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Just a couple of quick organic synthesis questions... thanks in advance watch

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    What is the reaction, reagents and conditions specifically to get from a carboxylic acid to an aldehyde. Also, how do you get DIRECTLY FROM nitriles to amides, and from amides to nitriles.... again please can yoiu make sure you state all the conditions, reagents and type of reactions if possible. Thanks in advance and I will rep for the person who gives me the best help!
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    I'm not aware of any reagent capable of partially reducing a carboxyl in this manner. However, it's a reasonably straightforward business to carry out a reduction to the alcohol (Pd catalyst and hydrogen,) followed by a partial oxidation to the carbonyl (Pyridinium chlorochromate - CrO3, HCl and pyridine.)

    The Ritter reaction is the only one I can think of to go from a nitrile to an amide directly, but it's not that general:

    http://en.wikipedia.org/wiki/Ritter_reaction

    Here's some nice catalytic chemistry for the last bit:

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1444911/
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    (Original post by resortini)
    What is the reaction, reagents and conditions specifically to get from a carboxylic acid to an aldehyde. Also, how do you get DIRECTLY FROM nitriles to amides, and from amides to nitriles.... again please can yoiu make sure you state all the conditions, reagents and type of reactions if possible. Thanks in advance and I will rep for the person who gives me the best help!
    you can use DIBAL, it is short for diisobutyl aluminium hydride, it is strong enough to reduce carbonyl but will only stop at aldehyde. nice and easy!

    nitrile to amides can go via nitrile -> amine -> amide, first step is to reduce with LiAlH4, then react with activated carnonyl like alkanoyl halide
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    As mentioned above, DIBAL is the simplest way of going straight from a carboxylic acid to an aldehyde, but it's also important that this reaction is done at -78 degrees celsius (dry ice / actone bath) to stop the reaction going right through to the primary alcohol.

    As for going from nitrile to amide, an easy method I've had a fair amount of success with a couple of weeks ago was to use aqueous sodium hydroxide and hydrogen peroxide. This takes you to primary amides (i.e. not substituted on the nitrogen). This works best with large groups attached to the carbonyl carbon, such as a benzene ring, otherwise the unhindered amide is susceptible to hydrolysis from leftover OH- ions and take you down to a primary amine.
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    reduction using NaBH4 to get from carboxylic to aldehyde

    And to get from nitrille to amide add H2 with a Nickel catalyst
    then react this amine with an acyl chloride to get amide
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    Hey, thanks for the reply, bear in mind I'm doing an AQA A2 exam, so that might not be in the syllabus (the thing you mentioned), how about NaBH4 to reduce carboxylic acids to aldehydes? and I am sure I heard somewhere you can convert nitriles to amides, and the converse, but hoe exactly (what would I be required to know for the syllabus, there is no mention of it in my book so maybe I won't get asked that, but I would like to know just in case!)
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    (Original post by operationx-ray)
    reduction using NaBH4 to get from carboxylic to aldehyde

    Not selective enough, you would get some alcohol too. Organic chemists tend to want to maximise yield of intended product.

    And to get from nitrille to amide add H2 with a Nickel catalyst
    then react this amine with an acyl chloride to get amide
    H2 with Ni catalyst is simple hydrogenation which most probably won't work on nitrile. there is another catalytic hydrogenation of nitrile using iridium complex of COD(cyclooctadiene). Hydrolysis would be easier and perhaps a cheaper option, maybe.
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    (Original post by shengoc)
    H2 with Ni catalyst is simple hydrogenation which most probably won't work on nitrile. there is another catalytic hydrogenation of nitrile using iridium complex of COD(cyclooctadiene). Hydrolysis would be easier and perhaps a cheaper option, maybe.
    yo, so the bit that guy wrote in red is fine (what conditions exactly, if you know what I mean, this is a reduction obviously (used in warm aqueous ethanol?),
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    (Original post by resortini)
    yo, so the bit that guy wrote in red is fine (what conditions exactly, if you know what I mean, this is a reduction obviously (used in warm aqueous ethanol?),
    you should consult your teacher about the exact reagents your syllabus requires you, a lot of stuff in uni is not within mark schemes, ie there are more than one ways to synthesize your product.

    I am still sticking with DIBAL - H at -78 degree C, for i see that as the most efficient way of reducing acid to aldehyde.

    NaBH4 won't work, I just realised that COOH are pretty inert. Please read the link.

    http://www.chemguide.co.uk/organicpr...reduction.html
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    (Original post by shengoc)
    you should consult your teacher about the exact reagents your syllabus requires you, a lot of stuff in uni is not within mark schemes, ie there are more than one ways to synthesize your product.

    I am still sticking with DIBAL - H at -78 degree C, for i see that as the most efficient way of reducing acid to aldehyde.

    NaBH4 won't work, I just realised that COOH are pretty inert. Please read the link.

    http://www.chemguide.co.uk/organicpr...reduction.html
    Thank you, bit late considering my exam is Wednesday and I am study leave lol.... anyway, on my sheet it says NaBH4, but obviously I share a similar view to yourself, that's why I'm questioning it lol.
 
 
 
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