- Intramolecular Hydrophobic Association of Two Alkyl Chains of Oligoethylene Glycol Diethers and Diesters in Water
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The octanol-water partition coefficients P of CnH2n+1O(CH2CH2O)mCnH2n+1 and CnH2n+1COOCH2CH2OCOCnH2n+1 are measured and analized on the basis of an empirical linearity between cavity surface area S and hydrophobicity.The slope a of log P vs. total alkyl chain length nt plots of these double chain compounds is smaller than that, aI, of oligoethylene glycol monoethers.The slope of log P vs. m plots at constant n is dependent on n and m for these diethers but is independent of n and m for the monoethers.These facts suggest that two alkyl chains of the diethers associate intramolecularly in water.As the distance d between two alkyl chains in the all-trans arrangement decreases, S of a solute molecule decreases.On the basis of the above results and the conformations of related compounds, several conformations of diethylene glycol diethers in water can be considered and the most probable conformation of ROCH2CH2OCH2CH2OR is suggested as follows: tggttg'g't.The conformations of ethylene glycol diethers and diesters are also suggested.
- Funasaki, N.,Hada, S.,Neya, S.,Machida, K.
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- Convenient Selective Monoacylation of 1,n-Diols Catalyzed by Ion-Exchange Resins
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Several 1,n-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were selectively monoacylated by transestrification in ester/octane solvent mixtures catalyzed by strongly acidic ion-exchange resisns.This method of selective esterification is quite simple and practical.The selectivity for monoester formation and initial rates of monoester formation depended on the ester/octane ratio of the solvents.The reasons for the selectivity are as follows: (1) The sulfonic acid-type ion-exchange resins usually contain 50-80percent water, and a strongly acidic aqueous layer is formed on the surface of the resins. (2) A partition equilibrium between the aqueous layer and the aprotic ester/octane layer is setup, and diols have higher partition coefficients than the product monoesters. (3) Acylation of the alcohols occurs in the aqueous layer and/or at the interface between the aqueous and the nonaqueous liquid layer. (4) The formed monoesters move away from the aqueous layer into the aprotic layer.
- Nischiguchi, Takeshi,Fujisaki, Shizuo,Ishii, Yasuhiro,Yano, Yoshihiro,Nishida, Akiko
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- Method for preparing amino alcohol derivative
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The invention provides a method for preparing an amino alcohol derivative. The method is characterized in that substitution reaction is carried out on ester groups of dihydric alcohol carboxylic esteror polyhydric alcohol carboxylic ester to obtain the amino alcohol derivative, wherein the amidogen is derived into sulfonamido, and at least one carboxylic ester group remains. The method for preparing the amino alcohol derivative has the advantages that the raw materials are cheap and obtained easily, the use quantity of catalysts is low, the reaction condition is simple, and the selectivity ofproducts is high.
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Paragraph 0072; 0073; 0074
(2018/11/22)
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- Saturation vapor pressures and vaporization enthalpies of esters of ethylene glycol and lower carboxylic acids
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Saturation vapor pressures and vaporization enthalpies of ethylene glycol and C1-C5 carboxylic acid disubstituted esters of normal and branched structures are determined by the transfer method in the tem-perature range of 295 to 327 K. Dependences of vaporization enthalpies versus the number of carbon atoms in a molecule and the retention indices are determined. An analysis of existing calculation schemes is given to help predict the vaporization enthalpy of the compounds under study.
- Maslakova,Krasnykh,Levanova
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experimental part
p. 1695 - 1700
(2012/01/12)
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- Ceric ammonium nitrate (CAN) - A useful catalyst for the rapid and high-yield esterification of carboxylic acids and alcohols with special reference to steroid and other multi-functional natural products
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Ceric ammonium nitrate (CAN) acts as a versatile catalyst for the esterification of carboxylic acids and alcohols, including steroids and other multi-functional natural products, in excellent yields under mild and convenient reaction conditions.
- Goswami,Chowdhury
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p. 955 - 957
(2007/10/03)
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- Preparation of Carboxylate Esters of Polyhydric Alcohols by Using a Sulfonated Charcoal Catalyst
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Ethane-1,2-diol, propane-1,2-diol, butane-1,4-diol and propane-1,2,3-triol are readily esterified by carboxylic acids in near quantitative yields in the presence of a sulfonated charcoal catalyst.
- Prager, Rolf H.,Yurui, Zhang
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p. 1003 - 1005
(2007/10/02)
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