CBSE Class 12 · 2002 · Delhi Compartment · Alcohols Phenols and EthersShort Answer

Of ethanol and n-propanol, which one gives the iodoform test, and why?

Solution

Iodoform requires CH

_{3}

CH(OH)– or CH

_{3}

CO–.
Ethanol, CH

_{3}

CH(OH)H: I

_{2}

/NaOH first oxidises it to ethanal, whose CH

_{3}

CO– group is then triiodinated and cleaved —

C H_{3} C H_{2} OH I_{2} /NaOH CH I_{3} ↓ (yellow) + HCOONa

n-Propanol (CH

_{3}

_{2}

_{2}

OH) oxidises to propanal, CH

_{3}

_{2}

CHO — no methyl next to C=O — so no iodoform.

CBSE Class 12 Board · 2002 · Delhi Compartment · Subjective