The application of gas and liquid chromatography in the studies on electrooxidation of organic compounds

Expanded graphite electrode (EGE), preconditioned 1 hr. in the electrolyte, was used to oxidize 0.1 M PhOH in 0.5 M KOH with a d.c. of 5 or 9 mA applied when the electrode attained 1.1 V. Galvanostatic curves were recorded with Hg/HgO/0.5 M KOH as the ref. electrode. At 9 mA, oxidn of PhOH gave first a potential jump of 0.7 V, then a drop, and again jumps marking successive oxidn. steps. On the5-mA curve, a 0.59 V plateau formed. Upwards of 0.83 V, rapid jumps occurred on both the 5 and 9-mV curves up to 1.1 V. Benzoquinone, hydroquinone and carboxylic acids were formed, as detd. by gas chromatography. At 5 mV, PhOH fell from 9.411 to 2.812 mg/ml (at 9 mV, to 7.934 mg/ml); hydroquinone was 0.665, benzoquinone 1.988, acids 2.075 mg/ml. At 9 mV, the concns. were 2.088, 0.282 and 1.300 mg/ml. At the EGE, oxidn. of hydroquinone to benzoquinone appeared to be the crucial step. Also important was CO2, dissolved in the electrolyte and pptg. as BaCO3.