Dismiss Notice
Hey Texans—join us for a DFW meetup! Click here to learn more.

Another SN2 reaction

Discussion in 'DAT Discussions' started by Awuah29, May 12, 2007.

  1. Awuah29

    Awuah29 Christian predent
    7+ Year Member

    Joined:
    Oct 13, 2003
    Messages:
    294
    Likes Received:
    0
    The answer here is 4. I was ruling for 2. It's for sure not 1,3 or 5. Anyone can explain?
     

    Attached Files:

  2. Note: SDN Members do not see this ad.

  3. laundry

    10+ Year Member

    Joined:
    Apr 29, 2007
    Messages:
    579
    Likes Received:
    41
    Status:
    Dentist
    yo...

    Since it's Sn2, we know it's not gonna give a racemic mixture; rather, it will give an inversion. In this case from S to R. Sn2 reaction rate does depend on the concentration of the nucleophile, so second choice is out too. Carbocations are formed in Sn1 reactions; in Sn2 you get a transition state with partial charges - third answer is out. Choice 4 is the correct one since Sn2 does give an inverted product.

    Another easy way to tackle problems of this sort is by looking at the choices. The last two choices are opposites of each other, so guess which 2 choices you have to choose from.:rolleyes:

    In short, the correct answer is 4.

    Cheers
     
  4. jdmsamurai

    2+ Year Member

    Joined:
    Feb 11, 2007
    Messages:
    237
    Likes Received:
    1
    Status:
    Dental Student

    why guess when you can just look at the rxn and see it uses ACETONE as the solvent....since ACETONE is a polar aprotic solvent you know its SN2...and from there choose the SN2 answer stating that SN2 does a "backside" concerted attack on the carbon which causes and inversion....that question should take no more than 10 seconds.
     
  5. laundry

    10+ Year Member

    Joined:
    Apr 29, 2007
    Messages:
    579
    Likes Received:
    41
    Status:
    Dentist
    I meant you can automatically narrow down to 2 choices, ace...I was just giving some advice on how to improve the performance. It's quite obvious that if the OP was as well trained in the Arts of SN2 as yourself, this thread wouldn't exist.

    And by the way...you don't need to look at the acetone at all or know anything about the solvent...why? it's because the questions already stated that it's an Sn2. :D i think i chiseled that down to...7 sec for ya.;)
     
  6. poc91nc

    poc91nc Membership Revoked
    Removed 7+ Year Member

    Joined:
    Nov 5, 2006
    Messages:
    552
    Likes Received:
    0
    Status:
    Dental Student
    Might only take ten seconds for you...but maybe a problem that might take 20sec for you can be done in 10 sec by "joe blow"

    Problem solving isn't set in stone...just go with whatever floats your boat. Kinda like the definition of a gene...remember? By the way...Molecular Biology of the Cell was written by 6 authors.
     
  7. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist 7+ Year Member

    Joined:
    Oct 25, 2006
    Messages:
    1,801
    Likes Received:
    5
    Status:
    Dentist
    I think his point was that this is a very simple question compared to others that may be asked on the test (it really is...). If it takes someone a while to get this, it might take them a really long time to get some of the harder questions.

    This was textbook SN2 = inversion.
     
  8. jdmsamurai

    2+ Year Member

    Joined:
    Feb 11, 2007
    Messages:
    237
    Likes Received:
    1
    Status:
    Dental Student
    thanks yea.....appreciate the backup...its not even a trick question...thats the thing....people think too hard sometimes...and with your gene definition again...so if i read a book based on 20 authors about science being crap written by creatonist it must be true huh?....until they set a standard definition then its hard to say...

    here is dictionary.com's definition of gene
    "the basic physical unit of heredity; a linear sequence of nucleotides along a segment of DNA that provides the coded instructions for synthesis of RNA, which, when translated into protein, leads to the expression of hereditary character. "

    so you are saying they are wrong...geezus....

    and i really think the ochem section isnt trying to give you hard questions...its trying to test your back understanding of ochem that is all....
     
  9. poc91nc

    poc91nc Membership Revoked
    Removed 7+ Year Member

    Joined:
    Nov 5, 2006
    Messages:
    552
    Likes Received:
    0
    Status:
    Dental Student
    Jesus christ....I was only kidding about MBC (I still stand by my original opinion that the definition of a gene is up in the air, your original definition is valid as well!!!). Your comment attempting to trivialize MBC as simply being the opinion of one author just amused me...that's all.

    The guy was just offering his opinion on how to tackle the problem...you just seemed so quick to disagree with heated conviction. Just wanted to point out that it's all relative...like a lot of other things. Like the problem might be really really easy for you....but maybe it's hard for the OP...big deal. Not everyone can be as intellectually gifted as you are. Feel better?
     
  10. laundry

    10+ Year Member

    Joined:
    Apr 29, 2007
    Messages:
    579
    Likes Received:
    41
    Status:
    Dentist
    ah, poc, you keep beating me to my own defense. :laugh:

    that problem would take me little time as well. I was trying to help the OP. ah, what's the use......+pissed+ lol...
     

Share This Page