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EK Orgo 1001 Error?

Discussion in 'MCAT Study Question Q&A' started by NigerianBull87, Jun 16, 2008.

  1. NigerianBull87

    NigerianBull87 2+ Year Member

    Jan 2, 2008
    Hey guys if anyone has the book you can reference my question on Page 16, problem 137 in the EK Organic 1001.

    Question: IN the assignment of absolute configuration, what priority does the CHO group have in the structure?

    Okay so the chiral carbon is connected to a Br, OH, "CHO", and CH3. Now the answer key says that the CHO takes second priority? Isn't that false? The priority should be 1.Br, 2. OH, 3."CHO" and 4. CH3 right. Priority begins with highest MW first and if there is a tie you look for the next substituent.

    Or maybe I am wrong about this one? What do you guys think?
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  3. cornpops21

    cornpops21 7+ Year Member

    May 25, 2008
    Hey NigerianBull,

    I attempted the problem and got the same answer as you, so then I checked the EK Forum and this is what Dr. Johnson (editor of the EK o-chem book) said:

    "According to the Cahn-Ingold-Prelog system, the atom with the highest atomic # is 1 and then priority decreases with atomic #. So Br is 1, OH is 2, CHO is 3, and CH3 is 4, you are correct."

    So yeah. We were both thinking correctly. Hope that helps!
    Last edited: Jun 16, 2008
  4. NigerianBull87

    NigerianBull87 2+ Year Member

    Jan 2, 2008
    thanks man I thought i was going crazy. I did the first 209 last night after the first lecture and was scared the problems were hypnotizing me or something.

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