42824-44-2Relevant articles and documents
Aminolysis of Y-substituted-phenyl 2-methoxybenzoates in acetonitrile: Effect of the o-methoxy group on reactivity and reaction mechanism
Um, Ik-Hwan,Bae, Ae Ri
, p. 7510 - 7515 (2011/11/13)
Second-order rate constants (kN) were measured for aminolyses of Y-substituted-phenyl 2-methoxybenzoates 2a-i and 4-nitrophenyl X-substituted-benzoates 3a-j in MeCN at 25.0 °C. The Bronsted-type plot for the reactions of 2a-i with piperidine curves downward, indicating that a change in rate-determining step (RDS) occurs. The Hammett plot for the reactions of 3a-j with piperidine consists of two intersecting straight lines, which might be taken as evidence for a change in RDS. However, the nonlinear Hammett plot has been suggested not to be due to a change in RDS but rather to the stabilization of the ground state of substrates possessing an electron-donating group (EDG) (e.g., 3a-c) through a resonance interaction, since the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with ρ = 0.54 and r = 1.54. The ρ value found for the reactions of 3a-j in MeCN is much smaller than that reported previously for the corresponding reactions in H2O (i.e., ρ = 0.75). It is proposed that the reactions of 3a-j in MeCN proceed through a forced concerted mechanism due to instability of T± in the aprotic solvent, while the reactions of 2a-i proceed through a stepwise pathway with a stabilized T ± through an intramolecular H-bonding interaction.
Determination of basic strength of aliphatic amines through ion pair formation in some ionic liquid solutions
D'Anna, Francesca,Vitale, Paola,Noto, Renato
experimental part, p. 6224 - 6230 (2009/12/08)
(Chemical Equation Presented) To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K.
Conjugation and proton exchange equilibria. Heteroconjugation constants in substituted phenol-piperidine systems in acetonitrile
Magonski, Jozef,Rajzer, Barbara
, p. 1181 - 1185 (2007/10/03)
It has been shown by mathematical transformations that the final equations and expressions required for determining equilibrium concentrations of major species in HA + B systems are analogous to those used previously for HA + A1- systems. Heteroconjugation constants K→AHB = [AHB]/([HA][B]) for eight substituted phenol (HA)-piperidine (B) systems in acetonitrile (AN) were determined from emf measurements. A fairly linear dependence between log K→AHB and ΔpKaAN = pKBH+AN - pKHAAN was observed with a slope of 0.52. The [KAHB2/(KAHA - KBHB+)]atδpKa=0 quotient appeared to be much greater than [KAHA1-2/(KAHA - KA1HA1-)]atΔpKa=0 calculated from results obtained previously for HA + A1- type systems. From this fact it has been concluded that the formation of AHB type complexes (relative to the AHA- and BHB+ type complexes) is likely to be favoured by their overall neutrality ensuring weaker peripheral interactions.
EFFECT OF THE NATURE OF THE LEAVING GROUP IN REACTIONS OF 2-X-N-ETHYLPYRIDINIUM SALTS WITH AMINES IN ACETONITRILE
Titskii, G. D.,Mitchenko, E. S.
, p. 1949 - 1954 (2007/10/02)
The rate-determining stage in the nucleophilic substitution reactions of 2-X-N-ethylpyridinium salts with piperidine in acetonitrile changes, depending on the nature of the leaving group X.In the case where X = Hlg the controlling stage is the formation of the C-N bond.When X = 4-NO2C6H4O3, 3,4-(NO2)2C6H3O, and 2,6-(NO2)2C6H3O, nucleophilic substitution at the carbon atom is controlled by cleavage of the C-X bond.Nucleophilic substitution at a carbon atom of the benzene ring predominates in the reaction of 2-(2,4-dinitrophenoxy)-N-ethylpyridinium salt with piperidine.
