EXCITED-STATE, PROTON-TRANSFER REACTIONS OF SUBSTITUTED NAPHTHOLS IN MICELLES - COMPARATIVE-STUDY OF REACTIONS OF 2-NAPHTHOL AND ITS LONG-CHAIN ALKYL DERIVATIVES IN MICELLAR SOLUTIONS OF CETYLTRIMETHYLAMMONIUM BROMIDE

Excited-state, proton-transfer (ESPT) reactions of 2-naphthol and its long-chain alkyl derivatives (6-hexadecyl-2-naphthol and 1-octadecyl-2-naphthol) were investigated in micellar solutions of cetyltrimethylammonium bromide (CTAB) and in ethanol solutions. Significant slowing down (by a factor of five to eight) of the photodissociation of 2-naphthol containing alkyl groups in comparison with non-substituted 2-naphthol was observed in CTAB micelles, in contrast with ethanol solutions where the rate constants of ESPT reactions with the acetate anion for a-naphthol and its long-chain alkyl derivatives are similar. Experimental results are rationalized in terms of the effect of the specific localization of the naphthol and naphtholate moieties of different hydrophobicity in the micelles and of the relationship between the kinetic and thermodynamic parameters of ESPT.