Xylene

Xylene is used as a chemical feedstock in the chemical industry. Xylenes can undergooxidation where the side methyl groups are oxidized to give a carboxyl group (COOH)yielding a carboxylic acid. The particular acid produced depends on the isomer oxidized. Wheno-xylene is oxidized phthalic acid is produced, and when p-xylene is oxidized terephthalic acidresults. Terephthalic acid is one of the main feedstocks in making polyesters.Terephthalic acid reacts with ethylene glycol to form the ester polyethylene terephthalate(PET). PET is one of the most common plastics used as food and beverage containers. PETcontainers contain the recycling symbol with a number 1. PET is marketed using a numberof commercial names; the most generic of these is polyester. It is also the material known asDacron. Mylar is PET in the form of thin films. Although all three isomers of xylene are usedas chemical feedstocks, the greatest demand is for para-xylene to produce terephthalic acid.The smallest demand is for meta-xylene. Approximately 30 million tons of xylenes are usedannually worldwide.
Also known as dimethylbenzene, C6H4(CH3)2 is an isomeric mixture of 0- m-, and p-xylene. It is a clear liquid with various grades having different boiling points, that is insoluble in water and soluble in alcohol and ether,and used in aviation gasoline, coatings, lacquers, rubber cements, organic synthesis, and polyester resin manufacture.