Zeneca Limited

Martin Lennon

Stephen Martin Brown

James Peter Muxworthy

John Heathcote Atherton

Ian Jeffrey Priestley

A process for the preparation of a compound of general formula I: ##STR1## wherein: R.sup.1 is hydrogen or C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or C.sub.2 -C.sub.6 alkynyl, any of which may optionally be substituted with one or more substituents selected from halogen and OH; or COOR.sup.4, COR.sup.6, CONR.sup.4 R.sup.5 or CONHSO.sub.2 R.sup.4 ;

Process for the nitration of diphenylethers

A process for the nitration of an aromatic or heteroaromatic compound with a nitrating agent comprising nitric acid or a mixture of nitric and sulphuric acids, characterised in that nitration is performed in a solvent comprising at least 50% v/v of a C.sub.1 -C.sub.6 alkyl ester of a C.sub.1 -C.sub.4 carboxylic acid. The process is of particular use for the nitration of diphenyl ethers to give compounds which are useful as herbicides or as intermediates in the synthesis of herbicides.

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Huddersfield, United Kingdom

Martin Lennon