The synthesis of benzo[k, I] thioxanthene-3,4-dicarboxylic acid-7,7-dioxide is described. Condensation of this heterocycle with amines, or oxidation of the corresponding imides of benzork, I] thioxanthene-3,4-dicarboxy/ic acid, affords a new range of dyes which colour syntheticpolymer fibres, esptxially polyester, in yellow shades of excellent fastness to light and sublimation.

Condensation of 3-and Cbromo-or nitro-7H-benzimidazo[2,1-a]benz[d,e]iso-quinolin-7-ones with 2-aminobenzenethiol, followed by Pschorr cyclisation of the resultant product, afforded the isomer mixture of the new heterocycles benzimidazo[l,t-b~thioxantheno[2,1,9-d,e,~soquinolin-7-one and benzimidaz0[2.l-a]thioxantheno[2,1 ,Bd,e,f,]isoquinolin-8-one. Separation of these ismers and their characterisation by unambiguous synthesis is reported. Small amounts of analogous 5-membered sulphur heterocycles were also formed by cyclisation in the 8-position of the naphthalene ring. These new heterocycles dye synthetic fibres in fluorescent orange and yellow shades, showing excellent fastness to light and sublimation. Principal mass spectra features of the compounds are given.

Condensation of benzo(k,i)thioxanthene‐3, 4‐dicarboxylic acid‐7, 7‐dioxide with o‐phenylenediamine gives a mixture of the new heterocycles benzimidazo(1, 2‐b) thioxantheno(2, 1, 9‐d, e, f) isoquinoline‐7‐one‐16, 16‐dioxide and benzimidazo(2, 1‐a) thioxantheno(2, 1, 9‐d, e, f) isoquinolin‐8‐one‐5, 5‐dioxide. Separation of these isomers is reported, together with their characterisation by unambiguous synthesis. Similar reaction with substituted o‐phenylenediamines affords other isomer mixes of the above. These new dyes colour polyester fibres in orange hues of excellent fastness to light and sublimation. Comparison of the dyes is made with the uncyclised sulphone derivatives of 7H‐benzimidazo(2, 1‐a) benz(d, e) isoquinoline‐7‐one, which are novel bright yellow dyes of good coloration and fastness properties on polyester.

Condensation of 3‐ and 4‐bromo‐ or nitro‐7H‐benzimidazo[2,1‐α]benz[d,e]isoquinolin‐7‐ones with 2‐aminobenzenethiol, followed by Pschorr cyclisation of the resultant product, afforded the isomer mixture of the new heterocycles benzimidazo[1,2‐b]thioxantheno[2,1,9‐d,e,f,]isoquinolin‐7‐one and benzimidazo[2,1‐a]thioxantheno[2,1,9‐d,e,f,]isoquinolin‐8‐one. Separation of these isomers and their characterisation by unambiguous synthesis is reported. Small amounts of analogous 5‐membered sulphur heterocycles were also formed by cyclisation in the β‐position of the naphthalene ring. These new heterocycles dye synthetic fibres in fluorescent orange and yellow shades, showing excellent fastness to light and sublimation. Principal mass spectra features of the compounds are given.

Durch Umsetzung der Anhydride (I) mit o‐Phenylendiamin (II) und o‐Aminothiophenol (III) entsteht das Isomerenpaar (IVa) und (IVb), das nach einer Pschorr‐Synthese ein Gemisch der Isomerenpaare (Va), (Vb), (VIa), (VIb), (VIIa) und (VIIb) ergibt.