Which reagent can you use to distinguish between 1-butanol and 2-butanol? Write down the reaction.

To distinguish between 1-butanol and 2-butanol, you can use the reagent known as chromic acid (CrO3 in sulfuric acid). This reagent is particularly useful because it can oxidize primary alcohols (like 1-butanol) but not secondary alcohols (like 2-butanol).

The reaction that occurs when 1-butanol is treated with chromic acid involves the oxidation of the alcohol to form butanal:

3 CH3(CH2)2OH + CrO3 → 3 CH3(CH2)CHO + Cr2O3 + 3 H2O

In contrast, when 2-butanol is treated with chromic acid, it will be oxidized to form 2-butanone, but since it is a secondary alcohol, it will react differently and will not yield an aldehyde:

3 CH3(CH2)2CHOH + CrO3 → 3 CH3(CH2)C(O)CH3 + Cr2O3 + 3 H2O

Thus, by treating the two alcohols with chromic acid, you can observe a color change in the mixture, indicating whether a primary or secondary alcohol is present. The oxidation of 1-butanol will lead to a noticeable change, while 2-butanol will show a different reaction with less distinct color change.