4 ml of Triton B (40%) (benzyltrimethylammonium hydroxide) was dropwise added to an acetonitrile solution (200 ml) containing 199 g of phenothiazine, 106 g of acrylonitrile, and a small quantity of Irganox 1010 (made by Ciba Geigy Co.). Irganox 1010 has the formula ##STR4## After refluxing for 3 hours while heating, 53 g of acrylonitrile was added thereto, followed by refluxing for a further 2 hours while heating. After being allowed to cool, acetone was added to the reaction solution to crystallize the reaction product. Crystals thus formed were collected by filtration, and recrystallized from 900 ml of acetone to obtain 135 g of the desired compound. m.p. 158°-160° C.
