الفهرس 
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Abstract
This won was directed towards the preparation of some new, as well as known coapounds from different omganic grou:)s. The prepared compounds have been tested as a potential molluscicidal agents againt 13iomphalaria, alexandrina and Bulinus trancatus.
The compounds include the following:
1.Tritylthiourea and semicarbazide derivatives (19a-k, 20 and 26a,b).
2.103,4-ThiadiazolL derivatives 28a-d.
3.--(27Chlorophenox)cinnamarnidos 32a-d, and ;x-(27 chlorophenoxy)-2-fyrYlacrylarr6des 36a,b.
4.1,2-Substituted nitroethylene derivatives 38a-j.
Biological screening of these compounds showed that N-trityl-Y1-4-pyridylthiourea (19i) was motive as molluscioide against Bulinus trancatus and Biomphalaria alexandrina at 1 and 1.5 ppm respectively, while other compounds belongs to the items 1, 2 and 3 were found inactive. All compounds belongs to the nitroethylene
series 38a-j, possessed molluscieidal activity of different degrees. However, an electron withdrawing substituents at the ethylenic bond resulted in enhancement of activity than an electron releasing moiety. These results are illustrated by the very low activity of the 2rmethyl-phenyl and 2-dimethylaminophenyl- derivatives (38e and j).
Plotting o’ values for the compounds with aryl substituents against activity afforded a straight line (cf. curve 1 and 2), although the number of compounds tested werellimited.