The invention discloses a preparation method of a sulfasalazine impurity D, belongs to the field of drug impurity synthesis, and provides the preparation method of the sulfasalazine impurity D, whichis reasonable in process design, strong in operability,
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Paragraph 0040; 0045; 0051; 0056
(2020/07/24)
Reversible heterochiral aggregation/dissociation of bis(2-hydroxyphenyl) diamides driven by UV/Vis irradiation
Light to dissolve: (R)- and (S)-diamides bearing a hydrogen-bonding framework (red in picture) and a trans-azobenzene unit (blue) form an insoluble heterochiral aggregate, which can be dissolved by photoisomerization of the azobenzene unit to the cis conformation by UV irradiation (365-nm). The insoluble aggregate was formed again by subsequent irradiation with visible light (>422-nm). The precipitation and dissolution is manifestly reversible. Copyright