Herbicidal Activity of Carbamoyl Triazole Herbicide
J. Agric. Food Chem., Vol. 54, No. 20, 2006 7725
Figure 2. Formulas of primary triazole herbicides.
representing the absorption of OdSedO. Especially influenced by the
lone pair electrons of the nitrogen atom, the two CH2CH3 are not in
1
magnetic equivalence, so in the HNMR spectra, the signal of CH2
shows broad peak, and the CH3 shows single, multiple, or broad peaks
in compounds C1-C2.
Figure 3. General formula of triazole compounds that will be synthesized.
Data for 3-benzeneselenonyl-[1,2,4]triazole-1-carboxylic acid di-
ethylamide (C1): yield, 86.0%; white solid; mp, 123-124 °C; TLC
for further use. Arylamine (0.02 mol) was dissolved in 20 mL of
methanol and was slowly added to 2.1 mL (0.08 mol) of concentrated
hydrochloric acid, stirred at the same temperature for 15 min, and then
cooled to -5 °C. A solution of 1.79 g (0.021 mol) of sodium nitrite in
10 mL of water was added dropwise to the mixture over a period of
15 min. When the dropwise addition was complete, the mixture was
stirred for another 40 min at 0 °C to obtain a nearly colorless solution
(B). Solution B was added dropwise to mixture A during 1 h, and 4.48
g (0.08 mol) of KOH in 15 mL of water was added carefully at the
same time to keep the pH at ∼12. After 5 h of stirring at 0 °C, methanol
was distilled off under vacuum, and the mixture was filtered. The filtrate
was extracted with chloroform (3 × 30 mL), dried over anhydrous
sodium sulfate, and purified with column chromatography through silica
gel with EtOAc/petroleum ether (v/v ) 1:1) to give A1-A12.
The pH value is the key factor for the reaction of the diazonium
salt with potassium 1H-[1,2,4]triazole-3-selenoxide to arylselanyl-1H-
[1,2,4]triazoles. Accordingly, the pH was adjusted to pH 12 using KOH
when the solution of diazonium (B) was added dropwise to mixture A.
General Synthetic Procedure for Arylselenonyl-1H-[1,2,4]triazole
(B1-B12). NaOH (0.66 g, 0.0166 mol) and Na2HPO4‚H2O (0.9 g, 0.0025
mol) were dissolved in 10 mL of water and added carefully to 0.0025
mol of a vigorously stirred mixture of corresponding arylselanyl-1H-
[1,2,4]triazoles (A1-A12) in 30 mL of methanol, followed by the quick
addition of 10 mL of aqueous of Oxone (3.07 g, 0.005 mol). After
room temperature had been maintained during 20 min of stirring, the
mixture was filtered and washed with 30 mL of methanol. The filtrate
was evaporated under reduced pressure to remove the methanol,
neutralized with 6 M NaOH, filtered, and dried in vacuum desiccators
to give B1-B12.
(silica gel, EtOAc/petroleum ether, 1:1) Rf ) 0.40; IR (KBr, cm-1
)
3090, 1700, 1480, 1450, 1425, 950, 890; 1H NMR (CDCl3) δ 8.90 (s,
1H, NdCHsN), 8.16 (d, J ) 7.44 Hz, 2H, ArH), 7.78 (t, J ) 7.34
Hz, 1H, ArH), 7.70 (t, J ) 7.62 Hz, 2H, ArH), 3.56 (br, 4H, CH2sC),
1.26 (s, 6H, CH3sC); ESI HRMS, m/z Anal. Calcd data for C13H16N4O323
-
Na80Se M + Na+: 379.0285. Found: 379.0280.
Data for 3-(3,4-difluorobenzeneselenonyl)-[1,2,4]triazole-1-carboxy-
lic acid diethylamide (C2): yield, 78.0%; yellow solid; mp, 118-120
°C; TLC (silica gel, EtOAc/petroleum ether, 1:1) Rf ) 0.40; IR (KBr,
cm-1) 3010, 1720, 1505, 1440, 950, 880; 1H NMR (MeOD) δ 9.22 (s,
1H, NdCHsN), 8.16 (td, J ) 12.16 Hz, J ) 2.07 Hz, 1H, ArH), 7.78
(dt, J ) 10.73 Hz, J ) 1.99 Hz, 1H, ArH), 7.70 (q, J ) 13.08 Hz, 1H,
ArH), 3.56 (br, 4H, CH2sC), 1.26 (br, 6H, CH3sC); ESI MS, m/z
(%) 415.1 (M + Na+) (12.5), 807.1 (2M + Na+) (100).
Data for 3-(3-trifluoromethylbenzeneselenonyl)-[1,2,4]triazole-1-
carboxylic acid diethylamide (C3): yield, 80.0%; white solid; mp, 117
°C; Rf ) 0.50 (silica gel, EtOAc/petroleum ether, 50:50); IR (KBr,
1
cm-1) 3140, 1705, 1510, 1480, 1450, 960, 895; H NMR (CDCl3) δ
8.86 (s, 1H, NdCHsN), 8.38 (s, 1H, ArH), 8.31 (d, J ) 7.98 Hz, 1H,
ArH), 7.96 (d, J ) 7.85 Hz, 1H, ArH), 6.80 (t, J ) 7.90, 1H, ArH),
3.48 (br, 4H, CH2sC), 1.19 (s, 6H, CH3sC); ESI HRMS, m/z Anal.
