Mass spectral fragmentation patterns of some new 3,7‐dichloro‐benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐dicarboxylic acid dianilides and 3,5‐dichloro‐dithieno[3,2‐b:2′,3′‐d]thiophene‐2,6‐dicarboxylic acid dianilides. II

The electron impact mass spectra of some benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐dicarboxylic acid dianilides and dithieno[3,2‐b:2′,3′‐d]thiophene‐2,6‐dicarboxylk acid dianilides are discussed. Dominant peaks in these dianilides are formed by the cleavage of a CN bond on one side of an anilino group. These ions fragment further by the cleavage of a CC bond on the other side of an anilino group and a CONRPhR′ group may be lost directly. After loss of CO, the characteristic benzodithiophene radical cation, C 10 H 2 S 2 Cl   2 □   + ., at m / z 256 and the dithienothiophene radical cation, C 8 S 3 Cl   2 □   + ., at m / z 262 are formed from their respective precursor compounds.