Preemergent pesticides herbicides

Potential Uses of These Polymers. We have studied the phenyl isocyanate modification of poly(vinyl alcohol) as a model system. Many uses exist for carbamates as medicines, pesticides and herbicides (67,68). For example, ethyl carbamate has been used to treat leukemia and multiple myeloma. Ethyl carbamate has also been used as an antidote for central nervous system poisoning by strychnine. The tranquilizer Meprobamate is a carbamate derivitive. Numerous pesticides and herbicides, such as Sevin and Propham, are also carbamate derivatives. Propham is isopropyl N-phenylcarbamate which bears a strong resemblence to the polymers of Equation 21, and this compound is used as a preemergence herbicide. Numerous other close analogs could be cited also. We might note also that the N-phenyl carbamoyl unit bears... 

Most of the milling runs presented in this paper were made on the small Crescent mills, particularly on Model 6000. This was done in an effort to fully explore the utility of this equipment as a laboratory tool for preparing very small samples of pesticide flowables. In these runs, a preemergence herbicide, dimethyl 2,3,5,6-tetrachloroterephthalate, was selected to serve as a model compound. This material has a melting point of 156 C and can be readily milled to the less than five micron size range. In the studies with the Crescent mills, a flaked technical was used which had been mortar and pestled and screened to less than 60 mesh feed material. 

Rain may also wash some of the spray off the leaves. Most pesticides are not compounds with high molecular weights. They can evaporate in the heat of the sun. Once airborne, they can travel to remote parts of the world, where rain can bring them to the surface again.52 This long-range aerial transport explains how remote lakes in the Arctic and remote islands in the oceans have become contaminated. The preemergence herbicide, acetochlor (11.12),... 

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