Preparation of Artificial Flavorings and Fragrances

Kammin, Sandra              Resurrection Lutheran School
                            928-6311
                          

Objectives

1.  To ignite the spark of learning which is latent in the depths
    of the student's mind.
2.  To allow the students an opportunity to learn the practical
    aspects of Chemistry.
3.  The students will be able to correctly write a laboratory 
    report.
4.  The student will prepare several kind of fragrant ester molecules.
5.  The student will develop the skill of naming esters.

Apparatus Needed:

1.  Salicylic acid (C7H6O3).
2.  Butyric acid (C4H8O2).
3.  Glacial acetic acid (100% acetic acid CH3COOH).
4.  b-Naphthol or 2-Naphthol (C10H8O).
5.  Sulfuric acid (H2SO4).
6.  n-Amyl alcohol (1-pentanol, C5H11OH).
7.  n-Octyl alcohol (1-octanol, C8H17OH).
8.  Methyl alcohol (methanol, CH3OH).
9.  Ethyl alcohol (ethanol, C2H5OH).
10. Beaker for water bath.
11. Test tubes.
12. Graduated cylinders, 10 mL.
13. Hot plate.
14. Labels.
15. Stirring rods.
16. Test tube holders.
17. Droppers.   

Recommended Strategy:

Caution:  Be careful with the acetic and sulfuric acids.  Wear
gloves and goggles.  Also extinguish all flames in the room 
because the alcohols are flammable.
1.  Prepare a water bath by filling a 250 mL beaker half full with
    water and heating it.
2.  Look at the table to find an acid and an alcohol that you will
    combine.

----------------------------------------------------------------------
TUBE         ALCOHOL               ACID          ESTER FRAGRANCE 
----------------------------------------------------------------------
1           n-amyl alcohol       butyric acid         apricot
2           n-amyl alcohol       salicylic acid       pineapple
3           n-amyl alcohol       glacial acetic acid  banana
4           n-octyl alcohol      glacial acetic acid  fruity
5           methyl alcohol       salicylic acid       wintergreen
6           methyl alcohol       2-naphthol           perfume
7           ethyl alcohol        butyric acid         apple
8           ethyl alcohol        glacial acetic acid  fruity

3.  Place 2 mL of the alcohol from the table for each ester chosen in a
    test tube.  Label the tube.
4.  If the acid is a liquid, add 2 mL of it to  the alcohol in the tube.
    If it is a solid, add 1g of it.
5.  The teacher will add 1 mL of concentrated sulfuric acid to the tube.
6.  Stir slightly and then place the test tube in a boiling water bath.
7.  After a few minutes check the tubes for fragrances by waving a 
    little of the vapor toward you.  If you fail to detect an odor,
    pour the content of the test tube into a beaker containing 25 to
    50 mL of warm water.

REACTION:

An ester molecule is formed when an alcohol molecule and an organic
acid molecule come together and a water molecule is released:

       RCOOH     +     HOR'------->  RCOOR'    +  H2O
organic acid         alcohol          ester       water

   The carbon group R stands for the rest of the acid molecule, and 
the carbon group R' stands for the rest of the alcohol molecule.
   Esters are named by first giving the alcohol name and then the 
acid name, which is changed to have an ATE suffix instead of an
IC suffix.  For example, ethyl alcohol with acetic acid produces
ethyl acetate.
   Read the labels on artificially flavored foods and candies to 
find additives that are esters.

QUESTIONS:

1.  Describe the odor of the ester produced in each tube you tested.
2.  Use the guide in the Reaction section to write the reaction for
    the ester you produced.
3.  Name the ester you produced.
4.  Why was sulfuric acid used?
  
References: 

Bird, Harold, Jr.  Laboratory Studies in General, Organic and 
Biological Chemistry, Freeman 1972 pp. 407-11.

Jarvis, Bruce and Paul Mazzocchi, Form and Function: An Organic
Module.  Harper and Row:  New York, 1978 pp. 68-70.