Organohalides are found to be effective catalysts for dehydrative O-alkylation reactions between alcohols, providing selective, practical, green, and easily scalable homo-and cross-etherification methods for the preparation of useful symmetrical and unsymmetrical aliphatic ethers from the readily available alcohols. Mechanistic studies revealed that organohalides are regenerated as reactive intermediates and recycled to catalyze the reactions.Scheme 1 Background of research. † Electronic supplementary information (ESI) available: Detailed condition screening tables, experimental details, characterization of the products, details of the mechanistic studies, and 1 H and 13 C NMR spectra of the products. See

The enthalpies of mixing of aqueous solutions have been determined for glycine and L-alanine with pyridine and methylpyridine by flow microcalorimetry at 298.15 K. In addition, the enthalpies of dilution at 298.15 K of aqueous solutions containing glycine, L-alanine, pyridine, and methylpyridine have been obtained, respectively. These data have been analyzed using the McMillan-Mayer theory, and heterotactic interaction coefficients are given for the interaction of glycine and L-alanine with pyridine and methylpyridine, among which the enthalpic pairwise interaction coefficients, h xy , are discussed in terms of solute-solute interaction and substituent effects.

No abstract

Densities of L-glycine, L-alanine, and L-serine have been measured with an oscillating-tube densimeter at 298.15 K in water + dimethylformamide (DMF) mixtures ranging from pure water to 45% DMF by mass. From these densities, apparent molar volumes and limiting apparent molar volumes of the three amino acids in the mixtures have been calculated. Transfer volumes were interpreted in terms of the structure-making or structure-breaking effects of these amino acids in the mixtures.

The dilution enthalpies of l-alanine in dimethylsulfoxide (DMSO) + water and dimethylformamide (DMF) + water mixtures at 298.15 K have been determined, respectively, using an isothermal titration calorimeter. On the basis of the McMillan−Mayer theory, the homochiral enthalpic interaction coefficients h XX of l-alanine in both of the mixtures of various mass fractions (w 2 = 0 to 0.3) have been calculated. It was found that h XX is positive at lower DMSO or DMF concentrations, but it becomes less positive and even negative with the increasing concentration of DMSO or DMF. The results were interpreted from the point of view of solute−solute interactions mediated by these two aprotic cosolvents.