XCII.—Separation of normal and iso-heptane from American petroleum
Journal of the Chemical Society Transactions
AN attempt made by one of US to separate the heptanes from American petroleum by fractional distillation, after removal of toluene by treatment with a mixture of nitric and sulphuric acids, was unsuccessful, owing to the presence of polymethylene compounds in the petroleum. It seemed possible, however that, by the action of bromine, the polymethylene compounds might yield higher bromine derivatives more readily than the paraffins, and that the heptylic monobromides might thus be obtained in a
... be obtained in a pure state. The bromides could then be reduced to the corresponding paraffins by means of nascent hydrogen. A preliminary experiment with about 90 grams of the fractionated petroleum, boiling between 98.65' and 99.65' and containing chiefly normal heptane and methylhexamethylene, gave promising results, a small quantity of a bromide boiling at about 93' under a pressure of 70 mm. being obtained. It was then decided to brominate a large quantity of the mixed heptanes--containing a considerable amount of methylhexamethylene, a little hexamethylene, and possibly some dimet hylpentamethylene. In the first experiment, 900 grams of bromine were gradually added to 760 grams of the petroleum (b. p. 96.5-102'), small quantities of aluminium bromide being introduced from time t o time. In this case, however, higher bromides of both the paraffins and polymethylene compounds were chiefly formed, for, on distillation, 605 grams of unaltered petroleum were recovered, and no monobromides could be isolated from the residue.