12.7 Elimination Reactions of Alcohols | Organic Chemistry

Chad covers the elimination of alcohols using concentrated sulfuric acid (H2SO4). He shows that elimination occurs via the E1 mechanism for tertiary and secondary alcohols and the E2 mechanism for primary alcohols. Chad also compares and contrasts unimolecular vs bimolecular dehydration and the significance of a difference in temperature. Finally, Chad concludes the lesson by showing the Pinacol Rearrangement including the complete mechanism.

00:00 Lesson Introduction
00:46 Elimination of Alcohols with conc. H2SO4 (including mechanisms)
06:55 Unique Elimination of an Alcohol with Rearrangement
10:12 Unimolecular vs Bimolecular Dehydration of Alcohols
13:52 The Pinacol Rearrangement (including mechanism)

[dhruvshah]

Thank you so much for uploading this and all you your other videos! Because of you I am able to survive college chem AND GET AN A! THANK YOU TRULY HAVE A GIFT OF TEACHING!!

[Viona]

11:35 should the back side attack alcohol be propanol instead of ethanol in this case? Because the product has 6 carbons in the chain. If the chain with 3 carbons is added with a two-carbon chain, then the product will have 5 carbons only.

I really like your videos btw :)

[nilsnickname]

Hello Chad,

there is a fault in your argumentation at about 12:18.
It is not very important, but I want to tell you.
You said "Elimination gets favoured at higher temperature, because it's more entropically favoured...".

Than you tell that in the elimination would have same number of reactants like the number of products.

And that in the substitution there would be more reactants than products.

When you write the equations and eliminate the parts, which you find on the left and also on the right side of the reaction equation arrow, you get the following result:

Elimination:

one alcohol molecule reacts. One alkene molecule and one water molecule are built.
So the number of reactants and products aren't the same.
One molecule becomes two molecules.

Substitution:

two molecules of alcohol react to give one ether molecule and one water molecule.
So the number of molecules doesn't change.

But, you are the best! Noone explains as good as you do!
I only repeat things that I learned years before.
I want to understand every single word and rewind the video if there is only a little bit that I don't understand.
Thats the only reason I find some "errors".

By the way - your wrong counting of molecules of the both reactions cancel each other, so that your interpretation lead to the correct overall result.

Best regards

Nils

[tzvifriedman]

Greetings! The bimolecular sn2 reaction: how did the alcohol work if it is a WEAK nucleophile?