3.3.7: Oxidising alcohols

Question 1

Carbonyl compounds
examples 2
general formula
FG

Answer 1

Aldehydes and ketones
CnH2nO
C=O

Question 2

Aldehyde

Answer 2

Functional group (C=O) always on carbon 1

Question 3

Ketone

Answer 3

Two alkyl groups attached to carbonyl carbon atom

Question 4

Carboxylic acids

Answer 4

COOH function group and general formula: CnH2n1+1COOH

Question 5

How to mildly oxidise primary and secondary alcohols?

Answer 5

Acidified (w/ H2SO4) potassium dichromate (VI)
K2Cr2O7
gently heated with ethanol.

Question 6

Primary alcohol oxidised to? > ?

Answer 6

firstly an aldehyde then a carboxylic acid

Question 7

Oxidising primary alcohols to carboxylic acids

Answer 7

mix w/ excess oxidising agent and heat under reflux

Question 8

Secondary alcohol oxidised to ?

Answer 8

Ketone

Question 9

Oxidising tertiary alcohols

Answer 9

don’t react with acidified potassium dichromate (solution stays orange)
so need to burn them

Question 10

Testing for aldehydes and ketones

Answer 10

Fehlings’
Benedict’s
Tollens’

Question 11

Result for tollens’ reagent with Ketones or aldehydes

Answer 11

silver mirror w/ an aldehyde

remains colourless w/ a ketone

Question 12

Result for fehlings/ benedicts with aldehydes and ketones

Answer 12

both deep blue
reduce to a brick red precipitate when warmed with an aldehyde
no change w/ a ketone