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THIDIAZURON

 

Plant growth regulator: phenylurea



NOMENCLATURE
Common name thidiazuron (BSI, E-ISO, (m) F-ISO, ANSI)
IUPAC name 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea 
Chemical Abstracts name N-phenyl-N'-1,2,3-thiadiazol-5-ylurea 
CAS RN [51707-55-2] 

PHYSICAL CHEMISTRY
Mol. wt. 220.2  M.f. C9H8N4OS  Form Colourless, odourless crystals.  M.p. 210.5-212.5 ºC (decomp.)  V.p. 4 ×10-6 mPa (25 ºC) (Langmuir method)  KOW logP = 1.77 (pH 7.3)  Henry 2.84 × 10-8 Pa m3 mol-1 (calc.)  Solubility In water 31 mg/l (pH 7, 25 ºC). In hexane 0.002, methanol 4.20, dichloromethane 0.003, toluene 0.400, acetone 6.67, ethyl acetate 1.1 (all in g/l, 20 ºC).  Stability Rapidly converted to photoisomer, 1-phenyl-3-(1,2,5-thiadiazol-3-yl)urea, in presence of light (l >290 nm). Hydrolytically stable at room temperature from pH 5-9. No decomposition in accelerated storage stability study (14 d, 54 ºC).  pKa 8.86
COMMERCIALISATION
History Plant growth regulator reported by F. Arndt et al. (Plant Physiol., 1976, 57, Supplement, p. 99). Introduced by Schering AG (now Aventis CropScience).  Patents DE 2506690; DE 2214632  Manufacturers Aventis
APPLICATIONS
Biochemistry Cytokinin activity.  Mode of action Plant growth regulator, absorbed by the leaves, which stimulates formation of an abscission layer between the plant stem and the leaf petioles, causing the dropping of entire green leaves.  Uses Used for defoliation of cotton, in order to facilitate harvesting.  Formulation types EC; WP; Oily flowable.