Oxidation Of Alcohols Flashcards
What do primary alcohols oxidise to
Aldehydes then oxidise further to carboxylic acids
What do secondary alcohols oxidise to
Ketones
Do tertiary alcohols oxidise and why
They do not as resistant to oxidation due to lack of hydrogen atoms on the carbon atom to which the hydroxyl group is attached, they do not have hydrogen on C-OH carbon but have a C-C bond to break so needs a stronger oxidising agent
What is aldehyde functional group and how to name
CHO with double bond between carbon and oxygen at terminal carbon, ends in anal
What is carboxylic acid functional group and how to name
COOH anoic acid
What is ketone functional group and how to name
C double bonded to O (carbonyl group) on any carbon other than terminal, ends in anone
How to oxidise primary alcohols to form aldehydes
Using an oxidising agent eg aqueous solution of acidified potassium dichromate, heat and distill immediately to prevent further oxidation to carboxylic acid
Equation for oxidation of primary alcohols to aldehydes
RCH2OH + [O] ——> RCHO(anal) + H2O
Half equation of oxidation of ethanol primary to form aldehyde
CH3CH2OH ——> CH3CHO + 2H+ + 2e-
Formula for oxidising agent and its colour change
K2Cr2O7 turns from orange to green when reduced
Conditions for full oxidation of primary alcohol to form carboxylic acid
-heat under reflux(prevents aldehyde from escaping before fully oxidising) with excess acidified oxidising agent potassium dichromate
Conditions for oxidation of secondary alcohols to form ketones
-oxidised by oxidising agent eg aqueous solution of acidified potassium dichromate and heat under reflux to prevent escape of volatile compounds and increase yield
How to distinguish between primary and secondary alcohols
-to distinguish between aldehydes and ketones
-using blue Fehling’s reagent and warm, they have Cu2+ ions that form a red-brown precipitate if an aldehyde present but no change with ketone
Conditions for dehydration of alcohols
-heat with excess concentrated phosphoric acid
Equation for dehydration of alcohols
Alcohol to alkene and steam
