Epronaz

Epronaz
Names
IUPAC name
N-ethyl-N-propyl-3-(propylsulfonyl)-1H-1,2,4-triazole-1-carboxamide
Preferred IUPAC name
N-ethyl-3-(propane-1-sulfonyl)-N-propyl-1H-1,2,4-triazole-1-carboxamide
Other names
  • эпроназ (Russian)
  • 三唑磺 (Chinese)
  • BTS 30 843[1]
  • N-ethyl-N-propyl-3-(propylsulfonyl)-1H-1,2,4-triazole-1-carboxamide
  • 1-[ethyl(propyl)carbamoyl]-3-(propylsulfonyl)-1H-1,2,4-triazole
  • 1-(N-ethyl-N-propyfcarbamoyl)-3-propylsulphonyl-1,2,4-triazole
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/C11H20N4O3S/c1-4-7-14(6-3)11(16)15-9-12-10(13-15)19(17,18)8-5-2/h9H,4-8H2,1-3H3
    Key: KCNUWLJAWRWKMO-UHFFFAOYSA-N
  • CCCN(CC)C(=O)N1C=NC(=N1)S(=O)(=O)CCC
Properties
C11H20N4O3S
Molar mass 288.37 g·mol−1
Melting point 51.5 °C (124.7 °F; 324.6 K) [1]
1.9 g/L[1]
Solubility in acetone 1000 g/L[1]
Solubility in benzene 500 g/L[1]
Hazards[3]
Lethal dose or concentration (LD, LC):
400-800 mg/kg (mouse, oral)
100-200 mg/kg (rat, oral)
2,000 mg/kg (rat, dermal)
500 mg/kg (rabbit, dermal)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Expronaz is a pre-emergent herbicide, which also acts in early post-emergence to control annual grasses.[1][2] Broadleaf weeds show some susceptibility, but only with very heavy doses. It was field trialled in the 1970s in the USA, Europe and Australia,[3] but has not been commercialised.[4]

Chemical properties

Epronaz is fairly stable under heat but decomposes completely at 250 °C, and melts at 51.0 to 51.8 °C. Visible light does not degrade it, but UV light does, though it was only seen in solutions of water or methanol, not benzene, so the degradation may depend on radicals in solution. Epronaz does not have particularly high volatility, at about one 2000th of the vapour pressure of trifluralin. 70 °C, 0.0124 μmHg, and at 102C, 0.392 μmHg.[1]

Its solubilities are 1.9 g/L (in water), 1000 g/L (in acetone), 167 g/L (in ethanol), 500 g/L (in benzene), 1000 g/L (in chloroform), 67 g/L (in diethyl ether), 4 g/L (in kerosene), 1 g/L (in light petroleum) and 333 g/L in xylene.[1]

Its Wiswesser line formula is T5NN DNJ AVN3&2 CSW3.[3]

Hydrolysis

Epronaz is very susceptible to hydrolysis, which is strongly dependent on temperature and pH. Its half-life under hydrolysis (time until half is gone) ranges from 688 days (at 20 °C and 6.3 pH) down to 44 minutes (70 °C and 8.1 pH). Temperature seems to have the stronger effect, as at 70 °C the half-life is reduced much more even at low pH (6.3) to 21 hours, than with high pH (8.1) and low temperature (20 °C), at 660 hours. It is expected that the hydrolysis products of epronaz are non-toxic, and that in typical soil conditions, it will be able to persist for a few weeks before breaking down.[1]

Hydrolysis products include N-ethyl-N-propylcarbamate, 1,3-diethyl-1,3-dipropylurea, N-ethylpropylamine, and carbon dioxide. A free triazole may also be present, which readily forms water-soluble salts.[1]

Application

Epronaz is supposed to be sprayed at 1-2 kg/Ha of active ingredient to control all common grassy weeds. The symptoms of pre-emergent use are failure to germinate, or severe twisting and stunting of the seedling. In early post-emergent use, the weed ceases to grow, darkens in colour, suffers malformed leaves, and dies. It is supposed to be used on soyabean, peanut, maize, cotton and small grains.[3]

Wheat, barley, maize and cotton can be injured by heavy applications, but show no symptoms at 1-2 kg/ha. Soyabean and peanut show no symptoms even at 8 kg/ha. There is evidence that epronaz might be effective even on soils with very much organic matter, where many other pre-emergence herbicides struggle. It can be applied post-emergently to grass until about the three-leaved stage.[3]

Epronaz appears to work by root uptake from soil, with no contact activity.[3]

History

Work at the Boots Company (later Schering Agriculture)[4] on N-carbamoyltriazoles started in 1969, after N-acyl-2,4,5-tribromo-imidazoles were found to be insecticidal and herbicidal post-emergently. Some N-dialkylcarbamoyl derivatives were active pre-emergently too, by a seemingly different mechanism to urea and triazine herbicides, suggesting the chance to discover a new class of herbicide. Of over 1000 molecules tested in this effort, epronaz was chosen for commercial development.[1][3]

Preliminary tests were done at Lenton Research Station, Nottingham, and Koree Research Farm, Australia.[3]

References

  1. ^ a b c d e f g h i j k Brookes, Robert F.; Copping, Leonard G. (December 1975). "Some chemical and physical properties of epronaz, a new herbicide". Pesticide Science. 6 (6): 665–673. doi:10.1002/ps.2780060614. Retrieved 15 February 2026.
  2. ^ a b "epronaz data sheet". www.bcpcpesticidecompendium.org. BCPC. Retrieved 15 February 2026.
  3. ^ a b c d e f g h Kopping, Leonard G.; Brookes, R. F. (November 1974). "BTS 30 843 -- A New Pre-Emergence Grass Herbicide" (PDF). Proceedings of the Twelfth British Weed Control Conference. 1. Hotel Metropol, Brighton, England: 809. Retrieved 17 February 2026.
  4. ^ a b MacBean, C. (2012). A World Compendium The Pesticide Manual Sixteenth Edition Supplementary Entries – Extended (16th ed.). British Crop Production Council. p. 232. ISBN 978-1-901396-86-7.
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