. Which of the following give iodoform test:
Correct answer: B. C2H5OH
- A. CH3OH
- B. C2H5OH
- C. Methanal
- D. 1-propanol
Explanation
Ethanol gives iodoform with iodine in the presence of NaOH. Formation of yellow crystals indicate that the alcohol is ethanol. Methanol does not give iodoform test. Ethanol is the only primary alcohol to give the triiodomethane (iodoform) reaction. If "R" is a hydrocarbon group, then you have a secondary alcohol. Lots of secondary alcohols give this reaction, but those that do all have a methyl group attached to the carbon with the -OH group.
Last updated
About Alcohols and Phenols
Alcohols are classified as primary, secondary or tertiary and studied through their hydrogen bonding, acidity, oxidation and reactions with active metals, acids and halogenating agents. Phenols require separate treatment because the hydroxyl group is attached to an aromatic ring, making their acidity and electrophilic substitution different from ordinary alcohols.
Practise Alcohols and Phenols
535 free Alcohols and Phenols MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Chemistry questions like this
Chemistry is on 12 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.