Wikipedia
m-Xylene (or meta-xylene) is an aromatic hydrocarbon, based on benzene with two methyl substituents. It is an isomer of o-xylene and p-xylene. The m stands for meta, meaning the two methyl substituents are at locants 1 and 3 on the aromatic ring. m-Xylene is commonly produced in BTX processes, and separated as needed from the other aromatic hydrocarbons.
The major chemical use of meta-xylene is in the manufacture of isophthalic acid, which is used as a copolymerizing monomer to alter the properties of polyethylene terephthalate (PET), making PET more suitable for the manufacture of soft drinks bottles. To convert m-xylene on an industrial scale to isophthalic acid, the two methyl groups are both catalytically oxidized to carboxyl groups. It is also used as a raw material in the manufacture of 2,4- and 2,6- xylidine as well as a range of smaller-volume chemicals.
This page provides supplementary chemical data on m-Xylene.