[Chemistry Class Notes] on Dichloromethane Pdf for Exam

Dichloromethane (CH₂C₁₂) which is also known as methyl chloride is a common salt solvent used in paint remover, pharmaceuticals, and metal cleaning agents.

Let us discuss dichloromethane in detail.

Dichloromethane, also known as DCM, methylene dichloride, methylene chloride, and Di-clo, is a slightly sweet-smelling clear organic liquid chemical solvent that poses significant workplace safety risks if strict handling instructions are not followed.

Dichloromethane is an organochloride compound having the chemical formula CH2Cl2. It is a colorless, volatile liquid with a moderately sweet aroma, which is a widely used solvent. Although not miscible with water, it is polar and miscible with several organic solvents. 

It is also called methylene chloride or Methylene dichloride. In general, it can be obtained naturally from macroalgae, oceanic sources, wetlands, and volcanoes. The majority of the Methylene dichloride in the environment is formed due to industrial emissions.

Methylene chloride is a colorless liquid that has a sweet, penetrating, and ether-like smell. It is a volatile liquid chlorinated hydrocarbon and is non-combustible. But if exposed to higher temperatures, it may produce toxic chloride fumes. Vapors are narcotic in nature at higher concentrations. Because of its nature, it is widely used as a paint remover and solvent.

The CH2C12 Structure is:

How is Dichloromethane (CH2C12) Used?

While Dichloromethane CH2C12 is not miscible in water, it can be dissolved in a wide range of organic solvents. These Properties of dichloromethane CH2Cl2 are combined with its volatility, making DCM a highly effective solvent in most industrial processes.

DCM is most commonly used as a paint remover. However, it has a wide range of applications and is generally used in aerosol products such as spray paints, insecticides, adhesives, and bathtub refinishing. It is also used to decaffeinate drinks.

So, we can say that, CH2Cl2 is soluble in water.

Caffeine Extraction

The Extraction technique is used to separate an organic compound like caffeine, from a mixture of compounds. Solvent-based extractions happen when the caffeine is removed by a chemical solvent, like ethyl acetate or Dichloromethane CH2C12.

Because the caffeine is more soluble in DCM (at 140 mg/ml) than it is in water (at 22 mg/ml), DCM became a preferred solvent to use in caffeine extraction. In coffee, the unroasted beans repeatedly rinse in Dichloromethane after being steamed. The DCM then extracts the caffeine from them before being drained away. This results in flavorsome coffee beans without the kick.

Because of some health risks associated with the Dichloromethane CH2C12, however, soon it was replaced by non-toxic alternatives. Also, white DCM has various advantages in industrial applications including its own risks.

Properties of Dichloromethane

Dichloromethane is a colorless solvent with a moderately sweet, chloroform-like aroma. It emits toxic fumes when heated and is highly volatile. Though it forms flammable vapor-air mixtures, it has no definite flashpoint. It is completely miscible with carbon tetrachloride, benzene, ethyl acetate, chloroform, diethyl ether, alcohol, and hexanes. Few of the dichloromethane properties are,

• Molecular Weight: 84.93 g.mol-1

• Boiling Point of CH2C12: 39.6 °C (103.3 °F; 312.8 K)

• Melting Point: −96.7 °C (−142.1 °F; 176.5 K);

• Solubility in Water: 25.6 g/L (15 °C) [17.5 g/L (25 °C), 15.8 g/L (30 °C), 5.2 g/L (60 °C)]

• Density: 1.3266 g/cm3;

• Viscosity: 0.43 cP (20 °C).

• Appearance-Colorless liquid

• Odor-Faint,

• Decomposes at 720 °C

Most dichloromethane hazards are connected with human health. Since the substance is extremely toxic, It seriously irritates the eyes, throat, nose, and harms the nervous system, and can be even fatal. It’s a proven fact that DCM is an animal carcinogen and can cause cancer in humans in case of prolonged exposure.

Production of Dichloromethane (DCM)

The Dichloromethane solvent was first prepared by a French chemist, Henri Victor Regnault, in 1839. He has isolated it from a chlorine and chloromethane mixture by exposing it to sunlight.

Dichloromethane can be synthesized by treating either methane or chloromethane with chlorine gas at temperatures between 400 and 500° C. They undergo a series of reactions that produce more chlorinated products. Approximately 4.00 000 tons were produced in countries such as Japan, Europe, and the United States in 1993.

This method resulted in a combination of chloromethane, chloroform, carbon tetrachloride, and Dichloromethane. They were further isolated by the distillation process.

Dichloromethane CH2C12 Uses

There are a number of uses of CH2C12 to be discussed, and some of them are given here.

Many of the uses of Dichloromethane are associated with its solvent properties. It serves as a part of paint strippers and varnish strippers in the household. In comparison, DCM is also used in bathtub refinishing.

The chemical is commonly used in industry and manufacturing. It is an important extractive solvent for food production and beverages. For example, the solvent is used to remove caffeine from coffee beans and tea leaves, to make spices, to form hops extract for beers, and more.

This substance is present in lubricating and degreasing products in the transportation industry, to clean the metal parts and surfaces safe and quickly. In addition, DCM is used in the manufacturing of synthetic fabrics, photographic films, inks, and several others.

Furthermore, the Dichloromethane is also used as a solvent in food technology, in aerosol formulations, a solvent in pharmaceutical manufacturing products,
can be used as a degreasing agent and also used in the manufacturing of electronics.

Some other uses of Dichloromethane:

• Used inorganic-based paint stripper as an active ingredient.

• In the manufacturing of other medicines and Pharmaceuticals.

• Aerosols for  Spray paint and insecticides.

• Used in preparing flavorings in beverage and food industries.

Health Hazards of Dichloromethane

Inhalation

Inhalation of methylene chloride causes irritation in the nose and throat. It impacts the central nervous system (CNS). It is a possible mutagen and is expected to be a human carcinogen.

Carbon Monoxide Poisoning

When dichloromethane has been inhaled and absorbed into the bloodstream, it gives rise to carbon monoxide. This happens because the enzyme Cytochrome P-450 metabolizes with DCM, and later the carbon monoxide is formed, and this can lead to carbon monoxide poisoning.

Limitations of Dichloromethane

• Dichloromethane has been classified as a neurotoxin and has proven to cause damage to the central nervous system (CNS) and the brain.

• Dichloromethane has also been classified as a probable human carcinogen by the EPA environmental protection agency as high levels of exposure causes lung and liver cancer in animals.

• If inhaled, it can cause wheezing, coughing, and shortness of breath.

• Irritation and redness can occur if liquid dichloromethane comes in contact with skin and can also lead to skin burns.

• It can also cause chemical burns to the eyes and severe irritation.

Conclusion

This is all about the organic compound dichloromethane, its properties, and its uses. Concentrate on the features and limitations to understand them well and develop your conceptual foundation.