Chemical reaction: The production of para-tertiary butylphenol is based on the alkylation of phenol with isobutylene in the presence of acid catalyst Amberlyst 36 Dry, Amberlyst 36 Wet Resin or KU-23 and separation of the reaction mixture by distillation. Alongside with para-tertiary butylphenol the reaction mass contains by-products – up to 1%-3% ortho-tret-butylphenol and up to 0.5%-1.5% 2,4-di-tret-butylphenol. As the process temperature decreases, the reaction mixture becomes enriched with ortho-tret-butylphenol. And with increase of molar ratio isobutylene/phenol and decrease of temperature the reaction mass is enriched with 2,4-di-tert-butylphenol.

he yield of reaction by-products ortho-tret-butylphenol and 2,4-di-tret-butylphenol increases sharply with increasing moisture in the reaction zone. With increasing pressure in the reaction zone the yield of by-products increases and the polymerisation of isobutylene also occurs. To obtain 2,4-di-TBP with a mass fraction of not more than 0,1% the alkylation reaction of phenol isobutylene should take place at 80°C-145°C, at atmospheric pressure, phenol:isobutylene molar ratio of 1:(0,1-0,4) and mass fraction of water in the reaction zone should not exceed 0,5%.