Production of isatoic anhydride and certain halo derivatives thereof

Claim 1

21 A method for producing am acid anhydride hich comprises mixing a compound having the wherein each of the symbols and represents a hydrogen or halogen atom and a substantially equivalent proportion a material reactive therewith to produce a salt of the compound with a quantity of water at leas sufficient to dissolve the per mole of the and at time when at least 50 per cent of the salt in an unhydrolized condition and not been converted to the corresponding equivalent to equivalents of a metal hypohalite to the resulting and the solution and taining it at a between and sufficiently low convert substantially all of the salt of the anhydride therein to free anhydride but sufficiently high to maintain therein both the the of an having the in which is a halogen when substantially all of the compound in the reaction mixture has been reacted at least as 22 far as the hut more than about per cent thereof has been reacted as far as the anhydride A according 1 said compound is for the production of isatoic a A method according to Claim 1 or 2 wherein said material is sodium hydroxide and said metal hypohalite is sodium method according to Claim 2 or wherein the temperature of mixture of the the material and the is not higher than preferably not higher than A method according to any preceding modified i that the addition of hypohalite ie made at time when at least 70 per cent of the salt remains in an insufficientOCRQuality