KOH alcohol elimination

[joonkimdds]

In DAT destroyer, KOH, alcohol brings elimination and it forms C=C with more substituted carbon thus more stable and i think that's called Zaitchev.

When I googled and found this page
www.funeducation.co.uk/a2resources/resources/organic_a2.ppt
(plz go down to page #13)

it shows that it forms C=C with less substituted carbon and I think that's called hoffman.

which one is correct?

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[Sublimation]

In DAT destroyer, KOH, alcohol brings elimination and it forms C=C with more substituted carbon thus more stable and i think that's called Zaitchev.

When I googled and found this page
www.funeducation.co.uk/a2resources/resources/organic_a2.ppt
(plz go down to page #13)

it shows that it forms C=C with less substituted carbon and I think that's called hoffman.

which one is correct?

Yes both are correct there is a slight difference here. When a chemist want to make a compound that has a alkene that does not follow zeitchevs rule, they place a very bulky base to eliminate, KOH will not in any case produce a hoffman product its just not bulky enough, however, a t-butoxide on the other hand will give u a hoffman product (also depending on the variables in the reaction).

 

[joonkimdds]

Yes both are correct there is a slight difference here. When a chemist want to make a compound that has a alkene that does not follow zeitchevs rule, they place a very bulky base to eliminate, KOH will not in any case produce a hoffman product its just not bulky enough, however, a t-butoxide on the other hand will give u a hoffman product (also depending on the variables in the reaction).

Thanks for ur answer.

How should I memorize this though? When I see KOH(alc), should I assume that answer can be either one(hoff and zaitchev).

 

[sciencegod]

for your purpoeses any elimination of alcohols will yield zaitchev unless its t-butoxide or LDA. theose 2 will yield hoffman.

 

[joonkimdds]

for your purpoeses any elimination of alcohols will yield zaitchev unless its t-butoxide or LDA. theose 2 will yield hoffman.

Thank you .

But what about CH3-CHCH3-CHBr-CH3? (from the link posted)
this is neither t-butoxide nor LDA (or is it?) but it yields Hoffman.

 

[sciencegod]

its bec of the high steric hindrance. don't think you have to worry bout this for the dta. just remember what I told you.

 

[joonkimdds]

I think I just found out why it can't form C=C with tertiary carbon.
Because that will make it go beyond octet.
(CH3)3 C=C is impossible