Method of preparing N-halogenated organic heterocyclic compounds

In a method of preparing an N-bromo-N'-chloro organic heterocyclic compound comprising reacting in an aqueous mixture under alkaline conditions:

• (a) a N-hydrogen organic heterocyclic compound having at least two N-hydrogen moieties and selected from the group consisting of:
• ##STR13## wherein R.sup.1 and R.sup.2 are independently selected from the group consisting of hydrogen, aryl, arylalkyl, alkylaryl, lower alkyl having 1 to about 6 carbon atoms, and cycloalkyl having about 3 to about 7 carbon atoms, and cycloalkyl formed from R.sup.1 and R.sup.2 together having 3 to about 7 carbon atoms;
• (b) with chlorine and a bromine-producing compound selected from the group consisting of elemental bromine, alkali metal bromides, alkaline earth metal bromides and mixtures thereof said bromine-producing compound being present in an amount sufficient to produce at least one N-bromo radical but less that sufficient to brominate all N-hydrogen radicals and said chlorine being present in an amount sufficient to produce at least one N-chloro radical;
• the improvement comprising conducting said reaction in the presence of a halogenated organic compound selected from the group consisting of halogenated aliphatic compounds having from 1 to about 6 carbon atoms, halogenated aromatic compounds and halogenated alicyclic compounds having about 6 carbon atoms wherein said halogenated organic compound is present in said aqueous mixture in an amount in the range of from about 5 to about 95 percent of the combined weight of the water and said organic halogenated compound to increase the particle size of said N-bromo-N'-chloro organic heterocyclic compound.