1. Dismiss Notice
  2. This forum is for support and discussion only. Please promote test prep materials/services (including AMAs) in the Special Offers subforum only. Thanks!
    Dismiss Notice
  3. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice

Ochem questions (from destroyer)

Discussion in 'DAT Discussions' started by yankees27th, Dec 5, 2008.

  1. yankees27th

    7+ Year Member

    Joined:
    Nov 3, 2008
    Messages:
    276
    Likes Received:
    1
    Status:
    Pre-Dental
    I was just going over ochem in Destroyer and I have a couple questions:

    #39 says that tertiary and secondary substrates favor E2, but don't they favor E1?

    #80: When you add the (CH3)3CO- to the 2-chlorobutane, why does a terminal alkene form instead of an internal alkene?

    Thanks
     
  2. Zubnaya Feya

    Zubnaya Feya Combinator
    5+ Year Member

    Joined:
    Nov 13, 2008
    Messages:
    971
    Likes Received:
    2
    Status:
    Dental Student
    Generally, E2 is favored over E1. I think E1 is the least favored out of the 4 rxn types (Sn1, Sn2, E1, E2). It depends on the solvent/conditions and so on as well.

    Tertiary alkoxides preferentially take away the less sterically hindered hydrogen, which is the hydrogen of the end carbon. This causes terminal alkene formation.

    Correct me if I am wrong.
     
  3. dentalmagnet

    2+ Year Member

    Joined:
    Oct 30, 2008
    Messages:
    248
    Likes Received:
    0
    He's right. Think of bases like K+ (CH3)3 as really bulky and can't fit where there are crowded carbons. So they take the least hindered hydrogen. This is the kinetic product and can also occur at low temperatures if you don't have a crowded base. A less crowded base at a high temperature would for a more stable carbocation. For ex: NaOCH3 at 70 degrees C. If temps aren't in the problem, go by the crowdedness of the base. I always remember, if I see KOtbu or another crowded base (LDA for ex) I go for E2.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  4. yankees27th

    7+ Year Member

    Joined:
    Nov 3, 2008
    Messages:
    276
    Likes Received:
    1
    Status:
    Pre-Dental
    Thanks both of you! :D
     

Share This Page