Saturday, October 18, 2008

Organic-3

1. Explain (a) Sulphanilic acids are soluble in dilute NaOH but not in dil.HCl.(b) The amphoteric nature of amide
2. .Draw the structure of optically active unsaturated compound having molecular formula C5H9Br that after addition of H2 becomes either optically active or show optical activity
3. 30.Write the mechanism of (a) Reimer Tiemann reaction (b) Esterification (c) Kolbe Synthesis
4. What is Lucas reagent?
5. How ill you convert phenol to aspirin? Give chemical equations.
6. What is oxoprocess? For what purpose it is used?
7. Explain why glycerol has high viscosity and is miscible with water in all proportion?
8. Which of the following are optically active compounds and why: (a) n-butyl bromide (b) secondary butyl chloride (c) isobutyl chloride (d) tertiary butyl chloride
9. What is a nitrating mixture?
10. Phenol is a very weak acid. What substitutions in the molecule can make it a stronger acid and a weaker acid & why?
11. Give the structural formulae and names of the products of the following reactions: (i) Chloroform is heated with aniline in presence of alc. KOH (ii) Phenol is treated with an excess of aqueous bromine
12. Write chemical equations for what happens when:- (i) 2-methyl-2-propanol vapours are passed over heated copper. (ii) A glyceride is treated with sodium hydroxide solution.
13. Give chemical test to distinguish between the following pairs of compounds 2-butanol and 2-methyl-2-propanol.
14. Account for the following:-(i) Methyl amine in water reacts with FeCl3 to precipitate ferric hydroxide. (ii) Arenes are more easily nitrated than aliphatic hydrocarbons.
15. Out of benzene & phenol which is more easily nitrated and why?
16. A sweet smelling organic compound ‘A’ is slowly oxidized by air in presence of light to a highly poisonous gas. On warming with Ag powder, it forms a gaseous substance ‘B’ which is also produced by action of calcium carbide on water. Identify ‘A’ & ‘B’ and write the equations of the reactions involved.
17. What is meant by (i) Absolute alcohol (ii) Methylated spirit (iii) Denatured spirit?
18. Write structures of the compounds whose IUPAC names are as follows:- (i) 2-Methylbutan-2-ol (ii) 1-Phenylpropan-2-ol (iii) 3,5-Dimethylhexane-1,3,5-triol (iv) 2,3-Diethylphenol (v) 1-Ethoxypropane (vi) 3-Methyl-2-ethoxypentane (vii) Cyclohexylmethanol
19. Draw the structures of all isomeric alcohols of molecular formula C5H12O and give their IUAPC names. Classify them as primary, secondary and tertiary alcohols.
20. Explain why is propanol higher boiling than butane.
21. Explain why are alcohols comparatively more soluble in water than the corresponding hydrocarbons.
22. Write equations for preparation of Propan-2-ol, from (i) an alkene, and (ii) A Grignard reagent.
23. Write notes on:- (i) oxymercuration-demercuration, and(ii) hydroboration
24. Give the structures and IUPAC names of monohydric phenols of molecular formula C7H8O
25. While separating a mixture of otho and para nitrophenols by steam distillation, name the isomer which is steam volatile.Give reason.
26. Give the equation of reaction of preparation of phenol from cumene.
27. You are given benzene, conc. H2SO4 and NaOH. Write the equation for the preparation of phenol using these reagents.
28. Give two reactions that show the acidic nature of phenol. Compare its acidity with that of ethanol.
29. Explain why is ortho-nitrophenol more acidic than ortho-methoxyphenol?
30. Explain how does the –OH group attached to a carbon of benzene ring activates it towards electrophillic substitution?
31. Give the equations of the following reactions:-
32. reaction of propene with mercuric acetate followed by hydrolysis (ii) oxidation of propan-1-ol with alkaline KMnO4 solution. (iii) reaction of bromine in CS2 with phenol. (iv) action of dilute HNO3 with phenol (v) treating phenol with chloroform in presence of aqueous NaOH at 343 K.
