Which test allows us to distinguish between the primary, secondary and tertiary alcohols?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Lucas test
The Lucas test uses the different rates at which the three classes react with conc. \( \ce{HCl} \) and \( \ce{ZnCl2} \) (order 3° > 2° > 1°):
\( \displaystyle \ce{ROH + HCl} \xrightarrow{\ce{ZnCl2}} \ce{RCl + H2O} \)
A secondary alcohol lies between the other two in reactivity.
NCERT (2026-27 edition):
7.4.4 Chemical Reactions – “The difference in reactivity of three classes of alcohols with HCl distinguishes them from one another (Lucas test). Alcohols are soluble in Lucas reagent (conc. HCl and ZnCl2) while their halides are immiscible and produce turbidity in solution. In case of tertiary alcohols, turbidity is produced immediately as they form the halides easily. Primary alcohols do not produce turbidity at room temperature.”