USEFUL IMPURITIES FOR OPTICAL RESOLUTIONS. 2. GENERALITY AND MECHANISM OF THE E RULE OF REVERSAL
USEFUL IMPURITIES FOR OPTICAL RESOLUTIONS. 2. GENERALITY AND MECHANISM OF THE E RULE OF REVERSAL
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对光学分辨率有用的杂质。
DOI：
10.1002/chin.198125079
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
M. Lahav
中科院分区：
文献类型：
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作者：
L. Addadi;J. Mil;M. Lahav
0 S '是一种分离的杂质，它在立体化学上类似于δ晶体的表面，在没有δ'时，= ki，在有S '时，kd>> ki。或（S）-谷氨酸。给出了6种解释，如配体交换，6种吸附，5种手性种子，4种手性溶剂效应，7等，但在缺乏统一机制的情况下，这些偶然的观察仍然是单独的好奇心，没有进一步研究。我们认为，在所有这些例子中，相同的机制，选择性吸附和抑制是负责决议。如果所提出的机制是正确的，则应发生以下事件模式。(i)当外消旋聚合物R，S在分离杂质S '存在下结晶时，与杂质绝对构型相反的对映体R应首先沉淀。S '的分子必须在立体化学上类似于S分子或晶体（例如，它可以是稍微修饰的底物分子或其二聚体、三聚体或寡聚体，其立体化学分别类似于晶体排列中的两个、三个或n个底物分子的立体化学），以便它可以优先吸附在晶体上。由于该效应是动力学的，因此必须通过实验确定拆分的最佳条件。受影响的对映异构体S应在第二批结晶中发现。
0 S'is a resolved impurity whichstereochemically resembles the surface of the 5 crystals; in the absence of 5’,= ki, in the pres-ence of S', kd» ki. or (S)-glutamic acid. 6 Explanations such as ligand exchange, 6 adsorption, 5 chiral seeding, 4 chiral solvent effects, 7 and the like were given, but in the absence of a unifying mechanism, these accidental observations remained as separate curiosities and were not investigated further. We suggest that in all these examples the same mechanism of selective adsorption and inhibition is responsible for resolution. The following pattern of events should occur if the proposed mechanism is correct.(i) Upon crystallizationof a racemic conglomerate R, S in the presence of a resolved impurity S', the enantiomer Rof absolute configuration oppositeto that of the impurity should precipitate first. Themolecule of S'mustbe stereochemically similar to the S molecule or to the/crystal (it may, for example, be a slightly modified substrate molecule or a dimer, trimer, or oligomer of it with a stereochemistry resembling that of two-, three-, or n-substrate molecules, respectively, in their crystalline arrangement), so that it can be preferentially adsorbed on the/crystal. Since the effect is kinetic, the optimal conditions for resolutionmust be determined experimentally. The affected enantiomer, S, should be found in the second crop of crystallization.