Chemistry Lab Report Ester

Title:

Preparation and isolation of an Ester

Aim:

To make an ester and purify it

Background Theory:

Esters are derived from carboxylic acids and alcohols with the presence of a catalyst. A carboxylic acid contains the -COOH group, and in an ester the hydrogen in this group is replaced by a hydrocarbon group of some kind. Sulfuric acid (H2SO4)is used as a catalyst for this reaction in order to accelerate the rate at which the product is formed. The general formula of an ester is RCOOR’ in which R is the alkyl group that comes from the carboxylic acid while R’ is the alkyl group that comes from the alcohol and COO is the functional group of the ester known simply as the ester group.
The general structural formula of an ester is as follows,

O
||

R
─
C
─
O
─
R’
The general equation for esterification is as follows,
RCOOH + R'OH ⇌ RCOOR' + H2O

This type of reaction is known as condensation reaction because water is produced. Water is produced from the hydroxyl group of the carboxylic acid and the hydrogen atom from the hydroxyl group of the alcohol as can be seen in the following formula.
R'-O
-H
+
HO-
OC-R
H+ →
R'-OOC-R (ester)
+
H2O

Since a catalyst is not consumed during the course of a reaction, you need to use only a small amount of sulfuric acid in order for it to be effective. The name of the ester formed is butyl ethanoate. This is because the ‘-anol’ part of the alcohol name becomes ‘-yl’ and the carboxylic acid part which has the name of ‘-ic acid’ will end with a ‘-ate’

1-butanol + ethanoic acid butyl ethanoate + water.

C4H9OH(aq) + CH3CO2H(aq) CH3CO2C4H9(aq) + H2O(l)

CH3CH2CH2CH2OH + CH2COOH  CH3COOCH2CH2CH2CH3 + H2O

The preparation of an ester involves three stages which are synthesis of the ester, isolation of the ester and lastly purification of the ester.

The first process is synthesis of the ester. This is done by reflux. Reflux is a process of heating the