O3, ozonolysis

Discussion in 'DAT Discussions' started by SpikeyMike83, Jul 23, 2006.

  1. SpikeyMike83

    SpikeyMike83 Senior Member

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    okay, this may just be me being stupid, but I always get confused with 03. In my text book, it says that terminal alkynes result in 1 carboxylic acid and a molecule of CO2.

    on page 372 of the 3rd edition of Kaplan, why does the last problem yield two carboxylic acids?

    I appreciate any help!
     
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  3. dat_student

    dat_student Junior Member

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    I don't have the book. Post the questions plz. :)
     
  4. SgtSadhu

    SgtSadhu Member

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    hey whats going on

    iite for what you were talking about they way i remember it is, when using hot kmno4:

    if their is 1 h on the c=c then it will be a carboxylic acid
    if their are 2 h's on the c=c it will be C02
    if their are 0 h's on teh c=c it will be a ketone

    ex: C-CH=C(CH3)-C -> C-C00H + KETONE

    C-CH=CH2 -> C-COOH + CO2
     
  5. dat_student

    dat_student Junior Member

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    :confused: Would u plz rephrase?
     
  6. SgtSadhu

    SgtSadhu Member

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    chek out the examples i left i dont really know how else to say it lol im sorry


    on the c=c you will have either a Hydrogens or substituents for ex:

    H2C=C(CH32 OR (CH3)HC=CH2 , you get the point

    so if on the C's on the double bond, if there is just 1 hydrogen bonded it will become a -COOH ex: (ch3)HC=CH(Ch3) -> Ch3-COOH + HOOC-C

    if there are 2 H's attached to either of the C's on the double bond, then that C will cleave into Co2 (two H's will be present on a double bond only at the terminal end)
    ex: H2C=CH(CH3) -> CO2 + H00C-C

    if there are no H's on either of the C's on teh double bond, you will get a ketone

    ex: (CH3)2C=C(CH3)2 -> CH3-CO-CH3 + CH3-CO-CH3
     
  7. SpikeyMike83

    SpikeyMike83 Senior Member

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    the reaction from the kaplan book is:

    1-hexyne + 1)O3, CCl4 2) H20 --> pentanoic acid + methanoic acid.

    i thought that because it was a terminal alkyne, you would end up with 1 COOH and 1 CO2.

    Why do you get what Kaplan says, and not the carboxylic acid and carbon dioxide?
     
  8. djeffreyt

    djeffreyt Senior Member

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    Spikey is right...the kaplan book is wrong. If you look up the same reaction online or in any textbook, the products should be a carboxylic acid and a CO2. Ozonolysis of terminal alkynes creates an unstable intermediate known as a carbanoic acid (essentially a carbonyl carbon bound to two -OH groups) which in the presence of water will form H2O and CO2
     
  9. SpikeyMike83

    SpikeyMike83 Senior Member

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    haha, i'm never right! we're sure about this?
     

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