Chem 30B Dr. R. Rinehart

ESTER SYNTHESIS

General Reaction:     carboxylic acid       +        alcohol         (+ H+                 ester           +       water

 

                          +  H2O

 

PROCEDURE:   WEAR YOUR GOGGLES!  You may also want to use the gloves provided. Start a boiling water bath by filling a 400 mL beaker about 2/3 full with water, adding a few boiling stones, and placing on an iron ring equipped with wire gauze and heating over a burner. While waiting for the water to boil, set up and label [# 1 to 8] eight  3 (12x75mm) test tubes. You may find it convenient to place the tubes into the metal heating bath rack, supported in a 250 mL beaker while you work. Into each tube, introduce ~ 1 mL [20 drops] of the appropriate acid and alcohol according to the scheme below. After all tubes have received these contents, carefully add 5-10 drops of concentrated sulfuric acid (H2SO4) to each tube. Mix by gently shaking the rack from side to side, then place the rack of tubes into the beaker of boiling water for 5-8 minutes. If the contents of a tube appear to be boiling, remove it until things settle down, then return to heat.

While waiting, you can fill in the table below by supplying the structures for each reactant and product. Also give the name of the ester formed.  After the period of heating is complete, remove the rack from the water bath and allow to cool before cautiously noting the smell using the procedure that has been described by the instructor. Record the description of the odor.

 

tube #

Acid

Alcohol

Ester

Odor

1

formic (methanoic)

 

 

 

ethanol

 

 

 

2

acetic (ethanoic)

 

 

 

ethanol

 

 

3

acetic (ethanoic)

 

 

 

 

isobutyl alcohol

 

 

4

acetic (ethanoic)

 

 

 

 

benzyl alcohol

 

 

5

propanoic

 

 

 

 

isobutyl

 

 

6

acetic (ethanoic)

 

 

 

 

1-octanol

 

 

7

acetic (ethanoic)

 

 

 

 

isopentyl

(3-methyl-1-butanol)

 

 

8

salicylic (o-hydroxybenzoic)

 

 

 

 

methanol

 

 

 

Ronald W. Rinehart, 2002   Close this window to return to class schedule or click here.