有機微量分析の研究 (第28報)

米国化学会推奨規格によるアルコキシル基定量装置に関する実験的検討

抄録

Investigations on the actual state of analytical process of alkoxyl group utilizing the apparatus recommended by the Committee of Microchemical Apparatus in American Chemical Society were described, The blank value due to the incomplete elimination of hydriodic acid vapor in the scrubber of this apparatus within the distillation time of 45 minutes and carbon dioxide flow of 10cc./min. (slightly less than 2 bubbles per second in the receiver) was at least 0.10cc. of 0.01N sodium thiosulfate which corresponds to 0.17% of methoxyl and 0.25% of ethoxyl group in 3mg. of a sample. On the other hand, the most accurate results were obtained at this distillation time in which the blank value was included, agreeing with the results of statistical study by the above committee. Therefore, it is supposed that some alkyl iodide was retained in the apparatus under the standard procedure. Comparisons between several wash liquids indicated that distilled water was not actually inferior to any other wash solutions in regard to this apparatus. The commercially available phenols added for dissolving the sample occasionally contained some alkoxyl impurities causing very high blanks. The use of Kirstens's reaction mixture from which the alkoxyl impurities were completely swept away by preliminary treatment appeared to be the best to be recommended.