1^st part:

Structure of Prontosil and Salvarsan are as follows

Prontosil Salvarsan

• Scientist Paul Ehlrich , in 1932 prepared the first effective antibacterial agent ,Prontosil which resembles in structure to the compound Salvarsan (Arsphenamine) , which was developed by also himself when he was researching with Arsenic based structures to produce less toxic substances for the treatment of Syphilis.

• The main resemblance b/w these 2 compounds (Salvarsan &Prontosil ) is the linkage b/w 2 Arsenics present in Salvarsan & linbkage b/w 2 Nitrogens in Prontosil.

• i.e., the –As=A s – present in Salvarsan & – N=N – present in Prontosil just that As atom present in Salvarsan instead of Nitrogen. And the fact that, both compounds convert to sulphonamide which is the real active compound ; as both the compounds are sulpha drugs.

2^nd part:

Yes, there is also resemblance between Azo dye and Prontosil in terms of linkage.

Azo-dye Prontosil

• The –N=N – linkage is present in both azo dyes & Protosil & in the same position holding 2 benzene rings.

• And like the tissues get coloured by the dyes selectively; Prontosil , the antibacterial agent selectivly binds to specific bacteria.