Analysis of solvent effects on the Menshutkin reaction

Solà, Miquel; Lledós, Agustí; Duran, Miquel; Bertrán, Juan; Abboud, José‐Luis M.

doi:10.1021/ja00008a013

Cited by 134 publications

(111 citation statements)

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“…The barrier from molecule-pair reactant to transition state is lowered by 11.8 kcal/mol to a value of 22.2 kcal/mol and the ion-pair product is now lower in energy than the molecule-pair reactant by 19.2 kcal/mol. The transition state geometry (see Figure 4) shows that it is occurring earlier in the reaction, an effect also observed in previous studies 15 and predicted by the Hammond postulate. Figure 5 shows the all ab initio and the two EFP water minimum energy paths (MEPs).…”

Section: Resultssupporting

confidence: 84%

“…The first part of the surface, that is, the molecule-pair reactant, transition state (1), and ion-pair product (1), is qualitatively the same as that predicted by Solà et al 15 However, Table 1 shows some quantitative discrepancies. The molecule-pair reactant to transition state barrier is found to be ∼10 kcal/mol higher than that in the earlier study.…”

Section: Resultssupporting

confidence: 75%

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Solvation of the Menshutkin Reaction: A Rigorous Test of the Effective Fragment Method

Webb

Gordon

1999

J. Phys. Chem. A

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The recently developed effective fragment potential (EFP) method is used to study the effect of two, four, six, and eight solvating water molecules on the Menshutkin reaction between ammonia and methyl bromide. The EFP method reproduces all ab initio geometries and energetics (including zero-point energy, thermal, and entropy effects) for the two-water case very accurately. Energetics from all ab initio single-point energies at the EFP geometries for the four, six, and eight water cases are in excellent agreement with corresponding EFP energetics. In the gas phase, the above Menshutkin reaction is kinetically highly unfavorable with a free energy of activation (at 298.15 K) of 40.6 kcal/mol at the RHF level with a double-ξ basis set augmented with polarization and diffuse functions. An ion-pair product is found, in agreement with previous work, in which the bromide anion is hydrogen-bonded to an ammonium hydrogen, giving a free energy of reaction of 2.8 kcal/mol. The addition of solvating water molecules has the effect of lowering the barrier and lowering the energy of the ion-pair product relative to the molecule-pair reactant. For eight solvating EFP water molecules, the free energy of activation is 22.8 kcal/mol and the free energy of reaction is −21.9 kcal/mol. Timings indicate that the EFP method allows the inexpensive addition of water molecules to a chemical system, accurately modeling all ab initio calculations with low computational cost. Disciplines Chemistry CommentsReprinted ( September 18, 1998; In Final Form: December 4, 1998 The recently developed effective fragment potential (EFP) method is used to study the effect of two, four, six, and eight solvating water molecules on the Menshutkin reaction between ammonia and methyl bromide. The EFP method reproduces all ab initio geometries and energetics (including zero-point energy, thermal, and entropy effects) for the two-water case very accurately. Energetics from all ab initio single-point energies at the EFP geometries for the four, six, and eight water cases are in excellent agreement with corresponding EFP energetics. In the gas phase, the above Menshutkin reaction is kinetically highly unfavorable with a free energy of activation (at 298.15 K) of 40.6 kcal/mol at the RHF level with a double-basis set augmented with polarization and diffuse functions. An ion-pair product is found, in agreement with previous work, in which the bromide anion is hydrogen-bonded to an ammonium hydrogen, giving a free energy of reaction of 2.8 kcal/mol. The addition of solvating water molecules has the effect of lowering the barrier and lowering the energy of the ion-pair product relative to the molecule-pair reactant. For eight solvating EFP water molecules, the free energy of activation is 22.8 kcal/mol and the free energy of reaction is -21.9 kcal/mol. Timings indicate that the EFP method allows the inexpensive addition of water molecules to a chemical system, accurately modeling all ab initio calculations with low computational cost.

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Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 75%

Solvation of the Menshutkin Reaction: A Rigorous Test of the Effective Fragment Method

Webb

Gordon

1999

J. Phys. Chem. A

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“…In this work, the partial atomic charges q A of methyl, ammonia and chlorine are computed according to the Mulliken [31] or Lçwdin [32] population analyses, in the following way: first, the VB electron density corresponding to the current VB wave function is calculated; second, the net charges are calculated following Equation (7) for the Mulliken population, or Equation (8) for the Lçwdin population:…”

Section: Wwwchemphyschemorgmentioning

confidence: 99%

“…Another Menshutkin reaction is the one between ammonia and methyl bromide, shown in Equation (4), which was studied by Solà et al [8] and Gordon and Webb.…”

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The Menshutkin Reaction in the Gas Phase and in Aqueous Solution: A Valence Bond Study

Ying

et al. 2007

ChemPhysChem

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The recently developed (L. Song, W. Wu, Q. Zhang, S. Shaik, J. Phys. Chem. A 2004, 108, 6017-6024) valence bond method coupled to a polarized continuum model (VBPCM) is applied to the Menshutkin reaction, NH3+CH3Cl-->CH3NH3(+)+Cl-, in the gas phase and in aqueous solution. The computed barriers and reaction energies at the level of the breathing orbital VB method (P. C. Hiberty, J. P. Flament, E. Noizet, Chem. Phys. Lett. 1992, 189, 259), BOVB and VBPCM//BOVB, are comparable to CCSD(T) and CCSD(T)//PCM results and to experimental values in solution. The gas-phase reaction is endothermic and leads to an ion-pair complex via a late transition state. By contrast, the reaction in the aqueous phase is exothermic and leads to separate solvated ions as reaction products, via an early transition state. The VB calculations provide also the reactivity parameters needed to apply the valence bond state correlation diagram method, VBSCD (S. Shaik, A. Shurki, Angew. Chem. Int. Ed. 1999, 38, 586). It is shown that the reactivity parameters along with their semiempirical derivations provide together a satisfactory qualitative and quantitative account of the barriers.

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Solvation effects on reaction profiles by the polarizable continuum model coupled with the Gaussian density functional method

1998

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An efficient version of the polarizable continuum model for solvation has been implemented in the Gaussian density‐functional‐based code called deMon. Solvation free energies of representative compounds have been calculated as a preliminary test. The hydration effects on the reaction profile of the Cl−+CH3Cl→ClCH3+Cl− reaction and the thermodynamics of the Menschutkin reaction have also been investigated. Finally, the conformational behavior of the 1,2‐diazene cis–trans isomerization process in water was examined. Comparisons between the results obtained and the available experimental data and previous theoretical computations have been made. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 290–299, 1998

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Analysis of solvent effects on the Menshutkin reaction

Cited by 134 publications

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Solvation of the Menshutkin Reaction: A Rigorous Test of the Effective Fragment Method

Solvation of the Menshutkin Reaction: A Rigorous Test of the Effective Fragment Method

The Menshutkin Reaction in the Gas Phase and in Aqueous Solution: A Valence Bond Study

Solvation effects on reaction profiles by the polarizable continuum model coupled with the Gaussian density functional method

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