芳香族カルボン酸のレーザー熱分解ガスクロマトグラフィー : 水素化アルミニウムリチウムの添加による効果

概要

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Pyrolysis of anaromatic carboxylic acid gives the product formed by decarboxylation, which is useful for the elucidation of the parent structure. To increase the yield of such a product, the authors addedlithium aluminum hydride(LiAlH_4) to each mixture composed of a sample acid and powdered carbon. Then the sample material was degraded by a defocused laser beam in the normal pulse mode. The laser output used was about 0.5 joule. The degradation pattern of benzoic acid changes remarkably by the addition of only slight amount of LiAlH_4. When the amount of this additive is more than or equal to 5wt%, almost similar results are obtained. In the degradation of several aromatic acids, the addition of LiAlH_4 results in significant increases in the relative yields of the decarboxylated products, e.g., benzene, toluene, chlorobenzene and anisole from benzoic, p-toluic, p-chlorobeuzoic and p-methoxybenzoic acids, respectively. These products keep characteristics of the parent structures. On the other hand, the yields of low molecular weight prodticts are decreased. LiAlH_4 is more effective than sodium borohydride. Some substituents are reduced by LiAlH_4 in the course of degradation piocess. When p-nitrobenzoic acid is degraded in the presence of LiAlH_4, nitrobenzene is not produced but aniline is.
社団法人日本分析化学会の論文
1977-01-10