食用黄色5号製造時における副成色素Trisodium salt of 6-hydroxy-7-(4-sulfophenyl)-5-(4-sulfophenylazo)-2-naphthalenesulfonic acidの生成条件

元データ 2001-08-31 日本食品化学学会

概要

In our previous report, we described the isolation of two unknown subsidiary colors from commercial Sunset Yellow FCF (Y5) and the identification of their chemical structures. The trisodium salt of 6-hydroxy-7-(4-sulfophenyl)-5-(4-sulfophenylazo)-2-naphthalenesulfonic acid (Y5-SA) is one of the subsidiary colors isolated and it has a sulfonatophenyl moiety located at the 7-position of Y5. As it was thought that Y5-SA is generated under the reaction conditions used in Y5 production, we investigated its mechanism of generation. The experimental synthesis of Y5-SA clarified the following points: 1) When a ratio of the the sulfanilic acid diazonium salt and the Schaeffer's salt were changed and then reacted, the quantity of Y5-SA that was generated increased when the quantity of the sulfanilic acid diazonium salt was increased. 2) When the sulfanilic acid diazonium salt was added to Y5, the amount of Y5-SA that was generated depended on time and the quantity of the sulfanilic acid diazonium salt. 3) There was little generation of Y5-SA at pH 8.0 〜 pH 10.0, and generation peaked at pH 12.0, and then decreaced at pH 13.0. Fig.5 shows the reaction pathways of Y5-SA. According to Mazzola et al, Y5 is balanced as shown in Fig.5-A. They also proved that the pKa of phenol is 12.0 by potentiometric titration and from the chemical shift change of ^<13>C-NMR. We concluded as follows: ・Y5 at pH 12.0 is balanced as shown in Fig.5-B. Phenoxide ions that are generated are delocalized and stabilized on the naphthalene ring. ・The anion localized at the 7-position of the naphthalene ring is highly reactive. ・This anion reacts with the cation generated by the decomposition of the sulfanilic acid diazonium salt (Fig. 5-C) to produce Y5-SA (Fig. 5-D). When Y5 is manufactured, Schaeffer's salt and sulfanilic acid diazonium salt are coupled in equal amounts. Therefore, to reduce the amount of Y5-SA in Y5, it is necessary to carry out the reaction at pH 10.0, which is the optimum pH for the coupling reaction used in the generation of Y5. Based on these reacts, Y5-SA can be used as a GMP marker during Y5 production.

著者

中澤 裕之 星薬科大学薬品分析化学教室
山田 真記子 三栄源エフ・エフ・アイ株式会社
合田 幸広 国立医薬品食品衛生研究所
中村 幹雄 三栄源エフ・エフ・アイ株式会社
森本 隆司 三栄源エフ・エフ・アイ株式会社
中澤 裕之 星薬科大学
中澤 裕之 埼玉県衛生研究所
合田 幸弘 National Institute Of Health Sciences
中澤 裕之 星薬科大学薬学部

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