Organic Chemistry

In an attempt to control multidrug resistant bacteria, a library of some new heterocyclic derivatives containing pyrazoline, isoxazole and pyrimidine ring systems bearing 1,3,5- triazine core were designed and synthesised from chalcones. Chalcones (AI-AV) react with hydrazine hydrate / glacial aceticacid, hydroxylamine hydrochloride / alkali and guanidine hydrochloride / alkali gives 1-acetyl pyrazoline (BI-BV), isoxazole (CI-CV) and 2-amino pyrimidine (DI-DV) derivatives respectively. The structures of all the newly synthesised compounds were assigned on the basis of FTIR, 1H NMR, 13C NMR spectral data as well as elemental analysis. In vitro antimicrobial proficiency of the title compounds were assessed against selected pathogens. The minimum inhibitory concentration (MIC) was determined by broth dilution method and recorded at the lowest concentration inhibiting growth of the organism. Compounds BI, BII, CII, CIII and DV exhibited excellent antimicrobial activity and said to be the most proficient members of the series.

The leaves of Sida acuta “Broom Weed” (Family: Malvaceae) was analysed for its proximate, anti-nutrients and mineral elements composition using standard methods. The proximate analysis showed the results to be (%) moisture 54.82, ash 7.94, crude protein 17.85, crude fat 2.70, carbohydrate 6.21, crude fibre 5.30, and caloric value 360.54 Kcal. The concentration of anti-nutrients (mg/100g) was observed to be oxalate 140.8, hydrocyanic acid 98.3, phytate 210.1 and tannin 603.7. The mineral element contents (mg/100g dry weight) were Na (81.90), K (117.40), Ca (44.32), P (1.15), Fe (1.01), Zn (1.07) and Mg (14.40). The study showed that the high concentration of anti-nutrients in Sida acuta Burn.f. obtained from this locality might cause health hazard if consumed in large quantity over a long period of time.

Ce(IV) ion and sulphate ion loaded MCM-41 materials effectively catalyze the condensation of 1,2-aromatic diamine with 1,2-diketones to afford quinoxaline derivatives under milder reaction conditions. Significant role of concentration of Ce(IV) ion has been investigated and comparative studies of catalytic efficiencies of both Ce-MCM-41 and sulfated MCM-41 have also been discussed.  Both reagents are found to efficient and reusable with consistent catalytic activity.

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.