GB661788A - Improved process for manufacturing dibromoalkanes - Google Patents

Abstract

Dibromoalkanes are obtained from a hydrocarbon composition containing C5 and C6 monoolefines by a process comprising conducting said composition to a reaction zone together with bromine and recycled reaction products from said zone. Preferably the pressure is sufficient to maintain the reactants in liquid phase, and the temperature may be - 100 DEG F. to +80 DEG F. The molecular ratio of recycled products to total olefine feed is preferably 1-10. The non-recycled portion of the reaction products is treated with sodium bicarbonate, followed by washing with water, and fractionation in apparatus of conventional type. Before fractionation, light hydrocarbons such as pentanes or hexanes may be added to form a low-boiling mixture with any water present, and also to effect stabilization of the products, phenolic substances such as alkylated phenols (2.4-di-tert.-butyl-4-methylphenol is mentioned), alpha- or beta-naphthols, or polyhydroxy aromatic compounds, may be added. The olefinic feed-stock may be obtained from the high-temperature steam cracking of gas oil, naphtha, or kerosene by a distillation process (see Group III). The products are lead scavenging agents for motor-fuels (see Group III).ALSO:<PICT:0661788/III/1> Motor fuels contain as lead scavenging agents dibromoalkanes obtained from compositions comprising C5 and C6 monoolefines by conducting said compositions to a reaction zone together with bromine and recycled reaction products from said zone. (see Group IV(b)). It is preferred to use 0.8-1.6 mols. bromine per mol. of lead and the fuel may comprise any base stock containing lead tetraethyl and may also contain dyes, lead stabilisers, colour stabilisers, gum flux agents, metal de-activators and anti-oxidants. The mono-olefinic feed used for preparing the dibromoalkanes may be obtained from a distillate from the high-temperature steam cracking of gas oil, naphtha, or kerosene or similar stocks by a distillation process comprising a first distillation stage in column 10, which has a head temperature of, e.g. 141 DEG F. and a second extractive distillation in column 20 with acetone as solvent (furfural, pyridine and amines are also mentioned), a head temperature of 140 DEG F. and a cut being made at 160 DEG F. through line 31 consisting mainly of isoprene and other diolefines.