Simazine production

Chlorophyll production inhibited more-than-additive toxicity observed in combination with simazine and malathion (Torres and O Flaherty 1976)... 

In the presence of hydroxy or perhydroxy radicals generated from Fenton s reagent, simazine undergoes dealkylation to give 2-chloro-4,6-diamino-s-triazine as the major product (Kaufman and Kearney, 1970). 

A preemergence herbicide used for general weed control including grasses and broad-leaved weeds in a range of crops Chemical transformation product. Parent simazine and atrazine Chemical transformation product. Parent atrazine... 

SPE LC/MS/MS methods have been developed for the determination of polar pesticides (as propanyl, thiobencarb, diuron, simazine, bentazone etc.) and of their degradation products in waters with LOQ aronnd 25 ng L (Figure 18.1) [73], for the determination of chloroacetamide herbicides (LOD=25ng L ) [74], of sulfonylureas, bentazone, and phenoxyacids in river and drainage waters (LOD of the order of few ng L" ) [9]. 

Just as atrazine is important in com, simazine is a pre-emergence triazine that provides broad-spectrum residual weed control in many of the important fruit and nut crops when applied either alone or in combination with a contact product such as glyphosate to control weeds at the time of application (Figure 1.5). 

Hundreds of triazine-containing products continue to be reviewed, registered, and used throughout the world, with regular reregistrations and safety reviews. While several of the triazines have been recently reviewed, the most comprehensive of these reviews in multiple countries involved atrazine and simazine. 

In 1977, when the above review was presented and published, the history of the s-triazine herbicides was already 25 years old, with the first synthesis of these chemicals completed in 1952. The filing of the first basic triazine patent case in Switzerland was on August 16, 1954, and the first commercial products appeared on the market in 1956, following the approval of simazine for use in corn by federal authorities in Switzerland on December 3, 1956. Several other agrochemical companies started immediately to work with their own s-triazine variations, using other radicals or amino-functions on the s-triazine ring. This further research was also briefly reviewed in Knusli s 1977 paper. 

G-30031, ipazine When ipazine was compared directly with simazine and atrazine, no special use or advantage could be defined. The product was discontinued early. 

Geigy started production of simazine in 1956 in Schweizerhalle, near Basel, Switzerland 2 years later, atrazine also was produced. Use of triazines for weed control to improve crop yields grew quickly, and a production facility was installed at McIntosh, Alabama in 1959. Smaller production units were operated in Mexico, Brazil, and Australia, and important development work by Geigy led to improved production processes. In 1970 a continuous process production unit was built by Geigy Agricultural Chemicals in the United States. 

Commercial production of simazine started in 1956 at the Geigy Schweizerhalle plant near Basel, Switzerland. Two years later, atrazine also was produced. Smaller production units were placed in operation in Mexico, Brazil, and Australia. In the fall of 1960, manufacturing of the triazines was started in the United States in McIntosh, Alabama. Examples of production pathways are included in Figure 3.1. 

Due to increasing demand for atrazine, in 1969 Geigy began production at a new plant in St. Gabriel, Louisiana. As part of the planning for the new facility, intensive research and development work was performed in Alabama and Basel to improve the production process. Instead of the batch process used previously, a new continuous production process was developed. The new and efficient Louisiana facility has been the recipient of numerous production, safety and environmental awards and recognitions, and is now the production site for all Syngenta atrazine, simazine, and terbuthylazine used worldwide. 

Most producers concentrated their production on the major triazines (e.g., atrazine, simazine, terbuthylazine, ametryn, and terbutryn). The producers of triazine herbicides through the 1990s are presented in Table 3.1, and producers since 2000 are listed in Table 3.2. 

Major uses added to the Simazine 80W label included US southern turfgrass species for sod production, sugarcane, pineapple, and strawberry (1961) apple, sour cherry, macadamia nut, asparagus, orange, lemon, perennial grass grown... 

The trade name Princep was introduced in 1969, and the US registration for technical simazine was granted in 1974. This allowed the technical material to be used by other companies to formulate and market products containing simazine. A water-based flowable liquid also was registered in 1974 and soon became the leading formulation of simazine sold in the United States. 

With the approval of simazine in 1957 by the USFDA, USDA, and USEPA, the basis and procedures for successful introductions of other chlorotriazines were established. Although additional development work was necessary for approval and registration of the subsequent chlorotriazines, the procedures to optimize the production, formulation, and directions for use and the protocols to analyze and understand metabolism and toxicology remained similar. Approval for the first commercial uses of simazine and atrazine in various countries are given in Tables 3.3 and 3.4, respectively. 

Introduction of simazine and atrazine use in corn production allowed farmers to leam novel technologies of preemergence or at-planting treatments for weed control. This required research, development, and educational programs to provide information farmers needed to modify, replace, or develop new application equipment. 

The triazine herbicides have revolutionized agricultural production of corn and more than 40 other crops. The yield increases, less labor-intensive production, and use for erosion control in conservation tillage are all benefits of the tri-azines, especially atrazine and simazine. Registered since the late 1950s, atrazine is still a mainstay of corn production and likely the most studied herbicide by regulatory agencies. 

During late 1994, the United States Environmental Protection Agency (USEPA) published a public document (PD-1) relative to the use of triazine herbicides by American farmers. In doing so, they placed atrazine and simazine in Special Review. USEPA s PD-1 triggered a benefits study of unprecedented proportions on the following issues benefits of atrazine and simazine use economic and biological impact of the loss of these products feasibility and efficacy of alternatives environmental benefits associated with atrazine and simazine use best management practices and comparative performance of alternatives. 

Analysis approach - corn and sorghum A two-tiered approach was also used to characterize the benefits associated with uses of atrazine and simazine in corn and sorghum. First, a comparative analysis was made of product labels. The following parameters were considered in this review performance profiles, including efficacy, spectrum, and crop tolerance label comparisons physical and chemical characteristics of the product hazard profiles economic benefits and other relevant issues, such as use restrictions, etc. 

Worker and environmental safety Atrazine and simazine are safe to apply according to the directions on the label. Nontarget safety margins are good because atrazine is nonvolatile and has low specific activity. In addition, avian, mammalian, and aquatic toxicities are low. Relative safety to nontarget plant species is a positive characteristic that is not always found in alternative products. 

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