- cis-trans Isomerism in Monoalkylhydroxamic Acids by 1H, 13C and 15N NMR spectroscopy
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The first example of cis-trans isomerism in monoalkylhydroxamic acids, detected by 1H, 13C and 15N NMR spectroscopy, is reported.The 15N NMR spectrum of CH3CO(15)NHOH gave a clear assignment of the OH and NH protons of both Z and E isomers.The assignment was confirmed by 1H and 13C NMR spectroscopy.A rotational barrier of isomerization (ΔG++c) of 17.8 kcal mol -1 was calculated from the variable-temperature 1H NMR spectra using the method of Shanan-Atidi and Bar-Eli.KEY WORDS cis-trans Isomerism 1H, 13C and 15N NMR Monoalkylhydroxamic acids Rotational barrier
- Brown, David A.,Glass, William K.,Mageswaran, Rajeswary,Girmay, Berhane
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- Preparation method of caprylhydroxamic acid
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The invention relates to the technical field of chemical synthesis, in particular to a preparation method of caprylhydroxamic acid, which comprises the following steps: 1. mixing hydroxylamine hydrochloride and methanol to prepare a hydroxylamine hydrochloride methanol solution with a certain concentration; step 2, adding the hydroxylamine hydrochloride methanol solution obtained in the step 1, liquid sodium methoxide and methyl caprylate into a reactor, and carrying out an oximation reaction for 300 seconds to 3 hours under the conditions of normal pressure and the reaction temperature of 60to 75 DEG C; and step 3, cooling the solution after the reaction in the step 2 to 15-30 DEG C, introducing hydrogen chloride gas until the pH value of the solution is 2-4, and then performing centrifugation, concentration, crystallizing, centrifugation and drying to obtain a caprylhydroxamic acid product. According to the method, the liquid sodium methoxide is used as a raw material for synthesizing the caprylhydroxamic acid, so that the yield of the product is greatly improved, the obtained product has high purity and few impurities, no wastewater is generated in the synthesis process, the production cost is reduced, and the method is more environment-friendly.
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Paragraph 0015-0049
(2020/02/14)
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- An expeditious hydroxyamidation of carboxylic acids
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Capitalizing on in situ activation with the cyclic phosphonic anhydride PPAA (1), the conversion of carboxylic acids into hydroxamic acids has been reduced to an experimentally simple one-pot operation that addresses the issue of polyacylation without resorting to a large excess of hydroxylamine or to protection. Scope and selectivity were satisfactory with a wide range of substrates, including α,β-unsaturated acids and hydroxyacids.
- Ech-Chahad, Abdellah,Minassi, Alberto,Berton, Luca,Appendino, Giovanni
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p. 5113 - 5115
(2007/10/03)
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- Direct Conversion of Hydroxamic Acids into Nitriles
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Aromatic and aliphatic nitriles are prepared in excellent yield from the corresponding hydroxamic acids and phosphorus tribromide in benzene solution.
- Liguori, Angelo,Sindona, Giovanni,Romeo, Giovanni,Uccella, Nicola
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