Chloroform - what is it? Getting, acting and applying chloroform

The discovery of many chemicals was not intentional, but accidental, during the synthesis or study of the properties of a substance. However, many of the randomly discovered substances became very important, they were used not only in chemistry, but also in medicine, industry and other fields. Just for such substances is chloroform, which will be discussed further.

Name

The name of this substance has several varieties. After all, like all organic compounds, it obeys the laws of the general nomenclature of molecules, trivial names and name, starting from the composition of the molecule.

Therefore, for chloroform, there are several variants of the name:

• Carbon trichloride;
• chloroform;
• Trichloromethane.

Chloroform: what is it? You can understand the names of the compound, but you can consider the geometric structure of the molecule.

The structure of the molecule

The chloroform molecule consists of three chlorine atoms and one hydrogen atom, each atom is connected to the central carbon. In fact, a trichloromethane molecule is a product of radical substitution of hydrogen atoms for chlorine atoms in a methane molecule under the influence of certain conditions.

In this case, all C-CL connections are completely equivalent, strongly polar. The C-H bond on the background of other bonds appearing in the molecule becomes even more polarized and becomes extremely vulnerable. Therefore, in the further processing of the molecule, the C-H bond is easily broken and hydrogen is replaced by other atoms (for example, also chlorine to form carbon tetrachloride).

Consider how chloroform looks. The formula has the form: CHCL _3. The structural formula will have the following form:

Both structures reflect the chemical essence that chloroform carries. The formula shows that the molecule is sufficiently stable and severe conditions must be applied to enter the reaction.

Physical properties

The physical properties of trichloromethane can be characterized as follows:

1. Under normal conditions (room temperature, normal atmospheric pressure 100 kPa, humidity not higher than 80%), this substance is a strongly odorous liquid that does not have a color. The smell of chloroform is sharp enough, heavy, enveloping, like the smell of ether. The taste is sweet, but you can not try it, because it is extremely toxic.
2. It does not dissolve in water, it can dissolve only in different types of organic solvents. With water, it can form low-concentration (0.23%) solutions.
3. The boiling point of this compound is lower than that of water, approximately 62 ^° C.
4. The melting point is sharply negative, -63.5 ^° C.
5. The density of chloroform is greater than the density of water and is 1.483 g / cm ³ .
6. The strong pronounced toxic character of the substance on the effect on the body belongs to the group of narcotic compounds.

When dissolved in water, carbon trichloride can form azeotropic mixtures. In this case, chloroform in the solution will be 97.5%, and water only 2.5%. The boiling point of such a solution is lower than that of pure trichloromethane and is 52 ^° C.

Chemical properties

Like all chlorine derivatives of methane, chloroform does not show chemical activity. Therefore, there are few reactions that are characteristic of him. For example, treatment with chlorine molecules in the process of technological production of all methane derivatives by chlorination. For this, liquid chloroform is taken, the reactions proceed as a radical mechanism, require the presence of ultraviolet radiation as an obligatory condition and quanta of light.

CHCL ₃ + CL ₂ = CCL ₄ + HCL

The reaction equation shows that the product is completely chlorine-substituted methane-carbon tetrachloride. Such reactions are one of the ways to produce carbon tetrachloride in industry.

Also, chemical properties include an azeotropic mixture with water, which chloroform is able to produce. What it is? That is, with the boiling of which the components of the solution do not undergo any changes. By boiling, this mixture can not be divided into fractions.

Another type of reaction in which chloroform can enter is the substitution of halogen atoms for other atoms or functional groups. For example, when it reacts with an aqueous solution of sodium hydroxide, it forms sodium acetate:

Chloroform + NaOH (aqueous solution) = sodium acetate + sodium chloride + water

In addition, an essentially significant reaction is the interaction of chloroform with ammonia and potassium hydroxide (concentrated solution), as a result of this interaction, potassium cyanide is formed .

Chloroform + ammonia + potassium hydroxide = KCN + potassium chloride + water

Storage of chloroform

In light trichloromethane decomposes with the formation of dangerous, poisonous products:

Chloroform = phosgene + hydrochloric acid + chlorine molecular + carbonic anhydride

Therefore, the storage conditions of chloroform should be special - bottles of dark glass with dense ground glass stoppers. The bottle itself should be stored away from sunlight.

Receiving

The preparation of chloroform is carried out in several ways.

1. Multi-stage process of chlorination of methane, which occurs by a radical mechanism under the influence of ultraviolet light and high temperature. As a result, not only chloroform is produced, but also three other products: chloromethane, dichloromethane and carbon tetrachloride. The reaction is as follows:

CH ₄ + CL ₂ = CH ₃ CL + HCL - chloromethane and hydrogen chloride form

CH ₃ CL + CL ₂ = CH ₂ CL ₂ + HCL - dichloromethane and hydrogen chloride

CH ₂ CL ₂ + CL ₂ = CHCL ₃ + HCL - trichloromethane (chloroform) and hydrogen chloride

CHCL ₃ + CL ₂ = CCL ₄ + HCL - tetrachloromethane and hydrogen chloride

In this way, trichloromethane is synthesized in industry.

