Commercial agricultural chemicals

Maleic hydra2ide [123-33-1] (10) is one of a number of commercial agricultural chemicals derived from maleic anhydride. Maleic hydra2ide was first prepared ia 1895 (39) but about 60 years elapsed before the iatermediate products were elucidated (40). 

Cost of commercial agricultural chemical and number of compounds screened... 

The initial entry of the oil and gas companies came in the 1920s when four competitors—Socal, Shell, Jersey Standard, and Phillips—began to produce chemicals. The first two commercialized agricultural chemicals. The other two, Jersey Standard and Phillips, concentrated on commercializing petroleum-based gasoline. However, it was the totally unpredictable and extraordinary demand of World War II that created the petroleum side of the polymer/petrochemical revolution. The four companies that had created their learning bases in the 1930s became the first movers in this new industry. 

Hydroxybenzaldehyde has extensive use as an intermediate in the synthesis of a variety of agricultural chemicals. Halogenation of Nhydroxybenzaldehyde, followed by conversion to the oxime, and subsequent dehydration results in the formation of 3,5-dihalo-4-hydroxybenzonitrile (2). Both the dibromo- and dhodo-compounds are commercially important contact herbicides, hromoxynil [1689-84-5] (2) where X = Br, and ioxynil [1689-83-4]( where X = I respectively (74). Several hydrazone derivatives have also been shown to be active herbicides (70). 

Prior to 1975, benzene was catalytically oxidized to produce maleic anhydride, an intermediate in synthesis of polyester resins, lubricant additives, and agricultural chemicals. By 1986 all commercial maleic anhydride was derived from oxidation of / -butane. It is expected that / -butane will remain the feedstock of choice for both economic and environmental reasons. 

The trialkylacetic acids have a number of uses ia areas such as polymers, pharmaceuticals, agricultural chemicals, cosmetics, and metal-working fluids. Commercially important derivatives of these acids iaclude acid chlorides, peroxyesters, metal salts, vinyl esters, and glycidyl esters. 

Commercially, neopentanoyl chloride is often the preferred starting material for the synthesis of peroxyesters, agricultural chemicals, pharmaceuticals, esters, and other fine chemicals because the reactivity of the acid haUde is generally greater than that of the acid. 

The major commercial applications of hydrazine solutions are as blowing agents ( 40%), agricultural chemicals ( 25%), medicinals ( 5%), and — increasingly — in boiler water treatment now as much as 20%. The detailed pattern of usage, of course, depends to some extent on the country concerned. 

Agricultural chemical companies conduct experimental research on new products to provide data to the EPA for registration of their products. Both the EPA and the agricultural chemical companies require that the data represent actual use conditions as closely as possible. The goal of small batch processing of samples is to simulate typical commercial practices as closely as possible. Therefore, SOPs that reflect commercial practices should be developed to meet the GLP specification. 

The apple crop of the nation, representing an investment by commercial growers of about 750,000,000 in land and trees alone, and with a crop averaging 240,000,000 to 250,000,000 a year during the past 5 years, is entirely dependent on the use of agricultural chemicals to control insects and diseases. 

The selective oxidation of ra-butane to give maleic anhydride (MA) catalyzed by vanadium phosphorus oxides is an important commercial process (99). MA is subsequently used in catalytic processes to make tetrahydrofurans and agricultural chemicals. The active phase in the selective butane oxidation catalyst is identified as vanadyl pyrophosphate, (V0)2P207, referred to as VPO. The three-dimensional structure of orthorhombic VPO, consisting of vanadyl octahedra and phosphate tetrahedra, is shown in Fig. 17, with a= 1.6594 nm, b = 0.776 nm, and c = 0.958 nm (100), with (010) as the active plane (99). Conventional crystallographic notations of round brackets (), and triangular point brackets (), are used to denote a crystal plane and crystallographic directions in the VPO structure, respectively. The latter refers to symmetrically equivalent directions present in a crystal. 

The active pesticide chemical is often less that 1% of the material applied these estimates do not include chemicals used to dissolve or carry the active pesticide chemical. Determining the amount used is difficult because there is no national requirement to report pesticide use. Commercial agriculture uses approximately 60%... 

With regard to worker exposure to nitrosamines present in agricultural chemicals, the volatile nature of these materials suggests inhalation and dermal contact as the major routes of absorption. There is a potential hazard of exposure to field applicators, especially commercial farmers and growers who regularly spray their crops and land. Manufacturers of the formulations may have workers who are exposed to unusually... 

Regardless of the pathways of induced resistance, the end result is identical - a plant with stimulated resistance to plant pathogens. Effective use of induced resistance promoters in I PM systems will likely dramatically reduce the use of conventional chemical fungicides and bactericides in commercial agriculture. It is likely that there are many nontoxic natural substances and microbial species awaiting discovery as induced resistance promoters. 

PCBs are mixtures of chlorinated hydrocarbons. Regarding the source of contamination, they can be divided into two main groups intentional (commercial products) and unintentional (by-products of combustion, such as an incinerator trace amounts of PCBs have been reported in agricultural chemicals or chemical products as impurities) (UNEP Chemicals, 2002). PCBs were produced commercially in the United States from 1929 to 1977. Due to their chemical inertness, heat resistance, a high dielectric constant and nonflammable properties, they have been used extensively for a variety of industrial purposes, such as dielectrics in transformers and large capacitors as heat exchange fluids and in plastics (WHO, 1993). 

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