Benzene, replacement

Both compounds included here are experimental and in each case the pyridine is a benzene replacement and is not essential for the activity. The urea (103) (79SAP7802440) is a member of a highly active series that kill insects by disrupting the formation of new insect cuticle, through inhibition of chitin synthesis. The cyclopropane ester (104) (78GEP2810881) is a heterocyclic analogue of the pyrethroid insecticides, an extremely successful new class which are active on a wide range of insects. 

On comparison of simple 1,2,4-triazoles with benzene, replacement of CH=CH in the latter by NH enhances reactivity towards electrophilic reagents but two replacements of CH by N act in the opposite direction (see Section 4.02.1.1). Comparison with other azoles is of greater heuristic value still (B-76MI41200). 

Aromatic systems conceptually derived from benzene replacing CH with N to get pyridine... 

Evaporate chloroform, n-pentane, and benzene replacing with carbon tetrachloride... 

Fill a chromatograph tank to a depth of about 0.5 in with benzene and place sheets of filter paper against the internal walls of the tank and dipping in the benzene. Replace the lid and leave the tank for 30 min to equilibriate in a constant temperature area fi ee fiom draughts. 

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