17.2 Flashcards
what are the 2 carbonyl compounds
aldehydes
ketones
(O=H)
what makes a carbonyl compound an aldehyde
if there is a hydrogen joined to the carbonyl group (=O is on the end on a chain)
what makes a carbonyl compound a ketone
if there are only hydrocarbon groups joined to the carbonyl group (=O is in the middle of the chain)
explain the polarity of carbonyl groups
the bond is polar because of the different electronegativities of carbon & oxygen
electron density is greater near oxygen
what are the physical properties of carbonyls and the difference between long & short chains
- distinctive smells
long chain - pleasant smell
short chain - unpleasant smell
explain carbonyls boiling temperature
intermolecular forces of intermediate strength
contain polar C=O group so form permanent dipole dipole attractions but no hydrogen bonding
what can’t most carbonyls not form hydrogen bonds
because all of their hydrogen atoms are joined to a carbon and therefor get in the way
are carbonyls soluble in water
shorter chain carbonyls are soluble in water ass they can form hydrogen bonds but as they get longer the hydrocarbons become more significant & solubility decreases
state the oxidation & reduction products for aldehydes & ketones
reduction:
aldehyde -> primary alcohol
ketone -> secondary alcohol
oxidation:
aldehyde -> carbonylic acid
ketone -> not easliy oxidized
what reactant & conditions are needed for the reduction of carbonyls to alcohols
lithium aluminum hydride (lithium tertrahydridolaluminate)
LiAlH4
dissolved in dry ether
how are aldehydes oxidized to carboxylic acids by acidified potassium dichromate (VI)
orange solution -> green solution
reduction of chromium from +6 to +3 causes colour change
how are aldehydes oxidised to carboxylic acids by fehlings & benedicts solution
dark blue solution -> red precipitate
conversion of copper(II)
complex to copper (I) oxide
how are aldehydes oxidised to carboxylic acids by tollens reagent (ammoniacal silver nitrate)
colourless solution -> silver mirror
conversion of silver(I) complex to metallic silver
