2,2,6,6-Tetramethyl-4-piperidinol (TMP) crystal is a very important intermediate in organic synthesis. To obtain an improved crystallization yield and desirable crystal-size characteristics, several commonly used organic solvents were investigated to determine the solubility of TMP using a gravimetric method. An ethanol solvent and a cooling crystallization method were chosen to obtain an improved theroretical yield. The cooling crystallization process of TMP in the ethanol solution was further optimized to crystallize larger crystals with a narrow crystal-size distribution using an orthogonal array design. Final TMP crystals with an average diameter of 1110 μm and a diameter span of 0.715 were obtained under laboratory conditions using the optimized process.

中文翻译：

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2,2,6,6-四甲基-4-哌啶醇（TMP）的溶解度和结晶过程

2,2,6,6-四甲基-4-哌啶醇（TMP）晶体是有机合成中非常重要的中间体。为了获得提高的结晶产率和所需的晶体尺寸特性，研究了几种常用的有机溶剂，以重量法测定TMP的溶解度。选择乙醇溶剂和冷却结晶方法以获得提高的理论产率。使用正交阵列设计进一步优化了TMP在乙醇溶液中的冷却结晶过程，以结晶出具有窄晶体尺寸分布的较大晶体。使用优化的方法，在实验室条件下获得了平均直径为1110μm，直径跨度为0.715的最终TMP晶体。