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JEE Main 2021 · Chemistry · Hydrocarbons · medium

The total number of monochlorinated products, counting stereoisomers separately, obtained from free-radical chlorination of 2-methylbutane is

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The total number of monochlorinated products, counting stereoisomers separately, obtained from free-radical chlorination of 2-methylbutane is
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Answer: 6

2-Methylbutane is (CH3)2CH−CH2−CH3\mathrm{(CH_3)_2CH-CH_2-CH_3} with four distinct types of hydrogen. Chlorination at (i) the two equivalent methyls on C2\mathrm{C_2} gives ClCH2CH(CH3)CH2CH3\mathrm{ClCH_2CH(CH_3)CH_2CH_3}, which has a stereocentre: 22 stereoisomers. (ii) The tertiary carbon gives (CH3)2CClCH2CH3\mathrm{(CH_3)_2CClCH_2CH_3}: 11. (iii) The CH2\mathrm{CH_2} gives (CH3)2CHCHClCH3\mathrm{(CH_3)_2CHCHClCH_3}, which has a stereocentre: 22. (iv) The terminal methyl gives (CH3)2CHCH2CH2Cl\mathrm{(CH_3)_2CHCH_2CH_2Cl}: 11. Total =2+1+2+1=6=2+1+2+1=6.
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