Patent ID: 6028219
Filing Date: 2000-02-22
Classification: C07C

Abstract:
A process for the preparation of a compound of general formula I: ##STR13## 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 ;R.sup.4 and R.sup.5 are each independently hydrogen or C.sub.1 -C.sub.4 alkyl optionally substituted with one or more halogen atoms;R.sup.6 is a halogen atom or a group R.sup.4 ;R.sup.2 is hydrogen or halo;R.sup.3 is C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl or C.sub.2 -C.sub.4 alkynyl, any of which may optionally be substituted with one or more halogen atoms; or halo;the process comprising reacting a compound of general formula II: ##STR14## wherein R.sup.1, R.sup.2 and R.sup.3 are as defined for general formula I; with a nitrating agent comprising a mixture of nitric and sulphuric acids in the presence of an organic solvent and in the presence of acetic anhydride, wherein the molar ratio of acetic anhydride to compound of general formula II is from about 1:1 to 3:1 and the organic solvent is tetrachloroethylene (perklone) and wherein the sulphuric and nitric acids are added sequentially to the reaction mixture.