Abstract: A process for the manufacture of aminomethanephosphonic acid comprises:a) reacting a compound of formula R--CH.sub.2 --NH--CO--NH--CH.sub.2 --R' wherein R and R', which may be the same or different, represent a phosphonation leaving group with a phosphonating agent and subsequentlyb) hydrolysing the product of step (a) to form aminomethanephosphonic acid.

Abstract: A process for preparing a compound comprising a monocyclic aromatic ring having at least a first substituent and a substituted sulphonyl group at the position para to the first substituent, the process comprising mixing a reactant comprising the monocyclic aromatic ring with the first substituent and hydrogen in the position of the ring para to the first substituent, with a sulphonic acid halide derivative in the presence of a naturally occurring or synthetic zeolite capable of catalyzing a sulphonylation reaction between the reactant and the sulphonic acid halide, under conditions in which the reaction will occur.