Weekly Assignment-6
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anish.chandrasekar.bloreWeekly Assignment-6
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anish.chandrasekar.bloreHYDROCARBONS
1. Why Wurtz reaction is not used for obtaining hydrocarbon containing odd no. of carbon atoms?
2. Sodium salt of which acid will be needed for the preparation of propane? Write chemical
equation for the reaction.
3. Write the isomers of pentane and arrange them in increasing order of b.p.
2,2-dimethylpropane < 2-methylbutane < Pentane .
4. Among staggered and eclipsed conformations, which is more stable and why?
I Important Questions
5.Write a short note on
a.Wurtz reaction b. Kolbes electrolytic method c. Decarboxylation
d. Aromatisation e. Isomerisation f. Pyrolysis
6. Convert
a. Methane to ethane
b. Butanoic acid to propane
c. Butanoic acid to hexane
d. Ethane to butane
e. Acetic acid to ethane
f. Hexane to benzene
7. Among staggered and eclipsed conformations, which is more stable and why?
8. Draw the Newman and Sawhorse projection formulae of staggered and eclipsed conformation of
ethane.
9. What is conformations? Name the two conformations of ethane.
10. Write the isomers of pentane and arrange them in increasing order of b.p.
11. How can you prepare 2, 3- Dimethyl butane by wurtz reaction?
12. Complete the following reactions:
13.convert
1.methane to ethane 2.sodium acetate to ethane 3.sodium acetate to methane
4.ethyl chloride to butane 5.sodium propanoate to butane 6.hexane to benzene
14. Draw the geometrical or cis-trans isomers of but-2-ene: CH3CH═CHCH3
15. Among cis and trans isomer, which has high boiling point and why?
16. Draw cis and trans isomers of the following compounds. Also write their IUPAC names :
(i) CHCl = CHCl (ii) C2H5CCH3 = CCH3C2H5
17. Which of the following compounds will show cis-trans isomerism?
(i) (CH3)2C = CH – C2H5 (ii) CH2 = CBr2 (iii) C6H5CH = CH – CH3 (iv) CH3CH = CClCH3 (iv)
propene.
18. Write IUPAC names of the products obtained by addition reactions of HBr to hex-1-ene
(i) in the absence of peroxide an(ii) in the presence of peroxide
II Important Questions
19.Write a short note on
i. Markownikov’s rule ii. Anti - Markownikov’s rule/ peroxide effect /Kharash effect
iii. β-elimination reaction iv. Ozonolysis
20. Write IUPAC names of the products obtained by the ozonolysis of the following compounds :
(i) Pent-2-ene (ii) 3,4-Dimethylhept-3-ene (iii) 2-Ethylbut-1-ene (iv) 1-Phenylbut-1-ene
21. An alkene ‘A’on ozonolysis gives a mixture of ethanal and pentan-3-one. Write structure and
IUPAC name of ‘A’.
22. Propanal and pentan-3-one are the ozonolysis products of an alkene? What is the structural
formula of the alkene?
23. An unknown alkene A on ozonolysis gives two isomeric carbonyl compounds B and C of the
molecular formula C3H6O. Write the structure of A, B and C.
24. Write chemical equations for combustion reaction of the following hydrocarbons:
(i) Butane (ii) Pentene (iii) Hexyne (iv) Toluene
25. What effect does branching of an alkane chain has on its boiling point?
26. Draw the cis and trans structures of hex-2-ene. Which isomer will have higher b.p. and high
meling point and why?
27. Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide,
the same reaction yields 1-bromopropane. Explain.
28. How will you detect the presence of unsaturation in an organic compound?
29. Convert
i. 2- Bromopropane to 1- Bromopropane ii. 1-Bromopropane to 2- Bromopropane
iii. Propan -1-ol to propene
30. Give the structure of alkene (C4H8) which adds on HBr in presence and in the absence of
peroxide to give the same product C4H9Br.
31. What happens when ethanol is heated with conc, H2SO4 at 443K?
32. Which of the following exhibits geometrical isomerism?
i. 2- methylpropene ii. 1- Butene iii. 2-Butene iv. 2,3-Dibromobutene
33. Complete the reaction
34. Arrange in decreasing order of acidic character.
i. Ethyne , Ethene , Ethane
ii. Ethyne , Propyne , But-2-yne
iii. Ethyne ,exane , Benzene
35. Why is benzene extra ordinarily stable though it contains three double bonds?
36. What are the necessary conditions for any system to be aromatic? [Explain Huckel rule]
37. Explain why the following systems are not aromatic?
38. How will you convert benzene into
(i) p-nitrobromobenzene (ii) m- nitrochlorobenzene (iii) p – nitrotoluene (iv) acetophenone?
39. In the alkane H3C -CH2- C(CH3)2 – CH2 -CH(CH3)2, identify 1°,2°,3° carbon atoms .
40. Arrange benzene, n-hexane and ethyne in decreasing order of acidic behaviour. Give reason.
41. Why does benzene undergo electrophilic substitution reactions easily and nucleophilic
substitutions with difficulty? Ans. Benzene ring is electron rich with 6 ∏ electrons
42. How would you convert the following compounds into benzene? (i) Ethyne (ii) Ethene (iii)
Hexane
43. Arrange the following compounds in order of their decreasing relative reactivity with an
electrophile, E+
(a) Chlorobenzene > p-nitrochlorobenzene > 2,4-dinitrochlorobenzene
(b) Toluene > p-H3C -C6H4 – NO2 > p-O2N-C6H4 – NO2.
44. Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and
why