Herbicides neburon

Propanil (3,4-dichloropropionanilide) is an important arylamide herbicide that is used in rice, barley, oat and wheat fields. The 3,4-dichloroaniline moiety is also found in the TV-substituted phenylureas linuron, diuron and neburon. Hence, exposure to 3,4-dichloroaniline derivatives will be common and has been associated with methemoglobinemia in humans142. 

SE Katz. Determination of the substituted urea herbicides linuron, monuron, diuron, neburon and fenuron in surface waters. J Assoc Off Anal Chem 49 452-456, 1966. 

R Deleu, A Copin. Extraction et dosage par chromatographie en phase gazeuse des herbicides nitro-fenc et neburon. Application a des eaux naturelles. J Chromatogr 171 263-268,1979. 

Figure 8.9. Separation of four phenylurea herbicides using (a) on-line UV detection at 254 nm and (b) on-line electrochemical detection with 1.35 V oxidation potential. Peaks 1, metoxuran 2, diuron 3, linuron 4, neburon. (Reprinted from Ref. 20 with permission.)...

Fig. I.7. Dependence of reiention factors, k. of phenylurea herbicides on the concentration, ip 9c vol. X IC" ), of 2-propanol in n-hepiane on a bonded-phase Separon SGX Nitrile, 7 pm, column (i50 X 3.3 mm i.d.) at 4(fC. Dry solvents were used. Sample compounds / = phenuron, 2 = bis-A, A -(3-chIoro-4-melhyl)phenylurea. 3 = neburon, 4 = metobromuron. Points experimental data solid lines best-fit plots of three-parameter Eq. (1.16) broken lines best-fit plots of two-parameter Eq. (1.15).

Fig. 1.23. Top the window diagram (the dependence of the resolution on the concentration of 2-propanol in ri-heptane as the mobile phase) for a mixture of eight phenylurea herbicides on a Separon SGX, 7.5 pm. silica gel column (150 x 3.3 mm i.d.). Bottom the separation with optimised concentration 1953 2-propanol in the mobile phase for maximum resolution. Column plaie number N = 5000. T = 40°C. flow rate 1 ml/min. Sample compounds neburon (/). chlorobromuron (2). 3-chloro-4-methylphenylurea (7). desphenuron (4). isoproturon (5). diuron (6). metoxuron (7). dcschlorometoxuron (S).

Fig. 1.33. Top the resolution window diagram for the gradieni-elulion separation of a mixture of twelve phenylurea herbicides on a Separon SGX Cix. 7.5 nm. column (150 x 3.3 mm i.d.) in dependence on the initial concentration of methanol in water at the start of the gradient, A. with optimum gradient volume Mg = 73 ml. Column plate number N =. 5000.. Sample compounds hydroxymetoxuron (/). desphenuron (2), phenuron (.1). metoxuron (4). monuron (5), monolinuron (6). chlorotoluron (7), metobromuron (X), diuron (9), linuron (/O), chlorobromuron (//). neburon U2). Bottom the separation of the twelve phenylurea herbicides with optimised binary gradient from 24 to l(X)9f methanol in water in 73 min. Flow rate I ml/min.

Pig. 9.12. (a) Principle of immunoaffinity solid-phase extraction, (b) An example of on-line immunotrapping and RP-HPLC of 13 phenylurea herbicides spiked into water. Analytes 1, phenuron 2, metoxuron 3, monuron 4, methabenzthiazuron 5, chlortoluron 6, fluomethuron 7, isoproturon 8, difenoxuron 9, buturon 10, Unuron 11, chlorbromuron 12, difluzbenzuron 13, neburon [65]. (Reprinted with permission.)... 

By varying the aryl substituent and the 1-substituents of 3-aryl ureas several effective herbicides have been prepared, such as neburon, l-butyl-3-(3,4-dichlorophenyl)-l-ntethylurea (27) trimeturon, 3-(4-chlorophenyl)-0,l,l-trimethylisourea (28) buturon, 3-(4-chlorophenyl)-l-methyl-1-(1-methylprop-2-ynyl)urea (29) and Proban , 3-(3,4-dichlorophenyl)-l-isopropyl-l-(2-propynyl)-urea (30). Hiose containing unsaturated side-chains include siduron, l-(2-niethyicyclohexyl)-3-phenylurea (31), and methazole, 2-(3,4-dichlorophenyI)-4-methyl-1,2,4-oxa azolidine-2,S-dione (32). 

