Alkylation of phenols with isobutylene

Abstract The kinetics of absorption of isobutylene in molten phenol, p ‐cresol and pyrocatechol were studied in a stirred cell using concentrated sulphuric acid as a catalyst. The absorption of isobutylene in molten phenols was found to conform to pseudo‐first‐order mechanism. The products of various reactions were analysed by gas‐liquid chromatography. The absorption of isobutylene in mono‐ t ‐butyl derivatives of phenols was studied in an agitated glass reactor. It was possible to eliminate the effect of diffusion. The values for the rate constant of the second‐order reactions between isobutylene and p ‐ t ‐butylphenol at 104°, isobutylene and 2‐ t ‐butyl‐ p ‐cresol at 70° and isobutylene and 4‐ t ‐butylpyrocatechol at 104° were 49, 40 and 56 ml/g mole/sec, respectively. Mass transfer influenced the rate of alkylation of phenol and p ‐cresol with isobutylene in a bubble column. However, no significant improvement was observed in the yield of the mono‐derivative, which in some cases is the desired product.