Aldehydes And Ketones Flashcards
What group do aldehydes and ketones contain?
Carbonyl group
Aldehydes and ketones
•Both contain a carbonyl group •Carbonyl group in aldehyde has a hydrogen atom attached- the aldehyde functional group occurs at the end of the carbon chain •In ketones- carbonyl group is located between two of the carbon atoms within the chain
Carbonyl functional group
.
Acetylaldehyde(ethanol)
.
Propionaldehyde(propanal)
.
Acetone( 2-propanone)
.
Cinnamaldehyde
.
Vanillin
.
Formaldehyde
.
benzaldehyde
.
Nucleophillic Reaction of propanal
.
Nucleophillic reaction of acetone
.
Idoform Test for methyl Ketone
.
fellings solution reaction
Tollens reagent in silver mirror test
Names of aldehydes end in
Al
Names of ketones end in
One
Bonding in the carbonyl group
•Oxygen In carbon to oxygen bond far more electronegative •One of the two pairs of electrons that make up carbon to oxygen double bond even more easily pulled towards the oxygen- double bond very polar
One Physical property of aldehydes and ketones
Sharp odor
Most important reaction of ketones and aldehydes
Nucleophillic addition reaction
Nucleophillic addition reaction
The addition of a nucleophile to an electrophillic acceptor
Nucleophile forms new bond to carbonyl group carbon, carbon oxygen double bond breaks, proton bonds to oxygen
Carbonyl group undergoes addition reactions
Nucleophillic addition reaction of propanal
.
Nucleophillic addition reaction of acetone
.
Electrophile
Electrophile is the carbonyl group carbon of the ketone or aldehyde
Nucleophile
Nucleophille- negatively charged ion(cyanide ion CN) or slightly negatively charged part of a molecule(lone pair on a nitrogen atom in ammonia NH3)
Aldehydes and ketones difference
Aldehyde has hydrogen atom attached to carbonyl group Makes aldehydes very easy to oxidise Ketones don’t have the hydrogen and resistant to oxidation except from powerful agents that can break carbon to carbon bonds
Aldehyde and ketone Boiling points
Rise rise as molecules get bigger Size of boiling point governed by strengths of intermolecular forces
Solubility in water
Small aldehydes and ketones soluble Solubility falls with increase in chain length
Oxidation of alcohols to make aldehydes and ketones
Oxidation of primary alcohol=aldehyde Oxidation of secondary alcohol=ketones
Adding of Hydrogen cyanide to carbon-oxygen double bond in aldehydes and ketones produces
Compounds called hydroxynitriles
Iodoform test for methyl ketone- description
Reaction with iodine in a NaOH solution and ketones containing a methyl group attached to the carbonyl Produces solid yellow iodoform-strong medical odor and used as an antiseptic
Aldehydes and ketones are oxidised using
Benedicts or fehlings solution Silver mirror test
Oxidation reaction of aldehydes and ketones
Used to distinguish aldehydes from ketones as ketones can’t be oxidised Blue green cu2+ is reduced for cuprous ion CU+ forming a reddish orange precipitate of Cu2O
Silver mirror test- description
Aldehyde treated with tollens reagent- converts aldehydes to carboxylic acids without attacking carbon-carbon bonds Precipitate of silver produced Reveals presence of aldehydes
Important aldehydes and ketones/ medical significance- example 1
•Formaldehyde- -colourless irritant gas with disinfectant properties(precipitates proteins) -40% aqueous solution used for conservation of anatomical samples
Important aldehydes and ketones/ medical significance- example 2
•Acetylaldehyde- -pungent volatile and flammable liquid -Used as camping fuel in small stoves
Reduction of an aldehyde leads to
Primary alcohol
Reduction of a ketone leads to
Secondary alcohol
Ketoacidosis
-metabolic state caused by uncontrolled production of ketone bodies that cause a metabolic acidosis - results in changes in blood pH -most common cause is diabetic ketoacidosis
