Product Development Story
1. OPC Development Story
OPC Development StoryIt was known that ortho-phthaloyl chloride (OPC) can be produced by chlorination and hydrolysis of ortho-xylene. The chlorination method takes a long time. In addition, the chlorination involves pentachloride, followed by hydrolysis, then chlorination again to produce OPC, which increases production costs.
Reported methodThe literature reports a one-step process using phosgene with phthalic anhydride in the presence of dicyclohexylformamide as a catalyst, but the cost of the catalyst is high. Our company manufactures and sell terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC) through the exchange chlorination reaction of terephthalic acid or isophthalic acid with benzotrichloride (BTC). Application to phthalic anhydride was examined in the presence of zinc at 160 ℃. At the end of the reaction, however, a reverse reaction occurred in which benzoyl chloride (BOC) returned to BTC, reaching equilibrium at a conversion rate of 93-95%. When the product was distilled, it could not be separated because the boiling points of phthalic anhydride and OPC are similar. A later literature survey revealed that this method was already known (J. Am. Chem. Soc. 1937, 59, 206), and the author reported that only 93-95% pure OPC could be obtained.
Our new method – uses existing equipment without heat.It was found that the reaction conversion was increased by heating to 200 ℃, but we further sought a method using existing equipment without heating. After repeated investigations of Lewis acids, we found zirconium chloride useful as a catalyst. When phthalic anhydride and 4-chlorobenzotrichloride are exchanged at 160 ℃ using ZrCl4 as a catalyst, a conversion rate of 99 % or higher is achieved. We applied for a worldwide patent.
Japanese Patent 5649288：JP2010-053126