the formation of titled product was indicated by a mild exotherm which reached its peak of 33 u00b0 c in ca 10 15 min and by the steady evolution of co 2 which was indicated by the bubbler after ca 110 minutes corresponding to a 10 excess the phosgene stream was turned off and heating to reflux was started after 15 20 minutes the heat was turned off the dry ice condenser was replaced by a cold water condenser and the excess phosgene was boiled off care should be taken to keep the product which is a crystalline moisture sensitive solid m p 91 u00b0 94 u00b0 c in solution by replacing the evaporated solvent and by adequate heating the solution was considered to be phosgene free when the phosgene indicator paper held in the vapor phase remained essentially colorless and this solution was used directly in the next example 2 this example illustrates the preparation of the novel n 39 cyclohexyl n n dimethylbenzamidine cdmb by a conventional method known in the prior art such as shown in references a b and d above to the solution of u03b1 chlorobenzylidene dimethylammonium chloride in methylenechloride described in example 1 there was added dropwise a solution of 49 6 g 0 5 mole of cyclohexylamine in 100 ml of methylenechloride the temperature of the ensuing exothermal reaction rose from 24 5 u00b0 to 42 5 u00b0 c thus keeping the solvent in reflux after the reaction subsided the reaction mixture consisting of a slurry of white solids in a pale yellow solution was heated to reflux with stirring after standing.