"P" is a hydrocarbon of molecular formula: C_8H_ 14 . On ozonolysis, "P" forms "Q". "Q" on treatment with alkali under reflux condition produces "R", which on treatment with I_2/NaOH gives a yellow precipitate. Acidification of the solution gives "S". The structure of "S" is given below: The correct structure of "P" is
D.
The structure of "S" is 2-methylcyclopent-1-ene-1-carboxylic acid. Since "S" is obtained by the acidification of the product from the iodoform reaction of "R", "R" must contain a methyl ketone group (-COCH_3). The iodoform reaction converts the -COCH_3 group into a -COOH group alongside the formation of a yellow precipitate of iodoform (CHI_3). Therefore, the structure of "R" is 1-acetyl-2-methylcyclopentene. "R" is formed by the intramolecular aldol condensation of "Q". Performing a retro-aldol condensation on "R" by cleaving the double bond in the cyclopentene ring yields octane-2,7-dione as "Q" (CH_3-CO-CH_2-CH_2-CH_2-CH_2-CO-CH_3). "Q" is obtained by the ozonolysis of "P". To determine the structure of "P", we perform retro-ozonolysis by removing the oxygen atoms from the two carbonyl groups of "Q" and connecting the corresponding carbon atoms with a double bond. Connecting the C2 and C7 carbons forms a six-membered ring with methyl groups at the double bond. Thus, "P" is 1,2-dimethylcyclohexene. Answer:
Related: Chemistry — Hydrocarbons · All PYQ Banks