148 Essays in Biochemistry 



CH 3 



I 



HN- — C— 



N N 



\ / 



N 



r\ 



(VIII) 



HN— — C- 



I II 



N N 



\ / 



N 



pletely eliminated, the 5-tolyltetrazoles are still appreciably stronger 

 acids than the corresponding toluic acids. 



In the halogen-substituted 5-aryltetrazoles the inductive effects as- 

 sociated with the electronegative halogen atoms favor electron displace- 

 ments that should cause these compounds to be stronger acids than 

 the parent 5-phenyltetrazole. The greater acid strength of the meta 

 isomer as compared with the other two may be explained if we again 

 assume that resonance phenomena are more pronounced with the meta 

 isomer than with the ortho or para isomers. Possibly the development 

 of a formal negative charge at the ortho and para carbon atoms is 

 opposed by the high concentration of electrons in the outer shell of 

 the halogen atoms attached at these positions. This would result in 

 a decrease in apparent dissociation constant of the ortho and para 

 isomers due to the lesser contribution of such forms to the resonance 

 hybrid (scheme IX, X = CI or Br) . 



:X: 



i 



-N C-f~\ 



I \\\=J<-f 



N N /X N N 



N N 



