Q25 of 22 Page 1

An aromatic compound ‘A’ of molecular formula C7H6O2 undergoes a series of reactions as shown below. Write the structures of A, B, C, D and E in the following reactions:


OR


(a) Write the structures of main products when benzene diazonium chloride reacts with the following reagents:


(i) H3PO2 + H2O


(ii) CuCN/KCN


(iii) H2O


(b) Arrange the following in the increasing order of their basic character in an aqueous solution: C2H5NH2, (C2H5)2NH, (C2H5)3N


(c) Give a simple chemical test to distinguish between the following pair of compounds: C6H5-NH2 and C6H5-NH-CH3.



A = C6H5COOH (benzoic acid)


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B = C6H5NH2 (aniline) (formed from Hoffmann bromamide degradation)


7.png


C = C6H5NHCOCH3 (N-phenyl ethanamide also called acetanilide)


7.png


D = C6H5CH2NH2 (benzylamine) (amides on reaction with LiAlH4 yields amines)


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E = 2, 4, 6- tribromoaniline (aniline on reaction with bromine water gives 2, 4, 6- tribromoaniline)


8.png


OR


(a)


(i) Benzene diazonium chloride is reduced to benzene. H3PO2 itself is oxidized to phosphorous acid. Nitrogen formed escapes as gas.


EQ3.jpg


(ii) This reaction is done to introduce a –CN group on benzene and is known as Sandmeyer’s reaction.


EQ1.pngEQ2.jpg


(iii) This reaction is done to introduce –OH group on benzene thereby forming phenol.


(b) For ethyl substituted amines, order of basicity is 2°>3°>1°.


This order is concluded from considering a subtle interplay of inductive effect, solvation effect and steric hinderance of alkyl group. Therefore, the order of basic strength is C2H5NH2 < (C2H5)3N < (C2H5)2NH


(c) Benzenesulphonyl chloride which is also known as Hinsberg’s Reagent reacts differently with primary and secondary amines.


C6H5SOCl + C6H5NH2 ¾ C6H5SONHC6H5


N- phenylbenzenesulphonamide


The ‘H’ attached to nitrogen in product i.e. sulphonamide is strongly acidic due to presence of strong electron withdrawing sulphonyl group. Hence, the product formed is soluble in alkali.


C6H5SOCl + C6H5NHCH3 ¾ C6H5SON(C6H5)CH3


N,N- Diphenylbenzenesulphonamide


This compound formed does not have any H- atom attached to N- atom. Hence, it is not acidic and product is insoluble n alkali.


More from this chapter

All 22 →
22

Write the names and structures of the monomers of the following polymers:

(i) Terylene


(ii) Buna-S


(iii) Neoprene


 23

Seeing the growing cases of diabetes and depression among young children, Mr. Chopra, the principal of one reputed school organized a seminar in which he invited parents and principals. 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. Chopra 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. Chopra? (ii) As a student, how can you spread awareness about this issue? (iii) Why should antidepressant drugs not be taken without consulting a doctor? (iv) Give two examples of artificial sweeteners.


 24

(a) Account for the following:

(i) Acidic character increases from HF to HI.


(ii) There is a large difference between the melting and boiling points of oxygen and sulphur.


(iii) Nitrogen does not form pentahalide.


(b) Draw the structures of the following:


(i) ClF3 (ii) XeF4


OR


(i) Which allotrope of phosphorus is reactive and why?


(ii) How are the supersonic jet aeroplanes responsible for the depletion of ozone layer?


(iii) F2 has lower bond dissociation enthalpy than Cl2. Why?


(iv) Which noble gas is used in filling balloons for meteorological observations?


(v) Complete the following equation: XeF2 + PF5 →


 26

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained:

t/s 0 10 20


[CH3COOCH3]/mol L-1 0.10 0.05 0.025


(a) Show that it follows pseudo first order reaction, as the concentration of water remains constant.


(b) Calculate the average rate of reaction between the time intervals 10 to 20 seconds. (Given: log 2 = 0.3010, log 4 = 0.6021)


OR


(a) For a reaction A + B → P, the rate is given by


Rate = k [A][B]2


(i) How is the rate of reaction affected if the concentration of B is doubled? (ii) What is the overall order of reaction if A is present in large excess?


(b) A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.