Alexander Dianin

Aleksandr Pavlovich Dianin (; 20 April 1851 – 6 December 1918) was a Russian chemist from Saint Petersburg. He carried out studies on phenols and discovered a phenol derivative now known as bisphenol A and the accordingly named Dianin's compound. He was married to the adopted daughter of fellow chemist Alexander Borodin. In 1887, Dianin succeeded his father-in-law as chair of the Chemistry Department at the Imperial Medical-Surgical Academy in St. Petersburg (now the S.M. Kirov Military Medical Academy).

Bisphenol A and Dianin's compound Dianin's method for preparing bisphenol A from 1891 The overall equation is simple, with water as the only by-product:

Mechanistically, the acid catalyst converts the acetone to a carbenium ion that undergoes an electrophilic aromatic substitution reaction with the phenol, producing predominantly para-substituted products. A second carbenium species is produced by protonation and loss of the aliphatic hydroxyl group, leading to bisphenol A (4,4'-isopropylidenediphenol) after a second aromatic substitution reaction. The process is not very selective, and a great number of minor products and side reactions are known. and basic conditions. The in situ generation of mesityl oxide adds another reactive olefin to the mixture. In cases where an olefinic moiety can interact with a phenolic hydroxyl group (typically as a result of ortho-substitution), rapid cyclisation reactions producing flavans and chromans occur.