1,5-Pentanediamine carbonate (PDAC) can be used as the raw material to prepare pentamethylene diisocyanate (PDI), a new biobased aliphatic isocyanate. The preparation of high-quality PDAC by crystallization is taken to be valuable for the preparation of PDI, and it can be used as an effective approach for the separation and purification of 1,5-pentanediamine from the biocatalytic system as well. In this work, the solubility of PDAC from 283.15 to 323.15 K in water and binary solvent mixtures was measured by the polythermal method, and the experimental solubility data were correlated and analyzed by the modified Apelblat equation and van’t Hoff equation. In addition, three crystallization methods were investigated, and PDAC crystals were finally prepared with high bulk density, good flowability, and stability. It was found that the PDAC has two crystal forms, both existing as a spherical aggregate. They were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetry and differential scanning calorimetry, and hot stage microscopy. Besides, the sensitivity of the two crystal forms to humidity and their transformation behavior were studied. Compared with form I, form II was proven to be the thermodynamic stable polymorph in the temperature range from 298.15 to 338.15 K.

中文翻译：

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1,5-戊戊二胺碳酸盐的热力学，表征和多晶型转变

1,5-戊二胺碳酸酯（PDAC）可用作制备五亚甲基二异氰酸酯（PDI）（一种新型的生物基脂肪族异氰酸酯）的原料。通过结晶制备高质量的PDAC被认为对PDI的制备很有价值，它也可以用作从生物催化体系中分离和纯化1,5-戊二胺的有效方法。在这项工作中，通过多热法测量了PDAC在283.15至323.15 K之间在水和二元溶剂混合物中的溶解度，并通过改进的Apelblat方程和van't Hoff方程对实验溶解度数据进行了关联和分析。另外，研究了三种结晶方法，最终制备了具有高堆积密度，良好的流动性和稳定性的PDAC晶体。发现PDAC具有两种晶体形式，两者均以球形聚集体形式存在。它们的特征在于扫描电子显微镜，傅立叶变换红外光谱，粉末X射线衍射，热重分析和差示扫描量热法以及热台显微镜。此外，研究了两种晶型对湿度的敏感性及其转变行为。与形式I相比，形式II在298.15至338.15 K的温度范围内被证明是热力学稳定的多晶型物。研究了两种晶型对湿度的敏感性及其转变行为。与形式I相比，形式II在298.15至338.15 K的温度范围内被证明是热力学稳定的多晶型物。研究了两种晶型对湿度的敏感性及其转变行为。与形式I相比，形式II在298.15至338.15 K的温度范围内被证明是热力学稳定的多晶型物。