Herbicide
HRAC  A WSSA  1; cyclohexanedione oxime



NOMENCLATURE
Common name tralkoxydim (BSI, draft E-ISO); tralkoxydime ((f) draft F-ISO)
IUPAC name 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-mesitylcyclohex-2-enone 
Chemical Abstracts name 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-(2,4,6-trimethylphenyl)-2-cyclohexen-1-one 
CAS RN [87820-88-0]  Development codes ICIA0604; PP604 (both ICI)

PHYSICAL CHEMISTRY
Composition Tech. material is 92-95% pure.  Mol. wt. 329.4  M.f. C₂₀H₂₇NO₃  Form Colourless, odourless solid.  M.p. 106 ºC; (tech., 99-104 ºC)  V.p. 3.7 × 10^-4 mPa (20 ºC, extrapolated)  K_OW logP = 2.1 (20 ºC, purified water)  Henry 2 × 10^-5 Pa m³ mol^-1 (purified water)  S.g./density 1.16 (25 ºC)  Solubility In water 6 (pH 5), 6.7 (pH 6.5), 9800 (pH 9) (all in mg/l, 20 ºC). In hexane 18, methanol 25, acetone 89, ethyl acetate 110, toluene 213, dichloromethane >500 (all in g/l, 24 ºC).  Stability Stable >12 w (15-25 ºC), 4 w (50 °C). DT₅₀ (25 ºC) 6 d (pH 5), 113 d (pH 7); after 28 d, 87% unchanged (pH 9).  pKa 4.3 (25 ºC) 

APPLICATIONS
Biochemistry Fatty acid synthesis inhibitor, by inhibition of acetyl CoA carboxylase (ACCase). Cell division inhibitor.  Mode of action Selective systemic herbicide, absorbed by the leaves and translocated acropetally in the phloem to the growing points.  Uses Post-emergence control of Avena spp. and other grass weeds (including Lolium spp., Setaria viridis, Phalaris spp., Alopecurus myosuroides and Apera spica-venti) in wheat and barley. Applied at 150-400 g/ha.  Formulation types EC; SC; WG.  Compatibility Compatible with a range of broad-leaved weed herbicides.

ANALYSIS
For tech./formulations, by lc using u.v. For residues, by lc using column switching technique.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD₅₀ for male rats 1258, female rats 934, male mice 1231, female mice 1100, male rabbits >519 mg/kg.  Skin and eye Acute percutaneous LD₅₀ for rats >2000 mg/kg. Mild skin and eye irritant (rabbits). Not a skin sensitiser (guinea pigs).  Inhalation LC₅₀ (4 h) for rats >3.5 mg/l air.  NOEL (90 d) for rats 20.5 mg/kg diet; (1 y) for dogs 5 mg/kg diet. NOAEL (90 d) for rats 250 ppm (20.5 mg/kg daily), for dogs 0.5 mg/kg b.w. daily.  Other Non-mutagenic in standard tests. Non-teratogenic in rabbits.  Toxicity class WHO (a.i.) III; EPA (formulation) III ('Achieve')  EC hazard (Xn R22)

ECOTOXICOLOGY
Birds Acute oral LD₅₀ for mallard ducks >3020, partridges 4430 mg/kg. Dietary LC₅₀ (5 d) for mallard ducks >7400, quail 6237 mg/kg diet.  Fish LC₅₀ (96 h) for mirror carp >8.2, bluegill sunfish >6.1, rainbow trout >7.2 mg/l.  Daphnia EC₅₀ (48 h) >175 mg/l.  Algae EC₅₀ (120 h) for green algae 7.6 mg/l.  Other aquatic spp. EC₅₀ (14 d) for Lemna gibba 1.0 mg/l.  Bees LD₅₀ (contact) >0.1 mg/bee; (oral) 0.054 mg/bee.  Worms LC₅₀ (14 d) 87 mg/kg.

ENVIRONMENTAL FATE
Animals Readily excreted from rats, as 4 different metabolites; no unchanged tralkoxydim is detected.  Plants Degrades rapidly in crops. At a limit of detection of 0.02 mg/kg, no residues of tralkoxydim or its metabolites have been found in wheat or barley at harvest, after application at up to double the recommended use rates.  Soil/Environment Degrades rapidly in lab. soil studies; typical DT50 2-5 d (aerobic), 3 w (flooded soil). Primary metabolites are in turn extensively degraded; within 30 dat, up to 44% of applied radioactivity is liberated as CO₂. Degradation is primarily microbial, but soil surface photolysis, aqueous photolysis and hydrolysis all occur. Field data are consistent with these results. K_oc 30-300; however, rapid degradation ensures that there is no significant movement of either tralkoxydim or its degradates down the soil profile.