Organic Chemistry

An aqueous medium multicomponent synthesis of trans-2-aroyl-5-methyl-3-aryl-3, 5-dihydrofuro [3, 2-c]-quinolin-4(2H)-one in pyridine by conventional and microwave irradiation, easy workup, smaller reaction time and lack of column chromatography are the significant feature of this protocol. The Phenacyl bromide with pyridine is first time used as starting with1-methyl-4-hydroxy quinolone, substituted aromatic aldehydes for the biological interest compound (4a-p) for this green transformation generating one C-O and two C-C bonds in one operation, Knoevenagel followed by Michael addition and intramolecular Cyclisation.

Recently in this laboratory the economical, environmental, solvent free, mild and having simple work-up reaction condition was developed for the green synthesis of a novel series of 1-substituted-3-(4-pyridinoimino)thiocarbamides (IIIa-e) having high product yield and avoid treacherous byproducts. The interactions of 4-cyanopyridine (I), concentrated hydrochloric acid and various thiourea (IIa-e) were carried out in microwave oven to synthesize (IIIa-e). The green chemistry parameters were maintained. The synthesized compounds were recrystalised and the structure of synthesized compounds were justified and established on the basis of elemental analysis, chemical characteristics and spectral studies.

In this study, Fusarium oxysporum AUMC9264 was isolated from Lupinustermis L. which was identified by a morphological method and 18S rDNA sequence comparison. Potato Dextrose Agar (PDA) was used for activation and subcultures of the fungal isolate while, Potato Dextrose Broth medium (PDB) used for metabolite production. The fungal extracts were tested in vitro for their Antimicrobial effects against some strains of bacteria and fungi. Ergosterol was isolated from the crude extract and elucidate according to 1H-NMR and its mass spectrometry analysis, n-Hexan fraction was identified by gas chromatography– mass spectrometry.

An environmentally benign and one-pot method for the synthesis of 1-naphthol azo dyes has been developed by using polymer-supported periodic acid (PPIA) as a new solid acid via grinding followed by a diazo coupling reaction by 1-naphthol under solvent-free conditions at room temperature. The obtained aryl diazonium salts supported on polymer (aryl diazonium polymer periodate), ArN2 +IO4 - were sufficiently stable to be kept at room temperature in the dry state. This method has the advantages such as: eco-friendly, heterogeneous reaction conditions, simple experimental procedure, high purity. The structures of the products have been characterized by several techniques using UV-Vis, FT-IR, 1H NMR, 13C NMR and mass spectra.

Volatile oils of Dioclea reflexa (Fabaceae) roots were obtained by hydrostillation and analysed using GC and GC-MS. A total of 15 compounds were identified; hydrocarbons being the dominating group of the compounds representing 69.27 %. Oxygenated monoterpenoids identified included terpinen-4-ol (2.47 %), myrtenal (1.69 %), verbenone (1.25 %), trans-pinocarveol (2.86 %) and thymol (1.30 %); also stearyl iodide (10.33 %) was identified.

Characterization of the ethanolic extract of Randiaaccuminata stem (chewing stick) was carried out using Fourier Transform Infrared (FTIR) Spectrophotometer. The result of the analysis showed that the stem of Randiaaccuminata contain primary and secondary amines, aliphatic amine, alkyl halide, aromatic amine, nitro compounds, alkyne, alkanes, chloride and fluoride ions. The chloride and fluoride ions present in this plant is responsible for its cleaning property. It also prevents tooth decay, remove tooth stain, eliminates tooth aches and also promote cleaner teeth.

Thin layer chromatographic technique with silica gel – ethyl acetate adsorbent - solvent system has been validated for the determination of herbicides. Precision of the method determined in terms of reproducibility yielded relative standard deviation of 0.3 % and 0.5 % for the Rf of the herbicides and diameter of spots respectively. The minimum detectable quantity (MDQ) of the herbicides ranges from 0.20 – 0.50 ng. The method has been applied to determine the efficiencies of acetone, acetonitrile, methanol, hexane and acetone/hexane (4:1) for the recovery of the herbicides, atrazine, ametryne, propanil, diuron and nitrofen in a forest zone soil in Ghana. Acetone and acetonitrile were found to have approximately equal efficiency as extraction solvents. Extraction with acetone, acetonitrile, acetone/hexane (4:1) yielded more than 90% recovery for all the herbicides. The highest recovery efficiency of 96.2% was obtained for atrazine using acetone. Extraction with methanol and hexane gave relatively low recoveries particularly, with the clean up extracts. In all, the clean up procedure with SPE cartridge equipped with C-18 as adsorbent reduced recovery by 9 – 13 %.

A novel series of 2-substitutedimino-6-amino-4-[2-isobutoxy-5(4-methyl-5-carboxy-1,3-thiazo-2-yl)]-phenyl-1,3,5-thiadiazines had been recently synthesized in this laboratory by refluxing 2-(3-substitutedthioamidoforma midino-4-isobutoxyphenyl)-4-methyl-5-carboxy-1,3-thiazoles with various isocyanodichlorides in acetone-ethanol medium in 1:1 molar proportion for 2 hours. The structures of all the synthesized compounds were justified on the basis of chemical characteristics, elemental analysis and spectral studies.

Condensation of ethyl acetoacetate 2 with thiosemicarbazide 1a gave hydrazone derivative 4 not pyrazolone 5. Pyrazolone 5 can be obtained by treatment of 4 with 5 % sodium hydroxide in ethanol. Reactions of 4 with phencyl bromide, aryl diazonium chloride , arylidene malononitrile afforded pyrazole derivatives 6, 7 and pyranopyrazole 8 respectively. Also, treatment of 4 with dimethylformamide dimethyl acetal (DMFDMA) gave compound 11 not 9 nor 10. Reactions of pyrazole derivatives 6 with arylidene malononitrile afforded condensed compound 15 which was obtained by reaction with aromatic aldehydes. While reaction of 6 with DMFDMA gave the corresponding enamine 16.