Carbonyls and carboxylic acids Flashcards
Carbonyl compound
Contain carbonyl function group
c=o
Adehydes
HAve their carbonyl group at the end of teh carbon chain
End their name in AL
Ketones
Have carbonyl group in teh middle
End in one
HAve a number to show where
Oxidation of aldehydes
Oxidise to carboxylic acids
Reflux with potassium dichromate and sulfuric acid
Carbonyl groups- reactivity
Carbon oxygen doble bond
Made up of a sigma and pie bond
POLAR ( unlike C=C whcih is unpolar)
Oxygen is more electronegative than carbon
Closer eectron density to oxygen
Neucleophiles attracted to slightly positive carbon
NEUCLEOPHILIC ADDITION
TYpes of reactions for carbonyl groups
Nucleophilic addition
REDUCING an aldehyde
Primary alcohol
reducing agent (H) NaBH4
Reducing a ketone
Secondary alcohol
Reducing agent
Neucleophilic addition- For NaBH4
:H- is the neucleophile
The lone pair of eletrons from hydride ion is arracted to delat positive carbon
Donates electrons
Dative covalent bond fromed
Pie bond in C=O breaks by heterolytic fission = Negatively charged intermediate
Oxyen atom donates a long pair of eelctrons to a hdyrogen in water ( gains the hydrogen, OH- left)
Pronated to form alcohol
Carbonyl compounds and HCN
Adds across C=O bond
Increasing chain length
- Lone pair of electrons from cyanide ion :CN-, attracted and donated to teh delta positive carbon in the C=O, dative covalent bond forms
- Bond breaks by heterolytic fission forming negative intermediate
- Both electrons go to the oxygen
H+ bonds to the oxogen to form OH
hydroxylnitrile formed
2-4 DNP
Dissolved in methanol and conc sulfuric acid
React with carbonyl grouspto form bright orange precipitate
Only works with C=O
Tollens reagant
Testing for aldehyde specifically
OXidised to carb acid easily
Silver mirror forms
Aldehyde oxidised and silver ions in teh tollens reagant reduced to silver
Reaction for tollens reagant
Ag(NH3)2 + e- ——— Ag (s) + 2NH3 ( aq)
