2,5-Dihydroxy-[1,4]-benzoquinone (DHBQ) reacts readily with secondary amines to 2,5-diamino compounds and with thiols to the corresponding 2,5-dithioether derivatives. The literature has been inconclusive about the detailed mechanism, as both ipso-substitution at C-2/C-5 and the sequence of C-3/C-6 addition and C-2/C-5 elimination would give exactly the same products. By means of selectively ¹³C isotopically labelled DHBQ it was demonstrated that the reaction with morpholine is an ipso-substitution, while the reaction with benzenethiol and 1-hexanethiol proceeds according to the addition/elimination mechanism, and the reaction with the respective thiolates according to both mechanisms in parallel. Strongly acidic media cause a peculiar “OH-fluxuational” effect in DHBQ with the two quinone oxygens and the two hydroxy groups changing positions relative to the carbon skeleton while maintaining the 2,5-dihydroxy-[1,4]-diketo pattern. With this study, the mechanism of the unwanted nitrogen and sulfur fixation in cellulose fiber processing and during degradation could be better understood.

中文翻译：

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2,5-二羟基-[1,4]-苯醌与亲核试剂的反应-ipso取代与加成/消除。

2,5-二羟基-[1,4]-苯醌（DHBQ）容易与仲胺反应生成2,5-二氨基化合物，并与硫醇反应生成相应的2,5-二硫醚衍生物。关于详细的机理，文献尚无定论，因为在C-2 / C-5处进行ipso取代，以及C-3 / C-6的添加顺序和C-2 / C-5的消除都会产生完全相同的产物。通过选择性的手段¹³ Ç同位素标记DHBQ已证实与吗啉反应为本位-取代，同时根据加成/消除机理与苯硫醇和1-己硫醇的反应进行，并且根据两种机理与相应的硫醇盐的反应并行进行。强酸性介质会在DHBQ中产生特殊的“ OH-通量”效应，其中两个醌氧和两个羟基相对于碳骨架的位置改变，同时保持2,5-二羟基-[1,4]-二酮模式。通过这项研究，可以更好地理解纤维素纤维加工过程中以及降解过程中不希望的氮和硫固定的机理。