DERIVATIVES OF THE CARBOXYLIC ACIDS

Document Sample
DERIVATIVES OF THE CARBOXYLIC ACIDS Powered By Docstoc
					2004


DERIVATIVES OF THE CARBOXYLIC ACIDS

(A)    The Hydroxamic Acid Test for Esters

Place 1 drop of ethyl ethanoate in a test-tube. Add 3 drops of a saturated solution of hydroxylammonium
chloride in methanol, followed by three drops of a saturated solution of potassium hydroxide in methanol.
Warm the mixture until it boils, and acidify with 2M hydrochloric acid. To this solution, add 1 drop of
iron(III) chloride solution.

Repeat the experiment using the following esters in turn: ethyl benzoate, methyl ethanoate, pentyl
ethanoate (amyl acetate).

(B)    Reactions of ethanoyl (acetyl) chloride.

1.     Place 1 drop of ethanoyl chloride in a test-tube. Carefully add 5 drops of water. Note the vigour of
       the reaction and the odour produced. Breathe upon the fumes.

2.     Perform this reaction in a fume cupboard. CARE. Place 10cm3 of 0.88 ammonia in a beaker. CARE.
       Add a few drops of ethanoyl chloride.

3.     CARE. To 5 drops of ethanol, add 1 drop of ethanoyl chloride. Breathe on the fumes. Also test the
       fumes with moist universal indicator paper.

4.     To 5 drops of phenylamine (CARE) in a test-tube, add 2 drops of ethanoyl chloride (CARE).

(C)    Reactions of ethanoic (acetic) anhydride.

1.     To 5 drops of ethanoic anhydride in a test-tube, add 5 drops of water. Contrast the reaction with B1
       above.

2.     To 5 drops of phenylamine (CARE) in a test-tube, add a little concentrated hydrochloric acid
       dropwise until the phenylamine dissolves. Add 3 drops of water, then 7 drops of ethanoic
       anhydride. Add saturated sodium ethanoate dropwise until a precipitate appears.

3.     Place 0.5g of phenol (CARE) in a test-tube and add 4cm3 of 2M sodium hydroxide solution,
       followed by 1cm3 of ethanoic anhydride. Cork the test-tube, then shake for a few minutes. Note the
       odour and nature of the product.

(D)    Reactions of ethanamide (acetamide)

1.     To about 0.1g of ethanamide in a test-tube, add 2cm3 of 2M sodium hydroxide solution. Boil, and
       test the vapour evolved with moist universal indicator paper. Note the odour.

2.     The Hofmann Degradation Reaction: To about 0.1g ethanamide in a test-tube, add 3 drops of liquid
       bromine (CARE: DANGEROUS). Add 2cm3 of 2M sodium hydroxide solution. ‘Cork’ the test-
       tube and shake for 2 minutes. Remove the bung, add 1 pellet of sodium hydroxide, and boil the
       solution gently. Note the odour. Test the vapours with moist universal indicator paper.

3.     Dissolve 0.1g of ethanamide in 1cm3 of water. Add 0.2g of sodium nitrite and shake until dissolved.
       Add 2M hydrochloric acid dropwise until the solution is just acidic to litmus. What is evolved?
       When the effervescence has ceased, make the solution alkaline with 2M ammonia solution. Boil,
       allow to cool, then add neutral iron (III) chloride solution dropwise.




HB Chem Derivatives of the Carboxylic Acids