Correlation of solute-solute interaction enthalpies in dimethylformamide by group additivity

The Savage and Wood group additivity method has been applied to enthalpic pair interaction coefficients of more than 30 solutes dissolved in N,N-dimethylformamide. The results are not satisfactory. Better results are obtained by using a method which accounts for the differences in the numbers of molecular groups between solute and solvent molecules. With this excess group additivity method reasonable correlations are obtained even for solutes as large as dipeptide amides.     

DMA水溶液的1H NMR研究

测量了N，N-二甲基乙酰胺(DMA)水溶液体系不同温度下全浓度范围的^1H NMR数据，对体系中的缔合情况进行了讨论。应用化学缔合模型求得了各缔合平衡常数K和缔合平衡的△H，结合N，N-二甲基甲酰胺(DMF)和N-甲基乙酰胺(NMA)水溶液的研究结果，发现酰胺自身结构和酰胺浓度是影响酰胺水溶液性质的主要因素。     

1-(3-吡唑基)薁-3-甲酸甲酯类衍生物的合成

室温下,1-乙酰基薁-3-甲酸甲酯与N,N-二甲酰胺缩甲醛缩合后再与肼或苯肼反应,合成了6个新的1-(3-吡唑基)薁类衍生物,其结构经1HNMR,MS和元素分析表征。并对反应机理进行了探讨。     

Synthesis of 2- and 4-chloropyrimidines with hydroxyphenyl substituents by the interaction of Vilsmeier-Haack reagents with (hydroxyphenyl)dihydropyrimidin-2- and -4-ones

The reaction of 2- and 4-hydroxypyrimidines containingortho- andpara-hydroxyphenyl substituents with Vilsmeier-Haack reagents generatedin situ from DMF and SOCl₂ or POCl₃ results in the chemoselective replacement of the heterocyclic hydroxyl group by chlorine and formylation of the phenolic hydroxyl group. Aryl formates are hydrolyzed under the conditions of their isolation to give the corresponding phenols, especially if the pyrimidyl fragment isortho to the formyloxy group.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1105–1108, June, 1993.     

Complex Formation of 1,10-Dibenzyl-1,10-diaza-18-crown-6 with Ni2+, Cu2+, Ag+ and Cd2+ Metal Cations in Acetonitrile–dimethylformamide Binary Solutions

Conductance measurements are reported for nickel(II), cupper(II), silver(I) and cadmium(II), salts in acetonitrile (AN)–dimethylformamide (DMF) binary solvents containing macrocyclic ligand, 1,10-dibenzyl-1,10-diaza-18-crown-6 (DBDA18C6) at different temperatures. The changes in molar conductance caused by addition of DBDA18C6 to solutions were analyzed by non-linear least squares to give stability constants of 1:1 metal cation–DBDA18C6 complexes. The results show that the stabilities of the complexes are sensitive to solvent composition and in some cases the sequence of stabilities is changed with changing the composition of the mixed solvents. The values of thermodynamic quantities (ΔH°c and ΔS°c) for formation of DBDA18C6-Ni²⁺, DBDA18C6-Cu²⁺, DBDA18C6-Ag⁺ and DBDA18C6-Cd²⁺ complexes were obtained from temperature dependence of the stability constants and the results show that the values of ΔH°c and ΔS°c for these complexes are sensitive to the nature and composition of AN–DMF binary solutions, but they do not vary monotonically with the solvent composition.     

Synthesis ofN-(amidomethyl)- andN- (imidomethyl)-α-amino acid esters by reactions of α-amino acid esters with formaldehyde and amides or imides

Reactions of hydrochlorides of glycine, alanine, phenylalanine, L-isolcucinc, and L-valine esters with aromatic and heteroaromatic carboxamides afforded hydrochlorides of the correspondingN-(amidomethyl)--amino acid esters.N-(Phthalimidomethyl)--amino acid esters were obtained by reactions of -amino acid esters containing free amino groups with formaldehyde and phthalimide, The¹H NMR studies demonstrated that the chiral centers of -amino acids may be retained in the course of condensation. Reactions of the Mannish bases obtained and their hydrochlorides with acetic anhydride and tosyl chloride afforded the correspondingN-aryl andN-sulfonyl derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp, 1761–1769, July, 1996.     

