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

dc.contributor.author Webb, Simon
dc.contributor.author Gordon, Mark
dc.contributor.author Gordon, Mark
dc.contributor.department Chemistry
dc.date 2018-02-17T07:54:02.000
dc.date.accessioned 2020-06-30T01:19:29Z
dc.date.available 2020-06-30T01:19:29Z
dc.date.copyright Fri Jan 01 00:00:00 UTC 1999
dc.date.issued 1999-02-01
dc.description.abstract <p>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 <em>ab initio</em> geometries and energetics (including zero-point energy, thermal, and entropy effects) for the two-water case very accurately. Energetics from all <em>ab initio</em> 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 <em>ab initio</em> calculations with low computational cost.</p>
dc.description.comments <p>Reprinted (adapted) with permission from <em>Journal of Physical Chemistry A</em> 103 (1999): 1265, doi:<a href="http://dx.doi.org/10.1021/jp983781n" target="_blank">10.1021/jp983781n</a>. Copyright 1999 American Chemical Society.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/chem_pubs/349/
dc.identifier.articleid 1354
dc.identifier.contextkey 7924885
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath chem_pubs/349
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/14798
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/chem_pubs/349/0-L_1999_Gordon_SolvationMenshutkin.pdf|||Fri Jan 14 23:42:59 UTC 2022
dc.source.bitstream archive/lib.dr.iastate.edu/chem_pubs/349/1999_Gordon_SolvationMenshutkin.pdf|||Fri Jan 14 23:43:00 UTC 2022
dc.source.uri 10.1021/jp983781n
dc.subject.disciplines Chemistry
dc.title Solvation of the Menshutkin Reaction: A Rigorous Test of the Effective Fragment Method
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication 1a5927c0-5a5f-440e-86e0-9da8dc6afda0
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
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