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Homework Help: Esters' high boiling point

  1. Oct 22, 2016 #1
    • You have to show your attempts at answering the question, this is a forum policy. Also, all homework like questions should go to homework forum.
    Why does 3-methylbutyl ethanoate have a higher boiling point than 3-methylbutan-1-ol and ethanoic acid?

    Attempt at a solution: I know that the ester has a marginally greater molar mass but I wasn't sure if this is the only deciding factor, particularly considering the strength of the other interaction forces between alcohol and carboxylic acid molecules.
    Last edited: Oct 22, 2016
  2. jcsd
  3. Oct 22, 2016 #2
    I cant give you the exact answer because of the rules but I can tell you this...it has something to do with intermolecular forces of attraction and this link may help you.
  4. Oct 22, 2016 #3
    I understand that intermolecular forces of attraction are stronger in alcohol and carboxylic acid but it doesn't make sense then that the ester would have a higher boiling point?
  5. Oct 22, 2016 #4
    The intermolecular forces do not depend entirely on the ability of a molecule to make hydrogen bonds.
  6. Oct 22, 2016 #5
    So would I be correct in saying that the ester's boiling point is slightly higher due to its larger molar mass?
  7. Oct 22, 2016 #6
    Yes :)...and remember this 3-methylbutyl ethanoate has a higher density than both ethanoic acid and 3-methylbutyl-1-ol, thus it is easy to say it will have a higher b.p cause of that and beacuse the induced dipole-induced dipole forces are greater.
  8. Oct 22, 2016 #7
    Hm... let´s compare various simple compounds with 6 heavy atoms.
    Hexane, C6H14: n-hexane 69 degrees, isomers less, down to neohexane, 50 degrees.
    Pentanols, C5OH12: 1-pentanol 138 degrees, isomers less, down to tertiary pentanol, 102 degrees.
    Ethers C5OH12: methyl tert-buthyl ether 55 degrees
    Aldehydes C5OH10: n-pentanal 102 degrees
    Ketones C5OH10: 2-pentanone 102 degrees, 3-methyl-2-butanone 92 degrees, 3-pentanone 101 degrees
    Acids C4O2H8: n-butyric acid 164 degrees, isobutyric acid 155 degrees
    Esters C4O2H8: ethyl acetate 77 degrees
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