Patent ID: 6215013
Filing Date: 2001-04-10
Classification: C07F

Abstract:
A method of preparing a compound of formula (I): formula (I) ##STR6##wherein:each R.sup.2 is independently selected from the group consisting of hydrogen, alkyl groups, alkali metals, alkaline earth metals and nitrogen-containing groups;R.sup.3 and R.sup.4 are independently selected from the group consisting of hydrogen and alkyl groups;R.sup.5 is selected from the group consisting of hydrogen, alkyl groups and ##STR7##wherein said method comprises the steps of:(a) azeotropically removing water from a reactant of formula (II): ##STR8##wherein: R.sup.1 is CHR.sup.3 R.sup.4 ; R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined above; and X is a number between 0 and 20; to form a dehydrated reactant (II);(b) pyrolysing said dehydrated reactant (II) at a temperature of from 170.degree. C. to 300.degree. C., and thereafter(c) optionally, converting any anhydrides formed by the pyrolysing step (b) to the corresponding acid or salt having the formula (I).