Syngenta Corporation

Syngenta Crop Protection, Inc.

Colin John Bennie

Alan John Whitton

David John Ritchie

Raymond Vincent Heavon Jones

Jennifer Ann White

Robin Fieldhouse

Paul Richard Evans

Kirstin Maccormick

Pascal Bugnon

Logan Thomson Nisbet

3-Isochromanone is prepared by partially chlorinating o-tolylacetic acid with sulphuryl chloride or chlorine gas in an inert organic solvent in the presence of a free radical initiator. The 2-chloromethylphenylacetic acid first obtained is converted to 3-isochromanone by treatment with a base and separated from unreacted o-tolylacetic acid, which is in the form of a salt, by a phase separation technique. The separated o-tolylacetic acid salt is converted to o-tolylacetic acid by controlled acidification and the o-tolylacetic acid is extracted for re-use. The invention reduces the formation of unwanted, over-chlorinated by-products and leads to a more efficient process.

Chemical process

A process for the preparation of 3-isochromanone which comprises contacting an o-xylene-&#x3b1;,&#x3b1;'-dihalide with carbon monoxide, in the presence of a catalyst and a hindered amine base in a liquid medium comprising water and a tertiary alcohol.

Process for preparing 3-isochromanone

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Grangemouth, United Kingdom

Colin John Bennie