Aldehydes and Ketones Flashcards
Where is the C=O group on an aldehyde?
The last carbon of a molecule
Where is the C=O group on an ketone?
One of the inner carbons on the chain
How is an aldehyde formed?
Oxidise a 1* alcohol using H+/K2Cr2O7 and distill
How is a ketone formed?
Oxidise a 2* alcohol using H+/K2Cr2O7
Give two tests for an aldehyde
Tollen’s reagent (ammonical silver nitrate) forms a silver mirror
Fehling’s solution turns brick red
What is the test for a carbonyl group?
2,4 DNPH, a yellow/orange ppt forms when an aldehyde or ketone is present
How is an aldehyde reduced?
Add NaBH4, a 1* alcohol is formed
How is a ketone reduced?
Add NaBH4, a 2* alcohol is formed
Why are aldehydes and ketones prone to nucleophilic attack?
The C=O bond group is polar with a large difference in electronegativity
What reaction occurs between HCN and an aldehyde?
Nucleophilic addition occurs
This is useful because it lengthens the carbon chain
Why do aldehydes and ketones have a higher BP than alkanes?
They have both VDW and dipole-dipole forces since the bond is polar
What is the test for a methyl ketone or an alcohol that can be oxidised to a methyl ketone?
Add I2 and NaOH(aq) a yellow ppt forms
