Methyl Carbamate 598-55-0
Methyl carbamate (also known as methyl carbamate or polyurethane) is an organic compound that is the simplest ester of carbamic acid (H2NCO2H). It is a colorless solid.
Methyl carbamate is made by reacting methanol and urea:
CO(NH2)2 + CH3OH → CH3OC(O)NH2 + NH3
It is also produced by the reaction of ammonia with methyl chloroformate or dimethyl carbonate.
Methyl carbamate (CH3OCONH2) is a simple organic compound consisting of a methyl group (CH3) attached to a carbamate functional group (OCONH2).
The carbamate group is a carbonyl (C=O) group with an amino (NH2) group attached.
Methyl carbamate is a polar molecule due to the electronegative oxygen and nitrogen atoms, which give it a dipole moment.
It has a tetrahedral molecular geometry around the carbonyl carbon atom.
Physical and Chemical Properties:
Chemical Formula: CH3OCONH2
CAS Number: 598-55-0
Molecular Weight: 75.08 g/mol
Appearance: White crystalline solid
Melting Point: 110-112°C
Boiling Point: 200°C
Melting point:56-58 °C (lit.)
Boiling point:176-177 °C (lit.)
Density:1,14 g/cm3
Refractive index:1.4125
Flash point: 93 °C
Storage conditions: Inert atmosphere, Room Temperature
Solubility:700 g/L (20°C)
Acidity Coefficient(pKa):13.37±0.50(Predicted)
Form:Adhering Crystals
Color:White
PH Value:6-8 (50g/l, H2O, 20℃)
Water Solubility:700 g/L (20 ºC)
Sensitivity:Moisture Sensitive
Methyl carbamate is a simple organic compound that is the methyl ester of carbamic acid.
It is a white crystalline solid with a faint ester-like odour.
Methyl carbamate is soluble in water, alcohol and other polar organic solvents.
It is moderately volatile and can be distilled under reduced pressure.
Methyl carbamate is relatively chemically stable but is subject to hydrolysis to form methanol and carbon dioxide.
Uses and Applications:
Carbamate pesticides are widely used in insecticides, herbicides and fungicides, and are also used as mosquito and cockroach killer. Commonly used ones are: Furadan, Carbaryl, Methomyl, Methomyl, Cordyceps, and so on.
Methyl carbamate is used mainly as a reaction intermediate in the textile and polymer industries. In the textile industry it is used in the manufacture of dihydroxymethyl carbamic acid methyl ester-based resins, which are applied to polyester/cotton blended fabrics as a stress-resistant finishing agent.The treated fabrics have good crease angle retention, are acid-turning resistant in commercial laundries, are chlorine-free, and are flame retardant.
Methyl carbamate is also used in the manufacture of pharmaceuticals, pesticides and polyurethanes.
Methyl carbamates are widely used as insecticides. They have anticholinesterase activity but do not produce cumulative effects.
Methyl carbamate is a chemical intermediate in the synthesis of various drugs, insecticides and other organic compounds.It is a precursor for the production of methyl isocyanate, which is used in the production of carbamate insecticides.
Methyl carbamate is used as a plasticiser, a fuel additive and as a component of certain paints and sealants.
In the past, it was also used as a rodenticide and insecticide, but its use in these applications has declined due to concerns about its toxicity.
1. Pharmaceutical and Agrochemical Intermediates:
Methyl carbamate is an important chemical intermediate used in the synthesis of various pharmaceutical and agrochemical products.
It is a precursor for the production of methylisocyanate, which is a key building block for many carbamate-based pesticides and herbicides.
Methyl carbamate can also be used as a starting material for the synthesis of certain anti-inflammatory, analgesic, and anticancer drugs.
2. Plasticizers and Coatings:
Methyl carbamate has been used as a plasticizer in various polymer and resin formulations, such as those used in paints, coatings, and adhesives.
It can improve the flexibility, impact resistance, and adhesion properties of these materials.
In some specialized coatings and sealants, methyl carbamate may be used as a crosslinking agent or curing additive.
3. Fuel Additives:
Historically, methyl carbamate has been used as a fuel additive, particularly in gasoline, to improve combustion efficiency and reduce engine deposits.
However, the use of methyl carbamate as a fuel additive has declined in recent years due to concerns about its potential toxicity and environmental impact.
4. Rodenticides and Insecticides:
In the past, methyl carbamate was employed as an active ingredient in some rodenticide and insecticide products.
These applications have decreased significantly due to the development of newer, more effective, and less toxic alternatives, as well as regulatory restrictions on the use of methyl carbamate-based pesticides.
5. Industrial Solvents and Cleaning Agents:
Due to its solvent properties and relatively low toxicity, methyl carbamate has been used in some industrial cleaning products and degreasing agents.
However, its use in these applications is limited, as more effective and environmentally friendly solvents and cleaning agents have become available.
Overall, the primary uses of methyl carbamate today are as a chemical intermediate in the production of pharmaceuticals, agrochemicals, and other specialty chemicals, rather than as a standalone product or additive. Its historical uses in fuel, pesticides, and industrial solvents have largely been phased out.
Synthesis and Production:
Methyl carbamate is typically synthesized by the reaction of methanol (CH3OH) with phosgene (COCl2) to form methyl chloroformate, followed by reaction with ammonia (NH3) to form the final product.
Alternatively, it can be produced by the reaction of methyl isocyanate (CH3NCO) with water.
