Marín-Yaseli Margarita R, Moreno Miguel, de la Fuente José L, Briones Carlos, Ruiz-Bermejo Marta
Centro de Astrobiología (INTA-CSIC), Dpto. Evolución Molecular, Ctra. Torrejón-Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain.
Instituto Nacional de Técnica Aeroespacial "Esteban Terradas" (INTA), Ctra. Torrejón-Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain.
Spectrochim Acta A Mol Biomol Spectrosc. 2018 Feb 15;191:389-397. doi: 10.1016/j.saa.2017.10.003. Epub 2017 Oct 12.
HCN polymerization is one of the most important and fascinating reactions in prebiotic chemistry, and interest in HCN polymers in the field of materials science is growing. However, little is known about the kinetics of the HCN polymerization process. In the present study, a first approach to the kinetics of two sets of aqueous HCN polymerizations, from NHCN and NaCN, at middle temperatures between 4 and 38°C, has been carried out. For each series, the presence of air and salts in the reaction medium has been systematically explored. A previous kinetic analysis was conducted during the conversion of the insoluble black HCN polymers obtained as gel fractions in these precipitation polymerizations for a reaction of one month, where a limit conversion was achieved at the highest polymerization temperature. The kinetic description of the gravimetric data for this complex system shows a clear change in the linear dependence with the polymerization temperature for the reaction from NHCN, besides a relevant catalytic effect of ammonium, in comparison with those data obtained from the NaCN series. These results also demonstrated the notable influence of air, oxygen, and the saline medium in HCN polymer formation. Similar conclusions were reached when the sol fractions were monitored by UV-vis spectroscopy, and a Hill type correlation was used to describe the polymerization profiles obtained. This technique was chosen because it provides an easy, prompt and fast method to follow the evolution of the liquid or continuous phase of the process under study.
HCN聚合反应是前生物化学中最重要且最具吸引力的反应之一，材料科学领域对HCN聚合物的兴趣也在不断增加。然而，人们对HCN聚合过程的动力学知之甚少。在本研究中，已对两组分别由NHCN和NaCN引发的HCN水相聚合反应在4至38°C的中等温度下的动力学进行了初步研究。对于每个系列，系统地探究了反应介质中空气和盐的存在情况。在这些沉淀聚合反应中，作为凝胶级分获得的不溶性黑色HCN聚合物转化过程中进行了为期一个月的反应，在此期间，在最高聚合温度下达到了极限转化率，并进行了先前的动力学分析。与从NaCN系列获得的数据相比，该复杂体系重量数据的动力学描述表明，对于由NHCN引发的反应，其与聚合温度的线性关系发生了明显变化，此外铵还具有显著的催化作用。这些结果还证明了空气、氧气和盐介质对HCN聚合物形成的显著影响。当通过紫外可见光谱监测溶胶级分时，也得出了类似的结论，并使用希尔型相关性来描述所获得的聚合曲线。选择该技术是因为它提供了一种简便、迅速且快速的方法来跟踪所研究过程中液相或连续相的演变。
