Abstract: Process for the preparation of a compound of formula or a salt thereof ##STR1## wherein R.sub.1 represents a hydrogen atom or a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)-- wherein R.sub.2 represents a phenyl, tolyl or C.sub.1-4 alkyl group and R.sub.3 represents a hydrogen atom or a phenyl or C.sub.1-4 alkyl group, which process comprises contacting nickel in an oxidation state of at least 3 with a 3-hydroxymethyl azetidine derivative of formula ##STR2## wherein R.sub.4 represents a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)-- and R.sub.5 represents a hydrogen atom or a hydroxymethyl group or a group of formula COOH or a salt thereof, followed, where R.sub.5 is not a hydrogen atom, by the decarboxylation of the compound of the 3,3-dicarboxylic intermediate product or a salt thereof and, if desired to produce a compound in which R.sub.1 represents a hydrogen atom, by deprotection of the N-atom.

Abstract: Process for the preparation of a compound of formula or a salt thereof ##STR1## wherein R.sub.1 represents a hydrogen atom or a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)--wherein R.sub.2 represents a phenyl, tolyl or C.sub.1-4 alkyl group and R.sub.3 represents a hydrogen atom or a phenyl of C.sub.1-4 alkyl group, which process comprises contacting nickel in an oxidation state of at least 3 with a 3-hydroxymethyl azetidine derivative of formula ##STR2## wherein R.sub.4 represents a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)--and R.sub.5 represents a hydrogen atom or a hydroxymethyl group or a group of formula COOH or a salt thereof, followed, where R.sub.5 is not a hydrogen atom, by the decarboxylation of the compound of the 3,3-dicarboxylic intermediate product or a salt thereof and, if desired to produce a compound in which R.sub.1 represents a hydrogen atom, by deprotection of the N-atom.

Abstract: The invention provides a process for the preparation of 4-fluorophenols of formula ##STR1## wherein n is 0 to 3, each R independently represents a halogen atom or an alkyl, alkoxy, cyano or optionally substituted amino group and Z represents a hydrogen or halogen atom or a cyano group characterized by reacting a fluorohalocyclohexadienone of formula ##STR2## wherein X represents a halogen atom, with a compound of formula A-Z, wherein Z is as defined above and A represents a hydrogen or alkali metal atom, provided that when both A and Z are hydrogen, the reaction is carried out in the additional presence of a Group VIII metal hydrogenation catalyst, and 4-fluorophenols of formula I per se wherein Z is a CN group.

Abstract: The invention provides a process for the preparation of 4,4-disubstituted cyclohexadienones of which at least one of the substituents is fluorine, which comprises reacting a compound of formula ##STR1## wheren X represents a hydrogen or halogen atom or an alkyl group, each R independently represents a halogen atom or an alkyl, alkoxy, or cyano or optionally substituted amino group, Z represents a hydrogen atom or an alkyl, acyl or aryloxycarbonyl group, and n is 0 to 4, with hydrogen fluoride and a Pb(IV) compound, in the presence of a compound which acts as a base towards HF.

Abstract: A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.