The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5mercapto-1,3,4-thiadiazole (I); 2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5'-nitro-2-'furyl]•methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5'-nitro-2-'furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I); 0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer's law was obeyed up to 4.0 ppm for compounds (I and II); 6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.

A series of new coumarin and N-amino-2-quinolone derivatives have been synthesized. The reaction of coumarin (1) with excess of  Hydrazine hydrate 98% yielded 1-amino-2-quinolone (2), Compound (2) was reacted with different Sulfonyl chloride to yield Sulfonamides [ N-(2-oxoquinolin-1(2H)-yl) methane sulfonamide (3), N-(2-oxoquinolin-1(2H)-yl) Benzene sulfonamide (4) and 4-methyl-N-(2-oxoquinolin-1(2H)-yl) benzene sulfonamide (5) ], while  reaction of  2-(4-methyl-2-oxo-2H-chromen-7-yloxy) acetic acid (8) with different amines yielded compounds [  2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(2-oxoquinolin-1(2H)-yl) acetamide (9) and N-(5-methyl-1,3,4-thiadiazol-2-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide (10) ] through amide linkage.The reactions and purity of the products were checked by TLC. The structures of the final compounds and their intermediates were confirmed by their melting points, IR spectroscopy, and elemental microanalysis.The coumarin and N-amino-2-quinolone derivatives were evaluated for their anti bacterial and antifungal activity. Key words: coumarin , 1-amino-2-quinolone, sulfonamide, amide, biological activity.