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在通空气条件下,回流竹红菌甲素(HA)(或乙素,HB)和Na_2SO_3的含1％NaOH强磁碱性水溶性生成14-脱羟基-15-脱乙酰基竹红菌甲素-13-位磺酸钠(13-SO_3Na-DDHA)(产率30％)和另一种红色的水溶性聚合物。当这一反应在吡啶-水(1:1/v:v)混合溶剂中进行,并用CuO作氧化剂时,只得到13-SO_3Na-DDHA一种水溶性产物(70％产率)。在后一体系中,由于改变了溶剂和氧化剂,使13-SO_3Na-DDHA的制备更加便利。反应体系的ESP研究表明,这一磺化反应首先是通过竹红菌素和Na_2SO_3之间热活化的电子转移进行的。电子转移的结果产生竹红菌素半醌负离子自由基和三氧化硫负离子自由基(S0_3)。硝基甲烷酸式负离子猝灭实验证明,由于竹红菌素的13位能在碱性、高温下活化,磺化的关键步骤是SO_3对其活化了的13位的亲电进攻。氧化剂在这一反应中的作用为:将产生的竹红菌素半醌负离子自由基氧化至其母体醌,增加反应物的相对浓度,同时使竹红菌素与SO_3~(2-)之间的电子转移循环进行,加速SO_3的产生。
In the air conditions, the return of Hypocrellin (HA) (or B, HB) and Na 2 SO 3 with 1% NaOH strong magnetic alkaline water-soluble 14-dehydroxy-15-dehydroacetylhikin (13-SO3Na-DDHA) (30% yield) and another red water-soluble polymer. When this reaction was carried out in pyridine-water (1: 1 / v: v) mixed solvent and CuO was used as oxidant, only 13-SO3Na-DDHA was obtained as a water-soluble product (70% yield). In the latter system, the preparation of 13-SO_3Na-DDHA is facilitated by changing the solvent and oxidizer. The ESP study of the reaction system showed that this sulfonation reaction was first carried out by thermally activated electron transfer between hypocrellin and Na_2SO_3. As a result of electron transfer, hypocrellin anthraquinone anion radical and sulfur trioxide anion radical (S0-3) are produced. Nitromethane acid anion quenching experiments show that, as hypocrellin position 13 can be activated in alkaline, high temperature, the key step of sulfonation is SO_3 on its activation of the 13-bit electrophilic attack. The role of the oxidant in this reaction is that the resulting hypocrellin half-quinone anion radical is oxidized to its parent quinone and the relative concentration of the reactant is increased, while the difference between hypocrellin and SO_3 ~ (2-) Of the electron transfer cycle, accelerate the generation of SO_3.