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Question 12.2:, Write the structures of products of the following reactions;, (i), , (ii), (iii), , (iv), , Answer, i., , ii., , iii., , 37
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(iv), , Question 12.3:, Arrange the following compounds in increasing order of their boiling points., CH3CHO, CH3CH2OH, CH3OCH3, CH3CH2CH3, Answer, The molecular masses of the given compounds are in the range 44 to 46. CH3CH2OH, undergoes extensive intermolecular H-bonding, resulting in the association of molecules., Therefore, it has the highest boiling point. CH 3CHO is more polar than CH3OCH3 and so, CH3CHO has stronger intermolecular dipole − dipole attraction than CH 3OCH3 CH3CH2CH3, has only weak van der Waals force. Thus, the arrangement of the given compounds in the, increasing order of their boiling points is given by:, CH3CH2CH3 < CH3OCH3 < CH3CHO < CH3CH2OH, Question 12.4:, 38
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Question 12.5:, Predict the products of the following reactions: (i), , (ii), , (iii), , (iv), , Answer, (i), , (ii), , (iii), , 40
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(ii), , (iii), , (iv), , Question 12.8:, Which acid of each pair shown here would you expect to be stronger?, (i) CH3CO2H or CH2FCO2H, (ii)CH2FCO2H or CH2ClCO2H, (iii) CH2FCH2CH2CO2H or CH3CHFCH2CO2H, , 42
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(iv), , Answer, (i), , The +I effect of −CH3 group increases the electron density on the O−H bond. Therefore,, release of proton becomes difficult. On the other hand, the −I effect of F decreases the, electron density on the O−H bond. Therefore, proton can be released easily. Hence,, CH2FCO2H is a stronger acid than CH3CO2H., (ii), , F has stronger −I effect than Cl. Therefore, CH 2FCO2H can release proton more easily than, CH2ClCO2H. Hence, CH2FCO2H is stronger acid than CH2ClCO2H., (iii), , Inductive effect decreases with increase in distance. Hence, the +I effect of F in, CH3CHFCH2CO2H is more than it is in CH2FCH2CH2CO2H. Hence, CH3CHFCH2CO2H is, stronger acid than CH2FCH2CH2CO2H., , 43
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(iv), , Due to the −I effect of F, it is easier to release proton in the case of compound (A)., However, in the case of compound (B), release of proton is difficult due to the +I effect of, −CH3 group. Hence, (A) is a stronger acid than (B)., , 44