Identify phenol and derivatives of alcohols

Iron(III) Chloride - Pyridine Test

Chemical properties

Identification of phenols. A. All phenols react with iron(III) chloride solution to form a color compounds. Phenols with one hydroxy group form a violet compounds, phenols with two OH- groups – blue compounds, thymol does not react with iron chloride

(a) Reaction with FeCl₃ : Phenol gives violet coloration with ferric chloride solution (neutral) due to the formation of a colored iron complex, which is a characteristic to the existence of keto-enol tautomerism in phenols (predominantly enolic form

Physical Properties

Complications

– Not all phenols or enols give positive results

Most oximes, hydroxamic acids, and sulfinic acids give a positive test

Bulky groups on the benzene ring, especially inthe ortho position, may cause the experiment to

show a negative result

Activating groups attached to the ring decreases the wavelength caused by less electron

excitation, thus causing a different color of positive result

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urethane of alcohol

3.5-Dinitrobenzoates of Alcohols