Question

Vapours of an alcohol X when passed over hot reduced copper, produce an alkene, the alcohol is:

• A. primary alcohol
• B. secondary alcohol
• C. tertiary alcohol
• D. dihydric alcohol

Answer 1

The correct option is C tertiary alcohol

Given: $X\left(ROH\right)+Cu\left(hot\right)\to alkene$

primary alcohol passed over Cu at ${300}^{\circ }C$ is dehydrogenated to aldehydes and hydrogen gas liberates

secondary alcohols are dehydrogenated to ketones with liberation of hydrogen gas

tertiary alcohol is dehydrated to alkene.

This method can therefore be used to distinguish between primary, secondary and tertiary alcohol

thus X should be a tertiary alcohol