Industrial production of methyl carbamate often involves continuous processes using specialized equipment and stringent safety measures due to the hazardous nature of the starting materials.
Synthesis of Methyl Carbamate:
The most common synthetic route for methyl carbamate involves a two-step process:
Reaction of methanol with phosgene:
Methanol (CH3OH) is reacted with phosgene (COCl2) to form methyl chloroformate (CH3OCOCl).
This reaction is typically carried out in the presence of a base, such as pyridine, to neutralize the hydrochloric acid byproduct.
Methyl chloroformate is an important intermediate in the production of various carbamate compounds.
Ammonolysis of methyl chloroformate:
The methyl chloroformate intermediate is then reacted with ammonia (NH3) to form methyl carbamate (CH3OCONH2).
This reaction involves the nucleophilic addition of ammonia to the carbonyl carbon of the methyl chloroformate, followed by the elimination of hydrogen chloride.
The reaction is typically carried out in an organic solvent, such as toluene or dichloromethane, to facilitate the separation of the methyl carbamate product.
Production of Methyl Carbamate:
Industrial-scale production of methyl carbamate often involves continuous processes using specialized equipment:
Phosgene generation:
Phosgene is typically generated on-site by the reaction of carbon monoxide (CO) and chlorine (Cl2) in the presence of a catalyst, such as activated carbon.
Phosgene generation requires strict safety measures due to the highly toxic nature of the gas.
Methyl chloroformate synthesis:
The phosgene is then reacted with methanol in a continuous flow reactor, often using a base catalyst to improve the reaction kinetics.
The methyl chloroformate product is typically purified by distillation or other separation techniques.
Ammonolysis step:
The methyl chloroformate is then reacted with ammonia gas or aqueous ammonia solution in a continuously operated reactor.
The methyl carbamate product is separated, typically by crystallization or evaporation, and further purified as needed.
Packaging and storage:
The purified methyl carbamate is then packaged, often in drums or other suitable containers, for distribution and storage.
Proper handling and storage procedures are crucial to ensure the safety and stability of the final product.
Reactivity and Degradation:
Methyl carbamate is susceptible to hydrolysis, both in acidic and basic conditions, which can break down the carbamate functional group.
Thermal decomposition can also occur at elevated temperatures, forming methanol, carbon dioxide, and other byproducts.
Under certain conditions, methyl carbamate can react with nucleophiles, such as alcohols or amines, to form substituted carbamates or ureas.
Microbial degradation of methyl carbamate has been reported, with some bacteria and fungi capable of using it as a carbon and nitrogen source.
Regulatory and Environmental Considerations:
Methyl carbamate is listed as a hazardous substance under various environmental regulations due to its toxicity.
Exposure limits and handling guidelines have been established for occupational settings to minimize the risks to workers.
Environmental fate and transport studies have shown that methyl carbamate can be persistent in certain soil and water environments, with the potential to bioaccumulate in some organisms.
Proper disposal and containment methods are essential to prevent environmental contamination and human exposure.
Toxicology and Safety:
Methyl carbamate is moderately toxic by ingestion or inhalation.
Symptoms such as nausea, vomiting, diarrhoea and respiratory distress can occur after exposure.
Prolonged or repeated exposure can also cause liver and kidney damage.
Appropriate personal protective equipment, such as gloves and respirators, should be used when handling methyl carbamate.
When working with this compound, proper ventilation and protective measures must be taken to minimise the risk of exposure.
Unlike its close relative, ethyl carbamate, it is not mutagenic to Salmonella (negative in the Ames test) but is mutagenic to fruit flies. Experimental evidence suggests that it is carcinogenic in rats and non-carcinogenic in mice. According to Proposition 65, the compound is “known to the State of California to be carcinogenic.
The causes of carbamate pesticide poisoning are similar to other pesticide poisonings. Productive poisoning is often seen when pesticides are applied without appropriate protective measures or in hot and humid environments, mainly through the skin and respiratory tract inhalation poisoning. Life poisoning is often seen in suicide or accidental poisoning, for oral poisoning.
Carbamate pesticide poisoning is acute, oral poisoning within 10 to 20 minutes of the onset of poisoning, the production of labour in contact with the poisoning of the majority of 2 to 6 hours onset. Similar to organophosphorus pesticide poisoning, especially muscarinic symptoms are more obvious. Mild poisoning has mild muscarinic symptoms and central nervous system symptoms, such as dizziness, headache, fatigue, nausea, vomiting, blurred vision, salivation, excessive sweating, pupil narrowing and so on. In addition to the above symptoms, moderate intoxication shows muscle tremor and increased blood pressure. Severe poisoning can appear pulmonary oedema, coma, cerebral oedema, whole blood cholinesterase activity in 30% or less, and in severe cases, there are respiratory muscle paralysis, respiratory failure, and even death. In addition, skin contamination can cause burning pain, flushing, rash; conjunctival contamination can cause burning sensation, tearing, pupil narrowing and so on.
Suspected poisoning by carbamate insecticides should be treated promptly, and a definitive diagnosis can be made by a clear history of exposure, symptoms, signs and symptoms, combined with the results of cholinesterase and toxicological tests. This type of poisoning leads to a decrease in blood cholinesterase activity, but it should be tested as soon as possible after the poisoning, and the cholinesterase activity will gradually recover as the duration of the poisoning increases. The poison is removed by gastric lavage, etc., and atropine, a potent antidote, is used. Unlike organophosphorus pesticide poisoning, oxime cholinesterase reenactors are prohibited in carbamate insecticide poisoning.