Kinetic study on pyridinolysis of aryl benzenesulfonates: factors governing regioselectivity and reaction mechanism was written by Um, Ik-Hwan;Jung, Yoon Jae;Dust, Julian M.. And the article was included in Canadian Journal of Chemistry in 2022.Safety of Pyridin-4-ol This article mentions the following:
A kinetic study is reported for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (1a-1f) and Y-substituted-Ph benzenesulfonates (2a-2f) with Z-substituted-pyridines. The reactions proceed through S-O and C-O bond scissions competitively. The Yukawa-Tsuno plot for the reactions of 1a-1f with 4-oxypyridine (S-O bond fission) exhibits an excellent linearity. The Bronsted-type plot for the reactions of 2,4-dinitrophenyl benzenesulfonate (1d) with pyridines (S-O bond fission) is also linear with βnuc = 0.62. The Bronsted-type plot for the reactions of 2a-2f with 4-oxypyridines (S-O bond fission) is linear with βlg = -1.17. Thus, the reactions have been concluded to proceed through a concerted mechanism, in which leaving-group expulsion is significantly more advanced than bond formation between the electrophilic center and nucleophile at the transition state. The Hammett plot for the reactions of 1a-1f with 4-oxypyridine (C-O bond fission) exhibits scattered points with ρX = 0.98. The Bronsted-type plot for the reactions of 1d with Z-substituted-pyridines (C-O bond fission) results in an excellent linear correlation with βnuc = 0.38. Thus, the reactions (C-O bond fission) have been concluded to proceed through a stepwise mechanism with a Meisenheimer complex, in which expulsion of the leaving group occurs after the rate-determining step. Factors governing regioselectivity and reaction mechanism are discussed. In the experiment, the researchers used many compounds, for example, Pyridin-4-ol (cas: 626-64-2Safety of Pyridin-4-ol).
Pyridin-4-ol (cas: 626-64-2) belongs to pyridine derivatives. Pyridines are an important class of heterocycles and occur in polysubstituted forms in many naturally occurring biologically active compounds, drug molecules and chiral ligands. 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.Safety of Pyridin-4-ol