mepiquat chloride
Plant growth regulator
quaternary ammonium
NOMENCLATURE
mepiquat chloride
Common name 1,1-dimethylpiperidinium chloride
CAS RN [24307-26-4] EEC no. 246-147-6 Development codes BAS 083 W (BASF)
mepiquat
Common name mepiquat (BSI, E-ISO, (m) F-ISO)
IUPAC name 1,1-dimethylpiperidinium
Chemical Abstracts name 1,1-dimethylpiperidinium
CAS RN [15302-91-7]
PHYSICAL CHEMISTRY
mepiquat chloride
Composition ³99% pure (w/w); tech. concentrate 600 g/l. Mol. wt. 149.7 M.f. C7H16ClN Form Colourless, odourless, hygroscopic crystals. M.p. 223 ºC (tech.) V.p. <0.01 mPa (20 ºC) KOW logP = -2.82 (pH 7) S.g./density 1.187 g/cm3 (tech., 20 ºC) Solubility In water >500 g/kg (20 ºC). In ethanol 162, chloroform 10.5, acetone, benzene, ethyl acetate, cyclohexane <1.0 (all in g/kg, 20 ºC). Stability Stable in aqueous media (7 d at pH 1-2 and pH 12-13, 95 ºC). Decomposes at 285 ºC. Stable in artificial sunlight.
mepiquat
Mol. wt. 114.2 M.f. C7H16N
COMMERCIALISATION
History Plant growth regulating properties of mepiquat chloride reported by B. Zeeh et al. (Kem-Kemi, 1974, 1, 621). Introduced by BASF AG in USA in 1980. Patents DE 2207575; US 3905798 Manufacturers BASF; Gharda; JIE; Sharda
APPLICATIONS
mepiquat chloride
Biochemistry Inhibits the biosynthesis of gibberellic acid. Mode of action Plant growth regulator, absorbed and translocated throughout the plant. Uses 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. Formulation types SL; UL. Selected products: 'Pix' (BASF); 'Mepex' (Griffin); 'Mepichlor' (Micro Flo); 'MepPlus' (contains Bacillus cereus, strain Bp01) (Micro Flo); 'Roquat' (Rotam); mixtures: 'Terpal' (+ ethephon) (BASF, DuPont, Bayer CropScience)
OTHER PRODUCTS
mepiquat chloride
'PixUltra' (with borate additive) (BASF); 'Ponnax' (BASF); 'Vallix 5' (IQV) mixtures: 'Cyclade' (+ chlormequat chloride+ ethephon) (BASF); 'Médax' (+ prohexadione-calcium) (BASF); 'Pix Plus' (+ Bacillus cereus) (BASF); 'Stronghold' (+ chlormequat chloride) (BASF); 'Banshee' (+ ethephon) (Barclay); 'Cyter' (+ chlormequat chloride) (De Sangosse, BASF); 'Terpitz' (+ ethephon) (Me2) Discontinued products mixtures: 'Mepex Plus-CP' * (+ 4-indol-3-ylbutyric acid+ cytokinins+ gibberellic acid) (Griffin)
ANALYSIS
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.
MAMMALIAN TOXICOLOGY
mepiquat chloride
Oral Acute oral LD50 for rats 464 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2000 mg/kg. Not irritating to skin and eyes (rabbits). Not a skin sensitiser. Inhalation LC50 (7 h) for rats >3.2 mg/l air. NOEL for rats 3000, mice 1000 ppm. ADI 1.5 mg/kg b.w. Toxicity class WHO (a.i.) III; EPA (formulation) II EC classification Xn; R22| R52, R53
ECOTOXICOLOGY
mepiquat chloride
Birds Acute oral LD50 for bobwhite quail >2000 mg/kg b.w. Dietary LC50 for mallard ducks and bobwhite quail >10 000 mg/kg diet. Fish LC50 (96 h) for trout 4300 mg/l. Daphnia LC50 (48 h) 68.5 mg/l. Algae EC50 (cell volume) (72 h) for Pseudokirchneriella subcapitata >1000 mg/l. Other aquatic spp. EC10 (18 h) for Pseudomonas putida 1630 mg/l. Bees Non-toxic to bees. Worms LC50 (14 d) for Eisenia foetida 440 mg/kg soil.
ENVIRONMENTAL FATE
Animals 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. Soil/Environment DT50 of mepiquat chloride 10 - 97 d at 20? ºC and 40% of maximum water-holding capacity. Koc 67 - 4685.
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