Q25 of 26 Page 1

An aromatic compound ‘A’ of molecular formula C7H7ON undergoes a series of reactions as shown below. Write the structure of A,B,C,D and E in the following reactions:


OR


(a) Write the structures of main products when aniline reacts with the following reagents:


(i) Br2 water


(ii) HCl


(iii) (CH3CO)2O/pyridine


(b) Arrange the following in the increasing order of their boiling point:


C2H5NH2 , C2H5OH, (CH3)3N


(c) Give a simple chemical test to distinguish between the following pair of compounds:


(CH3)2NH, (CH3)3N


(Hoffmann degradation)

(A= benzamide)


(B = diazonium salt)


(C= benzene)


(D = phenyl isocyanide)


(E= iodobenzene)


OR


(a)


Bromine water reacts with aniline to give 2,4,6-tribomoaniline.


(ii)


Aniline is a weak base. It donate the lone pair on nitrogen to proton from HCl to form phenyl ammonium chloride.


(iii)


Aniline reacts with acetic anhydride to give acetanilide. Aniline acts as a weak base, while acetic anhydride acts as electrophile.


(b) (CH3)3N < C2H5NH2 < C2H5OH


Amines and alcohols form hydrogen bonding but the hydrogen bonding in alcohols it stronger than in amines due to greater electronegativity of oxygen with respect to nitrogen. In the above question we have a primary amine, primary alcohol and a tertiary ammine. Tertiary ammine does not have hydrogen on nitrogen so no hydrogen bonding hence has the least boiling point out of the given three.


Then the primary amine has higher boiling point due to weak hydrogen bonding, while alcohol has the highest boiling point due to strong hydrogen bonding out of the given three.


(c) (CH3)2NH is a secondary amine while (CH3)3N is a tertiary amine. Hinsberg’s test is used to differentiate between primary, secondary and tertiary amines. The amines are reacted with benzene sulfonyl chloride and depending on the type of product obtained they confirmed.


(sulphonamine insoluble in base)



More from this chapter

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22

Give reasons:

(a) n-Butyl bromide has higher boiling point than t-Butylbromide.


(b) Racemic mixture is optically inactive.


(c) The presence of nitro(-NO2) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions.


 23

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

After reading the above passage answer the following:


(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?


 24

(a) Account the following:

(i) Acidic character increases from HF to HI.


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


(iii) Nitrogen does not form pentahalide.


(b) Draw the structures of the following:


(i) ClF3 : it has a bent –T shape


(ii) XeF4 : it has square planar geometry.


OR


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


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


(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 equation:



 26

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


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


(ii) Calculate the average rate of reaction, between the time interval30 and 60 seconds. (given: log 2= 0.3010, log 4 = 0.6021)


OR


(a) For a reaction , the rate is given by Rate


(i) How is the rate of reaction effected 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. (log 2 =0.3010)