1. Apolar versus polar solvents: a comparison of the strength of some organic acids against different bases in toluene and in water
- Author
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Domenico Spinelli, Gabriella Macaluso, Franco Ghelfi, Francesca D'Anna, Vincenzo Frenna, Salvatore Marullo, D'Anna,F, Frenna, V, Ghelfi, F, Macaluso, G, Marullo, S, and Spinelli, D
- Subjects
nitroaniline ,chemistry.chemical_classification ,Steric effects ,Base (chemistry) ,reazione di Boulton-Katritzsky ,acidi dicloroalcanoici ,chemistry.chemical_element ,Settore CHIM/06 - Chimica Organica ,acidi alogenoacetici ,Medicinal chemistry ,Toluene ,MRH, kinetic, ion pairs ,chemistry.chemical_compound ,chemistry ,Urea ,Polar ,Organic chemistry ,Physical and Theoretical Chemistry ,Carbon ,Stoichiometry - Abstract
The constants of ion-pair formation with 3-nitroaniline (3NO(2)A) for eight halogenoacetic acids (HAAs, 3a-h: TFA, TCA, TBA, DFA, DCA, DBA, MCA, and MBA), and five 2,2-dichloroalkanoic acids containing 3-8 carbon atoms (HAs, 5a-e: DCPA, DCBA, DCMBA, DCVA, and DCOA) have been determined in TOL at 298.1 K. The results obtained brought to evidence for HAAs the formation of ion-pairs with two different stoichiometries (base-acid, 1:1 or 1:2), while in contrast the HAs furnish only the 1:1 pairs. The different steric and electronic requirements of HAAs and HAs seem to be responsible for such an unlikely behavior. At the same time, the acid-catalyzed MRH of the (Z)-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole (1) into (2,5-diphenyl-2H-1,2,3-triazol-4-yl)urea (2) in the presence of the five HAs above has been investigated in TOL at 313.1 K. Thus, in contrast with previous results in the presence of several HAAs, a unique pathway for the rearrangement has been observed, again pointing out the importance of the above effects on the initial acid/base interactions. Finally the acidic strength of TFA against seven nitroanilines (NA, 4a-g: 4NO(2)A, 3NO(2)A, 3Me4NO(2)A, 4Me3NO(2)A, 2Me3NO(2)A, 2NO(2)A, and 3,5diNO(2)A) characterized by a very different basicity has been measured in TOL at 298.1 K.
- Published
- 2010