Biological activities herbicidal

CtHjCIjNS, PhC(S)NH2, a herbicide with a high level of biological activity. 

The correlations between chemical descriptors of molecular properties and biological activity, especially the activity of herbicides and/or plant growth regulators has been described (12). Several alternatives or improvements on the Hansch-Fujita QSAR system have been developed (13—15). 

Discovery. The traditional approach to new pesticide discovery was to make iatuitive changes ia the substitueats oa a promising primary chemical stmcture. Initially, materials from any source were subjected to screening for biological activity as iasecticides, herbicides, or fungicides. 

Pharmaceuticals and Agrochemicals. Thioglycohc acid and its esters are useful as a raw material to obtain biologically active molecules. In cephalosporine syntheses, (4-pyridyl)thioacetic acid [10351 -19-8] (65) and trifluoromethane (ethyl) thioglycolate [75-92-9] (66) are used as intermediates. Methyl-3-ainino-2-thiophene carboxylate can be used as intermediate for herbicidal sulfonylureas (67) and various thiophenic stmctures (68). 

Before the discovery of streptomycin, pyrazinamide (126) was one of the front runners in the treatment of tuberculosis. A broad spectrum of biological activity has been associated with pyrazine derivatives, ranging from the herbicidal activity of (127) to antibiotic activity... 

The Knorr pyrazole synthesis has been extensively utilized in the preparation of a number of pyrazoles as metal chelators, photographic dyes, herbicides, and biologically active... 

According to Urbanski et al. biological activity of 1,3-oxazine derivatives is due to the active CH2 group in the 2-position. Tne use of tetrahydro-l,3-oxazines was also suggested against some infections in veterinary service. The suggested use of tetrahydro-l,3-oxa-zines as herbicides did not seem to be a success. 

The herbicide activity ascribed to the 1,2,4-oxadiazole derivative 67 (60) has prompted the search for other biologically active derivatives. This example was prepared from the corresponding 5-chloromethyl-1,2,4-oxadiazole 63 via conversion to the HHT 65 through the aminomethyl analog 64. Reaction of the HHT 65 with diethyl phosphite under neat conditions produced the desired diethyl ester intermediate 66, which was hydrolyzed to 67. 

The biological activity of several halogenated herbicides in water is destroyed by ultraviolet irradiation (18). Irradiation seems to be a promising method for decontaminating small quantities of pesticides. The chemical similarity between the chlorinated dioxins and other chlo-rinted aromatic compounds suggested that if there were parallels in their photochemical behavior, sunlight might destroy dioxins in the environment. 

Hydrolysis of the isoxazole herbicide isoxaflutole rapidly produces a biologically active diketonitrile that is further degraded to products, which are partly bound to soil components and partly degraded to CO2 (Beltran et al. 2000 Lin et al. 2002 Taylor-Lovell et al. 2002) (Figure 1.24). 

The structure-selective, electron-capture detector (ECD) is the second aost widely used ionization detector [115-118]. It owes Buch of its popularity to its unsurpassed sensitivity to a wide range of toxic and biologically active coapounds. Consequently, it is widely used in trace analysis for the detemination of pesticides, herbicides and industrial chemicals in the... 

Vaughn SF (1999) Glucosinolates as natural herbicides. In Cutler HG, Cutler SJ (eds) Biologically active natural products agrochemicals. CRC Press, Boca Roton, FL81-91... 

The product is a broad-spectrum, non-selective herbicide particularly effective against perennial weeds such as nutsedge and bindweed. Since the effect of changes in structure on biological activity is similar in several series of compounds, this topic will be discussed later. 

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