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Major help needed!

  • 20-08-2011 4:00pm
    #1
    St3ph3n
    Registered Users, Registered Users 2 Posts: 22 ✭


    I have a test on Monday, with this exact question almost certain to come up:

    th_ScreenShot2011-08-20at165441.png


    Any help would be greatly appreciated as the reactions seem a bit obscure for the module I'm in!


Comments

  • #2
    AaronEnnis
    Registered Users, Registered Users 2 Posts: 151 ✭✭AaronEnnis


    Make the image a bit bigger and Il have a go at it.


  • #3
    St3ph3n
    Registered Users, Registered Users 2 Posts: 22 ✭St3ph3n


    ScreenShot2011-08-20at165441.png

    Hopefully that should work!


  • #4
    SOL
    Registered Users, Registered Users 2 Posts: 1,155 ✭✭✭SOL


    Okay, hopefully this is still intime for your exam,

    I haven't any way of conveniently doing this in pictures but I'll talk through what happens and hopefully that'll help.

    In the first one the strong base deprotonates the ketone forming an enolate, it will probably take a proton from the left side (the kinetic position) and since it is done at -78 there wont be any protons moving around, this will then attack the benzaldehyde, and from and aldol. if you want to look up the mechanism search for directed aldol reaction...

    the second part is a henry reaction, so the proton this time comes from the nitroethane, hence as you are asked later the weaker base, since nitroalkenes are more acidic than ketones, this then attacks the carbonyl carbon of the other molecule


  • #5
    SOL
    Registered Users, Registered Users 2 Posts: 1,155 ✭✭✭SOL


    part 3 is just a H/D exchange, atleast that is what I asssume they are going for, so imagine that you have keto/enol tautomerism happening and you can see how Ds start to replace H's

    Part 4 is addition of a malonate to a carbonyl. Diethyl malonate deprotonates (one of the CH2 protons) and then attacks the aldehyde, to form a secondary alcohol...


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