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carboxylic acid ---> aldehyde???

Discussion in 'DAT Discussions' started by Mstoothlady2012, Aug 12, 2007.

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  1. Mstoothlady2012

    Mstoothlady2012

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    Hi guys!

    I was wondering if any1 is familiar with reduction of carboxylic acid to aldehyde? I have never heard that before. I searched through Mcmurry book & destroyer but I cant find a single example. Its eating my head now! If some1 can give me reaction name or an example with reagents would be awesome! Its realted to achiever SNS 2 - # 100

    Thanks!
  2. sacjumpman

    sacjumpman

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    Damn. I should know this.... using Lindlar's catalyst or quinone or something rings a bell in order to "poison" the rxn and stop it from reducing all the way down to the primary alcohol. I thought I remembered something like that.

    But what was the reducing agent?? if/when I find it today, I'll let you know...damn damn damn
  3. sacjumpman

    sacjumpman

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    Oh yeah, and it probably sounds like I"m thinking of reducing alkynes down to alkenes, but I'm not.

    It just sounded familar to that...
  4. sacjumpman

    sacjumpman

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  5. sacjumpman

    sacjumpman

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    mstooth, are you sure it exists? I don't have achiever in front of me, so I don't know about #100....

    No google results, no destroyer.... maybe it is not a rxn...
  6. Mstoothlady2012

    Mstoothlady2012

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    this is what the question says

    carboxylic acids will not undergo...

    3 out of 5 choices are definitely wrong...1 is 100% wrong 1 i think is 50/50...

    I chose the first option- will not undergo reduction to form aldehydes & alcohols - which is 50/50 ...it under goes reduction to alcohol..but aldehyde?how the heck?

    correct ans - formation of imines with hydrazines - ketones do these but i got so excited by reading first choice...that didnt even read the other ones carefully.

    As far as i know there is no way you can reduce carboxylic acid to aldehyde. Yes you can convert derivative of carboxylic acid (ester) to aldehyde by reduction (1. DIBAH, toluene 2. H30+)

    If you can find it then it would be great...but dont bother yourself much! I gave up! i searched couldnt find it...so i will move on ahh:rolleyes:
  7. fancymylotus

    fancymylotus princess

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    Kaplan says that aldehyde intermediates are reduced down to alcohols in the process of reducing COOH-->OH with LAH.
  8. Mstoothlady2012

    Mstoothlady2012

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    yea thats true ..but it is so reactive that it doesnt stop at aldehyde ...then how is that considered a reaction?

    http://www.chemguide.co.uk/organicprops/acids/reduction.html

    Thanks for trying though!:)
  9. Lonely Sol

    Lonely Sol cowgoesmoo fan!

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    The only think that i can think of right off the bat is:

    _________1.h2/pd
    Ch3COOH------------------>CH3CHO
    _________2. PCC
  10. Mstoothlady2012

    Mstoothlady2012

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    yes but is that called reduction?
  11. hrndawg

    hrndawg

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    I just took that test and i was coming on to post this exact question! Well im happy everyone's on the case...ill go look in my text book.
  12. DDSelin2mori

    DDSelin2mori

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    Carboxylic acids can't react with H2/pd. i looked it up in my ochem class notes. From these notes LIAL[oc(ch3)3]3 is a weaker reducer compare to LiAh4. And it can reduce acyl halide to aldehyde. It can have same affect on carboxylic acids!( I'm not sure about that it's just a guess!)
  13. DDSelin2mori

    DDSelin2mori

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    I found this on the web “Partial reduction of carboxylic acids directly to aldehydes is not possible, but such conversions have been achieved in two steps by way of certain carboxyl derivatives.”

    http://www.freepatentsonline.com/6441246.html

    And also” these cyclic diaminoaluminum hydrides appear to be the reagents of choice for converting aromatic carboxylic acids to the corresponding aldehydes”

    From : journal.kcsnet.or.kr/main/j_search/ j_download.htm?code=B020935

    I think you don't need to know the mechanism for DAT. Just know that it is possible!!
  14. HeatingHomer

    HeatingHomer Member

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    Destroyer orgo #100 seems to imply that aldehydes cannot be derived from carboxylic acids.
  15. poc91nc

    poc91nc

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    I don't think a carboxy acid can be converted into an aldehyde in ONE step...but...it can be done in TWO steps...

    RCOOH ====> RCOCl =====> RCOH

    The second step just uses LiAlH(tert-butoxide)3
  16. mynamemule

    mynamemule

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    I think u have to have go to a acid halide first.
  17. Mstoothlady2012

    Mstoothlady2012

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    guys this is not a synthesis question....the question particularly says that carboxylic can be REDUCED (not synthesis) to aldehyde and alcohols...which i think is wrong.
  18. Mstoothlady2012

    Mstoothlady2012

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    thanks! that is the best that I have found the whole day. I guess i will just go with that, eventhough it doesnt provide any reagents or mechanism ah! its ok thanks again
  19. luckyluke2000

    luckyluke2000

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    r-cooh -->(LiAlH4; reduces carboxylic acid to alcohol) r-c-oh -->(PCC;weaker oxidizing agent,makes alcohol an aldehyde if primary alcohol)-->r-c=0 with a hydrogen off carbon.
    is this possible? thanks luke
  20. quocstazz

    quocstazz

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    Turn carboxylic acid into acid chloride, react with ethanol to form an ester, then use DIBAH.

    Dibah turns ester into aldehyde
  21. ktran17

    ktran17

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    Here you go, I used DIBAL-H a lot in ochem b =)

    "Esters or carboxylic acids can be either be reduced to their aldehydes with one equivalent of DIBAL-H or to their alcohols with two equivalents of DIBAL-H"
    This sentence can be found under the paragraph "Versatile Reducing Agent"

    Here's a source just for those non-believers ;D http://www.akzonobel.com/polymer/sy...luminum_hydride_ma_row_eng_tb_tcm96-16226.pdf

    Just realized this is an old thread fml =)
  22. Happyfaace

    Happyfaace

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    Ktran17 is absolutely right!

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