34900-00-0Relevant articles and documents
Solvent-dependent competitive rearrangements of cyclic tertiary propargylamine N-oxides
Szabo, Anna,Galstnibos-Farago, Agnes,Mucsi, Zoltan,Timari, Geza,Vasvari-Debreczy, Lelle,Hermecz, Istvan
, p. 687 - 694 (2004)
In protic media, cyclic propargylamine N-oxides 1 undergo solvent-dependent competitive rearrangements leading to enamino aldehydes 5, acrylamides 3, and secondary amines 4. The ratios of the products are evaluated and the possible mechanism of the compet
Modeling rate-controlling solvent effects. The pericyclic Meisenheimer rearrangement of N-propargylmorpholine N-oxide
Mucsi, Zoltan,Szabo, Anna,Hermecz, Istvan,Kucsman, Arpad,Csizmadia, Imre G.
, p. 7615 - 7631 (2007/10/03)
The activation parameters of the pericyclic Meisenheimer rearrangement and a competitive rearrangement of N-propargylmorpholine N-oxide were determined by experimental and computational methods. A number of aprotic and protic solvents of different polarities and hydrogen bond-forming abilities and the roles of electron-pair acceptor additives were investigated. The reaction kinetics were followed by means of NMR. In protic solvents, isotope-labeling experiments revealed a novel inverse secondary kinetic isotope effect (kH/k D about 0.8) for the rate-determining cyclization step, probably occurring because of a C(sp) → C(sp2) change in hybridization at the reaction center. In molecular computations at the B3LYP/6-31++G(d,p) level of theory, implicit, explicit, and joint explicit-implicit solvent models were used. The explicit-implicit model and molecular dynamic simulations gave the most accurate results. The components of the rate-controlling solvent effect are discussed, and general equations are proposed for accurate prediction of the solvent-dependent activation parameters.
Studies on Peroxidized Lipids. I. Interaction of Malondialdehyde with Secondary Amines and Its Relevance to Nitrosamine Formation
Kikugawa, Kiyomi,Tsukuda, Koichi,Kurechi, Tsutao
, p. 3323 - 3331 (2007/10/02)
Malondialdehyde (MDA) reacted with secondary amines (dimethylamine, diethylamine, piperidine, pyrrolidine and morpholine) at 37 deg C under mild acidic or neutral conditions to yield β-dialkylaminoacroleins (1-5) of trans, s-trans conformation.The optimal pH of the reaction was 3-5, and the yields were 15-55percent in a 6 hr incubation.The acroleins (1-5) were unstable under acidic and alkaline conditions, and produced a pink color on reaction with 2-thiobarbituric acid. β-Dimethylaminoacrolein (1) could be readily nitrosated in the acidic pH range to produce N-nitrosodimethylamine, and the rate of nitrosamine formation from 1 at pH 5.0 was much higher than that from dimethylamine; this is consistent with earlier observations of the stimulating effect of MDA on nitrosamine formation.Keywords-malondialdehyde; β-dimethylaminoacrolein; β-diethylaminoacrolein; β-piperidinoacrolein; β-pyrrolidinoacrolein; β-morpholinoacrolein; β-dialkylaminoacrolein formation; N-nitrosodimethylamine formation; 2-thiobarbituric acid test.