Investigation of the properties of triatomic alcohols

№ 7-laboratory work.

Investigation of the properties of triatomic alcohols.

Objective: to familiarize with the physical and chemical properties of Polyatomic alcohols.

Reagents and equipment: caustic soda, solutions of copper sulfate, glycerin, mannitol, bromine water, test tubes, alcohol lamp.

Experience  №1. Obtaining copper glycerate

Course of work: pour 2 ml of sodium hydroxide solution into the test, add a few drops of copper sulfate solution until a blue precipitate is formed. Instill 2-3 drops of glycerin on the resulting tincture. When mixing the mixture, the precipitate is dissolved, a solution of dark blue copper glycerate is formed. Write the reaction equations.

Experience №2. Oxidation of Polyatomic alcohol

Course of work: in the first sample, 3-4 drops of glycerol are instilled,in the second sample, 0.3 g of mannitol and 3 ml of water each are placed. The resulting solutions are divided into two parts. When strongly mixed with the addition of the first parts of the alkali solutions in the same amount and 3-4 drops of copper sulfate, solutions of purple or blue color are formed. When these solutions are heated to boiling, the colors do not change. In the second parts of the solutions, pour 4-5 ml of bromine water and slowly heat until the solution discolors. When cooling the formed colorless solutions, adding an alkaline solution in such a volume, instilling 4-5 drops of copper sulfate in them and stirring, solutions of purple or blue color are formed in both tests. When heated to boiling, the solutions are yellowish, then a precipitate of copper (I) oxide is formed of a yellowish-orange color. The latter reaction is based on aldehyde subgroups formed from the oxidation of polyatomic alcohols. Write the reaction equations and explain their chemistry.

Control question:

1.   Write the reaction equation between glycerol and copper (II) hydroxide.

2.   Write the equations of the oxidative reaction of glycerol and mannitol.