Prepn. of high-vacuum oils - by alkylating aromatic(s) with alkyl chlorite(s) in the presence of aluminium chloride

摘要

Prodn. of a high-vacuum oil (I) is effected by (a) alkylating an aromatic hydrocarbon (II) with one or more 8-12C normal sec. alkylchlorides (III) in the presence of 2-15 mol.% AlCl3 (based on (III)) at 20-100 deg.C until evolution of HCl ceases, (b)sepg. catalyst from alkylate, and (c) distilling the alkylate under vacuum to recover the fraction boiling at 220-250 deg.C/0.2-0.3 mm Hg as (I). (II) may comprise a condensed and/or non-condensed aromatic hydrocarbon. The (III):(II) mol. ratio is 2.5-5:1. (I) is used as a working medium in vacuum diffusion pumps, providing a vacuum of 3 x 10 power (-8) mm Hg in unbaked systems without N2 traps and 2-5x10 power (-9) mm Hg in baked systems without N2 traps. It has a low congealing temp. a low proper vapour tension (of the order of 10 power (-10) mm Hg) and relatively high flowability at room temp. The starting materials are relatively inexpensive.