1.3.2-Benzothiazathiolium chlorides are obtained by the action of sulphur monochloride on a primary aromatic amine, its salts, or N-acyl derivatives. Four reactions are involved, (i) the formation of the heterocyclic ring, (ii) the chlorination of the aromatic ring, (iii) replacement of electron-attracting groups in the orthoand para-positions by chlorine, and (iv) the oxidation of the sulphur atom in position 2. A likely sequence of reactions is considered, and experimental evidence is given in support of each stage. HERZ t found that a primary aromatic amine, its salts, or N-acyl derivatives, when heated with an excess of sulphur monochloride give a 1,3,2-benzothiazathiolium chloride provided that the amine has at least one unsubstituted ortho-position. An unsubstituted position para to the amino-group is simultaneously chlorinated. o-Toluidine, for example, gives (I; R1 = Me, R2 = Cl). R'Deactivating groups such as nitro-, carboxylic acid, sulphonic acid, or arsonic acid in the para-position are displaced by ch1orine.l The o-nitro-groups in 2-nitrot For a review of the Herz reaction see ref. 2.

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The 1,3,4-oxadiazotine is not isolable, since under the conditions of the reaction it will be converted into the C.

A number of sulphinylhydrazides, RCO*NH*NSO, have been prepared. They are readily hydrolysed to the corresponding hydrazide, and, on heating, are converted into the carboxylic acid or acid chloride.

When this was complete red needles separated.We acknowledge generous gifts of isodurene from the British Petroleum Co., Ltd., and from Esso Research Ltd.