May 12, 2024, 03:53:25 PM
Forum Rules: Read This Before Posting


Topic: Alkene alcohol elimination 1 reaction  (Read 4519 times)

0 Members and 1 Guest are viewing this topic.

Offline bmanth60

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Alkene alcohol elimination 1 reaction
« on: December 16, 2006, 08:39:37 PM »
With the elimination 1 reaction, i have an example:
http://www.chem.ualberta.ca/~tykwinsk/images/CHEM161.chapter7.pdf
Page 5, E1 elimination of alcohol with treatment of acid and heat.
How come when the elimination occurs, the hydrogen isn't the one that gets attacked? Instead, the CH3 is attacked?

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Alkene alcohol elimination 1 reaction
« Reply #1 on: December 17, 2006, 07:02:57 AM »
Hint: Remember it's a bulky base
My research: Google Scholar and Researchgate

Offline bmanth60

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Re: Alkene alcohol elimination 1 reaction
« Reply #2 on: December 17, 2006, 03:44:25 PM »
Um, even for the problem concerning E1 elimination of alcohols upon treatment with an acid and heat??

Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3215
  • Mole Snacks: +485/-21
  • Gender: Male
  • Physical Biochemist
Re: Alkene alcohol elimination 1 reaction
« Reply #3 on: December 17, 2006, 05:11:43 PM »
That reaction is incorrect.  The correct product should be (H2C)2=(CH2)2 (2,3-dimethyl-but-2-ene).  The reaction is obviously wrong because there are six carbons in the reactants but only five carbons in the product.

Offline bmanth60

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Re: Alkene alcohol elimination 1 reaction
« Reply #4 on: December 18, 2006, 01:32:01 AM »
Yea thanks for clearing that up, I was thinking that was the case, but was doubtful of prof making mistake.

Offline english

  • Chemist
  • Full Member
  • *
  • Posts: 534
  • Mole Snacks: +31/-10
  • Gender: Male
  • grad student
Re: Alkene alcohol elimination 1 reaction
« Reply #5 on: December 19, 2006, 08:16:43 AM »
The methyl group is not supposed to be attacked.  Elimination reactions require strong bases that react by removng a hydrogen proton (the hydrogen bond cleaves heterolytically). 

Even by showing the methyl substituent being removed, the problem is not correct in doing so even at that, because only the carbon next to the carbon bearing the OH group can be attacked.  This is the only way to form our double bond.


But yes the product does not have as many carbons as you began with, and since elimination reactions do not involve removal of carbons, this is a clear way to see that this reaction is not going to work that way.

Sponsored Links