Free radical substitution of alkanes and selectivity

27 questions on Free radical substitution of alkanes and selectivity from the Organic Reaction Mechanisms II: Electrophilic and Radical Reactions chapter: 6 NEET level, 11 JEE Main, 10 JEE Advanced. Each one opens with its answer and solution.

• In the chlorination of methane with Cl2 and light, which equation represents the chain initiation step? NEET level
• The relative ease of abstraction of hydrogen atoms from an alkane by a halogen radical follows the order NEET level
• How many different monochloro products (constitutional isomers) are possible when propane reacts with Cl2 in the presence of light? NEET level
• Which of the following halogens shows the highest selectivity in free radical halogenation of alkanes? NEET level
• Methane is treated with a large excess of Cl2 in sunlight until all hydrogen atoms are substituted. The final organic product is NEET level
• Which of the following is a chain termination step in the chlorination of methane? NEET level
• How many constitutional isomers of monochloro product are obtained when 3-methylpentane, CH3CH2CH(CH3)CH2CH3, is treated with Cl2 and light? (Stereoisomers are ... JEE Main level
• Which one of the following alkanes gives only one monochloro derivative on reaction with Cl2 and light? JEE Main level
• 2-Methylbutane is heated with Br2 in the presence of light. The major monobromo product is JEE Main level
• The greater selectivity of bromination compared with chlorination of alkanes is best explained by the fact that JEE Main level
• Which is the correct order of stability of the following free radicals? (i) CH3. (ii) CH3CH2. (iii) (CH3)2CH. (iv) (CH3)3C. JEE Main level
• Which of the following is a propagation step in the free radical chlorination of ethane? JEE Main level
• Toluene is treated with Cl2 under UV light without any Lewis acid catalyst. The major product is JEE Main level
• In the iodination of methane by I2 and light, the propagation step CH4 + I. -> CH3. + HI is JEE Main level
• Butane is chlorinated with Cl2 and light and the product 2-chlorobutane is isolated. It is obtained as JEE Main level
• Propane is monochlorinated with Cl2 and light at room temperature. Assume the relative reactivity per hydrogen atom is primary : secondary =1 : 3.8. Calculate t... JEE Main level
• Which of the following statements about the free radical chlorination of methane are correct? JEE Main level
• 2-Methylbutane is monochlorinated with Cl2 and light at room temperature. Take the relative reactivity per hydrogen as primary : secondary : tertiary = 1 : 3.8 ... JEE Advanced level
• 2,3-Dimethylbutane, (CH3)2CH-CH(CH3)2, is monochlorinated with Cl2 and light. If the relative reactivity per hydrogen is primary : tertiary = 1 : 5, the ratio o... JEE Advanced level
• 2-Methylbutane is monochlorinated with Cl2 and light. How many monochloro products are possible in total, counting all stereoisomers (enantiomers) as separate c... JEE Advanced level
• 2-Methylbutane reacts with Br2 and light. Relative reactivity per hydrogen is primary : secondary : tertiary = 1 : 82 : 1600. The percentage of 2-bromo-2-methyl... JEE Advanced level
• Use the bond dissociation energies CH3-H = 435, H-Cl = 431 and H-Br = 366 kJ mol^-1. The enthalpy changes (kJ/mol) for the hydrogen abstraction steps CH4 + X. -... JEE Advanced level
• Propylbenzene, C6H5CH2CH2CH3, is treated with Br2 and light. The major monobromo product is JEE Advanced level
• Assertion (A): Free radical bromination of propane gives mainly 2-bromopropane, whereas chlorination gives a considerable amount of 1-chloropropane. Reason (R):... JEE Advanced level
• Isobutane (2-methylpropane) undergoes monohalogenation. Which of the following statements are correct? (Relative reactivity per H in chlorination: primary : ter... JEE Advanced level
• Which of the monochlorination products of 2-methylbutane are chiral? JEE Advanced level
• Which of the following alkanes give only a single monochloro constitutional isomer on reaction with Cl2 and light? JEE Advanced level