Laboratory work 6. Vitamins

Experiment 1. Qualitative reactions to vitamin A (retinol).

Reaction with antimony chloride (III).

Place 1-2 drops of fish liver oil or solution of vitamin A in oil into a dry test tube, add 5-6 drops of antimony chloride (III) solution in chloroform and 2-3 drops of acetic anhydride. You will see blue coloring gradually turning pink-violet. The reaction is unspecific as it can be also given by some other compounds having conjugated double bonds.

1.2. Reaction with sulfuric acid (Drummond’s reaction).

Dissolve 1 drop of fish liver oil (or vitamin A) in 4 drops of chloroform and add 1-2 drops of strong sulfuric acid. You will see blue coloring immediately turning brown-red.

The given reactions are based on the dehydrating influence of antimony chloride (III) and sulfuric acid on vitamin A.

Vitamin A (vitamin A, retinol)

Experiment 2. Qualitative reactions to vitamin D (calciferol).

Reaction with bromine solution in chloroform.

Mix 0,5 ml of fish liver oil and 0,5 ml of bromine solution in chloroform in a dry test tube. The presence of vitamin D will give green-blue coloring. The reaction is unspecific.

Reaction with aniline.

Pour 0,5 ml of fish liver oil and 0,5 ml of aniline and strong sulfuric acid mixture into a dry test tube (15:1), mix properly, heat carefully up to boiling for a minute. If vitamin D is present, the color of this emulsion will be green and then - red. Leave the test tube at the room temperature. The emulsion is layered; the lower layer is turning bright-red.

Vitamin D (calciferol)

Experiment 3. Qualitative reactions to vitamin E (tocopherol).