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Synthesis problem - help plss

  1. Mar 15, 2005 #1
    hey

    what is the synthesis of N-ethylethanamide....need the equations

    (begin from the appropriate alkane, and any organic reactant can be used such as HCl, water and so forth)

    thank you!!!
     
  2. jcsd
  3. Mar 15, 2005 #2

    GCT

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    You can retro to find the synthons ethanoyl chloride and ethyl amine and go on from there. There are many possibilities.
     
  4. Mar 16, 2005 #3

    GCT

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    perhaps you can start with pentane and find a way to brominate/chlorinate on the second carbon. Or if you can start with 3-pentene, you can oxidize with permanganate, separate the two components. Transamine the higher boiling point carboxyl and perform a hoffmann degradation, convert the lower boiling point carboxyl to an its acyl chloride. Not quite sure, movies should be able to help you out better with this problem.
     
  5. Mar 17, 2005 #4
    got it?

    hello..

    can u please chk if this might work or how it can be improved

    1) ethane > ethanol > ethanal > ethanoic acid + ammonia = ethanamide >
    ethanamide + ethanol = N-ethylethanamide

    thanks :smile:
     
  6. Mar 17, 2005 #5

    GCT

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    The logic seems a bit fuzzy. First of your proposal is a bit inefficient, you'll lose yield in each step so you should limited the amount of steps or even use them in parallel fashion.

    That is you've got everything in a completely linear/series fashion. For instance, find a way to make ethanoyl chloride and ethyl amine separately, or even more efficiently. I've not nothing at this moment...nothing that comes to mind. For instance, start with propane, halogenate the propane, and oxidize to the carboxylic acid. Separate, trans-acyl one mixture and trans-aminate the other. Perform a hoffman degradation (you should look this up) on the amide mixture, and then subsequently combine the mixtures.

    You should be able to obtain the terminal propanol/oxidized product quite easily (allyl cation).

    [tex]propane \xrightarrow~ chloro-propane \xrightarrow~ propanoic acid [/tex]

    synthon 1
    [tex]propanoic acid \xrightarrow~ethanoyl chloride[/tex]
    synthon 2
    [tex]propanoic acid \xrightarrow~ propanamide \xrightarrow~ ethyl amine[/tex]

    combine the two
    [tex]C2H6C0Cl + C2H5NH2 \xrightarrow~ N-ethylethanamide [/tex]

    There's probably a better way
     
  7. Mar 18, 2005 #6

    chem_tr

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    GCT has gone a long way, I too think that starting with ethane and applying photochemical irradiation to get ethyl bromide, which will either by hydrolyzed to give ethanol (to acetic acid) or treated with cyanide and hydrolyzed to give acetic acid. This can be further treated with thionyl chloride to give acetyl chloride, which will then be reacted with ethylamine to give the product you need.

    Ethylamine can be prepared from already synthesized ethyl bromide and ammonia, by employing a much more amount of ammonia, or as GCT said, a Hoffmann degradation would be much more convenient from propionamide (propyl chloride+ammonia-->ethylamide).

    My post became the repeating of GCT's first post, so I'm saying I agree with him.
     
  8. Mar 18, 2005 #7
    i agree...but im not allowed to use Hoffmann degradation or "trans-acyl one mixture and trans-aminate the other."

    im only allowed to use halogenation, hydration, hydrohalogenation, addition, substitution, and combustion...just the basic stuff...im sry i didnt mention it before

    so..if u guys want to re-evaluate your/my method or think of other possibilities..

    thanks a bunch ppl
     
    Last edited: Mar 18, 2005
  9. Mar 19, 2005 #8

    GCT

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    Hi,

    you've got some pretty strict limitations here. Well, I can give you a general sugestion at the moment. I'll reply later if I come up with better suggestions.

    First,


    ethane--->chloro-ethane--->ethene-->addition to 1,2 chloro-ethene--->ethyne--->acetaldehyde--->alpha-bromo-acetaldehyde--->propanal

    For ethyl amine

    -Brominate ethane, and simply add ammonia under proper conditions.

    Final step

    You'll probably have to modify the propanal, anyways, you can combine the propanal derivative with the ethyl amine through nucloephilic substitution to obtain you final product.

    I'll have to do some research on this. This is probably not the best way
     
    Last edited: Mar 19, 2005
  10. Mar 19, 2005 #9

    GCT

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    halogenation of alkane, elimination, addition to alkene, elimination, hydration of alkyne (using mercury derivative), halogenation, SN2 substitution

    Some of the steps have some regioselective issues associated with it, other's in this forum will probably be able to help you out on the specifics, if a better proposal is not suggested.
     
  11. Mar 19, 2005 #10

    GCT

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    The following is much simpler,however a bit outside the measures you specified.

    ethane--->bromo-ethane--->CN-Et--->propanoic acid

    You can obtain ethyl amine from either bromo-ethane or CN-Et

    propanoic acid and ethyl amine--->N-ethylethanamide
     
  12. Mar 20, 2005 #11

    GCT

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    halogenation of an alkane, SN2 substitution with CN- as the nucleophile, hydrolysis of the nitrile
     
  13. Mar 21, 2005 #12
    hello tutor..

    thanku for ur help...ive got it!
     
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