In a 500-ml. flask, to which is attached an air condenser whose open end is protected by absorbent cotton or calcium chloride in a drying tube, are mixed 119 g. (0.75 mole) of 4-methylcarbostyril (p. 580) and 138 g. (82.5 ml., 0.9 mole) of freshly distilled phosphorus oxychloride. The mixture is maintained at 80–85° in a water bath for about 15 minutes until most of the solid has dissolved, and then it is warmed carefully for an additional 15 minutes on a wire gauze until solution is complete. The hot reaction mixture is poured into 1 l. of water containing 1 kg. of cracked ice.

The 2-chlorolepidine is extracted, using two 750-ml. portions of ether (Note 1). The extract is shaken with two 200-ml. portions of water and then dried over 50 g. of potassium carbonate. After removal of the ether, the residual oil is distilled from a 200-ml. modified Claisen flask. The colorless distillate boils at 132–135°/3 mm. and weighs 118–122 g. (89–92%). The distillate is melted if necessary and poured into 250 ml. of petroleum ether (b.p. 40–50°); the solution is then chilled in a freezing mixture; the crystals are filtered by suction and dried in a vacuum desiccator over paraffin. The snow-white 2-chlorolepidine melts at 58–59° and weighs 114–118 g. (86–89%).