Rz 10 assume that a similar transition state is involved in methyl transfer from any methylsulfonium compound. In order to test this hypothesis, we are continuing the study of nonenzymic transmethylation on molecules which are more closely related to SAM in structure, but which are not so readily decomposed in basic media.
Registry No. -ZaDicationic detergents (I), R?J+MeZ(CHz),N +Me2R 2Br-(where R = cetyl and n = 4 and 6), readily micellize, and the micelles are effective catalysts of the reactions of hydroxide ions with chloro-and fluoro-2,4-dinitrobenzene and hydroxide and fluoride ions with p-nitrophenyl diphenyl phosphate. With n = 4 and 6, those detergents are two-to fivefold better catalysts than cetyltrimethylammonium bromide, CTABr. The dicationic detergent R N +Me2CH2C=CCHz?J +MeaRBrz-also micellizes, but it and I (n = 2 ) are not markedly better catalysts than CTABr.
PYR1DIr:rusi AND EIPYRIDYLIUM ions readily undergo oneelectron reduction to give stable free-radicals and cation radicals respectively.' The one-electron reduction2 of 1,l'dimethyl-4,4'-bipyridylium dichloride (paraquat dichloride) is of great interest because of the correlation between ease of reduction and herbicidal activity, in a range of bipyridylium salts3 Since the oxygen-sensitive cation-radical (111) produced by one-electron reduction of paraquat (I) has an
Micelles of 1,1 -phenylhydroxypropy 1-2-dimethylalkylammonium bromide (I, alkyl = n-Ci0H2i, Ci2H25) are good catalysts of the reaction of p-nitrophenyl diphenyl phosphate in aqueous hydroxide ion, relative to micelles of the corresponding trimethylalkylammonium bromide because of nucleophilic participation by an ionized hydroxyl group in the detergent. The variation of rate with increasing hydroxide ion concentration can be explained in terms of ionization of the hydroxyl group at high pH, and p7fa « 12.7. There is no special catalytic activity of micelles of I for reactions of fluoride ion. Micelles of l,l-phenylmethoxypropyl-2-dimethyldodecylammonium bromide (II) are not particularly effective catalysts for reactions of hydroxide or fluoride ions with p-nitrophenyl diphenyl phosphate. The choline anion is approximately 35 times as reactive as hydroxide ion toward pnitrophenyl diphenyl phosphate.here are now many examples of micellar catalysis of reactions in solution, and the subject has been extensively reviewed.2-4 In most of the catalytic * To whom correspondence should be addressed.(1) Support of this work by the Arthritis and Metabolic Diseases Institute of the USPHS is gratefully acknowledged.(2) E.
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