1,1-dimethylpiperidinium chloride
C7H16ClN
Colourless, odourless, hygroscopic crystals.
223 ℃ (tech.)
<0.01 mPa (20 ℃)
1.187 g/cm3 (tech., 20 ℃)
In water >500 g/kg (20 ℃). In ethanol 162, chloroform 10.5, acetone, benzene, ethyl acetate, cyclohexane <1.0 (all in g/kg, 20 ℃).
Stable in aqueous media (7 d at pH 1-2 and pH 12-13, 95 ℃). Decomposes at 285 ℃. Stable in artificial sunlight.
= -2.82 (pH 7)
Inhibits the biosynthesis of gibberellic acid.
Plant growth regulator, absorbed and translocated throughout the plant.
Used on cotton to reduce vegetative growth and to advance maturation of the bolls; and to inhibit sprouting in onions, garlic and leeks. Used in combination with ethephon to prevent lodging (by shortening the stem and strengthening the stem wall) in cereals, grass seed crops, and flax. Typical application rates in cotton and onions are 0.04 kg/ha, and in cereals 0.2-0.6 kg/ha.
Acute oral LD50 for rats 464 mg/kg.
Acute percutaneous LD50 for rats >2000 mg/kg. Not irritating to skin and eyes (rabbits). Not a skin sensitiser.
LC50 (7 h) for rats >3.2 mg/l air.
for rats 3000, mice 1000 ppm.
1.5 mg/kg b.w.
WHO (a.i.) III; EPA (formulation) II
Acute oral LD50 for bobwhite quail >2000 mg/kg b.w. Dietary LC50 for mallard ducks and bobwhite quail >10 000 mg/kg diet.
LC50 (96 h) for trout 4300 mg/l.
LC50 (48 h) 68.5 mg/l.
EC50 (cell volume) (72 h) for Pseudokirchneriella subcapitata >1000 mg/l.
LC50 (14 d) for Eisenia foetida 440 mg/kg soil.
In rats, following oral administration of mepiquat chloride, c. 48% is excreted in the urine and c. 38% in the faeces, with <1% remaining in the tissues. The unmetabolised material constitutes c. 90% in each case.
DT50 of mepiquat chloride 10 - 97 d at 20℃ and 40% of maximum water-holding capacity. Koc 67 - 4685.
Product analysis by a gravimetric method or by ion-chromatography (hplc). Residues determined by ion-chromatography (hplc) of the parent compound or by glc with FID after conversion to 1-methylpiperidine. Details available from BASF, method no. CP 160, 1994.