Q21 of 26 Page 1

Give reasons for the following:

(i) Benzyl chloride is highly reactive towards the SN1 reaction.


(ii) 2-bromobutane is optically active but 1-bromobutane is optically inactive.


(iii) Electrophilic reactions in haloarenes occur slowly.


(i) The rate of reaction of SN1 reaction depends on stability of carbocation formed. The benzyl carbocation formed after removal of Cl is highly stabilized by resonance effect and thus, it is highly reactive towards the SN1 reaction.



(ii) 2-bromobutane is optically active but 1-bromobutane is optically inactive because 2-bromobutane have a chiral (all 4 groups attached to C* are different) carbon whereas 1-bromobutane is achiral.



(2-bromobutane)


(iii) In haloarenes, due to resonance the electron density increases on ortho and para position than at meta position. Further due to –I effect halogen has the tendency to withdraw electrons from benzene ring and hence the ring gets deactivated as compared to benzene. Hence, ESR of haloarenes occurs slowly.


More from this chapter

All 26 →
19

(i) MnO is basic whereas Mn2O7 is acidic in nature. Why?

(ii) Transition metals form alloys. Why?


(iii) Complete the following equation:


2 MnO2 + 4 KOH + O2→


 20

(i) What type of isomerism is shown by the complex [Ag(NH3)2][Ag(CN)2]?

(ii) On the basis of crystal field theory, write the electronic configuration for d4 ion if ΔO<P.


(iii) Write the hybridization and shape of [Ni(CN)4]2-. (Atomic number of Ni = 28)


 22

How do you convert the following:

(i) Aniline to phenol


(ii) Prop-1-ene to Propan-1-ol


(iii) Anisole to 2-methoxytoluene


OR


What happens when


(i) ethanol is treated with Cu at 573 K,


(ii) phenol is treated with CH3COCl / anhydrous AlCl3,


(iii) ethyl chloride is treated with NaOCH3 ?


Write chemical equations in support of your answer.


 23

Mr. Roy, the principal of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They all resolved this issue by strictly banning junk food in schools and introducing healthy snacks and drinks like soup, lassi, milk, etc. in school canteens. They also decided to make compulsory half an hour of daily physical activities for the students in the morning assembly. After six months, Mr. Roy conducted the health survey in most of the schools and discovered a tremendous improvement in the health of the students. After reading the above passage, answer the following questions:

(i) What are the values (at least two) displayed by Mr. Roy?


(ii) As a student, how can you spread awareness about this issue?


(iii) What are tranquilizers? Give an example.


(iv) Why is use of aspartame limited to cold foods and drinks?