Vol. 1 & Issue 1 ; Section A : Chemical Sciences

Date : May. to Jul.2011

 

Microwave assisted solid support synthesis of some 3, 5-Diaryl-∆2 -isoxazolines as potential antibacterial agents

Sheetal Shakhawat, Anju Devpura, Jayant P.Sing, Parul Sharma , Laxmi Lal Dangin and Shiv Sing Dulawat

  • Abstract

    An environmentally benign microwave assisted one pot approach for the synthesis of some 3,5-diaryl-2 -isoxazolines from substituted chalcones with hydroxylamine hydrochloride using basic alumina for its catalytic role as well as energy transfer medium is described. The reaction rate is brought down from hours to minutes along with improved yield as compared to conventional heating. All the synthesized compounds were tested for their in vitro antibacterial activity.

Structure-reactivity correlation in the oxidation of substituted benzaldehydes by benzyltriethyl ammonium chlorochromate

Sonu Barthora, Deepika Baghmara, Mamta Gilla, A. Choudhary L. Kotai and Vinita Sharma

  • Abstract

    Oxidation of thirty six monosubstituted benzaldehydes by benzyltriethyl ammonium chlorochromate in dimethyl sulphoxide, leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to chlorochromate and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs= a + b [H+]. The oxidation of duteriated benzaldehyde exhibits substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton’s triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of h suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed

Microwave assisted improved synthesis of chalcones under microwave irradiation and their antibacterial activity

Vikas Tiwari, Jayant P. Singh, Parul Sharma, Laxmi lal Dangi, Shiv S. Dulawat

  • Abstract

    Chalcones have been synthesized under microwave irradiation by Claisen-Schmidt condensation between substituted acetophenone and appropriately substituted benzeldehydes using catalytic amount of aq. NaOH. Reactions on microwave irradiations (MWI) resulted in enhancement of yield and reaction rates. The protocol offers several advantages such as simple procedure, fast reaction rate, mild reaction conditions and excellent yield.Structure elucidations of synthesized compounds have been accomplished by elemental analysis and spectral data. All the compounds have been screened for antibacterial activity by the cupplate method.

Kinetics and mechanism of oxidation of some thioacids by imidazolium fluorochromate

Mamta Gilla, A. Meenaa, A. Choudhary, M. Baghmar, I.K Sharma, L. Kotaic and Vinita Sharma

  • Abstract

    Oxidation of thioglycollic, thiolactic and thiomalic acids by imidazolium fluorochromate (IFC) in dimethylsulphoxide (DMSO) leads to the formation of disulphide dimmers. The reaction is first order in IFC. Michaelies-Menten type of kinetics is observed with respect to the thioacids. Reaction is failed to induce the polymerisation of acrylonitrile. The reaction is catalysed by hydrogen ions. The hydrogen ion dependence has taking the form kobs = a + b [H+]. The oxidation of thiolactic acid has been studied in nineteen different organic solvents. The solvent effect has been analysed by using Kamlet’s and Swain’s multiparametric equations. A mechanism involving the formation of a thioester and its decomposition in slow step has been proposed.

Removal of hazardous ions from water by photocatalytic desalination method

Shobha Rastogi, Manisha Sindal and Ajay Sharma

  • Abstract

    Water is the most essential component of life. Though on a global scale, there is abundance of water but the main problem is the availability of water in the right place and in the right form. Rajasthan is declared as a desert state because it faces scanty rainfall. The population of Rajasthan is wholly depending on ground water resources and 50% of water resources are unpotable. In urban and rural areas of Rajasthan that have access to water, a sizable population has difficulty to use drinking water with TDS (Total Dissolved Salts) level more than 500 mg / Lt. which is allowed limit in accordance with BIS (Bureau of Indian Standards). Solar desalination process to obtain potable water is competitive with other means of obtaining potable water. Much work has been done in the field of collection of solar energy and its use in desalination process. In the present work, photocatalytic solar desalination process has been developed to obtain good quality of water. For this some metal catalyst were used to increase efficiency of the process. Copper Sulphide, Lead Sulphide, Antimony sulphide etc. are proved to be the best one. The work is restricted to ground water and samples have been collected from different areas of Sirohi district of Rajasthan. The water samples were analyzed for different. water parameters like pH, Salinity, TDS, Conductance, Total hardness etc. and data’s were compared with standards given by APHA 1998 (American Public Health Association). After solar desalination process again water samples were analyzed for the same parameters. The quantityof water so produced was quite less and the rate was also very slow. Therefore, to enhance the rate of water production and to improve quality of desalinate water some photocatalysts have been used and found that TDS value of raw water is quite lower down by using these metal sulphides as photocatalysts.

Synthesis, characterization and antimicrobial activity evaluation of some new 4- Phenyl - 5- [3’, 5’-diaryl -2- pyrazolin-1-yl]-3, 4- dihydropyrimidine 2-(1H)-ones.

Gunwanti Malhotra and Y.K. Srivastava

  • Abstract

    Some novel dihydro pyrimidone derivatives containing pyrazoline nucleus have been prepared by condensation of 1-acetyl pyrazolines with urea and aromatic aldehydes in presence of NBS Catalyst. Newely prepared compounds have been characterised by their elemental analysis and spectral data. Their antimicrobial activities have been checked in vitro.