Amide herbicides

Acid amide herbicides Acid anhydrides Acid azine dyes Acid-base catalysis Acid-base chemistry Acid Black [1064-48-8]... 

Acid amide herbicides are nonionic and moderately retained by soils. The sorption of several acid amide herbicides has been investigated (369). Acetochlor [34256-82-1] is sorbed more than either alachlor or metolachlor, which are similarly sorbed by a variety of soils. Sorption of all the herbicides is well correlated to soil organic matter content. In a field lysimeter study, metolachlor has been found to be more mobile and persistent than alachlor (370) diphenamid [957-51-7] and napropamide [15299-99-2] have been found to be more readily leached (356). 

Health advisories have been issued (269) for diphenamid, metolachlor, pronamide, and propachlor. Other acid amide herbicides include butachlor [23184-66-9] and ethalfluralin [55283-68-6],... 

Achiral, C -symmetric unbridged metallocenes, 16 104 Achiral hydrobora ting agents, 13 667 Achiral molecules, 6 73 Acicular reinforcement, 5 554 Acid acceptors, in VDC polymer stabilization, 25 719 Acid-activated bentonites, 6 680-681 Acid amide herbicides, 13 319-320 Acid anhydrides, 10 403-406, 484 reactions with alkanolamines from olefin oxides and ammonia, 2 127 Acid-base catalysis, 5 205-209... 

Other examples of nonionic compounds (Fig. 10, Table 3) are the phenyl-amide herbicides (e. g., Diphenamid, moderately water soluble and nonvolatile), thiocarbamate, and carbothioate herbicides (e. g., Thiobencarb, low water solubility, high vapor pressure, relative mobility in soil systems) and benzonitrile herbicides (e.g., Dichlobenil, low water solubility, low vapor pressure, relative immobility in most soils) [151]. 

Fig. 20.6 shows the trend in consumption for the three most important types of herbicides. Carboxylic acids have been the standby for many years and were the first type of herbicide. They were replaced as number one by the heterocyclic nitrogen compounds in the 1970s. Carboxylic acids are making a comeback in the 1990s. A close third are the amide herbicides. The present percentage of consumption for herbicides is given in Table 20.7. 

A number of other herbicides have specific uses. The amide herbicides, of which propanil is typical, are used in large quantities. Propanil is made by the reaction of propionyl chloride and 3,4-dichloroaniline. 

Add Amides. The principal use of acid amide herbicides is the selective control of seedling grass and certain hroadleaved weeds. The majority of acid amide herhieide,x arc applied pre-emergence or pre-plum incorporated, except for propanil which is applied post-cmeigenee. 

Phenylcarbamate, phenylurea and many amide herbicides which yield anilines on hydrolysis can be detected after TLC by spraying with fluorescamine [100]. The limits of detection of a number of anilines separated by TLC and detected with fluorescamine are given in Table 4.16. A number of pesticides which yield anilines on hydrolysis or degradation is listed in Table 4.28. The analysis of anilines by this technique is described in Section 4.2.1.2.3. 

Herbicides are chemicals used to destroy unwanted plants (terrestrial or aquatic) called weeds. Herbicides fall into two broad categories inorganic (e.g., copper sulfate, sodium chlorate, and sodium arsenite) and organic (e.g., chlorophenoxy compounds, dinitrophenols, bipyridyl compounds, carbamates, and amide herbicides). Historically, inorganic compounds were the first available and the first used. There has been over a long period a continuous effort to develop herbicide compounds that are more selective—that affect weeds, as opposed to desirable plants. 

Propanil is one of a group of amide herbicides (made from aniline treated with organic acids), and is used extensively to control weeds in rice crops. Rice itself contains an enzyme that hydrolyzes propanil to 3,4-dichloroani-line and propionic acid, and so it is resistant to the herbicide. Weeds, lacking this enzyme, are adversely affected by it. (Mammalian liver cells also have an enzyme that causes this hydrolysis.)... 

Uses Napropamide is a slightly toxic amide herbicide. It is grouped by the USEPA under GUP.13 Napropamide is a selective systemic amide herbicide used to control a number of annual grasses and broadleaf weeds. It also is applied to soil growing vegetables, fruit trees and bushes, vines, strawberries, sunflowers, tobacco, olives, and other crops. The formulations include emulsifiable concentrate, wettable powder, granules, and suspension concentrates.12... 

