7. Ketones and Aldehydes

What are the similarities between Ketones and Aldehydes?

1. Both have general formula

   CₙH₂ₙO

2. Both have a carbonyl functional group

3. Lower boiling points/Higher solubility

4. NO H bonding

What are the differences between Ketones and Aldehydes?

position of carbonyl in molecule

Aldehyde Structure

carbonyl group attached to at least one hydrogen

• usually at end of molecule

Ketone Structure

carbonyl carbon connected to 2 carbons

• middle of molecule

How to Name Aldehydes

1. prefix is # of carbons (alkane)

2. ending goes from -e → -al

3. no position numbers since carbonyl is always carbon 1

How to Name Ketones

1. prefix is # of carbons (alkane) + position of the carbonyl

2. ending goes from -e → -one

3. if your ketone has two carbonyl groups: name, location, -dione/-trione

How are aldehydes and ketones created?

controlled oxidation of alcohols

How are aldehydes and ketones controlled in oxidizing reactions?

• oxidizing agents (oxygen-rich compounds)

• represented by [O]

What is the flow of oxidation for primary alcohols?

1. primary alcohol → aldehyde → carboxylic acid

2. orange → green

What is the flow of oxidation for secondary alcohols? What is their colour change?

1. secondary alcohol → ketone

2. orange → green

What is special about teritary alcohols?

they do not oxidized

How do you obtain aldehyde from a primary alcohol?

• stop the reaction by removing aldehyde from the reaction before it becomes carboxylic acid

How do you obtain aldehyde from a primary alcohol?

leave the aldehyde for prolonged period of time

Use apparatus for reflux (a distillation techinque)

Tell me about Reduction of Aldehydes and Ketones

1. use a suitable reducing agent (NaBrH₄) in an aqueous alcoholic solution or lithium aluminum hydride

2. in anhydrous conditions

3. followed by an aqueous acid (carboxylic acid)

Complete the statement: both reagents produce the _______ ion,…

both reagents produce the hydride ion, H⁻, which acts as nucleophile on electron-deficient carbonyl carbon

Reduction of a carboxylic acid produces…

an aldehyde

Reduction of an aldehyde produces…

a primary alcohol

Reduction of a ketone produces a…

secondary alcohol