated by ethyl trifluoro-aceto-acetate in carbontetrachloride. The optimum conditions for synthesis of ethyl2-bromo-4,4,4-trifluoro-3-oxo-butanoate: n (trifluoroacetyl ethyl acetate): n (bromine)=1.6:1, the yield ofproduct is61.6%, after a reaction temperature at about25℃and reaction time of16hours or n (trifluoroacetyl ethyl acetate): n (NBS)=1.3:1, the yield of product is87.1%after the reaction temperature is75℃, reaction time2hours.(2) Bromine andN-bromosuccinimide as bromine atoms of the introduction of reagents, ethyl2,2dibromo-4,4,4-trifluoro-3-oxo-butanoate is preparated with ethyl trifluoroacetoacetatein carbon tetrachloride. The optimum conditions for synthesis of ethyl2,2-dibromo-4,4,4-trifluoro-3-oxo-butanoate: n (trifluoro-acetyl ethyl acetate): n (bromine)=1:2.6,the yield of product is93.4%, after a reaction temperature at about25℃and reactiontime of20hours or n (trifluoroacetyl ethyl acetate): n (NBS)=1:2.15, the yield ofproduct is87.1%after the reaction temperature75℃and reaction time5hours. Tosynthesis the ethyl bromo-trifluoroacetoacetate with N-bromosuccinimide, theoprations are easy and we can have a high yield.(3)2-Chloro-4,4,4-trifluoro-3-oxo-butanoate is synthesized by ethyl trifluoroacetoacetate and thionyl chloride, theoptimal conditions for synthesis of the organic: n (trifluoroacetyl ethyl acetate): n(chloride sulfone)=1:3, the yiel is77.5%after a reaction temperature at about25℃and reaction time of20hours.2-Chloro-4,4,4-trifluoro-3-oxo-butanoate is usuallypreparated by ethyl trifluoroacetoacetate with chlorine or sulfuryl chloride, but in thisarticle using thionyl chloride, trifluoroacetic ethyl acetoacetate preparation of ethyl2-chloro-4,4,4-trifluoro-3-oxo-butanoate, the method never has been reported.3. The synthesis of the trifluoroacetone and bromo-trifluoroacetone:(1)Preparation of1,1,1-trifluoroacetone from ethyl trifluoroacetoacetate by hydrolysisand decarboxylation in sulfuric acid. The optimum conditions for synthesis of1,1,1-trifluoroacetone: the yield of product is52.4%, after a reaction temperature atabout80℃and reaction time of6hours;(2) Sulfuric acid as catalyst, 1-bromo-3,3,3-trifluoroacetone and2,2-dibromo-3,3,3-trifluoroacetone is obtained bytrifluoroacetic acid with ethyl2-bromo-4,4,4-trifluoro-3-oxo-butanoate or ethyl2,2-dibromo-4,4,4-trifluoro-3-oxo-butanoate, and then decarboxylation. The optimumconditions for synthesis of3-bromo-1,1,1-trifluoroacetone: n (ethyl2-bromo-4,4,4-trifluoro-3-oxo-butanoate): n (trifluoroacetic acid)=1:1.5, the yield of product is68.1%, after a reaction temperature at about100℃and reaction time of8hours; Theoptimum conditions for synthesis of3,3-dibromo-1,1,1-trifluoroacetone: synthesis ofethyl trifluoroacetoacetate n (ethyl2,2-dibromo-4,4,4-trifluoro-3-oxo-butanoate): n(trifluoroacetic acid)=1:1.5, the yield of product is72.6%, after a reactiontemperature at about110℃and reaction time of8hours.The other compounds and acetone class were characterized by using1H NMRand IR.