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How to distinguish between (i) Phenol and alcohol (ii) Prima

How to distinguish between (i) Phenol and alcohol (ii) Primary, secondary and tertiary alcohol

1 Answer

(i)Phenol on reaction with neutral FeCl3 gives purple colour whereas alcohols do not give purple colour.

$6C_6H_5OH + Fe^{3+} \to [Fe(OC_6H_5)_6]^{ 3-} + 6^{ H+}$ Purple colour

(ii) Primary, secondary and tertiary alcohol:

 Lucas reagent test:

$ROH + HCl \longrightarrow{

conc.HCl ZnCl2} RCl + H_2O $

If it is a primary alcohol, no turbidity appears at room temperature.

Turbidity appears only on heating. 

If it is a secondary alcohol, turbidity appears in 5 minutes. 

If it is a tertiary alcohol, turbidity appears immediately.

(iii)Methanol and ethanol:

 Iodoform test:

Ethanol when reacted with (I2 and NaOH) or NaOI gives yellow ppt of iodoform since it has the presence of $CH_3-CH (OH)-$ group.

$ C_2H_5OH +4I_2+ 6NaOH \to CHI_3 + 5NaI + 5H_2O + HCOONa$ Yellow ppt. $CH3OH + I_2+ NaOH \to$ NO YELLOW PPT

answered Jul 18, 2017 by pady_1