Verfahren zur Herstellung von 3,4-Dhiydro-m-thiazinen

In a modification of the process of the parent Specification for preparing dihydro-m-thiazines-D ,-3, 4 by reacting together a b -mercapto ketone, an oxo compound and ammonia or the ammonium salt of a weak acid, the b -mercapto ketone is formed while the reaction process is taking place by the action of hydrogen sulphide on an a ,b -unsaturated ketone. In one embodiment, 2, 2, 4, 6, 6-pentamethyldihydro-m-thiazine-D -3, 4 is formed by introducing H2S and ammonia into acetone alone, the a ,b -unsaturated ketone mesityl oxide presumably being first formed. Compounds actually prepared in examples are: 2-propyl-4, 6-dimethyl-, 2, 2, 4, 6, 6-pentamethyl-, and 2, 2, 4-trimethyl-6-phenyl-dihydro-m-thiazine-D -3, 4; 2, 2, 4, 6, 6-pentamethyl-dihydro-m-thiazine is converted to its picrate. The products have uses as medicinal, vulcanisation accelerators, pest control media, wood preservatives, weed-killers, rust-preventors and antiaging agents.