Esters

What are Esters?Can be naturally occurring in plants and contribute to the _______________ of fruits and flowers.

Uses: artificial/natural flavouring in foods, perfumes, cosmetics, oils, etc.

Esters can be made in the lab (__________)

pleasing odours

synthetic

Has a carbonyl (C=O) group attached to an oxygen atom (bonded to an alkyl group) and as well another alkyl group.

General Formula:

-COO-

EsterificationHow an ester is formedDone by reacting a ____________ with an _______ in presence of a catalyst (an acid) over heatSmall amounts of water is formed as well

carboxylic acid

alcohol

Naming EstersForm: (alcohol) (acid-anoate)

Example:

Drop –anol, replace with “yl”

Change from “-oic acid” to “-oate”

carboxylic acid alcohol

methylpropanoate

Naming EstersForm: (alcohol) (acid-anoate)

Example:

Drop –anol, replace with “yl”

Take parent name, add “anoate”

carboxylic acid alcohol

propylethanoate

Naming Esters

Draw the esterification reaction between methanol and ethanoic acid

Naming EstersExample: React methanol with butanoic acid.

methylbutanoate

Drawing Esters

propylbutanoate

Drawing Esters

butylheptanoate

Example

Draw the esterification reaction between propanol and hexanoic acid

propylhexanoate

Properties of Esters

Polar molecules (due to presence of O)

Lower melting points and boiling points than carboxylic acids and alcohols (they both have OH groups = stronger)

Smaller esters are gases (the ones you smell) and large esters are solids