Organic Chemistry

Hippuric acid 1 cyclized by using cyanuric acid (TCT) as environmentally benign catalyst to 2-phenyloxazol-5(4H)-one 2 further treated with aromatic aldehyde-Friedel Craft reaction to benzoylaminoketones 3 and finally cyclized using the same reagent (TCT) gives good yields of substituted 2,5 diaryloxazoles 4a-h under the reflux condition.

The kinetics of oxidation of cyclohexanol by PDC has been studied in non-aqueous medium. In this oxidation Cr(VI) is working as two-electron oxidizing agent. The reaction is first order with respect to each [oxidant], [TsOH] and [cyclohexanol]. The reaction is catalyzed by hydrogen ions. Low dielectric constant of the medium favors the reactivity. The observed experimental data have been rationalized as follows: the formation of dichromate ester in a fast pre equilibrium step and then decomposition of the ester in slow step via a compact transition state leading to the product, cyclohexanone.

We report herein the use of Nickel acetyl acetonate [Ni(acac)₂] as a new catalyst for the one-pot Biginelli reaction coupling of ?-ketoester, aldehydes and urea (or thiourea) to afford the corresponding dihydropyrimidinones/thiones.

The kinetics of oxidation of some para-substituted benzyl alcohols by PDC have been studied in DMSO spectrophotometrically acidified with TsOH. From good linear Eyring plots ?H# and ?S# are calculated. The reaction has unit dependence on each [PDC], [H+] and [Alcohol]. Electron-releasing substituent accelerates the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship. PDC is acting as two-electron transfer oxidant. A mechanism implicating the prior acid-catalyzed formation of dichromate ester followed by cyclic intermediate is proposed.

6-amino-4-(substitutedphenyl)-1-(2,4-dinitrophenyl)-3-methyl-pyrazolo [3,4-b] pyridine-5-carbonitrile have been prepared by the refluxation for six hours of 4-(substitutedbenzylidene)-2-(2,4-dinitrophenyl)-5-methyl-2,4-dihydro-pyrazol-3-one, malononitrile and ammonium acetate in presence of ethanol. The intermediate 4-(substituted benzylidene)-2-(2,4-dinitrophenyl)-5-methyl-2,4-dihydro-pyrazol-3-one have been prepared by the refluxation for five hours of 2-(2,4-dinitro phenyl)-5-methyl-2,4-dihydro-pyrazol-3-one with substituted benzaldehyde in presence of glacial acetic acid. The synthesized compounds were characterized by means of their IR, 1H-NMR spectral data and elemental analysis.

This study aims to analyze the phytochemical screening and antibacterial activity of leaves extract of Jatropha curcas against histamine forming bacteria, and determine of minimum inhibitory concentration. The extraction process is done by maceration method using hexane, chloroform, ethyl acetate and methanol. The extract was obtained continued by antibacterial activity test against histamine-forming bacteria. Concentration all extract of J. curcas is 1%, 10%, 20%, and 30% (w / v). Positive control using synthetic antibiotic ampicillin and negative controls used dimethyl sulfoxide (DMSO). The results of phytochemical screening showed that ethyl acetate and methanol extracts containing 5 secondary metabolites, while the hexane and chloroform containing only 2 secondary metabolites. Antibacterial activity test showed that the negative control and positive control do not provide inhibition against test bacteria. All types of extracts with concentrations of 1% to 30% (w / v) gave inhibition against test bacteria. The diameter of the inhibition of K. pneumoniae and C. perfringens for all jatropha leaf extract at a concentration of 1% (w / v) did not show any significant difference to the concentration of 10%. Lowest MIC (0.10% w / v) there at the ethyl acetate extract (E3) and methanol (E4) for the bacteria C. perfringens.

A new series of isoxazoles (7a-f), cyanopyridines (8a-f) and pyrimidinthiones (9a-f) have been prepared from chalcones (6a-f) having s-triazine nucleus. These chalcones on cyclisation with hydroxyl amine hydrochloride in the presence of alkali and malononitrile in the presence of ammonium acetate give isoxazoles (7a-f) and cyanopyridines (8a-f) respectively. Chalcones (6a-f) on condensation with thiourea in the presence of alkali give pyrimidinthiones (9a-f). Structures of newly synthesised compounds were established on the basis of their elemental analysis, IR and 1H NMR spectral data. Antibacterial activity (minimum inhibitory concentration MIC) against Gram-positive (S. aureus MTCC 96 and S. pyogeneus MTCC 442 ) and Gram-negative (P. aeruginosa MTCC 1688 and E. coli MTCC 443) bacteria, as well as antifungal activity (MIC) against C. albicans MTCC 227, A. niger MTCC 282 and A. clavatus MTCC 1323 were determined by broth dilution method.

The ultrasonic velocity, density and viscosity have been measured for the binary liquid mixture of polyvinyl alcohol+ water has been measured as a function of the composition of 303,308,313and318 K. The experimental data have been used to calculate some parameters namely, acoustic impedance (z), adiabatic compressibility (?), intermolecular free length (Lf), and relative association (RA). The results are discussed and interpreted in terms of structural and specific interactions that predominated by intermolecular hydrogen bonding.

A Coumarin derivative, 4-ethoxy-6-((hydroxymethoxy)methyl)-2H-chromen-2-one, was isolated from the stem bark of Jatropha multifida, and its structure was elucidated from UV, IR, MS and 2D NMR spectra. The compound has 1-oxygenated structure with a lactone moiety.

Ten new heterocyclic moiety containing Schiff bases have been synthesized by the condensation of 4,5-diazafluoren-9-one with substituted amines by using SnCl₂ as a catalyst under solvent free condition. The Schiff bases were obtained in good yields and easy to isolate. Some synthesized products were characterized by IR, NMR and MASS and also tested for antibacterial activities by disc diffusion method.