Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hi really need some insight into identifying these compounds.
    You are given NaOH, H2SO4 and both blue and red litmus paper. How do you determine between ethylbenzene carboxylate and benzenecarbonitrile?
    Thanks in advance
    • Community Assistant
    • Study Helper
    Offline

    17
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by Jjones97)
    Hi really need some insight into identifying these compounds.
    You are given NaOH, H2SO4 and both blue and red litmus paper. How do you determine between ethylbenzene carboxylate and benzenecarbonitrile?
    Thanks in advance
    The only thing that occurs to me is to heat the unknown compound in excess with NaOH.

    The ethylbenzene carboxylate will be hydrolysed giving an acid/alcohol pair, which will be acidic. If the organic is in excess this will ensure the reaction of all NaOH. This should then register acidic with blue litmus.

    If they are both then heated (again in excess) with H2SO4 the nitrile will be hydrolysed to a carboxylic acid (via the amide) and so will the ester.
    Offline

    2
    ReputationRep:
    (Original post by charco)
    The only thing that occurs to me is to heat the unknown compound in excess with NaOH.

    The ethylbenzene carboxylate will be hydrolysed giving an acid/alcohol pair, which will be acidic. If the organic is in excess this will ensure the reaction of all NaOH. This should then register acidic with blue litmus.

    If they are both then heated (again in excess) with H2SO4 the nitrile will be hydrolysed to a carboxylic acid (via the amide) and so will the ester.
    Hi Charco!

    I agree that the nitrile will become a carboxylic acid if refluxed with H2SO4. But what do you mean, 'via the amide'? Please could you explain this to me? I'd really appreciate it if you could!

    Secondly, I think that if the ester is hydrolysed under alkaline conditions (i.e. With NaOH) it forms the alcohol and carboxylate (not carboxylic acid). The alcohol and carboxylic acid is formed from acidic hydrolysis of esters. Do you agree?

    Thanks in advance!
    • Community Assistant
    • Study Helper
    Offline

    17
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by jasminetwine)
    Hi Charco!

    I agree that the nitrile will become a carboxylic acid if refluxed with H2SO4. But what do you mean, 'via the amide'? Please could you explain this to me? I'd really appreciate it if you could!
    RCN -- H2O --> RCONH2 -- H2O --> RCOOH


    Secondly, I think that if the ester is hydrolysed under alkaline conditions (i.e. With NaOH) it forms the alcohol and carboxylate (not carboxylic acid). The alcohol and carboxylic acid is formed from acidic hydrolysis of esters. Do you agree?

    Thanks in advance!
    Yes, while there is NaOH in the mix, but as soon as it has all reacted any further hydrolysis must make the acid.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 24, 2016

1,681

students online now

800,000+

Exam discussions

Find your exam discussion here

Poll
Should universities take a stronger line on drugs?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.