See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: In oxidative ozonolysis, the C=C double bond is cleaved. Each carbon of the double bond is oxidized: a terminal =CH2 group (with two hydrogens on the alkene carbon) gives formaldehyde (HCHO) under reductive ozonolysis, but under oxidative ozonolysis it gives CO2 (since HCHO is further oxidized to formic acid and then to CO2). A carbon bearing one hydrogen on the double bond gives a carboxylic acid. A carbon bearing no hydrogen (i.e., R2C=) gives a ketone, which is not further oxidized under standard oxidative ozonolysis conditions, so no CO2 is produced from that fragment. Step 1 - Analyze each option for terminal =CH2 groups (which produce CO2) vs. internal or disubstituted alkene carbons (which produce ketones, no CO2): (a) Methylenecyclohexane: structure is cyclohexane ring with exocyclic =CH2. The double bond is between the ring carbon (disubstituted, R2C=) and =CH2 (terminal, unsubstituted). The =CH2 end gives HCHO under reductive conditions, which oxidizes to CO2 under oxidative ozonolysis. So CO2 IS evolved from option (a). (b) The structure shown appears to be 1-methylenecyclohexane variant or (methylenecyclohexyl)methylene — looking at the image, it shows a cyclohexyl group attached to C=CH2, i.e., a terminal methylene. The =CH2 terminal carbon again produces CO2 under oxidative ozonolysis. So CO2 IS evolved from option (b). (c) 1,3-Butadiene: H2C=CH-CH=CH2. Both double bonds have terminal =CH2 groups and internal =CH- groups. The =CH2 groups give CO2, and the =CH- groups give CO2 as well (since -CH= under oxidative ozonolysis gives CO2 from the monosubstituted carbon... actually each =CH- gives formic acid then CO2, and =CH2 gives CO2). So CO2 IS evolved from option (c). (d) Cyclohexene: The double bond is endocyclic between two CH= carbons, each bearing one hydrogen and two ring carbons (i.e., each alkene carbon is -CH= with ring substituents on both sides). Under oxidative ozonolysis, cyclohexene gives a linear dicarboxylic acid (adipic acid, HOOC-(CH2)4-COOH). Neither alkene carbon is a terminal =CH2, so no formaldehyde is produced, and thus no CO2 is generated. The product is a dicarboxylic acid, not CO2. Step 2 - Conclusion: Only cyclohexene (option d) does not produce CO2 upon oxidative ozonolysis, because both alkene carbons are internal (each bears one H and two carbon substituents), yielding carboxylic acid groups rather than CO2. Therefore, the correct answer is D.