Industrial halogenated organic intermediates

Halogenated organic compounds are important end products of organic syntheses in both academic research and industry, where they find use as solvents, plastics, drugs, dyestuffs, pesticides, and weedicides. Their role as intermediates is at least equally vital they are stepping stones in very numerous procedures for the junction of C—N, C—O, and C—C bonds and for formation of C—O, C=C, and C=C bonds. 

One of the current trends in development of both academic and industrial organic synthesis is orientation of chemists on using chlorine-free ecologically benign processes, based on direct methods of C-H functionalization of aromatic compoimds, avoiding halogenated starting materials or intermediates. 

Intermediates are produced by a variety of reactions. Aromatic hydrocarbons undergo four electrophilic substitution reactions— the Friedel-Crafts reaction (alkylation and acylation), halogenation, nitration, and sul-fonation—as well as oxidation and reduction. These reactions lead to substituted hydrocarbons that can be further reacted to provide intermediates for dyes. The number of dye intermediates actually or potentially available is very large, and the technology of their manufacture is an important part of industrial organic chemistry. Intermediates are used not only for dye manufacture but also for the manufacture of other important products such as pharmaceuticals. 

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