The Student Room Group

AQA question

Which one of the following pairs reacts to form an organic product with only 2 singlets in its proton n.m.r. spectrum?
A ethene and bromine
B propan-2-ol and acidified potassium dichromate(VI)
C ethanol and concentrated sulphuric acid
D epoxyethane and water in the presence of dilute sulphuric acid

The mark scheme states the answer is D - epoxyethane..
From what i understand , epoxyethane reacting with water in the presence of dilute sulphuric acid produces ethane-1,2-diol, which doesn't have any singlets since both of the neighbouring carbons have 2 hydorgens attached each??
Original post by Chelsea12345
Which one of the following pairs reacts to form an organic product with only 2 singlets in its proton n.m.r. spectrum?
A ethene and bromine
B propan-2-ol and acidified potassium dichromate(VI)
C ethanol and concentrated sulphuric acid
D epoxyethane and water in the presence of dilute sulphuric acid

The mark scheme states the answer is D - epoxyethane..
From what i understand , epoxyethane reacting with water in the presence of dilute sulphuric acid produces ethane-1,2-diol, which doesn't have any singlets since both of the neighbouring carbons have 2 hydorgens attached each??


Both CH2 groups are in the same chemical environment and all of the hydrogens produce the same signal, i.e. a singlet.
The other singlet is formed by the two (again chemically identical environments) OH groups
Original post by charco
Both CH2 groups are in the same chemical environment and all of the hydrogens produce the same signal, i.e. a singlet.
The other singlet is formed by the two (again chemically identical environments) OH groups


Hi,
thankyou for the reply - I understand the bit about the OH group producing a singlet now but i'm still unsure about why the CH2 groups produce a singlet? Isn't a singlet formed when there are no hydrogens on the adjacent carbons- in this case there are still 2 hydrogens?
Original post by Chelsea12345
Hi,
thankyou for the reply - I understand the bit about the OH group producing a singlet now but i'm still unsure about why the CH2 groups produce a singlet? Isn't a singlet formed when there are no hydrogens on the adjacent carbons- in this case there are still 2 hydrogens?


singlets are formed when all of the protons are in the same environment and there are no adjacent protons in a different environment.

Benzene, C6H6 displays a six proton singlet.

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