Evidence for an intramolecular elimination mechanism in the aqueous decomposition of (N-Cl)-alcoholamines

Armesto, X. L.; Carretero, P; García, M. V.; Santaballa, J. Arturo

doi:10.1016/s0040-4020(96)01145-3

Cited by 10 publications

(16 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…: Hoffmann and Zaitsev intermolecular eliminations, 12 a Grob fragmentation, 13 and an intramolecular elimination. 10 The main process was found to be intramolecular elimination for the HO Ϫ -promoted decomposition of (N-Cl),N-ethylethanolamine, and Grob fragmen- tation in the case of the HO Ϫ -promoted decomposition of (N-Cl),N-tertbutylethanolamine. 10 Here, we report a joint kinetic and theoretical study of the base-promoted decomposition of (N-X),N-methylethanolamine.…”

Section: Introductionmentioning

confidence: 92%

“…10 The main process was found to be intramolecular elimination for the HO Ϫ -promoted decomposition of (N-Cl),N-ethylethanolamine, and Grob fragmen- tation in the case of the HO Ϫ -promoted decomposition of (N-Cl),N-tertbutylethanolamine. 10 Here, we report a joint kinetic and theoretical study of the base-promoted decomposition of (N-X),N-methylethanolamine. The mechanism of the process differs from the one previously proposed 10 in the intramolecular elimination process being concerted and general-base catalysed and, more particularly, in that the proposed fragmentation step corresponds to an unprecedented concerted base-assisted fragmentation.…”

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

Understanding the mechanism of base-assisted decomposition of (N-halo),N-alkylalcoholamines

et al. 2003

View full text Add to dashboard Cite

The base-assisted decomposition of (N-X),N-methylethanolamine (X = Cl, Br) takes place mainly through two concurrent processes: a fragmentation and an intramolecular elimination. The global process follows second order kinetics, first order relative to both (N-X),N-methylethanolamine and base. Interaction of the base with the ionizable hydroxylic hydrogen triggers the reaction. The intramolecular elimination pathway leads to formaldehyde and 2-aminoethanol as reaction products via base-assisted proton transfer from the methyl to the partially unprotonated hydroxylic oxygen, with loss of halide. Meanwhile, the fragmentation pathway leads to methylamine and two equivalents of formaldehyde via bimolecular base-promoted concerted breakage of the molecule into formaldehyde, halide ion and N-methylmethanimine. Kinetic evidences allow a crude estimation of the concertedness and characterization of the transition structure for both processes, which are slightly asynchronous, the proton transfer to the base taking place ahead of the rest of the molecular events. The degree of asynchroneity increases as the bases become weaker. Electronic structure calculations, at the B3LYP/6-31++G** level, on the fragmentation pathway support the proposed mechanism.

show abstract

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 92%

Understanding the mechanism of base-assisted decomposition of (N-halo),N-alkylalcoholamines

et al. 2003

View full text Add to dashboard Cite

show abstract

“…(3) correspond to the chains, which connect "valence"quarks and di-quarks 1 , and the last term corresponds to chains connected to the sea quarks-antiquarks. Here we do not consider the contribution of sea di-quarks and anti-diquarks, their contribution is important in the spectra of anti-baryons produced in the forward region [12]. The functions F h(n) i (x) being a convolution of the structure ψ(x), and fragmentation G(x) functions are writen as follows:…”

Section: Qgsmmentioning

confidence: 99%

Predictions of the Quark–Gluon String Model for pp at LHC

Kaidalov

Poghosyan²

2010

Eur. Phys. J. C

View full text Add to dashboard Cite

show abstract

“…13, 49 The two main reaction paths were found to be intramolecular dehydrohalogenation and Grob fragmentation. [50][51][52] As the N-chloramine 4 cannot undergo Groblike fragmentation, the intramolecular dehydrochlorination is the most feasible rearrangement mechanism in an alkaline aqueous environment (see Scheme 5). It has been shown earlier that bimolecular eliminations, in which OHassists in base-promoted eliminations, are much slower processes in comparison to intramolecular dehydrohalogenations, in which a free hydroxyl group catalyzes the reaction.…”

Section: N-chloro-4-(4-fluorophenyl)-3-(hydroxymethyl)piperidinementioning

confidence: 99%

Base-catalyzed reactions of environmentally relevant N-chloro-piperidines. A quantum-chemical study

2011

View full text Add to dashboard Cite

Electronic structure methods have been applied to calculate the gas and aqueous phase reaction energies for base-induced rearrangements of N-chloropiperidine, N-chloro-3-(hydroxymethyl)piperidine, and N-chloro-4-(4-fluorophenyl)-3-(hydroxymethyl)piperidine. These derivatives have been selected as representative models for studying the chemical fate of environmentally relevant chloramines. The performance of different computational methods (MP2, MP4, QCISD, B3LYP and B2PLYP) for calculating the thermochemistry of rearrangement reactions was assessed. The latter method produces energies similar to those obtained at G3B3(+) level, which themselves have been tested against experimental results. Experimental energy barriers and enthalpies for ring inversion, nitrogen inversion and dehydrochlorination reactions in N-chloropiperidine have been accurately reproduced when solvent effects have been included. It was also found that the combined use of continuum solvation models (e.g. CPCM) and explicit consideration of a single water molecule is sufficient to properly describe the water-assisted rearrangement of N-chlorinated compounds in basic media. In the case of N-chloro-4-(4-fluorophenyl)-3-(hydroxymethyl)piperidine, which represents the chlorinated metabolite of the antidepressant paroxetine, several different reactions (intramolecular addition, substitution, and elimination reactions) have been investigated. Transition state structures for these processes have been located together with minimum energy structures of conceivable products. Imine 4A is predicted to be the most stable reaction product, closely followed by imine 4B and oxazinane 8, while formation of isoxazolidine 7 is much less favourable. Calculated reaction barriers in aqueous solution are quite similar for all four processes, the lowest barrier being predicted for the formation of imine 4A.

show abstract

Evidence for an intramolecular elimination mechanism in the aqueous decomposition of (N-Cl)-alcoholamines

Cited by 10 publications

References 11 publications

Understanding the mechanism of base-assisted decomposition of (N-halo),N-alkylalcoholamines

Understanding the mechanism of base-assisted decomposition of (N-halo),N-alkylalcoholamines

Predictions of the Quark–Gluon String Model for pp at LHC

Base-catalyzed reactions of environmentally relevant N-chloro-piperidines. A quantum-chemical study

Contact Info

Product

Resources

About