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Chiral Symmetry Breaking and Deracemization of Sodium Chlorate in Turbulent Flow
Crystal Growth & Design ( IF 3.8 ) Pub Date : 2017-12-21 00:00:00 , DOI: 10.1021/acs.cgd.7b01247
Jaekyu Ahn 1 , Do Hyun Kim 2 , Gerard Coquerel 3 , Woo-Sik Kim 1
Affiliation  

The chiral symmetry breaking and deracemization of sodium chlorate were investigated when varying the agitation speed and cooling rate in cooling crystallization. At a low agitation speed, almost zero crystal enantiomeric excess occurred at the induction period. When increasing the agitation speed, the crystal enantiomeric excess at the induction period (called the “initial CEE”) increased due to the promotion of chiral symmetry breaking. The chiral symmetry breaking at the induction period (called the “initial chiral symmetry breaking”) also varied with the cooling rate. At a low cooling rate of 0.0738 °C/min, the initial CEE reached up to about 90% and was rapidly reduced when increasing the cooling rate. The experiments also showed enhanced deracemization of the chiral crystals when increasing the initial CEE. Thus, complete deracemization was achieved when the initial CEE was over 60%. The influence of the agitation speed and cooling rate on the initial CEE originated from secondary nucleation depending on the supersaturation at the induction period (called the “induction supersaturation”). Using a nucleation rate equation, the initial CEE was found to correlate well with the induction supersaturation. Also, varying the final setting temperature and agitator confirmed that secondary nucleation was significantly involved in the chiral symmetry breaking at the induction period.

中文翻译:

湍流中氯酸钠的手性对称性破坏和脱硝作用

当改变冷却结晶中的搅拌速度和冷却速率时,研究了氯酸钠的手性对称性破坏和脱硝作用。在低搅拌速度下,在诱导期几乎发生了零个晶体对映体过量。当增加搅拌速度时,由于促进手性对称性破坏,诱导期的晶体对映体过量(称为“初始CEE”)增加。诱导期的手性对称性破坏(称为“初始手性对称性破坏”)也随冷却速度而变化。在0.0738°C / min的低冷却速率下,初始CEE达到约90%,并且在提高冷却速率时迅速降低。实验还显示,当增加初始CEE时,手性晶体的脱脂作用增强。因此,当初始CEE超过60%时,完全脱硝。搅拌速度和冷却速率对初始CEE的影响源于二次成核,其取决于诱导期的过饱和度(称为“诱导过饱和度”)。使用成核速率方程,发现初始CEE与感应过饱和具有很好的相关性。同样,改变最终设定温度和搅拌器证实了在诱导期手性对称性的破坏中,二次成核作用显着。最初的CEE被发现与感应过饱和具有很好的相关性。同样,改变最终设定温度和搅拌器证实了在诱导期手性对称性的破坏中,二次成核作用显着。最初的CEE被发现与感应过饱和具有很好的相关性。同样,改变最终设定温度和搅拌器证实了在诱导期手性对称性的破坏中,二次成核作用显着。
更新日期:2017-12-21
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