Solvent Properties of Dichloromethane. II. The Reactivity of Dichloromethane Toward Amines.

Nevstad, Gunnar O.; Songstad, Jon; Rodríguez, Bárbara; Mörch, Lars; Norin, Torbjörn

doi:10.3891/acta.chem.scand.38b-0469

Cited by 45 publications

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“…The kinetics of the reactions of the benzhydrylium ions 2 with the tertiary amines 1a–d were then followed by monitoring the decrease of the absorbance of Ar 2 CH + at λ max . Unlike primary and secondary amines, tertiary amines react only very slowly with dichloromethane,69 which allowed us to study their reactivity also in CH 2 Cl 2 solution.…”

Section: Resultsmentioning

confidence: 99%

Nucleophilic reactivities of tertiary alkylamines

Ammer

Baidya

Kobayashi

et al. 2010

J of Physical Organic Chem

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The kinetics of the reactions of tertiary amines, triethylamine (1a), N‐methylpyrrolidine (1b), N‐methylpiperidine (1c), and N‐methylmorpholine (1d) with benzhydrylium ions (Ar2CH+) have been studied in acetonitrile and dichloromethane. The benzhydryl cations were generated by laser flash photolysis of quaternary phosphonium and ammonium tetrafluoroborates. For most reactions, exponential decays of the absorbances of the benzhydryl cations were observed because the carbocations were generated in the presence of a high excess of the amines (pseudo‐first‐order conditions). From the linear plots of kobs versus the amine concentrations, the second‐order rate constants k were obtained, which allowed us to calculate N and s for these amines in CH3CN and CH2Cl2. The linear free energy relationship log k = s(N + E) was thus used to integrate 1a–d into our comprehensive nucleophilicity scales. Copyright © 2010 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Nucleophilic reactivities of tertiary alkylamines

Ammer

Baidya

Kobayashi

et al. 2010

J of Physical Organic Chem

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“…One can also consider that there might be an alkylation reaction between the amine groups and the employed solvent, dichloromethane. It is acknowledged that the alkylation rate is very slow [64], but it can be accelerated in the case of macrocyclic amines that stabilize a reaction intermediate [65] by hydrogen bonding with neighbouring groups, which may be the situation in LP800 formulations with unreacted amine groups.…”

Section: Comparison Of Theory With Experimentsmentioning

confidence: 99%

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Fernández‐Francos

Ramis

2015

European Polymer Journal

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The network build-up process during curing of an epoxy resin using a hyperbranched poly(ethyleneimine) as crosslinking agent has been studied from a theoretical and experimental point of view. A systematic analysis taking into account the stoichiometry of the curing process has been performed. Conversion at gelation has been studied by thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). Crosslinking density has been studied by dynamomechanical analysis (DMA). Gel fraction after extraction in organic solvents has also been determined. The experimental results have been compared with a theoretical network build-up model based on the random recombination of structural fragments, showing good agreement between theory and experimental results, but deviations from the ideal epoxy-amine polycondensation appear as a consequence of the dilution of the hyperbranched crosslinker in off-stoichiometric formulations.  Expressions for relevant pre-gel and post-gel statistical averages are derived.  Experimental validation of predicted crosslinking and gelation is performed.  Nonidealities due to the densely branched structure of the crosslinker are described. ABSTRACTThe network build-up process during curing of an epoxy resin using a hyperbranched poly(ethyleneimine)as crosslinking agent has been studied from a theoretical and experimental point of view. A systematic analysis taking into account the stoichiometry of the curing process has been performed. Conversion at gelation has been studied by thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). Crosslinking density has been studied by dynamomechanical analysis (DMA). Gel fraction after extraction in organic solvents has also been determined. The experimental results have been compared with a theoretical network build-up model based on the random recombination of structural fragments,showing good agreement between theory and experimental results, but deviations from the ideal epoxyamine polycondensation appear as a consequence of the dilution of the hyperbranched crosslinker in offstoichiometric formulations.

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“…Low steric requirements of the amine are important for a relatively rapid reaction. Among the most reactive amines is quinuclidine, but some tertiary and secondary amines containing methyl groups (trimethylamine, dimethylamine) and certain cyclic secondary amines (pyrrolidine, piperidine) are also fairly reactive . Particularly noteworthy in the context of this work is the seminal finding that the parent bispidine (3,7‐diazabicyclo[3.3.1]nonane) reacts with CH 2 I 2 in refluxing methanol to afford, after base treatment, 1,3‐diazaadamantane .…”

Section: Introductionmentioning

confidence: 99%

Degradation of dichloromethane by bispidine

Cui

Goddard

Pörschke

2012

J of Physical Organic Chem

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An effective degradation reaction of CH2Cl2 by bispidine (3,7‐diazabicyclo[3.3.1]nonane, C7H12(NH)2, 1) is reported. The reaction starts as low as −20 °C and is quantitative with respect to 1. The overall reaction implies nucleophilic substitution of chloride, followed by a series of cascading acid–base reactions, ending with the formation of two easily separable products, one being soluble and the other insoluble. The starting 1, the intermediates, and the products show a variety of interesting solid‐state structures, associated with plasticity, N–H⋯N and N–H⋯Cl⋯H–N hydrogen bonding, and polymorphism. Copyright © 2012 John Wiley & Sons, Ltd.

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Solvent Properties of Dichloromethane. II. The Reactivity of Dichloromethane Toward Amines.

Cited by 45 publications

References 0 publications

Nucleophilic reactivities of tertiary alkylamines

Nucleophilic reactivities of tertiary alkylamines

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Degradation of dichloromethane by bispidine

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