IMAT 2014 Q46 [Oxidising Ethene]

The following are some compounds that can be made from ethene, C_2H_4:

C_2H_6, C_2H_5Br, C_2H_5OH, CH_2BrCH_2Br, ­-(CH_2CH_2)_{n-}

Which one of the compounds is made by oxidising ethene?

A. ­-(CH_2CH_2)_{n-}
B. C_2H_5Br
C. C_2H_5OH
D. CH_2BrCH_2Br
E. C_2H_6

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We know that oxidation is the loss of electrons. And so in this process, ethene must lose electrons from it’s double bond. The double bond breaks, and the electrons lost will be donated to willing ‘acceptors’. Usually, these ‘acceptors’ are halogens.

An example to be recalled here, could be the reaction of ethene and bromine to give 1,2 dibromoethane. This is known as an addition reaction.

Our answer is therefore D, since CH_2BrCH_2Br is formed when ethene reacts with bromine. First losing it’s double bond, then undergoing a substitution reaction.


Can you explain why B is incorrect?
B also has Br (halogen)…
What is the difference between B and D?

Addition reaction with Hydrogen halide will not oxidize alkene.
Addition reaction of alkene with diatomic bromine will oxidize carbon atoms.


wow excellent.But i perceive that it would be better understanding if you guys follow the following routine to solve this problem.

Question indicates that we should find the product of oxidation reaction of ethene(C2H4).Therefore we could acknowledge that it integrates the redox reaction and organic compounds.

For C2H6, the first one we should quickly eliminate, because of the definition of oxidation reaction, the addition of oxygen or removal of hydrogen. Obviously this is the reduction process, the addition of hydrogen.

For C2H5Br, according to the electronegativity trend,Br>C>H we could know the oxidation of each atom in C2H5Br and C2H4 is identical. NO any redox reaction occuring.

For C2H5OH,THE electronegativity trend is O(the 2nd most electronegative)>C>H,and then we could deduce that there is no any redox reaction too.

For CH2BrCH2Br. same as what stated above.


Thank you! It’s really helpful


Hi, could you please confirm if my understanding is correct?

So basically CH2BrCH2Br and C2H5OH, is both oxidised, but since the question asks for product of oxidation reaction, it should be a oxidation-reduction reaction therefore CH2BrCH2Br is the correct answer?

Also, I heard that an addition won’t necessarily lead to oxidation since it’s just the double bond changed to single bonds, can someone confirm this?

hi winter hope my response finds you well.

according to the electronegativity series in ethanol C2H5OH O 3.44>C 2.5 >H 2.2

We should assign negative oxidation state to O first with -2, and then we could work out that the ox. no of H and C are +1 and -2, no oxidation state changes.

therefore there is no any redox reaction occurring. AND we choose D

Oh seems like I made a mistake. Thank you for your kind response.