Study On The Synthesis Of The Precursors Of Parylene HT,E Films

Parylene films are one of the most advanced coating materials in the world,which is formed by vacuum vapor deposition of [2,2]paracyclophane and its derivatives.Parylene films have been widely used in aviation,aerospace,military,biomedical,cultural relics,file protection and other fields.Parylene HT film possesses excellent anti-aging,anti-ultraviolet and anti-radiation properties,which is one of the most outstanding films among Parylene films.Compared with other Parylene films,Parylene E film has unique structure which is almost optical isotropy and can be dissolved in some common solvents.Because of the special properties,Parylene E films have great application potential in some special fields.1,4-bis(difluorophenoxymethyl)benzene is one of the precursors of Parylene HT film.4-ethyl [2,2]paracyclophane and diethyl [2,2]paracyclophane were the precursors of Parylene E film.The synthetic processes of1,4-bis(difluorophenoxymethyl)benzene,4-ethyl[2,2]paracyclophane and diethyl[2,2]paracyclophane were investigat-ed in this paper.The most suitable process routes were chosen by taking various factors into consideration,which were expected to be used in industrial production.1,4-bis(chlorodifluoromethyl)benzene was synthesized by using 1,4-bis(difluoro-methyl)benzene.The effects of radical initiator type,amount of radical initiator,reaction temperature,illumination and reaction time on the reaction were investigated.The yield of the product was up to 81.5% under the following optimum process conditions: illuminated by fluorescent lamp,carbon tetrachloride as solvent,benzoyl peroxide as radical initiator,the mass ratio of radical initiator benzoyl peroxide to 1,4-bis(difluoromethyl)benzene is 0.15:1,reacted at 80 ? for 9 h.The product was identified as 1,4-bis(chlorodifluoromethyl)benzene by characterization analysis and the purity of the product was up to 96.7%.1,4-bis(difluorophenoxymethyl)benzene was synthesized by using 1,4-bis(chlorodifluoromethyl)benzene.The effects of reaction temperature,amount of phenol,alkali catalyst type,amount of alkali catalyst,type of solvent,amount of solvent,illumination and reaction time on the reaction were investigated.The yield of the product was up to 52.2% under the following optimum process conditions: under the condition of fluorescent lamp irradiation and nitrogen atmosphere,sodium hydride as alkali catalyst,the molar ratio of sodium hydride to 1,4-bis(chlorodifluoromethyl)benzene is 10:1,hexamethylphosphoryl triamide as solvent,the mass ratio ofhexamethylphosphatidyl triamide to 1,4-bis(chlorodifluoromethyl)benzene is24:1,reacted at 100 ? for 10 h.The product was identified as 1,4-bis(difluorophenoxy-methyl)benzene by characterization analysis and the purity of the product was up to 97.3%.200 g of 1,4-bis(difluorophenoxymethyl)benzene was synthesized for film forming test.4-ethyl [2,2]paracyclophane was synthesized by using [2,2]paracyclophane.The effects on the reaction of reaction temperature,amount of ethyl bromide,type of catalyst,amount of catalyst,type of solvent and reaction time were investigated.The yield of the product was up to 64.6% under the following optimum process conditions:in nitrogen atmosphere,1,1,2,2-tetrachloroethane as reaction solvent,anhydrous aluminium chloride as catalyst,the molar ratio of anhydrous aluminium chloride to[2,2]paracyclophane is 2:1,the molar ratio of ethyl bromide to [2,2]paracyclophane is10:1,reacted at-15 ? for 1.5 h.The product was identified as 4-ethyl[2,2]para-cyclophane by characterization analysis and the purity of the product was up to 96.7%.200 g of 4-ethyl [2,2]paracyclophane was synthesized for film forming test.A series of isomers of diethyl [2,2]paracyclophane were synthesized by using4-ethyl [2,2]paracyclophane.The effects of reaction temperature,amount of ethyl bromide,amount of catalyst and reaction time on the reaction were investigated.The yield of the product was up to 56.6% under the following optimum process conditions:in nitrogen atmosphere,1,1,2,2-tetrachloroethane as reaction solvent,anhydrous aluminium chloride as catalyst,the molar ratio of anhydrous aluminium chloride to[2,2]paracyclophane is 2:1,the molar ratio of ethyl bromide to [2,2]paracyclophane is6:1,reacted at-18 ? for 1 h.The product was identified as a series of isomers of diethyl [2,2]paracyclophane by characterization analysis and the purity of the product was up to 86.7%.200 g of diethyl [2,2]paracyclophane isomers were synthesized for film forming test.