2. The interaction between bleach and ethanol. This is a laboratory method.

3. The production of chloroform by electrolysis (the action of an electric current) on alkali metal chlorides in an atmosphere of acetone or ethyl alcohol. Also a laboratory method for obtaining trichloromethane.

Cleaning

After the chloroform is obtained, it needs to be cleaned. After all, if it is used for medical purposes, then the content of impurities in it is simply unacceptable. If the objectives of the application are technical, then the content of foreign substances should be limited.

There may be different impurities that contain chloroform. What it is? What are they?

• Ethanol.
• Hydrogen chloride.
• Phosgene.
• Chlorine.

There are two main ways to purify chloroform from these impurities:

• Abundant washing with water followed by drying (allows to completely get rid of ethanol);
• Trichloromethane is washed with a strong acid, then with strong alkali, followed by water. The subsequent treatment consists in drying using a dehydrating agent - calcium chloride. The material is then distilled in a fractionation column.

History of the discovery

Since when is chloroform known? What is it and why it was used before? Let's try to understand.

The first mention of this substance dates back to 1831. It was then that chemist Guthrie from Harbor received trichloromethane. However, his goal was not this substance, it was a successful by-product. Chemist was looking for solvents for rubber, experimenting and accidentally received chloroform.

In the same year and a year later two scientists, independently of each other, obtained this substance as a result of experiments. This is Eustace Liebig (who made a huge contribution to the development of chemistry) and Eugen Subiber. Their task was to find an anesthetic, and they found it. True, we learned about this effect of chloroform and began to use it somewhat later, only from the 1840s.

The structural formula and the interaction of atoms within the molecule were able to study and build a chemist-scientist Dumas in 1834. He also proposed and secured for chloroform its name, which it gave in honor of the ants. In Latin, the ant is pronounced as formiata, and the formic acid contained in these insects is able to form from chloroform. Proceeding from this, its name was determined.

Biological effect per person

It justifies its use as an anesthetic of chloroform. The action per person is very specific, covering several basic organ systems.

The degree of influence depends on such factors as:

• Concentration of inhaled substance;
• Duration of use;
• Way of penetration inside.

If it is a pure, medical chloroform, then its use is strictly dosed, precisely and locally. Therefore, of the possible contra-indications, only a few are realized. If we are talking about the evaporated chloroform in the air and inhaling it by man, then the action is much more serious and pernicious.

So, if you inhale trichloromethane for 10 minutes, there may be an edema of the respiratory tract, lung cramps, cough, and swelling in the throat. If the exposure does not stop, the poisoning will come immediately. The nervous system (both the brain and spinal cord) will be affected, a lethal outcome is possible.

Also, chloroform exerts a detrimental effect on the liver, digestive organs and kidneys. Its action is especially destructive if you take the solution inside. The following reactions of the body to the intake of chloroform are observed:

• dizziness;
• Vomiting and nausea;
• Persistent headaches;
• Depression of the nervous system and, as a result, fatigue;
• Elevated temperature;
• Allergic rashes, redness of the skin.

Studies and experiments on different animals showed the following results:

1. Prolonged intake of chloroform orally in the form of a liquid causes abortion, multiple pathologies and mutagenesis of future generations.
2. When living in an atmosphere of chloroform, animals were depressed, sluggishness and longevity of their life were significantly reduced.
3. Based on experiments in mice, a conclusion was made about the carcinogenicity of trichloromethane.

Such results were obtained by chemists and physicians in studying the effect on living organisms of chloroform.

Application in medicine

The first mention of the medical use of this substance is rooted in 1847. It was then that the scientist, physician, chemist Holmes Kut first suggested using chloroform as an anesthetic. The effect on a person has had a positive effect on the operation period - a complete deactivation of consciousness, the absence of any sensations.

However, later, when the patient regained consciousness, it became clear that he did not stop nausea, vomiting. Later, more precise standards for the use of this substance have been established, which make it possible to avoid such consequences.

An important role in the introduction of chloroform into medicine was played by the English obstetrician James Simpson. It was he who proved the positive meaning and effect of the compound during the process of childbirth.

However, over time, newer, safer and more modern methods of anesthesia emerged than chloroform. Its use in medicine has practically come to naught. Today it is applied in the form of:

• Ointment components for external use;
• As an additional anesthetic in combination with other substances and only in very small concentrations;
• As drops, relieving of nausea and vomiting.

Industrial applications

The industry also uses chloroform. Its application refers to various chemical syntheses, where for it the role of solvent, degreaser, main or additional component for obtaining important substances used in all spheres of human activity is assigned to it.