Chemical tests AQA A LEVEL CHEMISTRY

How would i distinguish between a secondary alcohol and a aldehyde?

Reply 1

How would i distinguish between a secondary alcohol and a aldehyde?

Secondary alcohol has OH attached to a Carbon, which is bound to 2 alkyl groups.

Aldehyde is C=O at end of molecule.
Ketone has C=O not at the end.

An alcohol can partially oxidise with H+, Cr2O7 orange to green

(edited 1 year ago)

Reply 2

EthanGolin

Original post by BankaiGintoki

Secondary alcohol has OH attached to a Carbon, which is bound to 2 alkyl groups.
Aldehyde is C=O at end of molecule.
Ketone has C=O not at the end.

nah i mean like what chemical test can i use to distinguish between the two

Reply 3

BankaiGintoki

I have a long winded way.
Go from alcohol to alkene using reflux and concentrated H3PO4. Then test for alkene using BR2, should go from orange to colourless. [aldehyde wont go to alkene]

(edited 1 year ago)

Reply 4

UtterlyUseless69

Original post by EthanGolin

How would i distinguish between a secondary alcohol and a aldehyde?

Keep it simple - just do Tollen’s test with ammoniated silver nitrate. The aldehyde will give a silver mirror, the 2° alcohol will just sit there and do nothing. No need for anything sophisticated

(edited 1 year ago)

Reply 5

EthanGolin

Original post by UtterlyUseless69

Keep it simple - just do Tollen’s test with ammoniated silver nitrate. The aldehyde will give a silver mirror, the 2° alcohol will just sit there and do nothing. No need for anything sophisticated