Organic Chemistry 2 Flashcards
7What group do aldehyde and ketone contain?
A carbonyl group
Why can’t aldehyde and ketone form hydrogen bonds with each other?
Because they don’t have a polar O-H bond
Can aldehyde and ketone hydrogen bond with water?
Yes, because although they don’t have polar OH groups, they have a lone pair of electrons on the O of the C=O group
How can you test for an aldehyde with tollen’s reagent?
- Tollens reagent is a colourless solution of silver nitrate dissolved in aqueous ammonia.
- If it’s heated in a test tube with an aldehyde, a silver mirror forms after a few minutes
What is the colour change when you heat an aldehyde with acidification potassium dichromate ions?
Colour change from orange to green
What can an aldehyde be reduced back to?
A primary alcohol
What reducing agent is needed for the reduction of an aldehyde to a primary alcohol?
LiAlH4 in dry ether ([H])
What can a ketone be reduced to?
A secondary alcohol
What type of reaction is the reduction of an aldehyde to a primary alcohol?
A nucleophillic addition reaction
What does hydrogen cyanide react with carbonyl compounds to give?
Hydroxynitriles
What are hydroxynitriles?
Molecules with a CN and an OH group
What type of reaction is the reaction between hydrogen cyanide and carbonyls?
Nucleophilic addition
Draw the mechanism for the reaction between hydrogen cyanide and a carbonyl
In book
How do you test for a carbonyl group using 2,4-DNPH?
-The 2,4-DNPH is dissolved in methanol and conc sulfuric acid.
- It reacts to form a bright orange precipitate of a carbonyl group
Which type of carbonyl react with iodine?
Those that contain a methyl carbonyl group
What happens when carbonyl with a methyl carbonate group react with iodine?
You get a yellow precipitate of CHI3 and an antiseptic smell
RCOCH3 + 3I2 + 4OH- ->
RCOO- + CHI3 + 3I- + 3H20
What can form with pure liquid carboxylic acids ?
Dimers
What is formed when you hydrolyse a nitrile?
A carboxylic acid and an ammonium chloride
How do you hydrolyse a nitrile?
- You reflux the nitrile with dilute HCl and then distilling of the carboxylic acid
CH3C=N + 2H20 + HCl ->
CH3COOH + NH4Cl
What happens when carboxylic acid reacts with a base?
A salt and water is formed
What happens when a carboxylic acid reacts with carbonate or hydrogencarbonate ions?
A salt, water and CO2 are formed
CH3COOH + NaOH ->
CH3COONa + H2O
2CH3COOH + Na2CO3 ->
2CH3COONa + H20 + CO2
CH3COOH + NaHCO3 ->
CH3COONa + H20 + CO2
What is used to reduce carboxylic acid to a primary alcohol?
The powerful reducing agent LiAlH4 in dry ether
What do you get when you react a carboxylic acid with PCl5?
An acyl chloride, POCl3 + HCl
RCOOH + PCl5 ->
RCOCL + POCL3 + HCL
What is the functional group of an ester?
COO
What does the name of the ester come frome?
- The first part of the name comes from the alcohol
- The second part of thr name comes from the carboxylic acid
Carboxylic acid + alcohol->
(In presence of an acid catalyst)
Ester and water
What type of reaction is esterification?
A condensation reaction
What happens in base hydrolysis of an ester ?
The ester is refluxed with a dilute alkali such as sodium hydroxide. A carboxylate ion and an alcohol are produced
What is the functional group of acyl chlorides?
COCl
Ethanoyl chloride + water ->
Ethanoic acid
Ethanol chloride + methanol ->
Methyl ethanoate + HCl
Ethanoyl chloride + Concentrated ammonia->
Ethanamide + HCl
Ethanoyl chloride + methylamine ->
N-methlyethanamide
Acyl chloride + water ->
Carboxylic acid
Acyl chloride + alcohol->
Ester + HCl
Acyl chloride + concentrated ammonia ->
Ethanamide + HCl
Acyl chloride + amine->
N-methly ethanamide
