Polyimide (PI) was widely used as alignment agent of TET-LCD because of its excellent advantages

while 4-BDAF was a key intermediate of alignment layer used for PI preparation. A new synthesis method of 4-BDAF was studied and the reaction conditions were optimized in this research. The results showed that optimal reaction conditions were: the molar ratio of hexafluroacetone

phenol and catalyst was controlled to be 1 ∶ 2 ∶ 2; methanesulfonic acid was chosen as the catalytic dehydrant; the reaction temperature was 155 ℃; and the reaction time was 11 h

respectively. The yield of 4-BDAF was 57%. The quality of the purified products could be equal to that from companies overseas. However

the price was competitive. And the technology could be industrialized easily.