In the hydration of a terminal alkyne using mercuric sulfate and sulfuric acid, the major product is a ketone. Which option correctly names the major product class?

Prepare for the Plovdiv Entrance Exam. Equip yourself with comprehensive study materials, including multiple choice questions and flashcards. Ensure success in your examination!

Water adds to a terminal alkyne under mercuric sulfate and sulfuric acid in a Markovnikov fashion, then the resulting enol tautomerizes to a carbonyl compound. The hydrogen attaches to the terminal carbon and the hydroxyl-bearing part attaches to the internal carbon adjacent to the R group, giving a vinyl intermediate that hydrolyzes to an enol. This enol quickly tautomerizes to a ketone, placing the carbonyl on the internal carbon and yielding a methyl ketone (R-CO-CH3). That’s why the major product class is a ketone. Aldehydes aren’t formed under this specific hydration mechanism because the carbonyl ends up on the internal carbon, not the terminal one.