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Exp. 12.3a The reactions of the phenolic functional group.

1. Solubility in H2O

Pipette         test-tube                       small beakers    full range indicator         Bunsen burner

(ethanol water + ethanoic acid water in 2 beakers)

1.     cm3 water into a test-tube

2.     Add small amount of methyl 4-hydroxybenzoate (solid)

3.     with pipette observe if dissolves  (should dissolve)

4.     Test for pH (bit less than 7) (also for the pH of ethanol(7) and acid(lower that phenol)) expl. delocalised system is formed in phenolic, which is less stable than acid (no sys. in alcohol).

2a. Phenolic compounds as acids. Action of sodium

DRY test-tube          Bunsen             phenolic            2.5 mm cube sodium

1.     Heat until phenolic melts and stop heating

2.     Add sodium and observe carefully (hydrogen should be given off, can collect under water)

3.     Before pouring down the sink add ethanol to the cool test-tube

4.     ? In ethanol O-H bond breaks, here should too

2b. Action of NaOH

test-tube       5 cm3 NaOH 2M           2 cm3 dilute HCl

1.     add phenol to alkali

2.     warm and observe for solubility (should be better than in water)

3.     add acid (neutralises NaOH)

2c. Action of Na2CO3

5 cm3 carbonate + phenolic (no reaction - weak acid)

3. Formation of an ester

0.5g phenol   4 cm3 2M NaOH           1 cm3 ethanoic anhydride           cork      ice-bath

1.     add alkali to phenol

2.     add anhydride to mixture

3.     cork tube and shake for few minutes

4.     anhydride is used instead of acid and alkaline conditions

4.a. Properties of the benzene ring

combustion spoon     Bunsen

Set phenolic to fire and observe flame

4.b. Iron (III) chloride

1.     dissolve some crystals of FeCl3 in 5 cm3 H2O and add 1 cm3 phenolic in H2O. Note colour

2.     Do the same with alcohol

4.c. Bromine

1.     shake phenolic with H2O

2.     Add bromine (reaction occurs readily, because of O delocalising electrons)

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