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36 formed. Add 1 drop of glycerin and shake the tube. A solution of copper glycerate is formed in blue. This reaction is used to detect organic compounds containing a diol fragment. In this case, a chelate compound is formed. Write the equation of complex formation. Experiment 2. Qualitative reactions to phenols. In four tubes containing 0.5 ml of a solution of pyrocatechol, resorcinol, hydroquinone and phenol, respectively, add 1–2 drops of ferric chloride solution (III). In the first test tube there is a green coloration (pyrocatechin), in the second – a violet stain (resorcinol), in the third – green coloration, very quickly turning into yellow (hydroquinone) and in the fourth reddish-violet staining (phenol). Phenol and its homologues form colored complexes with iron (III) ions: FeCl 3 + OH 6 Fe O O O O O O H 3 + 3HCl Write the structural formulas of diatomic phenols, name them by the IUPAC substitutive nomenclature. Experiment 3. Disproportionation of formaldehyde in aqueous solutions. Pipette 2–3 drops of formalin into the test tube (40% formaldehyde solution). Add 1 drop of methyl red indicator. What are you watching? Explain the observed phenomena in terms of the disproportionation of formaldehyde. Write an equation for this reaction. Experiment 4. Oxidation of formaldehyde by copper hydroxide. Pipette 10 drops of NaOH into the tube and about 1 ml of water, add 1% drop of 2% CuSO 4  solution. Aprecipitate of Cu (OH) 2  precipitates. Add 3 drops of formalin. Gently heat the test tubes to a boil. In a test tube, the precipitate first acquires a yellow color and then a red color. The change in the color of precipitation can be explained by the different degree of oxidation of copper: Cu (OH) 2 → CuOH → Cu 2 O Oxidation of formaldehyde proceeds through the formation of formic acid to carbon dioxide. Write the equations of reactions (2 equations).