orgo question

[elz787]

when using tertbutoxide for an E2 rxn, does it follow zaitsev's rule only when there is no steric hinderance?

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[elz787]

or is it always the least substituted alkene formed?

 

[mikester2]

or is it always the least substituted alkene formed?

Uh... you usually want the more substituted alkene formed. As always, there are exceptions.

 

[elz787]

i know the most substituted is formed usually but in the case of an E2 with tertbutoxide and steric hinderance around the leaving group, the least stable would be formed right?

 

[mikester2]

i know the most substituted is formed usually but in the case of an E2 with tertbutoxide and steric hinderance around the leaving group, the least stable would be formed right?

Not exactly sure what you are saying. Maybe you can depict a problem. THe reason you use terbutoxide is because you want a big bucky base for E2. Otherwise it would go sn2. Now if the leaving group was sterically hindered, such as, having more then one R group (teritery leaving group), then it would go E1.

 

[mccarth2]

when using tertbutoxide for an E2 rxn, does it follow zaitsev's rule only when there is no steric hinderance?

From what I remember when you use a less bulky base you get a mixture of Zaitsev (more substituted thermodynamic product, more prevalent) & Hoffman (less substituted kinetic product). In the absence of a bulky base the Zaitsev product will predominate. When a bulky base like t-butoxide is added only the hoffman product will be formed. E1 rxn's only follow Zaitsevs rule, whereas E2 follows Zaisev's and Hoffman's.