Aromatic reactivity. Part XXXVII. Detritiation of substituted 1- and 2-tritionaphthalenes

Abstract

Rates of detritiation in trifluoroacetic acid have been measured for a series of X-1- and X-2-tritionaphthalenes. Rates at 70·0°(in some cases, shown italicized, obtained by extrapolation from measurements at other temperatures), relative to that of the parent 1- or -2-tritionaphthalene, are as follows: (a) 1-tritio-compounds; (X =) 2-Me 300; 3-Me 2·75; 4-Me 83; 5-Me 2·18; 6-Me 1·31; 7-Me 2·90; 8-Me 1·53; 2-OMe 2·2× 10⁴; 4-OMe 8600; 5-OMe 3·87; 4-Ph 15·9; 2-F 1·71; 4-F 4·6; 5-F 0·043; 8-F 0·053; 2-Cl 0·26; 3-Cl 0·0023; 4-Cl 0·265; 5-Cl 0·028; 6-Cl 0·032; 7-CI 0·138; 8-CI 0·043; 2-Br 0·165; 4-Br 0·135; 5-Br 0·025; 8-Br 0·047; 2-I 0·32; 4-I ∼0·18; 8-I 0·066; (b) 2-tritio-compounds; (X =) 1-Me 270; 3-Me 3·59; 4-Me 2·99, 5-Me 1·76; 6-Me 19·4; 7-Me 1·59; 8-Me 3·11; 1-OMe 3·7×10⁵; 3-OMe 36; 4-OMe 1·58; 6-OMe 124; 1-F 0·54; 3-F 0·044; 4-F 0·014; 1-CI 0·074; 3-CI 0·043; 4-CI 0·0103; 5-CI 0·0105; 6-CI 0·184; 7-CI 0·029; 8-CI 0·0205; 1-Br 0·044; 3-Br 0·029; 4-Br 0·0096; 8-Br 0·0136; 1-I ∼0·087; 3-I 0·048; 4-I 0·0194. The main features of the results are discussed, and in some cases are qualitatively interpreted theoretically.