GB156122A - Process for the manufacture of diolefines and derivatives thereof - Google Patents

Abstract

Halogen or other derivatives capable of yielding diolefine hydrocarbons are obtained (1) by the pyrogenic decomposition of hydrocarbons such as turpentine, or hydroxy hydrocarbons, such as cyclohexamol, in presence of an agent such as a halogen or a hydrogen halide, or (2) by high-temperature chlorination of pentane or isopeutane. The reaction may be facilitated by the presence of a silicon alloy, such as ferro-, manganese-, or copper-silicon, a silicate, or a metal of the platinum group. The crude chlorinated hydrocarbons are purified by distillation; the diolefines can be recovered by removal of the halogen or hydrogen halide and utilized for rubber synthesis. Other starting materials mentioned are limonene, dipentene, cyclohexanols, diols and pinacones. According to examples:-(1) a mixture of benzene and limonene vapour with hydrochloric or hydrobromic acid is passed through a ferrosilicon tube charged with a catalytic material and heated to 550-600 DEG C.; the decomposition may take place under reduced pressure; the products are collected in a water-cooled condenser; (2) gasoline treated as in example 1 but at 600-800 DEG C. yields a mixture of (CH3) (CH2Cl):CH.CHCl.CH3, (CH3)2:CCl.CHCl.CHCl.CH3, (CH3)2:CCl.CH2. CH2Cl and CH3.CH2.CHCl.CHCl.CH3, from which, by splitting off hydrochloric acid, isoprene and piperylene can be obtained. Specification 156,139 is referred to.