First worked example: N2007/II/5

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Due to copyright issues, I cannot put up the question online. So i will refer to the question using the standard notation. E.g N2004/II/5a refers to the Nov 2004 Paper II Question 5a

First worked example : N2007/II/5

Look at the different compounds and identify functional groups present in each compound

Compound A contains the alkene functional group and aldehyde functional group

Compound B contains the alkene and ester linkage functional group. Be aware that the ester functional group OCO is different from the carbonyl functional group C=O

Compound C contains the alcohol(phenol) and alkene functional group

Compound D contains the alkene functional group

5a)
the reagent given is a acyl chloride

acyl chloride + alcohol --> ester + HCl

I still haven figure out the best way to draw structural formula and upload online. Once i think of something i will upload the structural formula

Ans: C


dilute HNO3 is able to catalyze the hydrolysis of esters

Esters are hydrolyzed to give carboxylic acids and alcohol

Ans: B

Na is able to react with phenol functional group to form the phenoxide ion

Ans: C

Tollen's reagent is actually an oxidizing agent which can oxidize aldehydes to carboxylic acid. However the reagent is alkaline hence the carboxylate ion is formed. Just be careful when you draw the structural formula.

Ans: A

5bi)
As mentioned earlier compound C has 2 functional groups: the alkene and phenol functional group. Only the alkene functional group will react with Br(aq) . Thus Br and OH will be added across the double bond

5bii)
reflux with hot concentrated acidified manganate will result in the oxidative cleavage of the double bond
As a result 2 carboxylic acids will be formed

5ci)

Pardon my bad drawing. Basically the aldehyde is being reduced to a primary alcohol


5cii)
Stage I
reagent: LiAlH4
Conditions: organic solvent, heat

StageII
reagent: ethanoic acid
Condition: dil HCl, heat

Ok this is the end of the first worked example. Please feel free to leave comments.

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