76738-62-0

Basic information

• Product Name: Paclobutrazol
• Synonyms: (2RS,3RS)-1-(4-Chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol;(r*,r*)-(+-)-thyl);1h-1,2,4-triazole-1-ethanol,beta-((4-chlorophenyl)methyl)-alpha-(1,1-dimethyle;2,4-Triazole-1-ethanol,.beta.-[(4-chlorophenyl)methyl]-.alpha.-(1,1-dimethylethyl)-,(R*,R*)-(±)-1H-1;Culter;duoxiaozuo;ici-pp333;pp333
• CAS NO: 76738-62-0
• Molecular Formula: C₁₅H₂₀ClN₃O
• Molecular Weight: 293.79
• EINECS: 266-325-7
• Product Categories: PLANT GROWTH REGULATOR;Pesticide intermediates;NULL;Pharmaceutical intermediates
• Mol File: 76738-62-0.mol
• Article Data: 6

Chemical Properties

• Melting Point: 165-166°C
• Boiling Point: 460.9 °C at 760 mmHg
• Flash Point: 232.6 °C
• Appearance: off-white to beige solid
• Density: 1.22
• Vapor Pressure: 2.72E-09mmHg at 25°C
• Storage Temp.: 0-6°C
• PKA: 13.92±0.20(Predicted)
• Sensitive: Hygroscopic
• Merck: 14,6984
• CAS DataBase Reference: Paclobutrazol(CAS DataBase Reference)
• NIST Chemistry Reference: Paclobutrazol(76738-62-0)
• EPA Substance Registry System: Paclobutrazol(76738-62-0)

Safety Data

• Hazard Codes: Xn,F
• Statements: 22-21/22-11
• Safety Statements: 36
• RIDADR: UN1325 4.1/PG 2
• WGK Germany: 3
• RTECS: XZ4803300
• HazardClass: 4.1
• PackingGroup: II
• Hazardous Substances Data: 76738-62-0(Hazardous Substances Data)

Usage

Description

Paclobutrazol (PBZ) is a triazole-containing plant growth retardant known for its ability to inhibit the biosynthesis of gibberellins, which are plant hormones that promote cell elongation and division. It also possesses antifungal properties and can be transported acropetally in plants, suppressing the synthesis of abscisic acid and inducing chilling tolerance. Paclobutrazol is commonly utilized in research to study the role of gibberellins in plant biology.
Chemical properties:
The pure form of Paclobutrazol appears as a white crystalline solid with a melting point of 165-166°C, a relative density of 1.22, and a vapor pressure of 1x10^-6 Pa at 20°C. It is soluble in various solvents at different concentrations, such as methanol (150 g/L), acetone (110 g/L), methylene chloride (100 g/L), hexane (10 g/L), xylene (60 g/L), water (35 mg/L), and cyclohexanone (180 g/L). The partition coefficient (n-octanol/water) is 1590. The pure product is stable at 50°C for 6 months, and its aqueous solution remains stable at room temperature for over 30 days, showing relative stability against UV light.

Uses

Used in Agriculture:
Paclobutrazol is used as a plant growth regulator to control the growth of various crops, including rice, fruit trees, and ornamental shrubs. It can improve the activity of indole acetic acid oxidase, reduce the level of endogenous IAA in rice seedlings, and promote leaf development. It also strengthens the root system, reduces lodging, and increases yield. In fruit trees, it can be used to shorten the tree and enhance ornamental value. For greenhouse vegetables like tomatoes and rape, it provides a strong seedling effect.
Used in Horticulture:
Paclobutrazol is employed by arborists to maintain deciduous and broadleaf trees near buildings, reduce the growth of trees near power lines, and extend the longevity of trees on sites with limited natural resources.
Used in Pest Control:
Paclobutrazol has an effect against rice blast, cotton red rot, cereal smut, wheat rust, and powdery mildew in various crops. It also exhibits inhibitory effects on some monocotyledonous and dicotyledonous weeds when used in appropriate amounts.
Used in Seed Treatment:
For the cultivation of late rice, paclobutrazol can be applied to strengthen seedlings and control excessive growth in machine-transplanted rice seedlings. It is also used for branch control and fruit protection in fruit trees, with applications typically performed in late autumn or spring.
Used as a Fruit Preservative:
Paclobutrazol can be utilized as a preservative in the fruit industry to extend the shelf life and maintain the quality of fruits.

Toxicity

The acute oral LD50 of rats was 2000mg/kg (male), 1300mg/kg (female); for mice oral: 490mg/kg (male), 1,200mg/kg (female); for rabbit, the acute oral LD50: 840 mg/kg (male), 940 mg/kg (female). Rat and rabbit: acute percutaneous LD50> 1000mg/kg. For rat, acute inhalation has a LC50: 4.79mg/L (male) (4h), 3.13mg/L (female) (4h). It has certain irritant effect on the skin and eyes of the rat and rabbit. The no-action dosage for feeding rats of 2 years is 250 mg/kg; the no-action dosage for feeding dog of 1 year is 75 mg/kg; No mutagenicity effect. For rainbow trout, LC50:27.8mg/L (96h), carp LC5023.5mg/L (48h), and Daphnia LC50> 7900mg/L. Low toxicity to bees, LD50> 0.002mg/only.