Other Uses for Aniline. Aniline currently is used as a raw material in most of the major groups of rubber-processing chemicals accelerators, antioxidants and stabilizers, and anti-ozonants. The most important of these are the thiazole derivatives and substituted para-phenylenediamines. The demand for aniline in these rubber-processing uses is expected to grow at less than 1 percent/year. In agricultural chemicals, the major use for aniline is as a raw material in the manufacture of amide herbicides for controlling annual... 

Gough, J. and Hall, L.H. (1999b). Modeling the Toxicity of Amide Herbicides Using the Electro-topological State. Envirort-ToxicoLChem., 18,1069-1075. 

Gough, J. and HaU, L.H. (1999b) Modeling the toxicity of amide herbicides using the electrotopological state. Environ. Toxicol. Chem., 18, 1069—1075. 

Two kinds of resistant biotypes have been noted one is highly-resistant (R) and is unaffected even by saturated solutions of dinitroaniline herbicide, whereas an intermediate-resistant (I) biotype is only 50X resistant to trifluralin and less than 10X resistant to oryzalin compared with the susceptible (S) biotype. Both R and I biotypes are cross-resistant to phosphoric amide herbicides. Tubulin from the R is able to polymerize into microtubules even in the presence of oryzalin, whereas that of the S biotypes cannot. Western blots of tubulin from the R biotype reveal two -tubulin isotypes whereas only one form is noted in the S biotype. Because the R biotype is hypersensitive to the microtubule-stabilizing agent taxol, it is likely that the R biotype is resistant by having hyperstabilized microtubules. The I biotype has no gross alteration in tubulin nor extreme sensitivity to taxol, indicating that this biotype has a different resistance mechanism than the R. 

Root tips squashes were also used to examine the cross-resistance of the R biotype to other mitotic disrupters. Mudge gi al- (3) had previously shown that field applications of all of the dinitroaniline herbicides were ineffective in controlling the R biotype, and this was confirmed using root tip squashes as well (20). The phosphoric amide herbicide amiprophosmethyl also inhibits polymerization of tubulin into microtubules (21) and causes the same kinds of mitotic disruption as the dinitroaniline herbicides. The R biotype is also cross-resistant to this herbicide (20). Because the structure of amiprophosmethyl and trifluralin are quite different, it is likely that mechanisms of resistance based upon translocation and/or metabolism of herbicides is unlikely (but see 16 for an exception). 

Starting with 3 the herbicidal activity is strongly increased by introduction of chlorine in the ortho-position, giving the selective paddy amide herbicide fentrazamide (4 2000, Lees ) [8] with excellent crop compatibility, even on young seedlings. 

Amide herbicides - preconcentration using SPMDs then bioassay. (2) Diethanol amides by solid-phase extraction-liquid chromatography-atmospheric pressure chemical ionization/electrospray ionization mass spectrometry (SPE-LC-APCI/ESI-MS) o-Phthaldialdehyde derivatization then reversed-phase LC with fluorescence defecfion. Chiral derivafizafion permifs separation of optical isomers on standard LC columns Anion exchange LC Ion-pair liquid chromatography... 

The systems to be discussed, the hydroxyoxazolidinones, 1, and the hydroxypyrrolidinones, 2, are shown below. These structures were derived by considering the known (1 ) classes of carbamate and amide herbicides such as barban, 3, chlorpropham, 4, and propanil, 5. We envisioned that cyclization of these classes of herbicides, combined with location of a hydroxy on the ring, would lead to herbicidal activity. We were especially interested in such compounds as they provide at least two potential binding sites at the receptor, the hydroxy and the amide. Furthermore, as a result of cyclization, the change in size and shape of molecules 1 and 2 relative to the simpler carbamates and amides, could provide additional information on the binding sites of all of these molecules 1-5. 

Triazine herbicides and quinoclamine, having the mode of action in inhibition of PS II (Photosynthesis at photosystem II) had low variability on sensitivities in different algal taxa. On tiie other hand. Amide herbicide such as Pretilachlor and Cafenstrole as well as sulfonylurea herbicides of bensulfiironmethyl and imazosulfuron had great variability on sensitivities in different algal taxa. These herbicide have in other the mode of action in inhibition of cell division or in inhibition of acetolactate synthase rather tiian in inhibition of PS II. Carbamate herbicide showed relatively low toxicity on algae. Daimuron and bentazone exhibit low toxicity on all tire tested species (Figure 3). 

Imide herbicides are exemplified by types similar to chlorphthalim and oxadiazon, which are expected to have a mode of action similar to acifluorfen. A cyclic amide herbicide is clomosone, a bleaching herbicide. These types will be discussed more fully later. Phosmet, an example of an insecticidal imide, also is an organophosphate and will be further discussed with the phosphorus compounds. 

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