The selective synthesis of benazaldehyde and substituted benzaldehydes from corresponding benzyl alcohols has been carried out by using hypochlorite as an oxidant in organic medium under phase transfer catalysis. The reaction is highly selective since no traces of benzoic acid or substituted benzoic acids have been detected and the yield is found to be more than 90%. The products obtained were precipitated as 2,4-dinitrophenylhydrazone and the recrystallised products were characterized by melting point and by spectrophotometric techniques like infra red and UV-Visible analysis.
Kinetics of the oxidation of primary aliphatic alcohols has been carried out using phase transferred monochromate in benzene. Tetrabutylammonium bromide (TBAB) and tetrabutylphosphonium bromide (TBPB) are used as phase transfer catalysts (PT catalyst). The reaction shows first order dependence on both [alcohol] and [monochromate ion]. The oxidation leads to the formation of corresponding aldehyde and no traces of carboxylic acid has been detected. The reaction mixture failed to induce the polymerization of added acrylonitrile which rules out the presence radical intermediates in the reaction. Various thermodynamic parameters have been evaluated and a suitable mechanism has been proposed.
Kinetic studies on the oxidation of benzyl alcohol and substituted benzyl alcohols in benzene as the reaction medium have been studied by using potassium dichromate under phase transfer catalysis (PTC). The phase transfer catalysts (PT catalysts) used were tetrabutylammonium bromide (TBAB) and tetrabutylphosphonium bromide (TBPB). Benzyl alcohols were selectively oxidised to corresponding benzaldehydes in good yield (above 90%). The order of reactivity among the studied benzyl alcohols is p-OCH3 > p-CH3 >-H > p-Cl. Plots of log k2 versus Hammett's substituent constant (σ) has been found to be curve in shape and this suggests that there should be a continuous change in transition state with changes in substituent present in the substrate from electron donating to electron withdrawing. A suitable mechanism has been suggested in which the rate determining step involves both C-H bond cleavage and CO bond formations in concerted manner.
Condom industry waste mainly consists of light magnesium carbonate (LMC), which is extensively used as a finishing powder during the final stages of condom production. This LMC waste (LW) is usually disposed of as a landfill, causing an increase in the hardness of water. LW generated in HLL Lifecare Limited, India, was procured, characterized by analytical techniques, and reutilized in natural rubber (NR) as a reinforcing filler. The prepared composites were subjected to rheological, mechanical, thermal and sorption characterizations. In comparison to NR neat, the composite with 3 phr (parts per hundred of rubber) LW showed a rise in tensile strength, tear strength, and modulus at 300% elongation by 22%, 20%, and 28%, respectively. A remarkable decrease in abrasion loss is also evidenced. The activation energy (Ea) for degradation, calculated by the Coats-Redfern (CR) method, showed 10 kJmol-1 increase for composite with 3 phr LW, proving its better thermal stability. It also exhibited higher solvent uptake resistance, as established by sorption experiments. The superior properties of this composite have been attributed to the uniform LW distribution and ameliorated NR-LW interaction. Hence, the prepared composites find considerable potential in manufacturing industrial NR components accomplishing a circular economy.
Ranitidine hydrochloride is a drug used to treat stomach acid production. It is commonly advised in
the treatment of peptic ulcer and gastrophaegal reflux. Ranitidine hydrochloride exists in two different
polymorphic forms, namely form I and form II. Various brands of ranitidine hydrochloride tablets
manufactured by different pharmaceutical companies in India were collected, finely powdered and
recrystallized from ethanol water mixture. The melting points of pure drug samples were determined to
assess the polymorphic form present in each sample. All the pure drug samples showed a melting point
in the range 135 to 138 °C and prove the existence of polymorph form I. The pure recrystallized drug
samples were kept at room temperature for about 60 days in order to study the changes in polymorphic
form if any and found fairly stable on prolonged storage. Infrared and UV-visible spectral studies have
been carried out by taking Zinetac 150 mg (GlaxoSmithKline Pharmaceuticals Ltd., Mumbai) as the
standard in order to prove the chemical constitution of the drug.
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