公开(公告)号：US4845285A

公开(公告)日：1989-07-04

申请号：US125103

申请日：1987-11-25

Applicant: Colin Hardy ,  Tony R. Martin ,  Jerzy Czyzewski ,  Daniel Levin

Inventor： Colin Hardy ,  Tony R. Martin ,  Jerzy Czyzewski ,  Daniel Levin

IPC: C07C311/51 ,  C07C303/40 ,  C07C311/02

CPC classification number: C07C311/02

Abstract: A process for preparing a compound of formula (II): ##STR1## or a tautomer or salt thereof in substantially pure form wherein R.sup.1 is C.sub.1-6 alkyl optionally substituted by one or more halogen atoms; R.sup.3 is hydrogen, fluorine, chlorine, bromine or iodine, C.sub.1-6 alkyl, trifluoromethyl or a cyano group; R.sup.4 is hydrogen, fluorine, chlorine, bromine, iodine or trifluoromethyl; R.sup.5 is fluorine, chlorine, bromine, iodine or trifluoromethyl; and R.sup.6 is hydrogen or C.sub.1-4 alkyl; which process comprises nitrating a compound of formula (III): ##STR2## or a salt thereof wherein R.sup.1, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are as defined above, in a solvent which is resistant to nitration under the desired reaction conditions and suitable for purification of the product of formula (II), heating the resultant solution to a temperature sufficient to at least partially dissolve the desired product and impurities and cooling the solution to precipitate the compound of formula (II) in substantially pure form.