Vol. 8 & Issue 4 ; Section A : Chemical Sciences

Date : Aug. to Oct.2018

 

Electrochemical Oxidation of Ascorbic Acid Mediated by Ru (III) Schiff-base Complex/Multi-Walled Carbon Nanotube/Nafion Modified Carbon Electrode

Mirha Pazalja

[DOI: 10.24214/jcbps.A.8.4.60110.]

  • Abstract

    Carbon electrodes modified with Ru(III) Schiff base complex, multi-walled carbon nanotubes and Nafion® were used to develop a low potential sensor for ascorbic acid. Voltammetry measurements showed oxidation of ascorbic acid at the modified glassy carbon electrode at the potential of +0.23 V, and the bare electrode displays no redox peaks in the investigated potential range from 0.00 to +0.35 V. Flow injection amperometric measurements were performed at the operating potential of +0.20 V vs. Ag/AgCl in Britton-Robinson buffer (pH=5.00) with a flow rate of 0.40 mL min-1, and injection volume 100 μL. The modified electrodes shows a fast electric current response for ascorbic acid oxidation. Current response increased with increasing ascorbic acid concentration (dynamic range = 0.50-100 mg L-1) and displayed good linearity (R2 = 0.9946). The limit of detection was 0.25 mg L-1, while the limit of quantitation was 0.85 mg L-1. The repeatability was calculated as 2.10 % (n=5 measurement).

Photoinduced Deoxygenation of Epoxychalcones on TiO2

Somasundaram N and Ananthanarayanan L

[DOI: 10.24214/jcbps.A.8.4.61118.]

  • Abstract

    One of the most important transformations in organic synthesis is the deoxygenation of epoxides to olefins as it allows the use of oxirane ring as a protective group for double bonds. Though a number of reagents are available to accomplish this process by multi-step and one-step procedures with retention or inversion of the geometry of carbon-carbon double bonds, not much photochemical methods have been developed for the deoxygenation of epoxides with retention of geometrical (trans) configuration. Herein, a simple TiO2-mediated one-pot method of photodeoxygenation of epoxychalcones (a,b-epoxyketones) is established. In nitrogen purged acetonitrile solution on irradiated TiO2 gives the correspondinga,b-unsaturated ketones with retention of geometric configuration in excellent yields (³ 75%).