Types of alkylation reactions and catalysts

Alkylation is a very broad reaction type and it can, depending on the nature of the alkylating agent, proceed either as a substitution or as an addition reaction. The alkylation by substitution of, for example, aromatic hydrocarbons, phenols or amines is based on the reaction with alkyl halides or alcohols. Some evidence indicates that, at least partly, the alkylation proceeds through the intermediate formation of alkenes from the alkylating agent when the reaction is conducted at atmospheric pressure and at high temperature. 

In this section we shall deal only with the reverse reaction to dealkylation by cracking (Sect. 2.5), that is with additions of alkanes and aromatic compounds to the carbon—carbon double bond. The former reaction is described only in a single paper [339] the formation of 2,2,4-trimethyl-pentane from isobutane and isobutene 

The reaction of aromatic compounds with alkenes giving alkylaromatic compounds has obtained more attention. A typical transformation is the alkylation of benzene by lower alkenes, e.g. 

Not only benzene and its alkyl derivatives can be used as the aromatic component but also naphthalene [341], phenol [340,341] and thiophene [341,342]. Low-molecular weight alkenes, Cj to C5, cyclohexene and dodecene have served as alkylating agents. 

Only strongly acidic solids can catalyse the heterogeneous alkylation of aromatic compounds. Amorphous aluminosilicates were the first catalysts 

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