Bucha and Todd described the herbicidal properties of neburon (27) together with those of monuron, fenuron and diuron as early as 1951, but neburon, introduced only in 1955, did not gain widespread use. 

Mixtures of R-40244 with appropriate grass herbicides such as linuron, trifluralin and terbutrine in sunflowers, linuron and metriburin in potatoes, chlortoluron and mitrofen -1- neburon in wheat show improved activity against grass weeds and several broad-leaved weeds. 

Herbicides Substituted urea herbicides Diuron, neburon, phenobenzuron and isoproturon Adsorption LiChrosorb SI 60 Water saturated with dichloromethane (the role of water being to block the most active silanol sites thereby... 

FIGURE 25.9 Capillary GC with fused-silica column coated with CP-Sil 5 (analogous to SB 30 and OV-101) of HFB derivatives of 13 phenylureas obtained after extraction of a Bosbaan river water sample spiked at 1 fjig/ level, and direct derivatization with HFB A. Injected amount corresponds to 0.1 ng of each herbicide. Symbol explanation Fm, fluometuron Fe, fenuron Mo, monuron Ml, monolinuron Ip, isoproturon Ct, chlorotoluron Mb, metobromuron Bu, buturon Di, diuron Li, linuron Cb, chlorbromuron Mx, metoxuron Nb, neburon. (From Brinkman, U. A. Th., de Kok, A., and Geerdink, R. E., J. Chromatogr., 283, 113, 1984. With permisssion.)... 

The herbicidal effect of aryl- and hetarylurea, systematically studied starting from first observations in 1946, was improved between 1951 [30] and 1973 [31]. From this chemistry today the compounds chloroxuron (Ciba, 1960), dimefuron (Hoechst, 1969), diuron (Du Pont, 1954), ethidimuron (Bayer, 1973), fenuron (Du Pont, 1957), fluometuron (Ciba, 1960), isoproturon (Hoechst, 1974), linuron (Hoechst, 1960), methabenzthiazuron (Bayer, 1968), metobromuron (Ciba, 1963), metoxuron (Sandoz, 1968), monolinuron (Hoechst, 1958), neburon (Du Pont, 1957), siduron (Du Pont, 1964) and tebuthiuron (Elanco, 1973) are still used. 

Fig. 5 Top. The resolution window diagram for RP gradient elution separation of phenylurea herbicides on a Separon SGX C18 7.5 p,m column (150 X 3.3 mm I.D.) dependent on the initial concentration of methanol in water at the start of the gradient A with optimum gradient volume Vg — 73 ml. Column plate number N = 5000 sample compounds 1, hydroxymetoxuron 2, desphe-nuron 3, phenuron 4, metoxuron 5, monuron 6, monolinuron 7, chlorotoluron 8, metobromuron 9, diuron 10, linuron 11, chlor-obromuron and 12, neburon. Bottom. The separation with optimized binary gradient from 24% to 100% methanol in water in 73 min. Flow rate = 1 ml/min T = 40°C.

The retention characteristics of nine phenylureas (e.g., phenuron, hydroxy-methoxuron, bis-A, A -(3-chloro-4-methylphenyl)urea, neburon, and 7V-phenylurea) were studied on a cyanopropyl column (A = 254 nm) under normal-phase conditions of hexane/IPA (90/10 to 10/90), and reversed-phase conditions of IPA/water (10/90 to 90/10). Complete resolution of all nine herbicides was not achieved, but six were well resolved and eluted within 15 min using an isocratic 90/10 hexane/IPA mobile phase [210]. Extensive tables of k values for a wide range of isocratic mobile phases for both the NP and RP separations were presented. 

Clamydomonas sp, Chlorella sp, and Chlorella NMI were found by Pillay and Tchan (1972) to be more sensitive than Chlorococcum, Nostoc, or Anabaena to monuron, diuron, and neburon. At very low concentrations (0.001 to 0.01 ppm) a stimulatory effect on Chlamydomonas and the two Chlorella species was observed, while at 0.1 to one ppm, the herbicides became strongly inhibitory. Stimulation by low concentrations of herbicides is well-established (Atkins 1965, Pillay 1967). 

Still working with Chlorella NMI and the herbicides atrazine, mon-uron, diuron, and neburon, Tchan et al. (1975) devised an assay procedure for the measurement of herbicides in soil and water. This technique was based on the eflEect that the photosynthetic inhibitors have on oxygen evolution during photosynthesis. Evolved oxygen was estimated by its influence on light generation by the bioluminescence system of a photobacterium. 

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