Durene

1,2,4,5- tetramethylbenzene

Crystalline white powder

Fixed

0.838 g · cm -3 ( 25 ° C)

79.2 ° C

196.8 ° C

Practically insoluble in water

1.4790 (81 ° C)

Risk

6990 mg · kg -1 ( LD50, rat, oral)

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Durene ( 1,2,4,5- tetramethylbenzene ) is substituted with four methyl groups, so that benzene and an aromatic hydrocarbon. It belongs with its isomers Prehnitol (1,2,3,4 -tetramethyl benzene ) and isodurene ( 1,2,3,5 -tetramethyl benzene ) to the group of tetramethylbenzenes and also to the group of C4 - benzenes.

History and characteristics

Durene was discovered in 1870 by Paul Jannasch and Rudolph Fittig. The discoverer report that it was the first hydrocarbon of the benzene series, which is solid at room temperature. The name was therefore selected (hard =) after the Latin durus. It is a white crystalline solid and, due to its symmetry (C 2) relative to the other two isomers of the highest melting point of 79.2 ° C.

In a 1H -NMR spectrum two signals are seen: the two aromatic hydrogen atoms (2H ) and four methyl groups ( 12H ); Durene is used as an internal standard.

Representation

The display is carried out by reaction of methyl chloride in the presence of aluminum chloride with benzene or p -xylene, or by reaction of formaldehyde / HCl with xylene mixtures. It is also a by-product of the methanol - to-gasoline process.

Use

The material is used inter alia for the production of pyromellitic dianhydride.