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Thread: Reagent choosing question

  1. #1 Reagent choosing question 
    New Member
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    May 2009
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    1
    I have two questions here, any one help me please?

    1.
    The transformation shown below can be accomplished in TWO reaction steps. From the following list, select the two reagents (or sets of reagents) which would most effectively bring about this conversion. Reagents:
    1. Conc H2SO4/heat
    2. CN-
    3. KMnO4
    4. (i) CH3MgI (ii) H3O+
    5. PBr3
    6. (i) BH3 (ii) H2O2
    7. CH3CH2O-/CH3CH2OH
    8. H2O/H+
    9. OH-/H2O
    10. (i) O3 (ii) Zn
    11. NaBH4
    12. HCl
    13. KI
    14. Na
    15. CH3CH2Br

    Please enter the reagent number (from the above list) for each of the two steps in the following synthesis:
    Step 1:
    Step 2:

    CH3-C(OH)H-CH3 -> (Step 1) -> (Step 2) CH3-C(OCH2CH3)H-CH3



    2.
    The transformation shown below can be accomplished in TWO reaction steps. From the following list, select the two reagents (or sets of reagents) which would most effectively bring about this conversion. Reagents:
    1. Conc H2SO4/heat
    2. CN-
    3. KMnO4
    4. (i) CH3MgI (ii) H3O+
    5. PBr3
    6. (i) BH3 (ii) H2O2
    7. CH3CH2O-/CH3CH2OH
    8. H2O/H+
    9. OH-/H2O
    10. (i) O3 (ii) Zn
    11. NaBH4
    12. HCl
    13. KI
    14. Na
    15. CH3CH2Br

    Please enter the reagent number (from the above list) for each of the two steps in the following synthesis:
    Step 1:
    Step 2:

    CH3-C(OH)-CH3 ->(Step1) ->(Step2) CH2O + CH3CHO

    Thank you so much For help


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  3. #2  
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    The first is pretty easy, the second is a bit more involved.

    But I guess you should show what you've tried so far, not just ask for the solution, shouldn't you?


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  4. #3 Re: Reagent choosing question 
    Forum Freshman
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    Quote Originally Posted by hellenqq
    I have two questions here, any one help me please?

    1.
    The transformation shown below can be accomplished in TWO reaction steps. From the following list, select the two reagents (or sets of reagents) which would most effectively bring about this conversion. Reagents:
    1. Conc H2SO4/heat
    2. CN-
    3. KMnO4
    4. (i) CH3MgI (ii) H3O+
    5. PBr3
    6. (i) BH3 (ii) H2O2
    7. CH3CH2O-/CH3CH2OH
    8. H2O/H+
    9. OH-/H2O
    10. (i) O3 (ii) Zn
    11. NaBH4
    12. HCl
    13. KI
    14. Na
    15. CH3CH2Br

    Please enter the reagent number (from the above list) for each of the two steps in the following synthesis:
    Step 1:
    Step 2:

    CH3-C(OH)H-CH3 -> (Step 1) -> (Step 2) CH3-C(OCH2CH3)H-CH3



    2.
    The transformation shown below can be accomplished in TWO reaction steps. From the following list, select the two reagents (or sets of reagents) which would most effectively bring about this conversion. Reagents:
    1. Conc H2SO4/heat
    2. CN-
    3. KMnO4
    4. (i) CH3MgI (ii) H3O+
    5. PBr3
    6. (i) BH3 (ii) H2O2
    7. CH3CH2O-/CH3CH2OH
    8. H2O/H+
    9. OH-/H2O
    10. (i) O3 (ii) Zn
    11. NaBH4
    12. HCl
    13. KI
    14. Na
    15. CH3CH2Br

    Please enter the reagent number (from the above list) for each of the two steps in the following synthesis:
    Step 1:
    Step 2:

    CH3-C(OH)-CH3 ->(Step1) ->(Step2) CH2O + CH3CHO

    Thank you so much For help
    Hello,

    Okay.. let's see what we can figure out here...

    In the first example you have a secondary alcohol and in the product you have an ether.
    You need to take note of 2 things....
    1. You need a non nucleophillic base to deprotonate the alcohol....
    The reason you need a non nucleophillic base is related to equilibrium.. can you tell me why? If you need help answering that let me know.. but it will be important when you want to answer more of these questions in the future...
    hint: you have 2 really good choices for that above...

    2. You then need to add the appropriate length carbon chain when making your ether.. hint: there is only one option for this above.. and alkyl halides are most commonly used for this...
    Can you tell me why? If you can't please don't hesitate to ask this is also very important for you to know...

    Now for the second problem...

    1. First you need to dehydrate your secondary alcohol...
    can you remember any good reagents for this? Think of the mechanism... and the
    reaction energy coordinate diagram..
    You'll need to put energy into this reaction to make it go...
    hint: you have only one good choice for this listed above..

    2. You'll need to do an oxidative cleavage... you have 2 options for this listed above....
    hint: KmnO4 and O3/ZN are you choices... one is better than the other..
    do a quick search to determine for yourself.. I'd be happy to verify but the best way to learn organic chemistry is to try these things first yourself....

    hope this helps..
    good luck. : )
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