Crystal Structure Analysis of IIIE

The molecular structure of IIIE-9 is shown in Fig. 4.7. The packing diagram of the unit cell IIIE-9 is shown in Fig. 4.8. Selected bond lengths and angles are presented in Table 4.9. It can be seen from the X-ray single crystal structure of IIIE-9 that all 

1 Herbicidal Activity of O-Methyl [l-(Substituted Phenoxyacetoxy) Alkyl]Methylphosphinates IIIA and IIIB 

As shown in Table 4.10, most of O-methyl [l-(2-nitrophenoxyacetoxy)aIkyl] methylphosphinates IIIA and O-methyl [l-(2-chloro -nitrophenoxyacetoxy)alkyl] methylphosphinates IIIB were almost inactive in pre-emergence application at 2.25 kg ai/ha except that IIIA-8 (R =2-ClPh) and IIIB-1 (R =Me) showed 90 % inhibitory activity against lettuce or crab grass, respectively. 

As shown in Table 4.11, although a few compounds showed weak herbicidal activity, most of ITT A and lilB, were almost inactive in post-emergence appheation at 2.25 kg ai/ha. 

As shown in Tables 4.10 and 4.11, mostof IIIA and IIIB were almost inactive in pre-emergence and post-emergence applications at 2.25 kg ai/ha. As shown in Tables 4.10 and 4.11 the introduction of 2-NO2 or 2-Cl,4-N02 as Y on the phenoxy-benzene ring in the phosphinate structure was not beneficial to herbicidal activity. 

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