33. Write short notes on:- (i) Kolbe reaction, (ii) Reimer-Tiemann reaction.
34. How are the following conversion carried out? (i) Propane Propan-2-ol (ii) Benzylchloride Benzyl alcohol (iii) Ethyl magnesium chloride Propan-1-ol (iv) Methyl magnesium bromide 2-methylpropan-2-ol
35. How will you prepare butan-1-ol from (i) 1-bromobutane and (ii) a suitable alkene?
36. Name the reagents used in the following reactions:- (i) oxidation of a primary alcohol to carboxylic acid (ii) oxidation of a primary alcohol to an aldehyde (iii) bromination of phenol to 2,4,6-tribromophenol (iv)benzyl alcohol to benzoic acid (v) dehydration of propan-2-ol to propene (vi) butan-2-one to butan-2-ol
37. How is ethane-1,2 diol prepare from (i) ethane (ii) ethylene oxide and (iii) 1,2-dibromoethane?
38. How is glycerol obtained as a by-product of soap industry? Write the equation of nitration of glycerol?
39. Write the names of reagents and equations for the preparation of the following ethers by Williamson synthesis: (i) 1-propoxypropane, (ii) Ethoxybenzene (iii) 2-methyl-2-methoxypropane and (iv) 1-methoxyethane
40. Illustrate with examples the limitations of Williamson Synthesis for the preparation of certain types of ethers.
41. How is 1-propoxypropane synthesized from propan-1-ol?
42. Preparation of ethers by acid dehydration of secondary ot tertiary alcohols is not a suitable method.Give reason.
43. Write the equation of the reaction of hydrogen iodide with:-
44. 1-Propoxypropanae (ii) methoxybenzene and (iii) Benzyl ethyl ether.
45. Write equations for the following reactions:- (i) Friedal Crafts reaction-alkylation in anisole (ii) Nitration of anisole (iii) Bromination of anisole in ethanoic acid medium and (iv) Friedal Crafts acetylation of anisole
46. Give mechanisms of following reactions: (a) Alcohol to ether (b)Alcohol to alkene
47. Dsitinguish between the following by suitable chemical test: (a) Phenol and benzoic acid (b) Ethanol and diethyl ether.
48. Write short notes on the following reactions: (a) Reimer-Teimeann Reaction (b) Kolbe’s reaction (c) Williamson synthesis
49. Convert he following reactions:- (a) C2H5OH + NH3 (b) (CH3)3CCl + KOH(alc.)
50. (c) CH3OH + CO (d) (CH3)3COH
51. Which of the following compounds would undergo aldol condensation, which the Cannizaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizaro reaction. (a) Methanal (b) 2-Methylpentanal (c) Benzaldehyde (d) Benzophenone (e) Cyclohexanone (f) 1-Phenylpropanone (g) Phenylacetaldehyde (h) Butan-1-ol (i) 2,2-Dimethylbutanal
52. How will you convert acetaldehyde into the following compounds? (a) Butan-2-one (b) Butane-1,3-diol (c) Buta-2-enal (d) Butan-1-ol (e) Butanoic acid (f) Buta-2-enoic acid
53. Write structural formulae and names of the four possible aldol condensation products from propanal and butanal. In each case, indicate which aldehyde served as nucleophile and which as elctrophile.
54. An organic compound with the molecular formula C9H10O forms 2,4-DNP derivative reduces Tollen’s reagent and undergoes Cannizaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.
55. An organic compound (A) [Molecular formula C8H16O2] was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic acid produced (B) Write possible structures of (A) and give their IUPAC names. Also write equations for the reactions involved.
56. N,N-Diethyl-m-toluamide is an active ingredient in many insect-repellant preparations. How will you prepare this compound from m-bromotoluene?
57. Give simple chemical tests to distinguish between the following pairs of compounds: (a) Propanal & Propanone (b) Methyl acetate and Ethyl acetate (c) Phenol & Benzoic acid (d) Benzoic acid and Ethyl benzoate (e) Benzamide and p-Aminobenzoic acid (f) Propanal & Diethyl ether. (g) Ethanal & Propanal (h) Propanoyl chloride and Propanoic acid.
58. How will you prepare the following compounds from benzene? Youmay use any inorganic reagent and any organic reagent having not more than one carbon atom.
