Iodoform Question
Watch this thread
Announcements
Page 1 of 1
Skip to page:
Dennizun_win
Badges:
1
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
The question is from Q5 Section A of Unit 4 June 2016 Edexcel GCE Chemistry. The question is attached, and apparently the answer to part (c) is D. Can someone explain why both W and Z produce iodoform when reacting with iodine in alkaline solution? I thought the iodoform test gives a positive result when the functional group CH3COR was present, i.e. all ethyl ketones and ethanal. Surely Z should not give a positive result as it doesn't even have a C=O group, let alone the CH3COR functional group.
0
reply
tony_dolby
Badges:
10
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report
#2
I am digging in to the dim and distant past (why do exam boards expect people to know such out-dated reactions!), but seem to remember that many secondary alcohols give a positive iodoform test. This would explain why Z is positive. W is expected because it is a ketone. X is an aldehyde, but you are right, the only aldehyde that gives a positive test is ethanal. Y is a primary alcohol, so it won't give a positive test (only ethanol works).
http://www.chemguide.co.uk/organicpr.../iodoform.html
http://www.chemguide.co.uk/organicpr.../iodoform.html
1
reply
Dennizun_win
Badges:
1
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
(Original post by tony_dolby)
I am digging in to the dim and distant past (why do exam boards expect people to know such out-dated reactions!), but seem to remember that many secondary alcohols give a positive iodoform test. This would explain why Z is positive. W is expected because it is a ketone. X is an aldehyde, but you are right, the only aldehyde that gives a positive test is ethanal. Y is a primary alcohol, so it won't give a positive test (only ethanol works).
http://www.chemguide.co.uk/organicpr.../iodoform.html
I am digging in to the dim and distant past (why do exam boards expect people to know such out-dated reactions!), but seem to remember that many secondary alcohols give a positive iodoform test. This would explain why Z is positive. W is expected because it is a ketone. X is an aldehyde, but you are right, the only aldehyde that gives a positive test is ethanal. Y is a primary alcohol, so it won't give a positive test (only ethanol works).
http://www.chemguide.co.uk/organicpr.../iodoform.html
0
reply
X
Page 1 of 1
Skip to page:
Quick Reply
Back
to top
to top