Nucleophilic substitution on perchloroindane; reactions and structural reassignments

Abstract

Nucleophilic substitution on perchlorindane (1) with ethoxide ion gives nonachloro-5-ethoxyindane (6), heptachloro-1,1,5-triethoxyindane (7), and 3,5,6-trichloro-4-ethoxy-2-trichlorovinylbenzoic acid (8). The results show that in perchloroindane (1) aromatic chlorines are more susceptible to substitution than aliphatic chlorines. Since this has not previously been realised, structures of the products (6), (7), and (8) given in the literature are incorrect. From these products the following new compounds have been synthesized: pentachloro-5-hydroxyindane-1,3-dione (9), pentachloro-5-ethoxyindane-1,3-dione (10), heptachloro-5-ethoxyindan-1-one (11), heptachloro-5-hydroxyindan-1-one (12) and its sodium salt (13), 2-bromohexachloro-5-hydroxystyrene (14), 2-bromohexachloro-5-methoxystyrene (15), 3,5,6-trichloro-4-hydroxy-2-trichlorovinylbenzoic acid (16), pentachloro-5-hydroxy-1H-inden-1-one (17), pentachloro-5-methoxy-1H-inden-1-one (18), 5,7,8-trichloro-6-ethoxyisochroman-1,4-dione (19), 5,6,8-trichloro-7-ethoxyisochroman-1,4-dione (20), trichloro-4-ethoxyphthalic acid (21) and its anhydride (22), 2,4,5-trichloro-3-hydroxybenzoic acid (25), 2,4,5-trichloro-3-methoxybenzoic acid (27) and its methyl ester (26), 3-bromo-2,5,6-trichloroanisole (28), and 2,4,5-trichloro-3-methoxybenzoyl chloride (29). An unexpected, abnormally easy hydrolysis of a dichloromethylene group in the salt (13) is reported. Some remarkable decarboxylations and ether cleavages in KBr–dimethyl sulphoxide are also described.