Clomazone Chemical Properties

Melting point:

25°C

Boiling point:

275.4°C

Density 

1.192

refractive index 

1.5388 (estimate)

Flash point:

157 °C

storage temp. 

Sealed in dry,2-8°C

solubility 

DMF: 33 mg/ml,DMSO: 16 mg/ml,Ethanol: 33 mg/ml,PBS (pH 7.2): 1 mg/ml

form 

Solid

pka

-1.48±0.40(Predicted)

color 

White to off-white

Water Solubility 

1.101g/L(temperature not stated)

BRN 

7480026

InChIKey

KIEDNEWSYUYDSN-UHFFFAOYSA-N

CAS DataBase Reference

81777-89-1(CAS DataBase Reference)

NIST Chemistry Reference

Dimethazone(81777-89-1)

EPA Substance Registry System

Clomazone (81777-89-1)

Safety Information

Hazard Codes 

Xn

Risk Statements 

20/22-36/38

Safety Statements 

26-36

RIDADR 

2902

WGK Germany 

2

RTECS 

NY2977000

HazardClass 

6.1(b)

PackingGroup 

III

Hazardous Substances Data

81777-89-1(Hazardous Substances Data)

Toxicity

LD50 in male rats, female rats, mallard duck-bobwhite quail (mg/kg): 2077, 1369, >2510 orally; in rabbits (mg/kg): >2000 dermally (Chen)

Clomazone Usage And Synthesis

Description

The molecular target site of clomazone has recently been determined. With clomazone, carotenoid synthesis is inhibited, but no intermediates in the carotenoidcommitted portion of the pathway accumulate (5,6). Synthesis of the derivatives of GGPP (gibberellic acid, phytol, carotenoids) is inhibited by clomazone (5–8). However, the synthesis of certain sesquiterpenoids and triterpenoids is not inhibited (9). Until recently, there was no credible report of the effect of clomazone on any enzyme of the terpenoid pathway (10–12). This was due to the fact that clomazone is a proherbicide and that the proper enzyme had not been tested.

Chemical Properties

Depending purity, it may be clear and colorless to pale yellow or brownish liquid. Commercially available as emulsifiable concentrates that can be dissolved in water

Uses

Herbicide.

Definition

ChEBI: A oxazolidinone that is 1,2-oxazolidin-3-one substituted by a 2-chlorobenzyl group at position 2 and two methyl groups at position 4.

Hazard

Moderately toxic by ingestion, inhalation, and skin contact. A reproductive hazard.

Agricultural Uses

Herbicide: Clomazone is a broad-spectrum herbicide used on rice, peas, pumpkins, soybeans, sweet potatoes, winter squash, cotton, tobacco and fallow wheat fields to control annual grasses and broadleaf weeds.

Trade name

CERANO®; COLZOR TRIO®; COMMAND®; COMMENCE®, DIBEL®; FMC® 57020; GAMBIT®; MAGISTER®; MERIT®; STRATEGY®

Synthesis

1. 1000 kg of water was added to a 4000 L reactor followed by 460 kg of 4,4-dimethylisoxazolidin-3-one. The mixture was stirred for 1 hour at room temperature. 2. 383kg of sodium carbonate (Na2CO3) was added to the reaction mixture in small portions. The temperature of the mixture was raised to 85°C and the mixture was stirred continuously at this temperature for 2 hours. 3. 672 kg of o-chlorobenzyl chloride (2-chlorobenzyl chloride) was added slowly and dropwise over a period of 5 hours at 85°C. The mixture was kept at the same temperature for 2 hours. After the dropwise addition was completed, the temperature was maintained at 85°C until the reaction was complete. 4. The reaction mixture was cooled to room temperature, 800 kg of dichloromethane was added and stirred at room temperature for 15 hours. 5. The aqueous phase was separated and the aqueous phase was extracted three times with dichloromethane. 6. Recover the dichloromethane by distillation followed by addition of 2000 kg of hexane to the reactor. The mixture was refluxed for 1 hour, then cooled to 10-15 °C and continued stirring for 1 hour. 7. The solid product was separated by filtration, washed several times with hexane and finally dried under high vacuum to give pure 2-(2-chlorobenzyl)-4,4-dimethyloxazolidin-3-one (815 kg, purity: 96%). Note: Similar results were obtained using sodium hydroxide instead of sodium carbonate as base.

Potential Exposure

Clomazone is a oxazolidione broadspectrum herbicide used on rice, peas, pumpkins, soybeans, sweet potatoes, winter squash, cotton, tobacco, and fallow wheat fields to control annual grasses and broadleaf weeds.

Metabolic pathway

By the preparative incubation of clomazone with microorganisms that have the ability to metabolize clomazone, the metabolites are identified via major biotransformation reactions which involve hydroxylation at the 5-methylene carbon and one of the 3-methyl groups of the isoxazolidone ring and at the 3 0 -position of the phenyl ring. Minor metabolic routes include dihydroxylation on the phenyl ring, cleavage of the isoxazolinone ring, or complete removal of the isoxazolinone ring to form 2-chlorobenzyl alcohol. Under aerobic conditions of soils, degradation of clomazone proceeds primarily by CO2 evolution and the formation of bound soil residues. In flooded soils, clomazone is found rapidly to degrade via the formation of the reductive product N-[(2-chlorophenyl)methyl]-3-hydroxy-2,2- dimethylpropionamide. In tolerant soybean cell suspension cultures, the only metabolite identified is b-glycosyl-2-chlorobenzyl alcohol.

Shipping

UN2902 Pesticide, liquid, toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.

Incompatibilities

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.

Waste Disposal

Do not discharge into drains or sewers. Dispose of waste material as hazardous waste using a licensed disposal contractor to an approved landfill. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Containers must be disposed of properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.

References

[1] Patent: WO2015/353, 2015, A1. Location in patent: Page/Page column 16; 17
[2] Patent: CN106749072, 2017, A. Location in patent: Paragraph 0018; 0021; 0024; 0027

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