Question

After Lucas test, if mixture remains clear than which alcohol is confirmed?

• A. Isobutyl alcohol
• B. Isopropy alcohol
• C. Secondary butyl alcohol
• D. Tertiary butyl alcohol

Answer 1

The correct option is A Isobutyl alcohol

• Lucas test is used to differentiate and categorize primary, secondary and tertiary alcohols using a solution of anhydrous zinc chloride in concentrated hydrochloric acid. This solution is commonly referred to as the Lucas reagent.
• Primary, Secondary, and Tertiary alcohols react with the Lucas reagent to form the chloroalkane at different rates. Tertiary alcohols react the fastest due to the fact the organic chloride has relatively low solubility in the aqueous mixture.
• Primary Alcohol: The solution remains colorless unless it is subjected to heat. The solution forms an oily layer when heated. Example: 1-Pentanol.
• Secondary Alcohol: The solution turns turbid and forms an oily layer in three to five minutes (varies based on the solubility). Example: 2-Pentanol.
• Tertiary Alcohol: The solution turns turbid and forms an oily layer immediately. Example: 2-methyl-2-butanol.