536-45-8Relevant articles and documents
Electronic and steric effects: How do they work in ionic liquids? the case of benzoic acid dissociation
D'Anna, Francesca,Marullo, Salvatore,Vitale, Paola,Noto, Renato
experimental part, p. 4828 - 4834 (2010/10/04)
(Figure Presented) The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydrogen bond and π-π interactions, namely [bm 2im][NTf2] and [bmpyrr][NTf2]. Data collected show that benzoic acids are less dissociated in ionic liquid than in water solution. Furthermore, the equilibrium constant values seem to be significantly affected by both the nature of ionic liquid cation and the structure of the acid. In particular, the ortho-steric effect seems to operate differently in water and in the aromatic ionic liquid, determining in this solvent medium a particular behavior for ortho-substituted benzoic acids.
CLEAVAGE OF THE PHENACYL ESTERS OF CARBOXYLIC AND THIOCARBOXYLIC ACIDS BY METAL ALKOXIDES
Morozov, A. A.
, p. 1138 - 1143 (2007/10/02)
During the cleavage of phenacyl esters with general formula XC6H4COCH2OCOR by metal alkoxides in alcohols and in ether-alcohol solutions the acids, esters, and ethers are formed as a result of cleavage of the C-C bond.The solvent participates in the formation of the ether and gives rise to transesterification of RCOOCH3 with catalytic participation of the metal alkoxide.The reactivity of the phenacyl esters of the thio acids is much higher.Before dissociation the esters of substituted benzoins C6H5COCH(OCOCH3).C6H4X-4 undergo irreversible rearrangement with the formation of isomeric products.
Effect of Distortion on the Hydrolytic Reactivity of Amides. 2. N-Pyramidalization: Decomposition of N-Benzoylaziridines in Aqueous Media
Slebocka-Tilk, H.,Brown, R. S.
, p. 805 - 808 (2007/10/02)
The decomposition of para-substituted N-benzoylaziridines (H, OCH3, NO2, Br) in buffered aqueous media is studied at 25 deg C as a function of pH in order to assess the effect of N-pyramidalization on the hydrolytic reactivity of the amide bond.Overall, the reaction shows three dominant terms: OH- and H2O attack on the neutral form and H2O attack on the protonated form of the amide.In base, the exclusive reaction is rate-limiting and irreversible attack of OH- on the C=O unit leading to normal hydrolytic products.This is shown by the first-order dependence on -> from pH 8 to 14 of the hydrolysis rate and by the fact that ca. 50percent 18O-enriched amide recovered from the hydrolysis medium as a function of time shows no 18O loss.Relative to N,N-dimethylbenzamide (kOH-25 deg C = 6.0 * 10-6 M-1 s-1), N-benzoylaziridine is ca. 200 000-fold more susceptible to OH- attack (kOH-25 deg C = 1.1 M-1 s-1).The kOH- terms follow a ?ρ relationship with ρ = 1.68.In acid, the products are not the expected hydrolytic ones of benzoic acid and aziridine.Rather, exclusive ring opening occurs to give p-X-C6H4C(=O)NHCH2CH2OX.In acetate buffers, product analysis by 1H NMR indicates that the ring-opened material consists of alcohol and acetate (X = H and C(=O)CH3).
