backwashed with saturated sodium chloride solution dried over sodium sulfate filtered and concentrated under vacuum the residual oil is dissolved in hexane filtered and reconcentrated to obtain the product oil 15 8 g 0 081 mole following the process of example 2 using 2 2 dimethylaminoethylamino 5 6 dimethyl pyrazine there is obtained n n dimethyl n 39 2 dimethylaminoethyl n 39 5 6 dimethyl 2 pyrazinyl urea dihydrobromide melting point 188 u00b0 c cuprous chloride 50 mg is added to a solution of dimethylamine 36 g 0 8 mole in 260 ml of isopropanol 2 6 dichloropyrazine 49 9 g 0 33 mole is added to the mixture with stirring and cooling to maintain the temperature at 35 u00b0 40 u00b0 c after 3 4 hr the cooling bath is removed and the reaction mixture is stored at ambient temperature for 16 hours and finally at 42 u00b0 48 u00b0 c for 3 hours the solvent is removed under vacuum and the residue is dissolved in dilute hydrochloric acid the aqueous solution is extracted with ether and then made basic with solid sodium bicarbonate and extracted with methylene chloride the organic extracts are washed with brine dried over sodium sulfate and concentrated under vacuum to obtain 49 g of product melting point.