METHOD OF SYNTHESIS OF UNSATURATED ALPHA-METHYLSTYRENE DIMER FOR CONTROL OF POLYMERIC CHAIN INCREMENT Russian patent published in 2000 - IPC

FIELD: chemical technology, petrochemistry. SUBSTANCE: dimerization of unsaturated dimer is carried in the presence of 70-75% sulfuric acid containing iron sulfate at 30-40 C. Dimerization process is carried out at volume ratio of acid to the parent substance = (0.32-0.38):100 at the rate 12%/h, not above, at the range from 0 to 92% of conversion. Then dimerization process is terminated at the rate no exceeding 2.3%/h being 30% of acid of its total amount is fed at the period of the first hour of dimerization. Method provides increased concentration of alpha-isomer in unsaturated in dimer, decreased content of residual alpha-methylstyrene in the end product, directed regulation of dimerization regime, increased yield of unsaturated dimer. EFFECT: improved method of synthesis. 1 cl, 2 tbl, 10 ex