- Systematic Evaluation of Sulfoxides as Catalysts in Nucleophilic Substitutions of Alcohols
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Herein, a method for the nucleophilic substitution (SN) of benzyl alcohols yielding chloro alkanes is introduced that relies on aromatic sulfoxides as Lewis base catalysts (down to 1.5 mol-%) and benzoyl chloride (BzCl) as reagent. A systematic screening of various sulfoxides and other sulfinyl containing Lewis bases afforded (2-methoxyphenyl)methyl sulfoxide as optimal catalyst. In contrast to reported formamide catalysts, sulfoxides also enable the application of plain acetyl chloride (AcCl) as reagent. In addition, it was demonstrated that weakly electrophilic carboxylic acid chlorides like BzCl promote Pummerer rearrangement of sulfoxides already at room temperature. This side-reaction also provided the explanation, why sulfoxide catalyzed SN-reactions of alcohols do not allow the effective production of aliphatic and electron deficient chloro alkanes. Comparison experiments provided further insight into the reaction mechanism.
- Motsch, Sebastian,Schütz, Christian,Huy, Peter H.
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supporting information
p. 4541 - 4547
(2018/09/13)
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- Aqueous solutions of geminal alkylammonium surfactants as a medium for reactions of long-chain amines
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The formation of surfactant-hydrophobic amine mixed aggregates reduces the pK a of long-chain amines by 1-1.5 units compared with those in molecular solutions and is an important factor responsible for the high catalytic effect of the system in
- Mirgorodskaya,Kudryavtseva
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experimental part
p. 42 - 48
(2009/05/30)
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- Pyridine-derived heterocycles as potential photoacylating reagents
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We prepared several pyridine-derived heterocycles and investigated their photoacylating properties. Among representatives of 4 families of compounds (1-acetyl-7-azaindole, 1-acetyl-7-azaindoline, 2-acetamindpyridine and 2-amidopyrimidines), the 2-aminopyrimidine derivatives were the most promising candidates. Photoacylation of dodecylamine yields up to 47% were obtained, upon irradiation with UV light at 254 nm.
- Helgen, Celine,Bochet, Christian G.
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p. 797 - 805
(2007/10/03)
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- On the Mechanism of Ester Aminolysis in the Presence of Alkylammonium Carboxylate Reversed Micelles
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The mechanism of ester aminolysis by alkylammonium carboxylate reversed micelles was examined.There are two possible pathways, one involving the carboxylate group of the surfactant acting as a general base and another in which it is acting as a nucleophile.The latter mechanism involves the formation of a mixed anhydride (derived from the surfactant and the ester) leading, on aminolysis, to two amides.It was not possible to detect the formation of the intermediate anhydride.Careful analysis of the reaction products showed that only one amide, that derived from ester,is formed.Thus the second mechanism is in error.The nature of the slow step was explored by studying the aminolysis of a series of esters: p-X-phenyl acetates (where X = CH3O, CH3, H, Br, CN, and NO2) by dodecylammonium propionate (DAP) and by dodecylamine plus DAP in benzene and in cyclohexane.Excellent correlations between the logarithm of the rate constant and the Hammett (?-) values were obtained.This implies that the phenoxide ion is the leaving group and that the slow step probably involves the collapse of the tetrahedral intermediate formed by the attack of the amine on the ester.Thus it appears that ester aminolysis in the micellar pseudophase and that in aprotic solvents proceed with the same mechanism and rate-limiting step.
- Seoud, Monica I. El,Vieira, Rita C.,Seoud, Omar A. El
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p. 5137 - 5141
(2007/10/02)
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