Production method

Preparation method one 1,2,4-triazole and 1-chloro-3,3-dimethyl-2-butanone were used as starting materials to synthesize α-1,2,4-triazole-3,3-dimethyl-2-butanone, followed with condensation reaction with chlorobenzyl chloride, generating the α-p-chlorobenzyl-1,2,4-triazole-3,3-dimethyl-2-butanone, and then followed by being reduced by sodium borohydride to get the paclobutrazol. This method is easy to obtain raw materials with less steps less. The main drawback is that during the reduction reaction using sodium borohydride (potassium), resulting in high cost. According to the literature, the Sodium Disulfite (Na2S2O4) is used as reductant for reaction at alkaline media (NaHCO3) and the selected solvent or solvent system (water-methanol, 6: 1, volume ratio), generating paclobutrazol. An example of the operation is as follows: 0.03 mol of NaHCO3 is mixed with 60 mL of water and heated with stirring to dissolving. Then, the chlorothiazone was completely dissolved in 10 mL methanol and then added into the aqueous solution of NaHCO3 in one time. The resulting turbid reaction mixture was heated and stirred, and the safety powder (0.03 mol) was added in 6 h in 6 h after refluxing. Perform reflux for 2h. After the end of the reaction, apply cooling, suction filtration, washing with water and drying to get paclobutrazol with the melting point of 146~154 ℃. The crude product was recrystallized from acetonitrile as a white solid with a m.p. of 162-163 ° C, product purity of 98.23%, and the yield of 98.81% base on calculation on clozapine. Preparation method two Take p-chlorobenzaldehyde and 3,3-dimethyl-2-butanone as the raw material to generate the corresponding ketene, with hydrogenation, bromination and reaction with 1, 2, 4-triazole, and finally reduced with boron hydride sodium to generate paclobutrazol. This method is easy to obtain raw materials, but the process is longer. Preparation method three 1-(p-chlorophenyl)-2-(1,2,4-triazol-1-yl) propionyl chloride is reacted with tert-butyl magnesium bromide, followed by reduction with sodium borohydride to generate paclobutrazol. Though the production steps of this method are few, but the raw material is rare, and easy to subject to hydrolysis, need to be carried out under anhydrous conditions.

Hazards & Safety Information

Category:? Pesticides Toxic classification:? poisoning Acute toxicity:? Oral-Rat LD50: 1300 mg/kg; Oral-mouse LD50: 490 mg/kg Flammability and hazardous characteristics:? Combustion produces toxic nitrogen oxides and chloride gases Storage and transportation characteristics Treasury: ventilated, low temperature and dry; store it separately from food raw materials for storage and transportation Fire extinguishing agent:? dry powder, foam, sand

Trade name

BONZI?; CLIPPER?; CULTAR?; ICI-PP 333?; MON-7325?[C]; PARLAY?; PICCOLO?; PP 333?; PROFILE?; TURF MANAGER?

InChI:InChI=1/2C15H20ClN3O/c2*1-15(2,3)14(20)13(19-10-17-9-18-19)8-11-4-6-12(16)7-5-11/h2*4-7,9-10,13-14,20H,8H2,1-3H3/t2*13?,14-/m10/s1

Synthetic route

paclobutrazol (76738-62-0) → C25H31ClN4O3S

Conditions	Yield
Multi-step reaction with 2 steps 1: sulphamoyl chloride / N,N-dimethyl acetamide / 0 - 20 °C 2: [bis(acetoxy)iodo]benzene; 1,3-dimethyl-imidazoline-2-selone / dichloromethane / Inert atmosphere View Scheme

paclobutrazol (76738-62-0) → paclobutrazole sulfamate

Conditions	Yield
With sulphamoyl chloride In N,N-dimethyl acetamide at 0 - 20℃;	1.26 g

Upstream product

• 63190-87-4 1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-one 
• 75-97-8 3,3-dimethyl-butan-2-one 
• 5469-26-1 1-Bromopinacolon 
• 58905-32-1 3,3-dimethyl-1-(1,2,4-triazol-1-yl)-2-butanone 
• 66346-01-8 1-(4-chlorophenyl)-4,4-dimethyl-pentan-3-one 
• 109-65-9 1-bromo-butane 
• 693-03-8 n-butyl magnesium bromide 
• 66346-00-7 α-(1,2,4-triazol-1-yl)-α-p-chlorobenzylchloride 

Relevant articles and documents

New lead compounds for brassinosteroid biosynthesis inhibitors

The first brassinosteroid biosynthesis inhibitor is reported. Among newly synthesized triazole derivatives, 4-(4-chlorophenyl)-2-phenyl-3- (1,2,4-triazoyl)butan-2-ol (6) was found to inhibit the growth of cress seedlings, and this inhibition was recovered by the treatment of brassinolide, suggesting that compound 6 primarily inhibits brassinosteroid biosynthesis.

Method for the treatment of plants with agrochemical tablet compositions

Novel method for applying agrochemicals to plants, which method consists in attaching to the surface of the plants tablets comprising at least one agrochemically active compound and at least one adjuvant, which is solid, liquid of pasty at room temperature, and optionally, one or more excipients optionally in admixture with one or more other additives and/or water.

Combating fungi with triazolyl-benzyloxy-ketones and-carbinols

Triazolyl-benzyloxy-ketones or carbinols of the formula STR1 in which A is a keto group or a CH(OH) group, X is a halogen atom or an alkyl or halogenoalkyl radical, and n is 0, 1, 2, 3, 4 or 5, or an addition product thereof with a physiologically acceptable acid or metal salt, which possess fungicidal properties. Intermediates wherein A is a keto group and the azole group is replaced by chloride or bromine are also new.