95% sodamide (2.77 grams) is added to a solution of phenthiazine (9.6
grams) in xylene (140 cc) at a temperature of 130°C and the mixture is
heated with reflux for 2 hours.
A 0.61 N solution (90 cc) of 1-chloro-2-methyl-3-dimethylaminopropane in
xylene is then added over 50 minutes and heating with reflux is continued for
20 hours. After cooling, the mixture is treated with water (40 cc) and N
methanesulfonic acid (70 cc). The aqueous layer is washed with ether, treated
with aqueous sodium hydroxide (density = 1.33; 10 cc) and extracted with
ether.
The extract is dried over potassium carbonate and evaporated and the residue
is distilled in vacuo. 3-(10-phenthiazinyl)-2-methyl-1-dimethylaminopropane
(12.6 grams) is collected, distilling between 150° and 175°C under a pressure
of about 0.3 mm Hg. By dissolving this base in acetone and adding ethereal
hydrogen chloride, a hydrochloride is obtained, MP 216° to 217°C.
