74669-56-0Relevant academic research and scientific papers
Electronic nature of substituent X governs reaction mechanism in aminolysis of 4-pyridyl X-substituted-benzoates in acetonitrile
Um, Ik-Hwan,Bae, Ae Ri
body text, p. 5781 - 5787 (2012/08/29)
A kinetic study is reported for aminolysis of 4-pyridyl X-substituted-benzoates 5a-i. Plots of pseudo-first-order rate constants (k obsd) vs [amine] curve upward for the reactions of substrates possessing a strong electron-withdrawing group in the benzoyl moiety (5a-d) but are linear for the reactions of those bearing an electron-donating group (5e-i), indicating that the electronic nature of substituent X governs the reaction mechanism. The k1k2/k-1 and k1k 3/k-1 values were calculated from the intercept and slope of the linear plots of kobsd/[amine] vs [amine], respectively. The Hammett plot for k1k2/k-1 consists of two intersecting straight lines, while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ρX = 0.41 and r = 1.58, implying that the nonlinear Hammett plot is not due to a change in rate-determining step but is caused by stabilization of substrates possessing an electron-donating group through resonance interactions. The small ρX suggests that the k2/k-1 ratio is little influenced by the nature of substituent X. The Bronsted-type plots for aminolysis of 4-pyridyl 3,5-dinitrobenzoate 5a are linear with βnuc = 0.98 and 0.79 for k1k2/k-1 and k1k3/k -1, respectively. The effect of amine basicity on the microscopic rate constants is also discussed.
Kinetic study on aminolysis of 4-pyridyl X-substituted benzoates: Effect of substituent X on reactivity and reaction mechanism
Lee, Jong Pal,Bae, Ae Ri,Um, Ik-Hwan
, p. 1907 - 1911 (2012/01/14)
A kinetic study is reported for nucleophilic substitution reactions of 4-pyridyl X-substituted benzoates 7a-e with a series of alicyclic secondary amines in H2O. The Bronsted-type plot for the reactions of 4-pyridyl benzoate 7c is linear with βnuc = 0.71. The corresponding reactions of 2-pyridyl benzoate 6, which is less reactive than 7c, resulted in also a linear Bronsted-type plot with βnuc = 0.77. The fact that the more reactive 7c results in a smaller βnuc value appears to be in accord with the reactivity- selectivity principle. The aminolysis of 7c has been suggested to proceed through a stepwise mechanism in which breakdown of the intermediate is the rate-determining step (RDS). The Hammett plot for the reactions of 7a-e with piperidine consists of two intersecting straight lines, i.e., ρX = 1.47 for substrates possessing an electron-donating group (EDG) and ρX = 0.91 for those possessing an electron-withdrawing group (EWG). In contrast, the corresponding Yukawa- Tsuno plot exhibits excellent linear correlation with ρX = 0.79 and r = 0.56. Thus, it has been concluded that the nonlinear Hammett plot is not due to a change in the RDS but is caused by stabilization of the ground state of the substrates possessing an EDG through resonance interaction between the EDG and the C=O bond of the substrates.
Acylation of 4-Pyridone
Effenberger, Franz,Mueck, Alfred Otto,Bessey, Eberhard
, p. 2086 - 2099 (2007/10/02)
Only N-acyl-4-pyridones (5) are isolable from the acylation of 4-pyridone (1) with aliphatic carboxylic anhydrides, and chlorides or free acids in the presence of dicyclohexylcarbodiimide.Similarly the reaction of 1with ortho substituted derivatives of benzoic acid leads only to N-acylation products 8, while benzoyl chloride as well as benzoic acid derivatives 7i-s (meta or para substituted), 3,5-dinitrobenzoyl chloride, and the 2,4-dimethyl substituted benzoyl chlorides 7v-z give exclusively 4-(acyloxy)pyridines 9.Reaction of phthaloyl chloride (10) with 1 yields both N- and O-acylation products.In solution even at room temperature the N-acylation compounds 2 and 8 are in equilibrium with the (acyloxy)pyridines 3 and 9, respectively.The position of the equilibrium depends mainly on the structure of the acyl residue, it is, however, also effected by temperature and polarity of the solvent.
