Ester Esterification Lab Report

Procedure :-
A) Fischer Esterification 's Procedure ( Direct esterification of a carboxylic acid with an alcohol ):-
1- Choose any pair of these caboxylic acids and alcohols . When using excess alcohol, a molar ratio 4:1 is used in the procedure. 2- Mix 0.48 mol methanol with 0.12 mol butyric acid in a dry round bottom flask .
3- Add 0.05 moles of concentrated sulphuric acid to round bottom flask very slowly and carefully then put a magnetic stirrer .
4- Set up reflux system using a clean and dry condenser .
5- Place the flask on the hot plate and heat the reaction for 45 minutes - 1 hour .
6- When the reflux is over , remove magnetic stirrer and allow the reaction to cool to room temperature .
7- Add 20 ml of ice water to a separating funnel

• it is a dehydrating agent ( allow the reaction to move forward towards ester formation ) .
2) The usage of dehydrating agents ( as CaCl or MgSo4) to remove excess water molecules trapped in the ester layer .

B) Synthesis of ester using acetic anhydride :-
1- Add 2-3 ml of acetic anhydride in a large dry test tube then add 3 drops of concentrated sulphuric acid and mix.
2- Get any one of these alcohols (1-propanol, 3-methyl-1- butanol, benzyl alcohol, or 1-octanol) in a small dry test tube .
3- Put the large tube in an ice bath and start to add alcohol by an increasing rate .
4- Put the tube in hot water (70º C) for 5 minutes .
5- Add 8 drops of water with constant shaking then leave the reaction to cool to room temprature.
6- Add 6 mL of ( 3 mL saturated NaCl +3 mL distilled water) i.e : half-saturated sodium chloride solution to the test tube with vigorous shaking and then wait until two layers form (upper layer is ester while lower layer which consists of a water solution of sulfuric and acetic acids ,should be discarded

8- Repeat step( 6 ).
9- Wash the ester layer with 6 ml saturated sodium chloride , shake and allow two layers to separate . At this point ,The ester layer should not be cloudy . Again discard lower layer.
10- Transfer the ester layer to a small dry test tube and dry the ester with anhydrous CaCl2 and stir for 10 min.
11- put it in a preweighed dry round bottom flask .
14- Determine the yield, refractive index, and % yield of ester.
Conditions :-
1) This reaction is catalyzed by acid, Like Fischer esterification.
2) Usage of water in step (5):So that after Estrification is completed , any excess unreacted acetic anhydride is hydrolyzed.
3) The addition of half-saturated NaCl (in step 6): to help in separating the two layers.
4) The usage of a Base (step 7): to neutralize remaning acid .
5) Usage of concentrated sodium chloride in step (9):To dry the ester from any dissolved