Oxidation of Aromatic Aldehydes to Esters: A Sulfate Radical Redox System was written by Guo, Ya-Fei;Mahmood, Sajid;Xu, Bao-Hua;Yao, Xiao-Qian;He, Hong-Yan;Zhang, Suo-Jiang. And the article was included in Journal of Organic Chemistry in 2017.Reference of 628-13-7 This article mentions the following:
A mild oxidative esterification of various aromatic aldehydes by sulfate radical redox system was presented. In the reaction pathway exploration, the transiency of MeOSO3– was disclosed, which was generated from esterification between the in situ generated HSO4– and MeOH, a rate-limiting step in the process. More importantly, the selectivity-controlling step was represented by the subsequent nucleophilic displacement between MeOSO3– and aldehydes. The ionic oxidant 1a ((NH4)2S2O8) with more N-H numbers in the cation, as compared with 1c ((Bu4N)2S2O8) and 1d ((PyH)2S2O8), has better performance in the oxidative esterification of aldehydes. In the experiment, the researchers used many compounds, for example, Pyridinehydrochloride (cas: 628-13-7Reference of 628-13-7).
Pyridinehydrochloride (cas: 628-13-7) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Reference of 628-13-7