aldehydes and ketones Flashcards
what is an aldehyde?
If the C=O is on the end of the
chain with an H attached it is an
aldehyde.
what does an aldehyde name end in?
it ends in -al
what are carbonyls?
Carbonyls are compounds with a C=O bond.
They can be either aldehydes or ketones
are carbonyls soluble?
The smaller carbonyls are soluble
in water because they can form
hydrogen bonds with water.
what are the intermolecular forces in carbonyls?
Pure carbonyls cannot hydrogen bond to
themselves, but are attracted instead by
permanent dipole forces.
why is the C=O bond polarised?
The C=O bond is polarised because
O is more electronegative than
carbon. The positive carbon atom
attracts nucleophiles.
how does a C=C bond compare to a C=O bond?
In comparison to the C=C bond in
alkenes, the C=O is stronger and does
not undergo addition reactions easily
what is potassium dichromate?
Potassium dichromate K2Cr2O7
is
an oxidising agent that causes
alcohols and aldehydes to
oxidise.
what is the oxidation pathway of a primary alcohol?
Primary alcohol to aldehyde to carboxylic acid
what is oxidation pathway of secondary alcohol?
secondary alcohol to ketones
what is the oxidation pathway of a tertiary alcohol?
tertiary alcohols do not oxidise
can ketones be oxidised?
NO!
for the reaction of aldehydes to carboxylic acid what are the reagents and conditions?
Reagent: potassium dichromate (VI) solution and
dilute sulfuric acid.
Conditions: heat under reflux
what is the full equation for the reaction?
Full equation for oxidation
3CH3CHO + Cr2O7 2- + 8H+
arrow
3 CH3CO2H + 4H2O + 2Cr3+
what is the observation of potassium dichromate?
Observation: the orange dichromate ion
(Cr2O7
2-) reduces to the green Cr 3+ ion
