A2 Unit 4.4,4.6 & 4.7 Aldehydes, Ketones, Amines, Amino Acids, Perides and Proteins

Aldehydes and Ketones

PREPARATION OF ALDEHYDES FROM ALCHOLS

PREPARATION OF KETONES FROM ALCOHOLS

Chemical Reactivity

As the carbonyl functional group has a double bond, it undergoes addition reactions - just like the double bond of the functional group in alkenes.

Alkenes undergo electrophillid addition reactions because the electron cloud of the Tt bond is attacked by electrophiles.

There is a Tt bond in the carbonyl group as well, but it is between two atoms of different electronegativities, C and O. The density of the charge cloud is greater at the more electronegative oxygen end.

Therefore, the bond is Polar Since C=O is polar, the electron deficient carbon atom is susceptible to attack by nucleophiles. Their reactions are nucleophilic addition reactions.

Why don’t substitution reactions occur and are aldehydes more reactive than ketones?

Addition Reaction & Questions

(Practice questions on pg. 6)

Why aren’t aromatic carbonyl compounds soluble in water?

Reaction of Aldehydes and Ketones with 2,4-dinitrophenyl hydrazine (Brady’s Reagent)

Nucleophilic Addition/ Elimination Reaction & Specified Prac.

Risk Assessment & Reactions of Aldehydes and Ketones

Chemical Tests

Reduction Reactions of Aldehydes and Ketones with NaBH4

The mechanism is similar to that of the addition of hydrogen cyanide, only in this case the nucleophile is ..... once the NaBH4 has reacted with the carbonyl compound, water is added to provide the protons.

Reactions of the Carbonyl Group with Brady’s Reagent & Practical Methods

Reaction Summary Sheet