5-Acetyl-6-amino-4-methylthio-2-phenylpyrimidine and its use in the synthesis of functionalized pyrido[2,3-d]pyrimidines and pyrimido-[4,5-d]pyrimidines

Schemes for the synthesis of MeS-substituted pyrido[2,3-d]pyrimidin-5-one, pyrimido[4,5-d]pyrimidine, and 4-methylenepyrimido[4,5-d]pyrimidin-2-one based on 5-acetyl-6-amino-4-methylthio-2-phenylpyrimidine, which was prepared from the adduct of benzoyl isothiocyanate with acetylketeneN-benzoylaminal, were suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1324–1328, July, 1995.The work was carried out with financial support from the Russian Foundation for Basic Research (Grant No. 94-03-08964).     

Relation between stability constants of metal ion cryptates in two solvents and the transfer activity coefficients of the metal ions

The extrathermodynamic assumption of Lejaille and Bessière that _1,2 log K (LM ⁿ⁺ )=–G _tr (M ⁿ⁺ ) in which K is stability constant and L is cryptand 2.2.2, 2 _B 2 _B 2, 2.2.1, or 2.1.1 has been tested in dipolar aprotic solvents for M ⁿ⁺ being Li⁺, Na⁺, K⁺, Ag⁺, Tl⁺, and Ba²⁺. The relation has been found generally acceptable for the dipolar aprotic solvents propylene carbonate, acetonitrile, N,N-dimethylformamide and dimethylsulfoxide, provided the size of the ion is equal to or smaller than the cavity of the cryptand. The relation does not hold for the hydrogen bonded donating solvents, water, and methanol.     

Synthesis of 8,8-R,R-8,9-dihydro[1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazolin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones

Three-component condensation of 3-amino-1,2,4-triazole (or its 5-methyl and 5-methylthio derivatives), dimedone (or cyclohexane-1,3-dione), and dimethylformamide dimethyl acetal afforded 8,8-R, R-8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6(7H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2805–2807, December, 2005.     

A comparative study on the hydrolysis of acetic anhydride and N,N‐dimethylformamide: Kinetic isotope effect,transition‐state structure,polarity, and solvent effect

Recent studies have shown that general‐base assisted catalysis is a viable mechanistic pathway for hydrolysis of smaller anhydrides. Therefore, it is the central purpose of the present work to compare and contrast the number of hydrogen atoms in‐flight and stationary in the transition state structure of the base‐catalyzed mechanisms of 2 hydrolytic reactions as well as determine if any solvent effects occur on the mechanisms. The present research focuses on the hydrolytic mechanisms of N,N‐dimethylformamide (DMF) and acetic anhydride in alkali media of varying deuterium oxide mole fractions. Acetic anhydride has been included in this study to enable comparisons with DMF hydrolysis. Comparative studies may give synergistic insight into the detailed structural features of the activated complexes for both systems. Hydrolysis reactions in varying deuterium oxide mole fractions were conducted in concentrations of 2.0M , 2.5M , and 3.0M for DMF and 0.10M for acetic anhydride at 25°C. Studies in varying deuterium mole fractions allow for proton inventory analysis, which sheds light on the number and types of hydrogen atoms involved in the activated complex. For these systems, this type of study can distinguish between direct nucleophilic attack of the hydroxide ion on the carbonyl center and general‐base catalysis by the hydroxide ion to facilitate a water molecule attacking the carbonyl center. The numerical data are used to discuss 3 possible mechanisms in the hydrolysis of DMF.