CCL:G: Can we find the transition state of SN1 reaction by using

 Sent to CCL by: MIQUEL =?iso-8859-1?Q?SOL=C0_I_PUIG?= [miquel.sola.^.udg.es]
 Dear Wenrui and Steve,
 We addressed this question some years ago. We found that the energy
 profile for the Ch3Cl -> CH3+ + Cl- reaction in the gas phase increases
 monotonically, whereas the presence of either uniform electric fields or
 solvents changes the energy profile, causing the appearance of a
 transition state and the increase of the exothermicity of the process. The
 reference is:
 M. Solà, E. Carbonell, A. Lledós, M. Duran and J. Bertrán.
 "Ab initio study of the effect of external perturbations in the
 dissociation of CH3Cl"
 J. Mol. Struct. (THEOCHEM) 255 (1992) 283-296.
 Hope this helps,
 Miquel
 > Sent to CCL by: Steve Bowlus [chezbowlus!A!goldrush.com]
 > It would not surprise me that this type of reaction must be modeled with
 >   explicit solvent.  Stabilization of the products relative to the TS is
 > attained by solvation of the separated ions, i.e. the physical
 "flow" of
 > solvent between the nascent ions, and the direct (dipolar?) interaction
 > of solvent with the ions.  Most physical organic books should have a
 > discussion of solvent-separated reaction partners, and most likely SN1
 > reactions in particular.
 >
 > Cheers,
 > Steve
 >
 >
 > Wenrui Zheng wenruizheng:gmail.com wrote:
 >> Sent to CCL by: "Wenrui  Zheng" [wenruizheng..gmail.com]
 >>
 >> Dear all,
 >>    Recently I have failed to find the transition state of the first
 step
 >> of solvolyses of alkyl halide RX,for example tert-Butylchloride in
 >> methanol solvent
 >> by using Gaussian03.
 >> RX->R+ + X-
 >> Following the lengths of C-Cl increasing,the potential energy rises all
 >> along,which
 >> is the same with the case of in methanol solvent by using PCM model.
 >>
 >> Now I have some questions:
 >> 1. Can we on earth find the transition state of SN1 reaction by using
 >> Gaussian03?
 >>
 >> 2. Is traditional transition state theory adapt to any system for
 >> example this one ?
 >> If it is true then how can this kind of reaction happen and how can we
 >> calculate the
 >> reaction rate?
 >>
 >>   Regards,
 >>
 >> Wenrui Zheng>
 >
 >
 >