Home
Class 12
CHEMISTRY
Explain the followinng in one or two sen...

Explain the followinng in one or two sentences (i) Displacement of cyanide and amide ion is never observed in nucleophilic substitution reaction.
(ii) RCl is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture.

Text Solution

Verified by Experts

(i) HCN `(pK_(a)10) and NH_(3)(pK_(a)11.25)` are very weak acids. Therefore, their conjugate bases, i.e., `CN^(-)` ion and `NH_(2)^(-)` are very strong bases. Since strong bases are bad leaving groups, their displacement in nucleophilic substitution reactions is never observed.
(ii) Iodide ion is a powerful nucleophile and hence reacts rapidly with RCl to form RI.

Further because `I^(-)` ion is a better leaving group than `Cl^(-)` ion, therefore, RI is more rapidly hydrolysed than RCl to form ROH, .
The `I^(-)` ion thus regenerated recycles in the above reaction thereby explaining its catalytic effect.
Promotional Banner

Topper's Solved these Questions

  • HALOALKANES AND HALOARENES

    PRADEEP|Exercise HOTS PROBLEMS|1 Videos

  • HALOALKANES AND HALOARENES

    PRADEEP|Exercise VALUE BASED QUESTIONS WITH ANSWERS|4 Videos

  • HALOALKANES AND HALOARENES

    PRADEEP|Exercise ADDITIONAL QUESTIONS (LONG ANSWER QUESTIONS)|4 Videos

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    PRADEEP|Exercise Curiosity Questions|2 Videos

  • ORGANIC COMPOUNDS CONTAINING NITROGEN

    PRADEEP|Exercise IMPORTANT QUESTIONS FOR BOARD EXAMINATION|27 Videos

Similar Questions

Explore conceptually related problems

RCI is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture. Explain.

RCI is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture. Explain.

Explain why displacement of cyanide ion and amide ion by other nucleophiles is not observed in nucleophilic substitution reaction.

(i) Why are haloalkanes more reactive towards nucleophilic substitution reaction than haloarenes ? (ii) Which one of the following two substance sundergoes S_(N)1 reaction faster and why ?

Statement-I: Nucleophilic substitution reaction on an optically active alkyl halide gives a mixture of enantiomers. Because Statement-II: The reaction occurs by S_(N^(1)) mechanism.

(a) Aryl halides are less reactive in nucleophilic substitution reactions. (i) Write any two reasons for less reactivity. (ii) Give one example for nucleophilic substitution reactions of aryl halides (b) Write a method for the preparation of alkyl halides. (c) Which of the following is not a polyhalogen compound. (i) Chloroform (ii) Freon (iii) Carbon tetrachloride (iv) Chlorobenzene