chemotherapy 

 Table 13 



Relation between Acidity and Activity of Sulphonamides :- 



,R 



NH2< 



143 



COMPOQND 



/j-Aminobenzoic acid - 

 Sulphanilamide - 

 N^-Methylsulphanilamide 

 N^-Phenylsulphanilamide 



Sulphapyridine 

 Sulphathiazole 



iSulphadiazine 

 Sulphathiadiazole 



Sulphacetamide - 

 N^-Chloracetylsulph- 



anilamide 

 N^-Ethylsulphonyl- 



sulphanilamide 



R 



H- 

 CH3- 



~N 



I r 



N N 



CH3CO- 



Ka 



2-1 X 10-5 

 3-7 X 10-11 

 1-7 X 10-11 

 2-5 X 10-10 



3-7 X 10-9 

 7-G X 10-8 



3-3 X 10-' 



1-7 xlO-5 



4-2 X 10-8 

 1-6 X 10-4 

 7-9 X 10-4 



Since the curve shows a maximum, which corresponds 

 very nearly with the compounds sulphadiazine and 



