The dichloromethane, also known as methylene chloride, it is an organic compound whose chemical formula is CHtwoCltwo. Specifically, it is an alkyl halide derived from methane gas. Unlike methane, this compound is a colorless, polar liquid.
It was initially synthesized in 1839 by the French chemist and physicist Henri Victor Regnault (1810-1878), who managed to isolate it from a mixture of chlorine and chloromethane exposed to sunlight..
Dichloromethane is produced industrially by treating methane or chloromethane with chlorine gas at elevated temperatures (400-500 ºC). Together with dichloromethane, chloroform and carbon tetrachloride are produced in the process, which are separated by distillation..
Dichloromethane is used as a solvent that allows the welding of plastic materials and to degrease metals. It is also used in the decaffeination of coffee and tea, as well as a hop extractor and diluent for color additives and inks for marking fruits..
Dichloromethane is a toxic compound that can cause irritation of the nasal passages and throat by inhalation. Liver damage has been reported in workers exposed to high concentrations of dichloromethane. In addition, it is a mutagenic agent, being suspected of being carcinogenic.
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The first image showed the structural formula of CHtwoCltwo, in which its covalent bonds C-H and C-Cl stand out. Above it also has its structure represented by a model of spheres and bars. Note with the naked eye that the C-H bonds (white spheres) are short, while the C-Cl bonds (green spheres) are long.
The geometry of the CHtwoCltwo it is tetrahedral; but distorted by the bulkier chlorine atoms. One end of the tetrahedron is defined by the two chlorine atoms, more electronegative than those of hydrogen and carbon. Hence, in the CH moleculetwoCltwo a permanent dipole moment is established (1.6D).
This allows the dichloromethane molecules to interact with each other through dipole-dipole forces. Likewise, these intermolecular interactions are responsible for the fact that this compound exists as a liquid despite its low molecular mass; a liquid that, however, is quite volatile.
Colorless liquid.
84.93 g / mol.
Sweet, similar to chloroform.
205 - 307 ppm.
1.3266 g / cm3 (20 ºC).
- 97.6 ºC.
39.6 ºC.
25.6 g / L at 15 ° C and 5.2 g / L at 60 ° C.
Dichloromethane is barely soluble in water. While both molecules, CHtwoCltwo and HtwoOr, they are polar, their interactions are inefficient, possibly due to the repulsion between the chlorine and oxygen atoms.
Miscible with ethyl acetate, alcohol, hexane, benzene, carbon tetrachloride, diethyl ether, chloroform, and dimethylformamide.
Log P = 1.19.
57.3 kPa (25 ° C). This pressure corresponds to approximately 5.66 atm, reflecting a high vapor pressure..
2.93 in relation to air taken as 1.
1.4244 (20 ºC).
0.413 cP (25 ° C).
Dichloromethane is not flammable, but when mixed with air it forms flammable vapors above 100 ºC.
556 ºC.
It is stable at ambient temperature in the absence of humidity, having a relative stability when compared to its congeners: chloroform and carbon tetrachloride..
It tends to char at high temperatures (300-450 ºC), when its vapors come into contact with steel and metal chlorides.
May decompose on contact with hot surfaces or a flame, emitting toxic and irritating fumes of phosgene and hydrogen chloride..
Dichloromethane attacks some forms of plastics, rubbers, and coatings.
28.82 kJ / mol at 25 ºC.
28.20 dynes / cm at 25 ° C.
Dichloromethane reacts strongly with active metals, such as potassium, sodium, and lithium. Reacts with strong bases, eg potassium tert-butoxide. It is incompatible with caustics, oxidants and chemically active metals.
Additionally, it reacts with liquid oxygen in sodium and potassium alloys and nitrogen tetroxide. In contact with water it can corrode some stainless steels, nickel, copper, as well as iron.
Most of the uses and applications of dichloromethane are based on its properties as a solvent. Due to this characteristic, dichloromethane is used in the food, transport, medicine production industries, etc..
Dichloromethane is used in the decaffeination of coffee beans and tea leaves. It is also used for the extraction of hops for beer, beverages and other flavorings for foods, as well as for the processing of spices..
Dichloromethane is used for the preparation of cephalosporin and ampicillin, in addition to the manufacture of antibiotics, steroids and vitamins..
It is also used as a solvent in the production of cellulose triacetate (CTA), used in the creation of security films.
It is an ideal compound for the production of printed circuit boards, being used to degrease the aluminum surface before adding the photoresist layer to the board.
Dichloromethane is a solvent found in varnishes and paint separators, used to remove varnishes or paint coatings from various types of surfaces..
It is used to degrease metal parts and surfaces present in railway equipment, as well as in aircraft components.
It is used as a spray propellant (aerosols) and as a blowing agent for polyurethane foam. It is also used as a fluid in some types of Christmas lights.
Inhalation of dichloromethane can cause irritation of the upper airways, coughing, wheezing or shortness of breath..
It can cause reddening of the skin, and if the compound remains on it for a long time, cause chemical burns. In contact with the eyes, dichloromethane produces a severe irritation that can extend to a burn.
In addition, it acts as a neurotoxin generating visual, auditory and psychomotor disturbances; but these effects are reversible when the inhalation of dichloromethane is stopped.
Dichloromethane can affect the central nervous system, causing headaches, mental confusion, nausea, vomiting, and memory loss..
In animals it produces harmful effects on the liver, kidneys, central nervous system and cardiovascular system.
Regarding carcinogenesis, no significant increase in cancer deaths has been reported in workers exposed to dichloromethane. However, studies in animals have shown an increase attributable to dichloromethane in the incidence of liver and lung cancer, as well as benign tumors of the mammary glands..
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