The Carbonyl group

The carbonyl group

• Dipole-dipole forces between the molecules
• Boiling points higher than alkanes
• Difference in electro-negativity ----> strongly polar
• NUCLEOPHILIC reagents can attack the C+
• contains double bonds so unsaturated ----> addition reactions are possible
• most typical reactions are nucleophilic addition

   CARBONYL GROUP

Aldehyde- AL

• the aldehyde group can occur at the end of the group

Ketones - ONE

• A ketone fewer than 3 carbons is not possible

Solubility

• short chain aldehyde and ketone's mix completely with water as h bonds form between O from the carbonyl group and H20
• As chain length increases the carbonyl group gets less soluble
• Short chain aldehyde's and ketone's are liquids - pleasant smells scent soaps and food

Addition of Hydrogen Cyanide (ketone)

• Ketone's can't be oxidised as the C-C bond must be broken

• increased length of carbon chain by 1 carbon -----> HYDROXYNITRILE
• Aldehyde's ---> oxidised to carboxylic acids----> oxidising agent K dichromate

• In a aldehyde or unsymmetrical ketone, the HCN can attack above or below the flat C=O group

Reduction

• reducing agents will reduce Aldehyde's and Ketone's to alcohols

• 1 reducing agent NaBH4--------> generates H- NUCLEOPHILE HYDRIDE ION H-

• C=O is reduced but not the C=C as it is repelled by HIGH ELECTRON DENSITY in the C=C BOND.

• BUT the H- is attracted to the C+ of the C=O bond

Reducing an Ketone - NUCLEOPHILIC ADDITION REACTION

Reducing an Aldehyde - NUCLEOPHILIC ADDITION REACTION

Reducing an Aldehyde - NUCLEOPHILIC ADDITION REACTION