Diethylbenzenes

Diethylbenzene is any of three isomers with the formula C₆H₄₂. Each consists of a benzene ring and two ethyl substituents. The meta and para have the greater commercial significance. All are colorless solids.

Compound names	m.p. °C	b.p. °C	Density g/cm³	Refractive Index
1,2-Diethylbenzene, o-diethylbenzene	31.2	183.5	0.8800	1.5035
1,3-Diethylbenzene, m-diethylbenzene	83.9	181.1	0.8602	1.4955
1,4-Diethylbenzene, p-diethylbenzene	42.8	183.8	0.8620	1.4967

Production and applications

Diethylbenzenes arise as side-products of the alkylation of benzene with ethylene, which can be described as two steps. The first step is the industrial route to ethylbenzene, which is produced on a large scale as a precursor to styrene.
The diethylbenzene is an inadvertent side product.
Using shape-selective zeolite catalysts, the para isomer can be produced in high selectivity.
Much diethylbenzene is recycled by transalkylation to give ethylbenzene:

Diethylbenzene is used in a mixture with methyl and/or ethyl biphenyls as a low temperature heat transfer fluid.
Diethylbenzene is dehydrogenated to give divinylbenzene :
DVB is used in the production of crosslinked polystyrene.