Department of Chemistry and Biochemistry, University of San Diego, 5998 Alcala Park, San Diego, California 92110, United States.
J Phys Chem A. 2020 Dec 3;124(48):10019-10028. doi: 10.1021/acs.jpca.0c09922. Epub 2020 Nov 18.
Building on our previous free-energy map ( , 122, 6769-6779) examining the reactions of monomeric glycolonitrile, we explore the formation of its dimers and trimers in aqueous solution under neutral conditions. While 5-membered rings are kinetically favored, open-chain oligomers with ester or amide linkages are thermodynamically favored. Accessing the 5-membered rings also provides a potential route to glyoxal that bypasses preforming glycolamide, the thermodynamic sink for monomers. However, finding a kinetically accessible route to glycine starting from glycolonitrile in the absence of added ammonia at room temperature proved challenging; the best case involved an intramolecular nucleophilic substitution reaction in a dimer containing neighboring imine and amide groups. Our free-energy map also examines routes to experimentally proposed moieties, explaining why some are observed in low yield or not at all.
基于我们之前的自由能图谱（, 122, 6769-6779），该图谱研究了单体乙腈醇的反应，我们探索了在中性条件下其在水溶液中形成二聚体和三聚体的过程。虽然五元环在动力学上是有利的，但具有酯或酰胺键的开链低聚物在热力学上是有利的。进入五元环也为绕过单体热力学阱——乙二酰胺，提供了一条通往乙醛酸的潜在途径。然而，在室温下，在没有添加氨的情况下，从乙腈醇出发找到一条通往甘氨酸的动力学上可行的途径是具有挑战性的；最好的情况是在含有相邻亚胺和酰胺基团的二聚体中发生分子内亲核取代反应。我们的自由能图谱还研究了实验提出的部分途径，解释了为什么有些途径的产率低，甚至根本不存在。
