Unimolecular reactions, implicit in terms E= 1 and SN1, pass through unimolecular transitions states, involving just the= substrate molecule, t-butyl chloride. So, we cannot simulate their transit= ion states using both the nucleophile or base (OH-) and the substrate (t-Bu= Cl). The first step of these reactions would be the Cl-C(CH3)3 bond breakin= g, followed, as a second step, by the attack of OH- as a base on one of the= H atoms (in E1 reaction) or as a nucleophile on the cationic carbon (SN1).= Otherwise, you may want to study the bimolecular processes (E2 and SN2), w= hich occur in just one step. In this case, you should direct the attack of = the anioic species (OH-) to the central carbon (SN2) or to one os the methy= l hydrogens (E2) (that are statistically more prone to attack: 9 to 1, just= ifying the E2 preference in high OH- conentrations). You should also consid= er that OH- is more basic than nucleophilic, favoring E2 reactions.

2012/9/25 Nguyen Minh Ly nguyen= minhly2209*|*yahoo.com &= lt;owner-chemi= stry[]ccl.net>

Sent to CCL by: "Nguyen Minh Ly" [nguyenminhly2209,yahoo.com]
I have a problem to discuss. I survey the SN1 reaction of tert-butyl chlori= de
and OH- by:
1 / Optimization of structures with Gaussian
2 / Optimize to find the transition state in the first stage of the SN1
reaction (using QST2 keyword)

As we all know, this reaction depends on the concentration of OH-. If
concentration of OH- is low (dilute solution), the reaction will occur SN1.= If
concentration of OH- is high (special solution), the reaction will occur E1= .

But in GaussView, when I optimized to find the transition state in the firs= t
stage of the SN1 reaction, I can only draw a molecule C4H9Cl and a OH- in Reactants window, a molecule C4H9OH and a Cl- in products window. This mean= s
that the rate of C4H9Cl and OH- concentration in the solution was 1:1
(corresponding to the high concentration of OH-). So E1 reaction will occur= !

But I want to find the transition state in the first stage of the SN1 react= ion.
How can do this ?

Please help me
Thank you

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