Nucleophilic Ion Pairs. 5. Facile Cleavage of Amide Substrates by a Hydroxamate Anion in Aprotic Solvents. Efficient Inhibition by Minute Amounts of Water

Seiji Shinkai, Naotoshi Nakashima, Toyoki Kunitake

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

A quaternary ammonium salt of the hydroxamate anion was found to cleave several N-methylanilide substrates very readily at room temperature in dry, aprotic media. In contrast, the reaction was very slow in protic media and, for example, a rate difference of >105 was observed between dimethylformamide and formamide media for the reaction of N-methyl-p-nitroacetanilide and tetraethylammonium N-methylmyristohydroxamate. The reaction was efficiently suppressed by minute amounts of water and a kinetic isitope effect (KH2O/KD2O) of 1.3-1.5 was observed for some substrates. These results indicate that both the nucleophilic attack and the proton transfer to the tetrahedral intermediate were facilitated in dry, aprotic media. The reaction of the hydroxamate and p-nitrophenyl acetate was facilitated in dry, aprotic media and in aqueous cationic micelles. Thus, the complete suppression of the amide cleavage in the cationic micelle was attributed to the inefficient proton transfer to the tetrahedral intermedate.

Original languageEnglish
Pages (from-to)5887-5892
Number of pages6
JournalJournal of the American Chemical Society
Volume100
Issue number18
DOIs
Publication statusPublished - Jan 1 1978

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Proton transfer
Micelles
Amides
Anions
Protons
Negative ions
Ions
Dimethylformamide
Tetraethylammonium
Water
Substrates
Ammonium Compounds
Salts
Kinetics
Temperature
4-nitrophenyl acetate
formamide

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Nucleophilic Ion Pairs. 5. Facile Cleavage of Amide Substrates by a Hydroxamate Anion in Aprotic Solvents. Efficient Inhibition by Minute Amounts of Water. / Shinkai, Seiji; Nakashima, Naotoshi; Kunitake, Toyoki.

In: Journal of the American Chemical Society, Vol. 100, No. 18, 01.01.1978, p. 5887-5892.

Research output: Contribution to journalArticle

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abstract = "A quaternary ammonium salt of the hydroxamate anion was found to cleave several N-methylanilide substrates very readily at room temperature in dry, aprotic media. In contrast, the reaction was very slow in protic media and, for example, a rate difference of >105 was observed between dimethylformamide and formamide media for the reaction of N-methyl-p-nitroacetanilide and tetraethylammonium N-methylmyristohydroxamate. The reaction was efficiently suppressed by minute amounts of water and a kinetic isitope effect (KH2O/KD2O) of 1.3-1.5 was observed for some substrates. These results indicate that both the nucleophilic attack and the proton transfer to the tetrahedral intermediate were facilitated in dry, aprotic media. The reaction of the hydroxamate and p-nitrophenyl acetate was facilitated in dry, aprotic media and in aqueous cationic micelles. Thus, the complete suppression of the amide cleavage in the cationic micelle was attributed to the inefficient proton transfer to the tetrahedral intermedate.",
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N2 - A quaternary ammonium salt of the hydroxamate anion was found to cleave several N-methylanilide substrates very readily at room temperature in dry, aprotic media. In contrast, the reaction was very slow in protic media and, for example, a rate difference of >105 was observed between dimethylformamide and formamide media for the reaction of N-methyl-p-nitroacetanilide and tetraethylammonium N-methylmyristohydroxamate. The reaction was efficiently suppressed by minute amounts of water and a kinetic isitope effect (KH2O/KD2O) of 1.3-1.5 was observed for some substrates. These results indicate that both the nucleophilic attack and the proton transfer to the tetrahedral intermediate were facilitated in dry, aprotic media. The reaction of the hydroxamate and p-nitrophenyl acetate was facilitated in dry, aprotic media and in aqueous cationic micelles. Thus, the complete suppression of the amide cleavage in the cationic micelle was attributed to the inefficient proton transfer to the tetrahedral intermedate.

AB - A quaternary ammonium salt of the hydroxamate anion was found to cleave several N-methylanilide substrates very readily at room temperature in dry, aprotic media. In contrast, the reaction was very slow in protic media and, for example, a rate difference of >105 was observed between dimethylformamide and formamide media for the reaction of N-methyl-p-nitroacetanilide and tetraethylammonium N-methylmyristohydroxamate. The reaction was efficiently suppressed by minute amounts of water and a kinetic isitope effect (KH2O/KD2O) of 1.3-1.5 was observed for some substrates. These results indicate that both the nucleophilic attack and the proton transfer to the tetrahedral intermediate were facilitated in dry, aprotic media. The reaction of the hydroxamate and p-nitrophenyl acetate was facilitated in dry, aprotic media and in aqueous cationic micelles. Thus, the complete suppression of the amide cleavage in the cationic micelle was attributed to the inefficient proton transfer to the tetrahedral intermedate.

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