Introduction

The United States produces about $19 billion worth of organic (petroleum-based) chemicals annually. These organic chemicals are used as intermediates in synthesis of economical chemicals, such as plastics, nylon fibers, adhesives, agrochemicals, and pharmaceuticals. Many of these synthesis processes either use chlorine or halogens directly or as intermediates, such as chlorobenzenes in the manufacture of pesticides and dyes, and vinyl chloride (12 million tonsyr~ in USA) in the synthesis of polyvinyl chloride (PVC). The export of downstream products of these syntheses, such as ethylene dichloride, vinyl chloride monomer, and PVC polymer rose to 1229 million metric tons in 1995. This article identifies those economical HHCs, produced and used in the USA and abroad, which have caused and are causing ecological and human health (occupational, environmental) concerns.

Hydrocarbons in which the hydrogen (forming the carbon and hydrogen bond, R-C—H) is replaced with a halogen substituent (R-C—X or RX) become chemically more stable and hydrophobic. These properties can be affected by various other factors also, such as carbon chain length and its branching, functional groups, etc. This halogenation of aliphatic (acyclic and alicyclic) and aromatic (one and more benzene rings) hydrocarbons includes a diversity of economical chemicals, used globally in amounts of millions of tons per year (Table 1).

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