Question

Answer the following:
(i) Haloalkanes easily dissolve in organic solvents, why?
(ii) What is known as a racemic mixture ? Give an example.
(iii) Of the two bromoderivatives, `C_6H_5CH (CH_3) Br and C_6H_5CH (C_6H_5)Br`, which one is more reactive in `S_(n^1)` substitution reaction and why?

Answer 1

(i) Haloalkanes are easily dissolve in organic solvents becouse the new forces of attraction set up between holoalkanes and solvent are of the same strength as the forces of attraction being broken between solvent molecules and haloalJltanes. Hence energy released.
(ii) A mixture containing two enantiomers in equal proportions will have zero optical rotation, as the rotation due to one isomer will be canceiled by the rotation due to other isomer. Such a mixture is known as racemic mixture : for example(`pm`) butan-2-ol.
(iii) The carbocation intermediate obtained from `C_6H_5CH (CH_5) Br [ i.e., C_6H_5CH (C_6H_5)^+]` is more stable than that obtained from `C_6H_5CH (CH_3) Br (i.e., C_6H_5 CH (CH_3)^+]` because it is stabilised bg two phenyl groups due to resonance.
For `S_(N^1)` reaction : `C_6H_5CH (C_6H_5) Brgt C_6H_5CH (CH_3) Br`