Pesticide intermediate, catalytic

Catalytic amidation/cyclization step in a pesticide intermediate... 

Figure 3 Sampling system for catalytic amidation/cyclization reaction in pesticide intermediate.

Cyclic Hydrocarbons. The cyclic hydrocarbon intermediates are derived principally from petroleum and natural gas, though small amounts are derived from coal. Most cycHc intermediates are used in the manufacture of more advanced synthetic organic chemicals and finished products such as dyes, medicinal chemicals, elastomers, pesticides, and plastics and resins. Table 6 details the production and sales of cycHc intermediates in 1991. Benzene (qv) is the largest volume aromatic compound used in the chemical industry. It is extracted from catalytic reformates in refineries, and is produced by the dealkylation of toluene (qv) (see also BTX Processing). 

Organophosphate and carbamate pesticides are potent inhibitors of the enzyme cholinesterase. The inhibition of cholinesterase activity by the pesticide leads to the formation of stable covalent intermediates such as phosphoryl-enzyme complexes, which makes the hydrolysis of the substrate very slow. Both organophosphorus and carbamate pesticides can react with AChE in the same manner because the acetylation of the serine residue at the catalytic center is analogous to phosphorylation and carbamylation. Carbamated enzyme can restore its catalytic activity more rapidly than phosphorylated enzyme [17,42], Kok and Hasirci [43] reported that the total anti-cholinesterase activity of binary pesticide mixtures was lower than the sum of the individual inhibition values. 

Cyclohexene oxide is an important intermediate used, for example, in synthesis of pesticides. A process for catalytic epoxidation of cyclohexene to cyclohexene oxide by reaction-controlled phase-transfer catalysis has been commercialized in China since 2003. It is an envirorunent-friendly process compared to the polluting traditional chlorohydrin method. 

Esters, especially methyl esters, can also be used as feedstock. The product ketones are useful as solvents for elastomers, polyvinyl acetate and other plastics, as extraction solvents, and as intermediates in making pesticides, herbicides, and pharmaceuticals. For many of the commercial products, acetic acid is one of the reactants. Certain aldehydes can also be condensed catalytically (acid/aldehyde or aldehyde/aldehyde) to give ketones. 

A number of modern industrial processes are based on the catalytic carbonyl at 1 on of organic substrates by carbon monoxide. ll In contrast, the application of carbon monoxide as reductant in organic synthesis is confined to relatively few exampl es. 2l In recent years the catalytic carbonyl at I on of nitro compounds has become a ery intense field of research. This is due to the fact that 3 series of industrially important compounds can be obtained - om nitro compounds and carbon monoxide in a single step azo compounds, amides, amines, oximes, ureas, urethanes and isocyanates [ 3] and indoles. Ureas and urethanes are important final products and intermediates in the synthesis of ert ll eps and pesticides. On the other hand mono and di-1 socyanates are very important intermed 1 a es in the manu-i-acture of pesticides, polyurethane foam plastics, synthetic leather, adhesives and coatings. 

Reduction of nitro compounds to amines is a synthetically important reaction (98) and is practiced since the birth of modern chemical industry—many aromatic amines are key intermediates in production of dyes and pesticides. However, the stoichiometric reductions using iron or alkali metal hydrogen sulfides or catalytic hydrogenations with heterogeneous catalysts leave room for improvements in selectivity, especially with reference to halonitro-derivatives. There are many homogeneous catalysts such as the rhodium carbonyls in the presence of amines or chelating diamines, or [Rus(CO)i2] in basic amine solutions that are... 

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