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CBSE Class 12 Chemistry 2017 Delhi Set 1 Solved Paper

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Question : 26
Total: 26
(a) Write the product (s) in the following reactions:
(ii) CH3−
CH3
|
CH
−O−CH2−CH3
HI
─────▸
 ? ?
(iii) CH3−CH=CH−CH2−OH
PCC
─────▸
 ?
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
(i) Ethanol and phenol
(ii) Propanol and 2-methylpropan-2-ol
OR
(a) Write the formula of reagents used in the following reactions :
(i) Bromination of phenol to 2, 4, 6-tribromophenol
(ii) Hydroboration of propene and then oxidation to propanol.
(b) Arrange the following compound groups in the increasing order of their property indicated:
(i) p-nitrophenol, ethanol, phenol (acidic character)
(ii) Propanol, Propane, Propanal (boiling point)
(c) Write the mechanism (using curved arrow notation) of the following reaction :
CH3−CH2−
+
O
H2
CH3CH2‌OH
─────▸
 CH3−CH2−
+
O
|
H
−CH2 −CH3+H2O
Solution:  
(a) (i) Acetylation of salicylic acid:
Hence, the products are aspirin and acetic acid.
(ii) CH3−
CH3
|
CH
−O−CH2−CH3
HI
───▸
CH3−
CH3
|
CH
−OH
Isopropyl‌alcohol
+
CH3−CH2−I
Iodoethane
Hence, the products are Isopropyl alcohol and iodoethane.
(iii) CH3−CH=CH−CH2−OH‌ ‌
PCC
────▸
‌
CH3−CH=CH−CHO
But−2−enal
Hence, the product is But-2-enal.
(b) (i) Distinguish between ethanol and phenol:
 Test  Ethanol  Phenol
  Coupling reaction  Negative test  Positive test
Reaction will be :
 Iodoform test  Positive test
Reaction will be :
  Negative test
(ii) Distinction between propanol and 2-methylpropan-2-ol
By Lucas test
CH3−CH2−CH2−OH
Propanol
‌
‌ Conc. HCl ‌
────▸
ZnC2
 Turbidity appears after heating
CH3−
CH3
|
C
|
OH
−CH3
2−Methylpropan−2−ol
 Turbidity appears very quickly
OR
(a) (i) Br2∕H2O
(ii) (BH3)2,H2O2∕OH−
CH3−CH=CH2‌
‌ (a) ‌BH3∕THF
‌ (b) ‌H2O2∕OH
 CH3−CH2−CH2−OH
(b) (i) p-nitrophenol > phenol > ethanol
(ii) propanol > propanal > propane
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