ALKYLATION

Alkylation is usually used to increase performance of a product and involves the conversion of, for example, an amine to its alkylated homologs as in the reaction of aniline with methyl alcohol in the presence of sulfuric acid catalyst:

Thus, aniline, with a considerable excess of methyl alcohol and a catalytic amount of sulfuric acid, is heated in an autoclave at about 200 C for 5 or 6 hours at a high reaction pressure of 540 psi (3.7 MPa). Vacuum distillation is used for purification.

In the alkylation of aniline to diethylaniline by heating aniline and ethyl alcohol, sulfuric acid cannot be used because it will form ether; consequently, hydrochloric acid is employed, but these conditions are so corrosive that the steel used to resist the pressure must be fitted with replaceable enameled liners.

Alkylation reactions employing alkyl halides are carried out in an acidic medium. For example, hydrobromic acid is formed when methyl bromide is used in the alkylation leading, and for such reactions an autoclave with a replaceable enameled liner and a lead-coated cover is suitable.

In the petroleum refining industry, alkylation is the union of an olefin with an aromatic or paraffinic hydrocarbon:

Alkylation processes are exothermic and are fundamentally similar to refining industry polymerization processes but they differ in that only part of the charging stock need be unsaturated. As a result, the alkylate product contains no olefins and has a higher octane rating. These methods are based on the reactivity of the tertiary...