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Organic chemistry tests

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
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.
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!
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.

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