Imperial Chemical Industries Limited

Zeneca Limited

Peter J Cleare

David J Milner

Nazim Punja

Michael J Robson

Mark A Spinney

Albert Edward Kaye

Harjinder Singh Bansal

Bernard W Terry

Winston Costain

A process for preparing a compound of formula (I) ##STR1## wherein X is oxygen or sulphur, by (a) reacting a substituted ortho-nitro or -nitroso phenol or a substituted ortho-nitro or -nitroso thiophenol with an alkali metal dithionite reducing agent in an alkaline reaction medium in the presence of carbon disulphide, to form a substituted 2-mercaptobenz-oxazole or -thiazole, acidifying the reaction mixture and collecting the 2-mercaptobenz-oxazole or -thiazole; and then (b) reacting the 2-mercaptobenz-oxazole or -thiazole with a compound of formula (IV)

Process for preparing nematicidal benzoxazole and benzthiazole compounds

The invention provides insecticidal compositions exhibiting excellent knockdown activity against public health pests, in particular cockroach species, comprising compounds of formula (I): ##STR1## wherein X represents a group of formula: ##STR2## where (i) R.sup.1 and R.sup.2 are each selected from hydrogen, halo and C.sub.1-4 alkyl, or (ii) R.sup.1 is hydrogen and R.sup.2 represents either R.sup.3 (R.sup.4)C.dbd.CH-- or R.sup.3 (R.sup.4)(R.sup.5)C--CH(R.sup.5)--, where R.sup.3 and R.sup.4 are selected from hydrogen, methyl, halo and C.sub.1-2 haloalkyl and R.sup.5 is selected from chloro and bromo. The invention also provides methods of use of the compositions, novel compounds of formula (I) and processes for their preparation.

Insecticidal compounds characterized by enhanced knockdown effect

4-.beta., .beta.-dichlorovinyl (or dibromovinyl)-3,3-dimethylbutyrolactones are prepared from 1,1-dichloro (or dibromo)-4-methylpenta-1,3-diene by reacting with an acid of formula CH.sub.2 R.CO.sub.2 H in presence of a salt of a metal in one of its higher valency states, especially manganese (III), cerium (IV), or vanadium (V). Higher yields are obtained in the presence of the anhydride of the acid and of the sodium or potassium salt of the acid. Treatment of the lactones with an inorganic acid halide opens the lactone ring with formation of the corresponding 4-haloacid halide, which with alcohols affords the corresponding 4-haloacid ester, cyclised by bases to a 3-.beta.,.beta.-dichloro (or dibromo)vinyl-2,2-dimethylcyclopropanecarboxylic ester, intermediate for insecticides such as the m-phenoxybenzyl ester.

Lactones

The present invention relates to a process for the preparation of valuable chemical intermediates in the preparation of 2(2,2-dichlorovinyl)-3,3-dimethylcyclopropane carboxylic acid derivatives.

Preparation of halogenated aldehydes

A compound of formula: ##STR1## where Q, R and Z are independently selected from chlorine or bromine provided that Q is always bromine when either of R and Z are bromine.

A process for the preparation of cyclopropane compounds which comprises reacting a compound of formula:

Preparation cyano substituted cyclopropane

Aldehydes of the general formula ##STR1## wherein Z is chlorine or bromine which are intermediates in the productions of insecticides.

The invention relates to the reductive dehydrohalogenation of .alpha. -haloalcohols to alkenes with powdered zinc in glacial acetic acid.

Growing community of inventors

Ascot, United Kingdom

Peter J Cleare