Partial molar volumes of amino acid derivatives in water

The partial molar volumes at infinite dilution for a number of hydrochlorides and sodium salts of N-methyl derivatives of , -aminocarboxylic acids in water at 25°C are measured and related to their van der Waals volumes. Results indicate that 4.96±0.48 water molecules hydrate a betaine hydrochloride. Volumes of proton ionization and interaction terms are evaluated. Group contributions to the partial molar volumes are also reported.     

Synthesis and molecular structure of 3-(2-aryl-2-oxoethyl)-3-methoxy-2-oxo-2,3-dihydroimidazo-[1,2-<Emphasis Type="Italic">a</Emphasis>]pyridine hydrochlorides

Reactions between 2-pyridylamides of Z-4-aryl-2-hydroxy-4-oxobut-2-enoic acids with diazomethane have been used to synthesize 3-(2-aryl-2-oxoethyl)-3-methoxy-2-oxo-2,3-dihydroimidazo[1,2-a]pyridines, which form hydrochlorides with hydrochloric acid. The structure of the latter has been demonstrated by XRD for the hydrochloride of 3-methoxy-2-oxo-3-(2-phenyl-2-oxoethyl)-2,3-dihydroimidazo[1,2-a]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 464–468, 2007.     

Microwave‐Assisted One‐Pot Preparation of Tetrahydro‐β‐carboline Hydrochlorides under Solvent‐Free Conditions

An efficient and environmentally friendly synthesis of tetrahydro‐β‐carboline hydrochlorides via Pictet–Spengler reaction was described. Tryptamine hydrochlorides were used as the reactant and no additional acid catalyst was needed. This reaction was completed within 2.5–9 min in good yield.     

Synthesis of 2,5-disubstituted 1,3,4-oxadiazoles containing benzothiazolylthiol grouping

A series of 2,5-substituted 1,3,4-oxadiazoles containing 2-benzothiazolylthiomethyl grouping has been synthesized by condensing derivatives of (2-benzothiazolylthio)acetic acid with imino ester hydrochlorides and hydrazides of carboxylic acids, by the cyclodehydration of N-acyl-N-(2-benzothiazolylthioacetyl)hydrazines under the action of POCl, and also by the reaction of 2-mercaptobenzothiazole with 2-chloromethyl-1,3,4-oxadiazoles in the presence of sodium methylate.I. M. Gubkin Russian State University for Petroleum and Gas, Moscow 117917. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 249–255, February, 2000.     

Partial molar volumes of organic compounds in water. VI. α,ω-diaminoalkane hydrochlorides

Measurements of the partial molar volumes in water at 25°C of the mono-and dihydrochlorides of the ,-diaminoalkanes, up to a chain length of 10 carbon atoms, are reported. Volumes of ionization have been determined and the electrostriction of the solvent calculated. Effects of the substituents are felt up to the -carbon atom, but thereafter are only very weak or nonexistent.     

Synthesis of 6-acylpyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine derivatives from 5-acetyl-4-aminopyrimidine hydrochlorides

Reaction of 2,6-disubstituted 5-acetyl-4-aminopyrimidine hydrochlorides with acetylacetone or benzoylacetone afforded new substituted 6-acylpyrido[2,3-d]pyrimidines. The reaction of these hydrochlorides with ethyl acetoacetate also proceeds according to the classical version of the Friedländer condensation to form the corresponding pyrido[2,3-d]pyrimidine-6-carboxylic acid esters.     

Spectrophotometric determination of trazodone, amineptine and amitriptyline hydrochlorides through ion-pair formation with molybdenum and thiocyanate

Extraction spectrophotometric method has been developed for the determination of tricyclic drugs such as trazodone (TZH), amineptine (APH) and amitriptyline (ATPH) hydrochlorides in pure form and in the dosage forms coming from different Egyptian markets. The method based on the formation of ion-pairs between these drugs under investigation and inorganic complex of Mo(V)-thiocyanate followed by its extraction with methylene chloride. The optimum conditions for the ion-pairs formation are established. The method permits the determination of TZH, APH and ATPH over the concentration range of 2-28, 2-32 and 1-30 microg ml(-1), respectively. The Sandell sensitivity (S) is found to be 0.105, 0.138 and 0.118 g cm(-2) for TZH, APH and ATPH, respectively. The SD is found to be 0.16-0.377, 0.12-0.259 and 0.091-0.286 and the R.S.D. are 0.14-0.55, 0.12-0.399 and 0.095-0.485 for TZH, APH and ATPH, respectively. The method is applicable for the assay of the investigated drugs in different dosage forms and the results are in good agreement with those obtained by the official method.     

Synthesis of 2-Substituted Benzimidazoles, Benzoxazoles, and Benzothiazoles from Arylsulfonyl(thio)propionitriles

The reaction of nitriles and of methyl imino ester hydrochlorides of arylsulfonyl(thio)propionic acids with o-phenylenediamine, o-aminophenol, and o-aminothiophenol has been studied. A series of new 2-substituted benzazoles has been synthesized containing arylsulfonyl(thio)propionic acid fragments.     

Efficient and Straightforward Synthesis of Tetrahydrocarbazoles and 2,3-Dimethyl Indoles Catalyzed by CAN

A simple protocol was established to synthesize 2,3-dialkyl indoles and various tetrahydrocarbazoles via Fischer indole synthesis. This method uses ceric ammonium nitrate as a catalyst for the Fischer indole synthesis with substituted phenyl hydrazine hydrochlorides and 2-butanone, phenyl propanal, and cyclohexanone. This process is a practical synthetic method for the preparation of various 2,3-disubstituted alkyl indoles and tetrahydrocarbazoles.     

Transition metal free K2CO3 mediated thioarylation,selenoarylation and arylation of 2-aminomaleimides at ambient temperature

Transition metal free thioarylation, selenoarylation and arylation of 2-aminomaleimide, using thiophenols, diaryl diselenides and arylhydrazine hydrochlorides respectively, has been reported in DMSO under aerobic condition in presence of K₂CO₃ at room temperature. The reaction occurs smoothly without prerequisite N-protection of 2-aminomaleimide. The synthesis of novel, polyfunctionalized maleimides has been achieved by the direct C–H activation of enamines. Thioarylation and selenoarylation are proposed to be proceeding via disulfides/diselenides and arylation has been proposed to be proceeding via aryl free radicals.