- Sulfuranes Lacking Benzoannelation. Sulfuranes and Other Hypervalent Molecules Studied by 17O-NMR
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The rates of hydrolysis of benzoannelated vs nonbenzoannelated sulfuranes, viz. 5 vs 3 or 5 vs 4, were compared. Benzoannelation was found to provide very modest kinetic stabilization. Crystal structures of sulfuranes 3 and 4 were obtained and compared with each other, with a dibenzoannelated sulfurane, 17, and with a non-sulfurane analogue of 4. Bond length variations could be understood in the context of simple resonance arguments. 17O NMR studies of 3-5 showed that this technique was indeed sensitive to sulfurane structure. For example, the chemical shifts of the two carbonyl oxygens of 4 differed by over 20 ppm. Other hypervalent systems, mainly iodinanes, were studied by 17O NMR. A variety of theoretical methods were surveyed to test how well they could reproduce the geometry of 3. Density functional theory calculation outperformed ab initio geometry optimization at the MP2/3-21G(*) level. Finally, a cis-trans isomerization of the double bond of 11 and one of the two double bonds of 10 was studied.
- Ho, Zwei-Chang,Livant, Peter,Lott, William B.,Webb, Thomas R.
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- Preparation method of butynedioic acid
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The invention provides a preparation method of butynedioic acid, which comprises the following steps of dissolving malic acid, inorganic alkali and sulfonyl chloride in an organic solvent, and reacting at room temperature until the malic acid is completely reacted to obtain an intermediate system, and carrying out heating reaction on the intermediate system to obtain butynedioic acid, wherein the organic solvent comprises dimethyl sulfoxide. According to the preparation method, the cheap and easily available malic acid is taken as a raw material, the butynedioic acid product is obtained by a one-pot method, the reaction condition is mild, a high-temperature and high-pressure environment and a concentrated acid and concentrated alkali reaction condition are not needed, the post-treatment process is simple, and the preparation method has the advantages of low cost and environmental friendliness, and is favorably applied to industrial production.
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Paragraph 0035; 0048; 0070-0100
(2021/08/25)
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- Preparation method of butynedioic acid
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The invention discloses a preparation method of butynedioic acid. The method comprises the following steps of: (1) firstly, carrying out water-free and oxygen-free treatment on a closed reaction kettle; (2) putting calcium carbide, a solvent, a catalyst and an auxiliary agent into the reaction kettle, introducing carbon dioxide into the reaction kettle, and heating and pressurizing for reaction; (3) separating the reacted mixture obtained in the step (2) to obtain a liquid mixture, and adding a KOH solution into the liquid mixture; stirring to separate out a white precipitate; and dissolving the white precipitate in hot water, acidifying with concentrated sulfuric acid, cooling, separating out the white precipitate, and filtering to obtain the product. The synthesis method disclosed by theinvention is relatively environment-friendly and low in production cost.
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Paragraph 0023-0049
(2020/07/21)
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- Process for preparing alkynecarboxylic acids by oxidation of alkyne alcohols
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A process for preparing alkynecarboxylic acids includes the oxidation of an alkyne alcohol with a hypohalite in the presence of a nitroxyl compound at a pH of greater than 7 with continual addition of the alkyne alcohol and of the hypohalite to the reaction mixture.
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- OXIDATION OF ALCOHOLS BY ELECTROCHEMICALLY REGENERATED NICKEL OXIDE HYDROXIDE. SELECTIVE OXIDATION OF HYDROXYSTEROIDS
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Primary alcohols, α,ω-diols and secondary alcohols are easily transformed into carboxylic acids, dicarboxylic acids or ketones, respectively, by heterogeneous oxidation with nickel oxide hydroxide electrochemically regenerated at a nickel hydroxyde electrode.The results are discussed in comparison to those of the nickel peroxide and chromic acid oxidation.The oxidation rate decreases with increasing steric hindrance of the alcohol, thus allowing the selective oxidation of the 3-position in hydroxysteroids.
- Kaulen, Johannes,Schaefer, Hans-J.
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p. 3299 - 3308
(2007/10/02)
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