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Need destroyer ochem help...

Decan

Full Member
10+ Year Member
May 9, 2007
493
4
  1. Dental Student
    Hello all. I need some clarification on question 80 in the destroyer. I understand that Cl will replace OH, and that the second step would yield an alkene. But why would it create 1-butene and not 2-butene before step 3?

    Thanks for the help!
     

    Speeddater

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    10+ Year Member
    Dec 8, 2006
    124
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    1. Pre-Dental
      Hello all. I need some clarification on question 80 in the destroyer. I understand that Cl will replace OH, and that the second step would yield an alkene. But why would it create 1-butene and not 2-butene before step 3?

      Thanks for the help!

      Hey Decan, how's the studying? I just took topscore 1 natural science test, & here's how I did:

      Bio - 20
      G. Chem - 17 (I was so pissed, careless mistakes, & wasn't focused)
      Orgo - 21
      TS - 20

      Anyway, for your question, I just went over that problem yesterday too. What you must do is becareful of the temptation to jump straight to the answers. ALWAYS analyze your reactants before doing anything. I tend to make the mistake & jump straight to the answers, & that's probably why I get scores like 21 in orgo & 19 on the real thing, when I can be getting 29's, heh. I'm still working on this myself! The (CH3)3CO-K+ is a bulky base and won't be able to attack further within the butane molecule, so it will attack from the end. One thing my Kraplan teacher told me, is that whenever you have a bulky base, & you have a secondary or tertiary alkyl halide, you'll always get the Hoffmann elimination, aka the less substituted product. Had it been something like NaOCH3, a strong base, then you would get the Zaitstev or more substituted product. Hope this helps! Let me know if you need help with anything else. :)
       

      Decan

      Full Member
      10+ Year Member
      May 9, 2007
      493
      4
      1. Dental Student
        Thanks! I knew that but like you said, I jumped straight to the answers. Stupid mistake...

        As for studying, its coming along. I havent taken any practice tests yet. I did well on the science section my last time through but my orgo could've been better so I'm really drilling on that. I think that with your current scores, you should have no problem on the real thing...nice job! When is D-Day for you? Mine is July 16th...I'm freaking out!
         

        TimeforDAT

        Full Member
        10+ Year Member
        Jun 9, 2007
        135
        0
        1. Pre-Dental
          Hey Decan, how's the studying? I just took topscore 1 natural science test, & here's how I did:

          Bio - 20
          G. Chem - 17 (I was so pissed, careless mistakes, & wasn't focused)
          Orgo - 21
          TS - 20

          Anyway, for your question, I just went over that problem yesterday too. What you must do is becareful of the temptation to jump straight to the answers. ALWAYS analyze your reactants before doing anything. I tend to make the mistake & jump straight to the answers, & that's probably why I get scores like 21 in orgo & 19 on the real thing, when I can be getting 29's, heh. I'm still working on this myself! The (CH3)3CO-K+ is a bulky base and won't be able to attack further within the butane molecule, so it will attack from the end. One thing my Kraplan teacher told me, is that whenever you have a bulky base, & you have a secondary or tertiary alkyl halide, you'll always get the Hoffmann elimination, aka the less substituted product. Had it been something like NaOCH3, a strong base, then you would get the Zaitstev or more substituted product. Hope this helps! Let me know if you need help with anything else. :)
          what happens when you have a bulky base with a primary halide? do you still get E2 with the less substituted alkene?
           
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