3.8 - Aldehydes and Ketones Flashcards
What is the carbonyl group?
C=O
What is the functional group and general formula for an aldehyde?
R - C - H
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O
What is the functional group for a ketone?
R - C - R
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O
How do you name aldehydes?
-al
How do you name ketones?
-one
What kind of intermolecular forces do molecules with the carbonyl group have? Why?
Permanent dipole-dipole due to the polar C=O bond
O is delta -
How soluble are they in water? What influences solubility?
They form hydrogen bonds between water molecules and oxygen of C=O. As C chain length increases, solubility decreases.
Which bond in carbonyl compounds is usually involved in reactions? Why?
C=O, due to the polarity of the bond
There is a large difference in electronegativity between C and O.
What is the strongest bond in carbonyl compounds?
C=O
Why is the addition of HCN important?
It increases the length of the carbon chain by one carbon atom - very useful
Will the product of HCN added to a carbonyl compoud have optical isomers? Why?
Yes they will.
In the aldehyde/ketone, the carbonyl carbon planar, so the :CN- can attack from weither above or below, forming two enantiomers.
What is the name of the product when HCN is added to a carbonyl compound?
Hydroxynitriles (have OH and CN groups)
What is Fehling’s solution? What colour is it?
Copper complex ions, blue
What happens when an aldehyde is added to Fehling’s solution?
Reduced to Cu+ ions -> colour changes to brick red ppt
What happens when a ketone is added to Fehling’s solution?
No visible change -> stays blue
