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Apolar versus polar solvents: a comparison of the strength of some organic acids against different bases in toluene and in water.
MedLine Citation:
PMID:  20873823     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
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.
Authors:
Francesca D'Anna; Vincenzo Frenna; Franco Ghelfi; Gabriella Macaluso; Salvatore Marullo; Domenico Spinelli
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  114     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  10969-74     Citation Subset:  -    
Affiliation:
Dipartimento di Chimica Organica E. Paternò, Università degli Studi di Palermo, Viale delle Scienze-Parco d'Orleans II, 90128 Palermo, Italy.
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