Alkylation can be described as the addition or insertion of an alkyl group into a molecule. Significant changes in chemical and physical properties can be brought about by alkylation and the process is often considered as a direct means of imparting new qualities to a compound.
Alkylaromatic compounds and their derivatives are industrially significant because of their versatile applications. The products are termed as petrochemicals because they have been produced from raw materials which are based on crude petroleum. In the middle of the 19th century, aromatic compounds were based on coal coking by-products. Later, in the 20th century, crude oil and natural gas became increasingly important as sources of raw materials because their production, transportation and processing were more economical than in the case of coal.
Alkylaromatic compounds and their derivatives have found wide industrial applications in different fields. These compounds are liquid insulators, synthetic lubricating oils, antifreezers, hydraulic fluid, intermediates for detergents etc. They have also found application in rocket engineering, automobile transport, aircraft etc. Halogenated alkyl aromatic compounds are liquid dielectrics and are favored for use in transformers, capacitors, cables, condensers, etc. Production and uses of synthetic fuels, lubricating oils and polymeric materials have been increasing day by day. But these compounds tend to undergo thermal degradation in the presence of heat, light, air, oxygen, ozone etc. Antioxidants are effectively used for their protection against such deterioration. Phenol and their derivatives are the most effective antioxidants and multifunctional stabilizers in such media. Some of the derivatives of phenol exhibit strong herbicidal, bactericidal and insecticidal activities.
Owing to the practical importance of alkylaryl compounds, alkylation process has earned much importance and attention of the scientists since its invention. Consequently alkylation of aromatic compounds with different alkylating agents in the presence of several acidic catalysts was investigated. But reactions of phenols, isomeric cresols and chloroderivatives of phenols with cyclopentyl chloride, tert.-butyl chloride and 2-methylcyclohexanol in the presence of anhydrous aluminium chloride and perchloric acid have not been sufficiently investigated. Thus synthesis of alkylaromatic compounds by the tert.-butylation of phenol, isomeric cresols with tert.-butyl chloride and cycloalkylation of phenol, p-chlorophenol and isomeric cresols with cyclopentyl chloride and 2-methylcyclohexanol will have both industrial and academic values.