How many structurally and stereochemically distinct isomeric alkynes with the molecular formula will — Hydrocarbons Chemistry Question

💡 Solution & Explanation

A white precipitate with Tollens' reagent indicates a terminal alkyne ($-C\equiv CH$). We must find all terminal alkynes for $C_6H_{10}$: (1) Hex-1-yne (straight chain). (2) 4-methylpent-1-yne. (3) 3,3-dimethylbut-1-yne. (4) 3-methylpent-1-yne. Notably, 3-methylpent-1-yne ($CH_3CH_2C^*H(CH_3)C\equiv CH$) contains a chiral center at carbon-3. Thus, it exists as a pair of enantiomers (*d* and *l* forms). Total isomers = $1 + 1 + 1 + 2 = 5$.