Chemical process for preparing alkyl esters or the amide of 3-(.beta.,.beta .
AssigneeImperial Chemical Industries PLC
InventorsIan Ferguson, Robert J. Lindsay
Life of this patent
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Abstract
Process for the preparation of 1-lower alkoxycarbonyl-3-(.beta.,.beta.-dichlorovinyl)-2,2-dimethylcyclopropanes from the corresponding 1-cyano-1-carboxylic acid ester by hydrolysis, decarboxylation of the free carboxylic acid, reaction of the cyclopropane nitrile with a lower aliphatic alcohol and anhydrous hydrogen chloride, followed by alcoholysis or hydrolysis of the reaction product so obtained to give the desired ester or carboxylic acid. Includes a method for the separation of essentially pure cis- and trans-isomers from the mixed nitriles. The products are useful intermediates for the preparation of pyrethroid insecticides.
Claims2
A process for the preparation of a mixture of essentially cis-ester and amide compound of the formula:
- ##STR11## wherein T represents --NH.sub.2 or the group OR in which R is a lower alkyl group and X represents a chlorine atom or a bromine atom, which comprises treating a mixture of cis- and trans-nitrile of formula:
- ##STR12## wherein X has the meaning stated above, with dry hydrogen chloride and an alcohol R.OH, wherein R has the meaning stated above, at a temperature at which only the trans-nitrile reacts, the cis-nitrile being left substantially unreacted, separating the unreacted cis-nitrile from the reaction mixture, followed by reaction of the cis-nitrile at an elevated temperature with dry hydrogen chloride and an essentially anhydrous alcohol R.OH and isolating from the reaction product the mixture of essentially cis- ester and amide compounds of formula (II).
A process for the preparation of an essentially trans-ester of the formula:
- ##STR13## wherein T represents the group OR in which R is a lower alkyl group and X represents a chlorine atom or a bromine atom, which comprises treating a mixture of cis- and trans-nitriles of formula:
- ##STR14## wherein X has the meaning stated above, with dry hydrogen chloride and an alcohol R.OH, wherein R has the meaning stated above, at a temperature at which only the trans-nitrile reacts, the cis-nitrile being left substantially unreacted, separating the unreacted cis-nitrile from the reaction mixture, mixing the reaction mixture, from which the cis-nitrile has been separated, with water, heating the aqueous mixture to effect conversion of the initial reaction product into the corresponding trans-ester, followed by isolation of the trans-ester from the reaction mixture.
Dependencies are inferred from the claim text.