Showing papers on "o-Cresol published in 2004"

Selective C-methylation of phenol with methanol over borate zirconia solid catalyst

Abstract: Selective C -methylation of phenol to o -cresol and 2,6-xylenol in high yields has been carried out with methanol over borate zirconia solid acid catalyst. The maximum conversion of 70 and 65% selectivity for corresponding ortho -alkylated products ( o -cresol and 2,6-xylenol) was obtained with 1–2% anisole as O -alkylated product. A series of borate zirconia catalysts with 5–30 mol% B 2 O 3 loading were prepared and calcined at different temperatures. The XRD results reveal the formation of single phase cubic zirconia after addition of B 2 O 3 . The cubic structure was stable up to 650 °C, above which it transformed to monoclinic structure. Borate zirconia containing 5 mol% B 2 O 3 calcined at 650 °C was found to be the most active catalyst among the series indicating the influence of composition and structure on the conversion and selectivity. The FTIR results provided the evidence for the vertical orientation of phenol aromatic ring on the catalyst surface, which explains the selective C -alkylation of phenol. The influence of various experimental parameters on phenol conversion and product selectivity has been investigated. The catalyst was active for 150 h time on stream without any deactivation showing its longer life. The catalytic activity and selectivity is correlated with its acidity and structure.

Electrochemical Study of Iodide in the Presence of Phenol and o-Cresol: Application to the Catalytic Determination of Phenol and o-Cresol

Abstract: The electrochemical oxidation of iodide in the presence of phenol and o-cresol was investigated at a glassy carbon electrode in buffered media by cyclic voltammetry, linear sweep voltammetry and controlled–potential coulometry. The experimental results indicate that the phenol and o-cresol convert to their derivatives after participating in a halogenation coupled reaction (quasi-catalytic reaction) following the oxidation of iodide to iodine. The concentrations of phenol and o-cresol have been determined in aqueous solutions according to the linear dependence of quasi-catalytic peak currents with the concentration. The calibration graphs show two linear sections of 0.0 to 1.0×10-4 M and 2.0×10-4 to 1.0 ×10-3 M for phenol and 4.2×10-5 to 1.0×10-4 M and 2.0×10-4 to 1.0×10-3 M for o-cresol. The theoretical detection limits and the relative standard deviations for ten measurements of phenol and o-cresol are 1.125×10-5 M, 1.06% and 4.201×10-5 M, 1.44%, respectively.