59. Methyl benzoate (b) m-Nitrobenzoic acid (c) p-Nitrobenzoic acid (d) Phenyl acetic acid (e) p-Nitrobenzaldehyde.
60. How will you bring about the following conversions in not more than two steps? (a) Propanone to Porpene (b) Propanal to Butanone (c) Ethanol to 3-Hydroxybutnal (d) Benzaldehyde to Benzophenone (e) Benzaldehyde to 3-Phenylpropan-1-ol (f) Benzaldehyde to α-Hydroxyphenylacetic acid(g) Benzoic acid to Benzaldehyde (h) Propanoyl Chloride to Diproppyl amine (i) Propanoic acid to propenoic acid (j) Benzene to m-Nitroacetophenone (k) Bromobenzene to 1-Phenylethnaol (l) Benzoyl chloride to Benzonitrile (m) Benzoic acid to m-Nitrobenzyl alcohol.
61. Describe the following:- (a) Acetylation (b) Cannizaro reaction (c) Trans-esterification (d) Decarboxylation (e) Cross aldol condensation (f) Hoffmann bromide reaction (g) Saponification.
62. Give plausible explanation for each of the following: (a) Cyclohexanone from cyanohydrin in good yield but 2,2,6-trimethylcyclohexanone does not. (b) There are two –NH2 groups in semicarbazide. How ever, only one is involved in the formation of semicarbazones. (c) During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst, the water or the ester should be removed as fast as it is formed.
63. Why do nitro compounds have higher boiling points than the hydrocarbons having almost molecular mass?
64. How would you prepare p-nitroaniline from aniline?
65. Explain what happens when aniline reacts with a mixture of sulphuric acid and nitric acid?
66. How is nitrobenzene converted into aniline under neutral conditions?
67. Explain why does nitrobenzene on nitration with nitric acid and sulphuric acid from only m-dinitrobenzene?
68. How will you prepare 1-nitropropene from acetaldehyde?
69. How can you convert 2-nitropropane to acetone?
70. Write structures for the following compounds? (a) Butyronitrile (b) Phenylacetonitrile (c) Propylcarbylamine.
71. Why is acetonitrile preferred as a solvent for running organic reactions?
72. Explain the role of mineral acid in the reaction of a carbonyl compound with aq. KCN?
73. How is that a ketone reacts with Grignard reagent to form a tertiary alcohol but in the reaction of a nitrile with Grignard reagent reagent, a ketone is formed?
74. How will you convert benzonitrile to acetophenone (C6H5COCH3)?
75. Draw structures for the following compounds: (a)N-isopropylaniline (b) p-toluidine (c) tert.butylamine
76. Arrange the following sets in order of their basic strength: (a) Ethyl amine, Ammonia and Triethylamine (b) Aniline, p-nitroaniline, p-toluidine
77. How will you prepare a pure sample of a primary amine from a primary alkyl halide?
78. How will you convert alkyl an alkyl halide into a primary amine having one carbon atom less than the alkyl halide used?
79. How can a carboxylic acid be converted to an amine having one carbon atom less than the alkyl halide used?
80. Explain the observed Kb order: Et2NH > Et3N>EtNH2 in aqueous solution where Et is ethyl.
81. What will be the basic strength order of EtNH2, Et2NH, Et3N in gas phase? Explain.
82. Why are amines less acidic than comparable alcohols?
83. Why are primary amines higher boiling than tertiary amines?
84. Why are aromatic amines weaker bases than aliphatic amines?
85. How can you find out whether a given amine is a primary amine? Write the chemical reaction involved in the test you perform.
86. How can you separate a mixture of primary, secondary and tertiary amines? Write chemical reaction involved in the process.
87. How do aromatic and aliphatic tertiary amines react with nitrous acid?
88. Explain how does the presence or absence of hydrogen on N of maines affect the modes of their reactions with nitrous acid?
89. How ill you prepare ethyl amine from acetaldehyde?
90. Amino group is o,p-directing for aromatic electrophillic substitution. Why does aniline on nitration gives a substantial amount of m-nitroaniline?
91. Why does bromination of nailine, even under very mild conditions give 2,3,5-tribromoaniline instaneously?
92. How can you convert p-toluidine to 2-bromo-4-methylaniline?
93. How can you convert aniline to iodobenzene?
94. How can you convert benzonitrile from aniline?
95. Why is an amide more acidic than an amine?
96. How to converted Nitro compound into aldehyde &Ketone ?

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