Department of Physical Chemistry, University of Chemistry and Technology, Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, CZ-162 06 Prague, Czech Republic.
Molecules. 2023 Jul 16;28(14):5440. doi: 10.3390/molecules28145440.
As a follow-up to our effort to establish reliable thermodynamic data for amino acids, the heat capacity and phase behavior are reported for -acetyl glycine amide (CAS RN: 2620-63-5), -acetyl-L-alanine amide (CAS RN: 15962-47-7), -acetyl-L-valine amide (CAS RN: 37933-88-3), -acetyl-L-isoleucine amide (CAS RN: 56711-06-9), and -acetyl-L-leucine amide (CAS RN: 28529-34-2). Prior to heat capacity measurement, thermogravimetric analysis and X-ray powder diffraction were performed to determine decomposition temperatures and initial crystal structures, respectively. The crystal heat capacities of the five -acetyl amino acid amides were measured by Tian-Calvet calorimetry in the temperature interval (266-350 K), by power compensation DSC in the temperature interval (216-471 K), and by relaxation (heat-pulse) calorimetry in the temperature interval (2-268 K). As a result, reference heat capacities and thermodynamic functions for the crystalline phase from 0 K up to 470 K were developed.
作为我们为氨基酸建立可靠热力学数据工作的后续，我们报告了 -乙酰甘氨酰胺（CAS RN：2620-63-5）、-乙酰-L-丙氨酸酰胺（CAS RN：15962-47-7）、-乙酰-L-缬氨酸酰胺（CAS RN：37933-88-3）、-乙酰-L-异亮氨酸酰胺（CAS RN：56711-06-9）和 -乙酰-L-亮氨酸酰胺（CAS RN：28529-34-2）的热容和相行为。在进行热容测量之前，分别进行了热重分析和 X 射线粉末衍射，以确定分解温度和初始晶体结构。通过 Tian-Calvet 量热法在（266-350 K）温度范围内、通过功率补偿 DSC 在（216-471 K）温度范围内以及通过弛豫（热脉冲）量热法在（2-268 K）温度范围内测量了这五种 -乙酰氨基酸酰胺的晶体热容。结果，开发了从 0 K 到 470 K 的晶相的参考热容和热力学函数。
