Oxidation of a primary alcohol with acidified potassium dichromate, distilling the product as it forms, gives

  • A. a ketone
  • B. an aldehyde
  • C. a carboxylic acid
  • D. an alkene

Explanation

Distilling removes the aldehyde as soon as it is produced, before it can be oxidised further, whereas heating under reflux keeps it in the flask and the reaction continues to the carboxylic acid. The orange dichromate turns green as chromium is reduced from plus 6 to plus 3. Secondary alcohols stop at the ketone, since no hydrogen remains on the carbonyl carbon.

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