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OChem ?

Discussion in 'Pre-Dental' started by Beagle, Jul 23, 2002.

  1. Beagle

    Beagle Meet BEAGLE
    7+ Year Member

    Joined:
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    Two Questions....

    Which of the following is the strongest acid?
    A. ClCH2CH2CO2H

    B. Cl2CHCO2H

    C. CH3CHClCO2H

    D. CLCH2CHClCO2H

    E. CH3CH2CO2H


    The answer is B. I thought the answer was D because the Chlorine is adjacent to the Carboxylic Acid. Doesn't a Cl adjacent to a COOH make it more acidic???
    Anyone know why the answer is B?

    2. How many Primary Hydrogens are present in the compound:

    2-methyl-pentane

    The answer is 9. Can someone tell me what a primary H is??


    Thanks guys!
     
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  3. Buckyball

    Buckyball Play with my "Buckyballs"
    7+ Year Member

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    Hi Beagle,

    Here's a response to your two questions:

    1). The strongest acid is B, because there are two chlorines attached to the carbon which is alpha to the carbonyl carbon, whereas in D, there is only one Chlorine on the carbon alpha (adjacent) to the carbonyl carbon.

    2). 2-methyl-pentane has 9 primary hydrogens - a primary hydrogen is a hydrogen that is attached to a primary carbon. Therefore, in 2-methyl-pentane, the structure is like so:

    CH3CH(CH3)CH2CH2CH3

    The methyl in brackets is on the second carbon counting from the left. The primary carbons in this structure are the methyl on the second carbon, as well as the end "CH3's". So, each has 3 hydrogens, making a total of 9. They are called primary carbons because they are only attached to one other carbon. A secondary carbon, on the other hand, is attached to two carbons, such is the case with CH2's in the middle. A tertiary carbon is one that is attached to three carbons, and there is only one in this structure: the CH which is number 2. Therefore, that hydrogen is a tertiary hydrogen.

    I know i've gone into a lot of detail, but I hope this helps.

    Bucky

    How many Primary Hydrogens are present in the compound:

    2-methyl-pentane

    The answer is 9. Can someone tell me what a primary H is??


    Thanks guys! [/B][/QUOTE]
     

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