Aldehydes + Ketones Flashcards
What is a carbonyl group?
C=O
What is the functional group and general formula for an aldehyde ?
RCHO (Carbon with =O, -H and -R)
What is the functional group for a ketone ?
RCOR’ (C=O in the middle of chain)
How do you name aldehydes ?
-al suffix (C=O is the end of the chain)
How do you name ketones ?
-one suffix (designate what number C=O is on)
What kind of intermolecular forces do molecules with a carbonyl group have ?
VDW and permanent dipole-dipole forces due to the polarity of C=O (O is d-)
Are molecules with a carbonyl group water soluble ? Why?
Yes - they form hydrogen bonds between water molecules and oxygen of C=O
As chain length increases, solubility decreases.
Which bond in carbonyl groups is typically involved in reactions ? Why?
C=O, due to polarity of the bond (large difference in electronegativity and electron density)
What is the strongest bond in carbonyl compounds ?
C=O
Draw / describe a mechanism for the nucleophilic addition of a carbonyl compound (Nu represents nucleophile)
•d+ on C, d- on O (C=O)
•Arrow from lone pair of Nu to d+ C
•Arrow from =O to O
•This gives C-O-
•Arrow from lone pair of O to H+
Why is the electrophilic addition of HCN to a carbonyl compound important ?
As it increases the length of the carbon chain by 1 - very useful
Will the product of HCN electrophilic addition to a carbonyl compound have optical isomers ? Why ?
•Yes they will
•This is because in aldehydes / ketones the carbonyl group is planar, so the CN- can attack from either above or below
•This results in two enantiomers.
What is the name of the compound when HCN is added to a carbonyl compound ?
Hydroxynitriles (Have both OH and CN groups)
What is Fehlings solution ? What colour is it ?
It is copper complex ions, blue.
What happens when an aldehyde is added to Fehlings solution ?
Cu is reduced to Cu+ ions -> colour change to brick red ppt
