Carbenes and nitrenes

27 questions on Carbenes and nitrenes from the General Organic Chemistry III: Reaction Intermediates chapter: 5 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• How many electrons are present in the valence shell of the carbon atom of a carbene such as :CH2? NEET level
• In singlet methylene, :CH2, the carbon atom is best described as NEET level
• Dichlorocarbene, :CCl2, is conveniently generated in the laboratory by treating NEET level
• In the Reimer-Tiemann reaction (phenol, CHCl3, aqueous NaOH, then acid), the electrophile that attacks the phenoxide ring is NEET level
• A nitrene, R-N:, is best described as NEET level
• cis-But-2-ene is treated with CH2I2 and a zinc-copper couple in ether (Simmons-Smith reaction). The product is JEE Main level
• trans-But-2-ene reacts with singlet dichlorocarbene (from CHCl3 and t-BuOK). Which statement describes the product correctly? JEE Main level
• Pyrrole is heated with chloroform and sodium ethoxide (Ciamician-Dennstedt rearrangement). The main product is JEE Main level
• Propanoic acid is converted to its acid chloride with SOCl2, which is treated with excess diazomethane. The product is then heated with Ag2O and water. The fina... JEE Main level
• Singlet dichlorocarbene :CCl2 is much less reactive and more selective than singlet :CH2. The main reason is that JEE Main level
• The relative rates at which dichlorocarbene (an electrophilic carbene) adds to alkenes increase with alkyl substitution of the double bond. Which alkene reacts ... JEE Main level
• Singlet methylene :CH2 inserts into C-H bonds of 2-methylpropane, (CH3)3CH. Assume that the insertion is completely unselective, with every C-H bond equally lik... JEE Main level
• Which statement about the ground states of the simplest carbenes is correct? JEE Main level
• Singlet methylene :CH2 inserts into the C-H bonds of 2-methylbutane, (CH3)2CH-CH2-CH3. How many different constitutional isomers of C6H14 can be formed? (Count ... JEE Main level
• Which of the following reagent systems can serve as a source of dichlorocarbene, :CCl2? JEE Main level
• Which of the following reactive intermediates have only six electrons in the valence shell of the central atom? JEE Main level
• (S)-2-Methylbutanamide, CH3CH2-CH(CH3)-CONH2, is treated with Br2 and aqueous NaOH (Hofmann degradation). The product is JEE Advanced level
• 2-Diazo-1-phenylethanone, C6H5-CO-CHN2, is heated with Ag2O in methanol. The main organic product is JEE Advanced level
• 4-Methylphenol (p-cresol) is heated with CHCl3 and aqueous NaOH, and the mixture is then acidified. The major product is JEE Advanced level
• Singlet ethoxycarbonylnitrene, EtO2C-N:, is generated by photolysis of ethyl azidoformate in the presence of (E)-but-2-ene. The nitrene adds to the double bond ... JEE Advanced level
• Dichlorocarbene is an electrophile. Its addition to para-substituted styrenes p-X-C6H4-CH=CH2 is faster when the ring is electron-rich. Which is the correct ord... JEE Advanced level
• Benzoyl azide, C6H5-CO-N3, is heated in dry ethanol until nitrogen evolution stops. The main organic product is JEE Advanced level
• Hexanediamide, H2N-CO-(CH2)4-CO-NH2, is treated with excess Br2 and aqueous NaOH. The organic product is JEE Advanced level
• In which of the following reactions is dichlorocarbene the species that attacks the organic substrate? JEE Advanced level
• Which of the following statements about singlet and triplet methylene are correct? JEE Advanced level
• Which of the following statements about the Hofmann and Curtius rearrangements are correct? JEE Advanced level
• Racemic 3-methylcyclohexene reacts with singlet dichlorocarbene to give 7,7-dichloro-2-methylbicyclo[4.1.0]heptane. The cyclopropane ring can only be cis-fused ... JEE Advanced level