| 摘要 |
Para-terphenyls are obtained by contacting a dimer of an alpha-alkylstyrene with iodine, an iodine-containing compound or an oxide of a Group 6 metal as catalyst; also obtained are alpha-alkylstyrene monomer and a tertiary alkyl aromatic hydrocarbon. In a preferred 3-stage process a tertiary alkyl substituted aromatic hydrocarbon is first oxidised to the hydroperoxide which is then decomposed to obtain a phenol. The by-product alpha-alkylstyrene is dimerised in a second stage and catalytically converted to a para-terphenyl in a third stage. The tertiary alkyl aromatic hydrocarbon byproduct is recycled to the first stage and the alpha-alkylstyrene monomer to the dimerisation. The alkylstyrene may have a C1-C5 alkyl group on the alpha carbon and may contain up to three nuclear alkyl substituents; alpha-methylstyrene is preferred in which case cumene is used as the tertiary alkyl compound. Dimerisation may be effected at 65 DEG C.-105 DEG C. with 0.5-5 volumes of 30%-65% sulphuric acid per volume of monomer. The iodine or iodine compound is used in an amount of 0.5%-2.5% mol of the dimer and the conditions may be 350 DEG C.-550 DEG C., 0.7 atmospheres absolute to 17 atmospheres gauge pressure, and 1 second to 5 minutes. Suitable iodine compounds are isopropyl iodide, benzyl iodide and cyclohexyl iodide. Metal oxide catalysts are preferably molybdenum or chromium oxide supported on alumina, silica or pumice; promoters such as palladium or platinum, cobalt, rubidium or potassium, or cerium may be added. The para-terphenyl is an insoluble solid and is separated from other products by filtration. |
