Organic Chemistry

Problems 295

d. h. l.

e. i. m.

f. j.

g. k.

19. a. Draw resonance contributors for the following species, showing all the lone pairs:
    
    
    1. 
       
       
       
       2. 
          
          
          
          3. b. For each species, indicate the most stable resonance contributor.
          
          
          
          
       
       
       
       
    
    
    
    


20. Draw resonance contributors for the following ions:

a. b. c. d.

21. Are the following pairs of structures resonance contributors or different compounds?

a. d.

b. e. and

c.

22. a. Draw resonance contributors for the following species. Do not include structures that are so unstable that their contributions to
    the resonance hybrid would be negligible. Indicate which species are major contributors and which are minor contributors to
    the resonance hybrid.
    
    
    1. 
       
       
       
       7. 
          
          
          
          13. 
              
          
          
          
          
       
       
       
       
    
    
    2. 
       
       
       
       8. 
          
          
          
          14. 
              
          
          
          
          
       
       
       
       
    
    
    3. 
       
       
       
       9. 
          
          
          
          15. 
              
          
          
          
          
       
       
       
       
    
    
    4. 
       
       
       
       10. 
           
           
           
           16. 
               
           
           
           
           
       
       
       
       
    
    
    5. 
       
       
       
       11. 
           
           
           
           17. 
               
           
           
           
           
       
       
       
       
    
    
    6. 
       
       
       
       12. 
           
           
           
           18. 
               
           
           
           
           
       
       
       
       
    
    
    
    

b. Do any of the species have resonance contributors that all contribute equally to the resonance hybrid?

O

CH 2 COCH 2 CH 3

−

CHCH 2

O

HCCH

−

O

O−

CH 3 N

+

O

CH 3 CCHCCH 3

O

CO −

3

2 -

OCH 3

Cl

CH 3 CH CHCH 2

+

CH CH 2

HCNHCH 3

O

CH 3 C

• HC‚N

O

O−

CH 3 CH N

− +

CH 3 CH CHCH CHCH 2

CH 2 NH 2

CH 3 CH 2 COCH 2 CH (^3) +
O
CH 3 CH“CHOCH 3
OH
CH 3 C CHCH 3
O
CH 3 CCH 2 CH 3 and
CH 3 CH“CHCH 2 C

• CH 3 C H 2


• 
  

  CH 3 CH CHCHCH CH 2 and CH 3 CHCH CHCH CH 2 HCH“CHCH 3

  
  


• 
  


• 
  

  and
  O
  and
  O

  
  


• −


• 
  
  
  
  • CH 2 N 2 N 2 O NO 2 -
    CH 2
    CH 3
    CH 3 CCH+ 2 CH
    CH 2 “CHCH 2 CH“CH 2 CH 3 CH 2 NHCH“CHCH 3 CH 3 CH“CHOCH 2 CH 3
    CH 3 CH 2 C
  
  
  
  


• 
  

  CH 3 CH 2 NHCH 2 CH“CHCH 3 HCH“CH 2
  BRUI07-263_297r4 21-03-2003 11:32 AM Page 295