Calcd data for C14H14N4O3F323Na80Se M + Na+: 447.0159. Found:
447.0146.
Data for 3-(2,6-dimethylbenzeneselenonyl)-[1,2,4]triazole-1-car-
boxylic acid diethylamide (C4): yield, 82.0%; white solid; mp, 110-
112 °C; Rf ) 0.51 (silica gel, EtOAc/petroleum ether, 1:1); IR (KBr,
cm-1) 3140, 1710, 1470, 1450, 945, 890; 1H NMR (CDCl3) δ 8.92 (s,
1H, NdCHsN), 7.42 (t, J ) 7.58 Hz, 1H, ArH), 7.22 (d, J ) 7.55
Hz, 2H, ArH), 3.56 (br, 4H, CH2sC), 2.81 (s, 6H, ArCH3), 1.26 (s,
6H, CH3sC); ESI HRMS, m/z Anal. Calcd data for C15H20N4O323Na80-
Se M + Na+: 407.0598. Found: 407.0592.
The oxidation of arylselelanyl-1H-[1,2,4]triazoles to arylselenonyl-
1H-[1,2,4]triazoles is a laborious job for the synthesis of the compounds
introduced above. Only arylseleninyl-1H-[1,2,4]triazoles have been
obtained when the method was tried with H2O2, benzoyl Peroxide
(BPO), and K2S2O8. Oxone, a strong oxidant produced by BASF Co.,
has been selected by luck at last. The pH value is also the key factor
for the oxidation reaction, so the buffer solution of NaOH and Na2-
HPO4 was used to adjust the pH of the reaction mixture to 8-9. In
addition, the solution of Oxone should be added quickly so that the
pH of the mixture reaches the goal quickly.
Data for 3-(4-chlorobenzeneselenonyl)-[1,2,4]triazole-1-carboxylic
acid diethylamide (C5): yield, 77.0%; white solid; mp, 122-123 °C;
Rf ) 0.44 (silica gel, EtOAc/petroleum ether, 1:1); IR (KBr, cm-1
)
3100, 1700, 1480, 1460, 1440, 955, 890; 1H NMR (CDCl3) δ 8.91 (s,
1H, NdCHsN), 8.10 (d, J ) 8.60 Hz, 2H, ArH), 7.67 (d, J ) 8.56
Hz, 2H, ArH), 3.56 (br, 4H, CH2sC), 1.27 (s, 6H, CH3sC); ESI
HRMS, m/z Anal. Calcd data for C13H15N4O323Na80Se M + Na+:
412.9896. Found: 412.9902.
General Synthetic Procedure for Arylselenonyl-[1,2,4]triazole-
1-carboxylic Acid Diethylamide (C1-C12). The corresponding
arylselenonyl-1H-[1,2,4]triazole (B1-B12) was added (0.002 mol),
followed by 0.55 g (0.004 mol) of anhydrous K2CO3, to anhydrous
acetone (30 mL). The mixture was stirred for 20 min, 0.5 mL of
triethylamine (TEA) and 0.41 g (0.003 mol) of diethylcarbamoyl
chloride were added in turn, and the mixture was continuously stirred
for 2-3 h. Then the mixture was filtered, solvent was distilled off under
vacuum, 50 mL of H2O was added, and the mixture was extracted with
chloroform (3 × 30 mL), dried over anhydrous sodium sulfate, and
separated on silica column with EtOAc/petroleum ether (v/v ) 1:1) to
give pure products C1-C12.
Data for 3-(2,4,6-trimethylbenzeneselenonyl)-[1,2,4]triazole-1-car-
boxylic acid diethylamide (C6): yield, 47.0%; mp, 155-157 °C; Rf )
0.47 (silica gel, EtOAc/petroleum ether, 1:1); IR (KBr, cm-1) 3118,
1
2925, 2454, 1710, 1264, 945, 886; H NMR (CDCl3) δ 8.83 (s, 1H,
NdCHsN), 6.95 (s, 2H, ArH), 3.50 (br, 4H, CH2sC), 2.69 (s, 6H,
ArCH3), 2.27 (s, 3H, ArCH3), 1.19 (br, 6H, CH3sC); ESI HRMS, m/z
Anal. Calcd data for C16H22N4O323Na80Se M + Na+: 421.0755.
Found: 421.0750.
Data for 3-(4-nitrobenzeneselenonyl)-[1,2,4]triazole-1-carboxylic
acid diethylamide (C7): yield, 44.0%; mp, 151-152 °C; Rf ) 0.43 (silica
gel, EtOAc/petroleum ether, 1:1); IR (KBr, cm-1) 3140, 2985, 1721,
Arylselenonyl-1H-[1,2,4]triazoles could be easily recognized in
1
infrared spectra. The peaks appeared at νmax ) 890 and 950 cm-1
,
1528, 1350, 1264, 860, 737, 956, 893; H NMR (CDCl3) δ 8.91 (s,