Chapter 1.6 Carboxylic Acids, Esters, and Fats

Carboxylic Acids Organic compounds that contain a carboxyl group (-COOH) In aqueous solution one of the H+ is removed easily which makes the solution acidic

Naming Carboxylic Acids Find the alkane name of the longest chain and drop the –e Replace it with –oic acid If –OH group present use the prefix “hydroxy” If more than 1 –COOH use prefix “di”, “tri”, etc

Name The Following:

Draw the Structure of 2-methylbutanoic acid

Practice Time! P. 48 #1, 2

Properties of Carboxylic Acids Very polar because of =O and –OH which form H bonds with one another and other polar solvents (water) 5 carbon or less very soluble; the longer the HC chain, the less soluble they are Share properties with other acids Affect indicators React with bases to form salts and water Melting points higher because of dipole interactions

Esters AKA organic salts Contains a carbonyl group, bonded to a second oxygen atom which is bonded to another carbon atom Responsible for the odours of fruits, flowers, perfumes Formed by the condensation reaction of a carboxylic acid and an alcohol

Naming Esters Determine which part came from the alcohol and start the name with that by changing the ending to –yl Name the part with the carboxyl group and change the ending to –oate

Name this Ester:

Draw the Structural Diagram for: ethyl methanoate

Practice Time! P. 50 #1, 2

Properties of Esters Compared to carboxylic acids, esters are missing their –OH group so they are less polar Don’t form H bonds Less soluble in water than carboxylic acids Lower BP than carboxylic acids Similar BP/MP to aldehydes and ketones Small esters are gases at room temperature Large esters are waxy solids

Reactions of Carboxylic Acids and Esters

1. Formation of Carboxylic Acids Aldehydes oxidize into carboxylic acids as an additional oxygen atom is added. (Ketones can’t be oxidized further) Butanal + (O)  butanoic acid

2. Formation of Esters (Esterification) This is a condensation reaction in which an alcohol and a carboxylic acid react to form an ester and water. acid + alcohol  ester + water

3. Reverse Esterification (Hydrolysis) When esters are treated with an acid or a base, they will split into an alcohol and a carboxylic acid if water is added as well.

Example 1 Write equations to show the TWO chemical reactions that form butanoic acid from an alcohol

Example 2 Draw the structural formula equation that shows the reaction that forms propyl butanoate.

Example 3 Writ the structural formula equation for the hydrolysis of ethyl propanoate by sodium hydroxide solution.

HOMEWORK P. 53 #1 Read & summarize p. 53 (Fats & Oils) P. 55 #1-9