Imperial Chemical Industries Limited

Zeneca Limited

Michael S Howarth

Brian Geoffrey Cox

Edward George Scovell

David John Watson

Stewart Reid Korn

Gordon Jamieson

David M Tomkinson

Decarboxylation process

A method for the preparation of a pyridazinone derivative having the general formula I: ##STR1## where: R.sup.1 is a phenyl group, optionally substituted, R.sup.2 is H, alkyl or carboxy, R.sup.3 is H, alkyl or alkoxy and R.sup.4 is alkyl; said method comprising reacting a hydrazone of glyoxylic acid halide having the formula VII: ##STR2## in which X is halogen, with an ester of formula VIII; ##STR3## in the presence of an alkaline earth base.

Method of preparing pyridazinone derivatives

A process for the preparation of a fluoroaromatic or fluoroheterocyclic compound, which comprises diazotizing the corresponding amino-aromatic or amino-heterocyclic compound in hydrogen fluoride and decomposing the diazonium salt in the diazotization mixture so formed, characterized in that decomposition is carried out at super atmospheric pressure.

Process for preparation of fluoroaromatic or fluoroheterocyclic compounds

Fluoromethylpyridines of the formula: ##STR1## wherein the group F.sub.n H.sub.3-n C-- may be ortho, meta or para to the ring nitrogen atom, n is 1, 2 or 3, m is 1 to 4, X is Cl, Br, I or F and, when m is 2, 3 or 4 the substituents represented by X may be the same or different, at least one X being ortho or para to the F.sub.n H.sub.3-n C-- group, are prepared by reacting a compound of the formula: ##STR2## wherein Y is Cl, Br, I or F and m is 1 to 4, with potassium fluoride in a polar aprotic solvent under substantially anhydrous conditions. These fluoromethylpyridines are useful as intermediates for herbicides. 3,4,5-trifluoro-2-trifluoromethylpyridine and 2,6-difluoro-3-difluoromethylpyridine are novel compunds.

Process for the preparation of fluoromethylpyridines

A process for the purification of esters of phosphorus thioacids having the formula: ##STR1## wherein R is an organic radical which is attached via a carbon atom thereof to X;

Process for the purification of esters of phosphorus thioacids

m-Phenoxybenzyl esters of carboxylic acids are prepared from the methyl or ethyl esters of the acids by reaction of the latter with m-phenoxybenzyl alcohol in the presence of a tetra-aryl titanate as catalyst.

Manufacture of esters

m-Phenoxybenzyl esters of carboxylic acids are prepared from the methyl or ethyl esters of the acids by reaction of the latter with m-phenoxybenzyl alcohol in the presence of a transesterification catalyst of the formula Ti(O.CO.R).sub.2 Z.sub.2 in which R is a hydrocarbon radical and Z is a bidentate chelate compound.

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Lancashire, United Kingdom

Michael S Howarth