Important Hydrocarbons Formulas for JEE and NEET

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?  Points to remember in Alkane
Wurtz reaction (Reagent : Na, ether) 1º & 2º alkyl halides give this
reaction.
R ? X + 2Na ? ? ? ? ?
ether
   R ? R ; R ? X + R? ? X  + 2Na
? ? ? ? ?
ether
 R ? R?  + R ? R + R? ? R?
   + 2Na 
? ? ? ? ?
ether
  
?  Points to remember in Alkene & Alkyne
Characteristic reaction of Alkene & Alkyne is Electrophilic addition reaction.
Mechanism
Step 1 : Attack of the electrophile on ? bond forms a carbocation.
C = C +  E ? C ? C
+
|
|
E
+ on the more substituted carbon
+
Step 2 : Attack by a nucleophile gives the product of addition.
? C ? C +  Nu:
+
|
|
E
     
Nu E
| |
C C
| |
? ? ?
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?  Points to remember in Alkane
Wurtz reaction (Reagent : Na, ether) 1º & 2º alkyl halides give this
reaction.
R ? X + 2Na ? ? ? ? ?
ether
   R ? R ; R ? X + R? ? X  + 2Na
? ? ? ? ?
ether
 R ? R?  + R ? R + R? ? R?
   + 2Na 
? ? ? ? ?
ether
  
?  Points to remember in Alkene & Alkyne
Characteristic reaction of Alkene & Alkyne is Electrophilic addition reaction.
Mechanism
Step 1 : Attack of the electrophile on ? bond forms a carbocation.
C = C +  E ? C ? C
+
|
|
E
+ on the more substituted carbon
+
Step 2 : Attack by a nucleophile gives the product of addition.
? C ? C +  Nu:
+
|
|
E
     
Nu E
| |
C C
| |
? ? ?
  
e.g. (a) Addition of water +  H
2
O    
(b) Addition of hydrogen halides (where HX = HCl, HBr, HI)
R ? C ? C ? R? ? ? ? ?
?X H
 
) addition v Markovniko (
R CX CH R ? ? ? ?
? ? ? ?
?X H
X H
| |
R C C R
| |
X H
? ? ? ?
Note: When electrophiles are: Cl
+
, Br
+
, I
+
, NO
2
+ 
or Hg
2+
 then stereochemistry is
important and major product is formed by anti addition.
?  Points to remember in Alkyl halide
Nucleophilic substitution Reaction (S
N
1, S
N
2)
S
N
1 reaction :
R?X + H
2
O 
3
AgNO
???? ?
 R
+
 + AgX?
?? ?
ROH (R may rearrange)
Alkylhalide are hydrolysed to alcohol very slowly by water, but rapidly by
silver oxide suspended in boiling water.
S
N
2 reaction :
Mechanism :  
HO   R ? X 
?
 
?? ?
 
? ?
X
....
R
....
O H
? ?
 
?? ?
HO ? R + X
?
HO
?
 + 
C
b
d
X
a
?? ?
 
b
d
a
? ?
X
....
C
....
O H
? ?
?? ?
 
C
HO
d
b
a
 + X
?