Vinita Sharma

Kinetics and mechanism of oxidation of aliphatic primary alcohols by quinolinium bromochromate

Oxidation of nine aliphatic primary alcohols by quinolinium bromochromate (QBC) in dimethylsulphoxide leads to the formation of the corresponding aldehydes. The reaction is first order with respect to both QBC and the alcohol. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form:kobs = a + b[H+]. The oxidation of [1,1-2H2]ethanol (MeCD2OH) exhibits a substantial primary kinetic isotope effect. The reaction has been studied in nineteen different organic solvents. The solvent effect was analysed using Taft’s and Swain’s multiparametric equations. The rate of oxidation is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been proposed.

Biobutanol from Renewable Agricultural and Lignocellulose Resources and Its Perspectives as Alternative of Liquid Fuels

Biobutanol (n-C4H9OH, available as fermentation product of various carbohydrate derivatives obtained from different resources of agricultural production such as crops and wastes) is one of the most promising biofuels in the near future. It can be produced by the so-called ABE (acetone-butanol-ethanol) type anaerobic fermentation discovered by Pasteur [1, 2] and industrialized by Weizmann [3]. Main problems associated with industrial production of biobutanol include high energy demand for processing of dilute ferment liquors and high volume of wastewater. A bioreactor with a volume of 100 m3 produces at 90% filling ratio 1053 kg of butanol, 526 kg of acetone and 175 kg of ethanol together with 2900 kg of carbon dioxide, 117 kg of hydrogen and 84150 kg of wastewater. Efforts to increase productivity and decrease production costs resulted in many new methods. This chapter summarizes some selected results on methods of biobutanol production.

Kinetics and mechanism of the oxidation of diols by bromine in acid solution

Kinetics of oxidation of five vicinal diols, four non-vicinal diols, and two of their monoethers by bromine in strong acid solutions have been studied. The vicinal diols yielded the products arising out of glycol bond fission while the other diols yielded the hydroxycarbonyl compounds. The reaction is first order with respect to both bromine and the diol. The rate decreases with an increase in the acidity. The oxidation of [1,1,2,2-2H4] ethanediol showed the absence of a primary kinetic isotope effect. The value of solvent isotope effect, k(H2O)/k(D2O), at 303 K for the oxidation of ethanediol, propane-1,3-diol and 3-methoxybutane-1-ol are 4.71, 1.04 and 1.07 respectively. A mechanism involving a glycol bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidised by a hydride-transfer mechanism as are monohydric alcohols.

REMOVAL OF FLUORIDE FROM DRINKING WATER BY QUARTERNARY AMINISED RESINS FROM SAW-DUST

Safe drinking water is a severe problem in many parts of the various countries including India a fast developing country. Authors have used some low-cost materials and their products as one of the best adsorbents for the removal of fluoride from water mainly used for drinking and other domestic purposes. Results are appreciable to be applied in large scale purposes.

Kinetic study of the oxidation of aliphatic aldehydes bybis(2,2′-bipyridyl) copper(II) permanganate

Kinetics of oxidation of aliphatic aldehydes, to the corresponding carboxylic acids, by bis(2,2′-bipyridyl)copper(II) permanganate (BBCP) has been studied. The reaction is first order with respect toBBCP. Michaelis-Menten type kinetics were observed with respect to the aldehyde. The formation constants for the aldehyde-BBCP complexes and the rates of their decomposition, at different temperatures, have been evaluated. Thermodynamic parameters for the complex formation and the activation parameters for their decomposition have also been determined. The reaction is catalysed by hydrogen ions; the acid-dependence being of the form:kobs = a +b [H+]. The oxidation of MeCDO exhibited a substantial kinetic isotope effect (kH/kD = 4.33 at 303 K). The role of aldehyde hydrate in the oxidation process has been discussed. A mechanism involving formation of permanganate ester and its slow decomposition has been proposed.