カルボン酸類による非水滴定の研究(EDTA導電率滴定によるDMF中の一酸化炭素の定量ならびに亜硫酸ガス,硫化水素と共存する場合のそれぞれの定量)

概要

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Non-aqueous titrimetry of CO, SO2, H2S and their mixtures with EDTA was investigated by conductimetric titration using dimethylformamide (DMF) as solvent suitable for EDTA. It was found by direct conductimetric titration that SO2 and H2S are dissolved in DMF forming an addition compound which react with EDTA at the molar ratios of 4:1 and 2:1. On the other hand, the results of IR observation showed that CO did not form an addition compound with EDTA, but reacted with dimethylamine (DMA) to form DMF equivalently. The reaction is proposed as follows. CH3 CH3 > NH+CO→CH3 CH3 > N-C _??_ O H It is also shown by conductimetric titration in DMF that dimethylamine reacts with EDTA in DMF to yield four successive addition species (DMF : EDTA=4:1, 2:1, 3:2, 1:1) and with SO2 or H2S to produce a soluble compound such as (CH3)2NH·SO2. Then dissolving CO into DMF containing a known quantity of dimethylamine and titrating with EDTA-DMF standard solution, CO can be determined differentially from the result of determination of excess dimethylamine. In the case of a triple gas mixture, using DMF containing dimethylamine, SO2 was firstly titrated in two steps, secondarily, H2S also in two steps, and finally, the excess of dimethylamine in four steps.
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