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. 

Dichlorodibenzo[6,e][l,4]dioxin, see TCDD Dichlorodibenzofurans, see PCB-1248 Dichlorodihydroxyaniline, see Neburon Dichlorodihydroxybiphenyls, see TCDD... 

CASRN 555-37-3 molecular formula CizHieCFNzO FW 275.18 Soil. Neburon undergoes dealkylation of the terminal nitrogen atom, ring hydroxylation, and degradation to dichlorodihydroxyaniline. Residual activity in soil is limited to approximately 3 to 4 months (Hartley and Kidd, 1987). 

Chemical/Physical. Neburon hydrolyzes under basic conditions forming aniline derivatives. The half-life of neburon in 0.50 N sodium hydroxide at 20 °C is 167 d (El-Dib and Aly, 1976). 

FIGURE 5.4 Effect of the gradient dwell volume, V7>. the elution volume, Vj, in reversed-phase chromatography. Solute neburon, retention equation (Equation 5.7) with parameters a=A, m = 4. Linear gradients 2.125% methanol/min (a) from 57.5% to 100% methanol in water in 20min ( i = 50) (b) from 75% to 100% methanol in water in 11.75 min (k = 10). Vg uncorrected calculated from Equation 5.8, Vg + Vg, Vg, added to Vg uncorrected, Vg corrected calculated from Equation 5.21. (A) A conventional analytical C18 column, hold-up volume y ,= ImL flowrate l.OmL/min. (B) A microbore analytical C18 column, hold-up volume y = 0.1mL flow rate 0.1 mL/min. 

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. 

Fig. 7 Chromatograms obtained after the preconcentration of 50 ml of a diluted industrial effluent spiked at 1 pg L 1 with a mixture of triazines and phenylureas through a styrene-divinylbenzene (SDB) SPE cartridge (a) and through the terbutylazine MIP cartridge (b). Compounds (1) deethylatrazine (DEA), (2) monuron, (3) deethylterbutylazine (DET), (4) atrazine, (5) diuron, (6) terbutylazine, (7) neburon. UV detection at 220 nm [46]...

Urea Fenuron, Siduron and Urox Monuion Monoiinuron Metobromuron Diuron, Neburon and Linuron Chlorotoluron Chlorbromuron Fluometuron Aniline m-Chloroaniline p-Chloroaniline p-Bromoaniline 3,4-Dichloroaniline 3-Chloro-4-methylaniline 3-Chloro-4-bromoaniline m-Trifluoromethylaniline... 

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.)...

Metoxuron 2=F enuron 3 =Monouron 4=Isoproturon 5=Chlorotoluron 6=Diuron 7=Metabenzthiazuron 8=Neburon 9 =Linuron, Chlorobromuron 10=ButuronA. 

Common Name Neburon Synonym Kloben, Neburea, Neburex... 

DCPI (3.4 dichloro phenyl isocyanate) diuron, linuron, neburon, sulcofuron DDT dicofol... 

Methyl 2 butene 1 ol see MBO Methyl butyl amine neburon Methyl 8 butyl ketone see Pinacolone 2 Methyl butyric acid pentanochloro... 

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.)... 

Due to the thermal lability of the urea group, phenylureas are not amenable to GC-MS. They are frequently analysed by LC-MS. The general stmcture is shown below. The phenyl ring is substituted with halogen(s), methoxy, methyl, trifluoromethyl, or 2-propyl substitution. The Rj side chains are methyl groups for most phenylureas, while the Rj side chain can be methyl like in diuron, methoxy like in linuron, butyl like in neburon, or a proton like in monomethylmetoxuron. 

The appearance of ESI mass spectra depends on the solvent conditions, especially on the extent of sodium contamination. Sodiated molecules were observed as the base peak for chlortoluron, isoproturon, diuron, linuron, and diflubenzuron [34], while protonated molecules and only weak sodiated molecules were observed for monuron, diuron, and neburon [14], Some phenylureas can also be analysed in negative-ion ESI, where deprotonated molecules as well as acetate or formate adducts can be observed, depending on the mobile-phase composition [9],... 

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