Glycerin is a trihydric alcohol. It is used in medicine, food industry, cosmetology and even for the preparation of dynamites. What are the properties of glycerin? Can I get it at home?
What is glycerin?
Glycerin is an organic substance and is a trihydric alcohol. Its chemical form is C3H8O3 or HOCH2 -CH(OH)-CH2OH. The meaning of the word glycerin is directly related to its properties. The name comes from the ancient Greek word "glycos", or "sweet", due to the sweetish taste of the substance.
Glycerin is a clear liquid, quite viscous and absolutely odorless. It is non-toxic and non-poisonous, so it does not pose any danger in direct contact with the skin. In the natural environment, glycerin is part of animal fats, and is also found in most vegetable oils. An insignificant part of it is in the blood of animals.
Glycerin was first discovered in 1783, when the chemist Carl Scheele was saponifying fats with lead oxide. During the heating of the oxide withsoapy solution began to form with olive oil. After evaporating it, a viscous sweetish syrup formed.
Properties
The substance has a high hygroscopicity, that is, the ability to absorb moisture and retain it. Its boiling point is 290 degrees Celsius. When boiling, glycerin partially decomposes. At a temperature of 362 degrees, it can ignite spontaneously. Under normal conditions, the substance does not have volatile properties, but evaporates when heated. Combustion is accompanied by the release of water and carbon dioxide.
Glycerin is insoluble in fats, hydrocarbons and arenas, but highly soluble in water and alcohols. When added to water, the solution shrinks or decreases in volume, and the temperature rises. In such a mixture, the freezing point of water decreases.
When interacting with mineral and carboxylic acids, glycerol forms esters. At their core, these are fats that are involved in the metabolic process and perform important biological functions in the animal body. Some of them are, for example, phospholipids.
An ester is also trinitroglycerin. The substance is formed from the combination of glycerol with nitrous acid. It is an oily, toxic and highly explosive liquid that is sensitive to the slightest manipulation.
Glycerin and copper hydroxide form a dark blue solution with complete dissolution of the precipitate, which indicates the acidic properties of alcohol. Glycerin is able to dissolve aromatic alcohols, alkalis, sugars, s alts and other organic andinorganic compounds.
Methods of obtaining
The very first way in history to obtain glycerin is saponification. He appeared immediately after the discovery of the substance by the chemist Scheel. The result of this process is a soap solution with glycerin. After that, they must be separated from each other, which is done using sodium chloride. The glycerin must then be thickened and purified by distillation or activated charcoal.
Another way involves adding water to the oil. At a certain pressure, they are heated and stirred for ten hours, and then cooled. After cooling, the substances are clearly divided into several layers: in the lower - glycerin with water, in the upper - acids.
The substance is also obtained by hydrolysis of carbohydrates, such as starch, cane sugar. But then not a pure liquid is formed, but a mixture with various glycols.
All these methods help to get the so-called food glycerin. It is harmless to humans and is added to the preparation of certain foods. In contrast to it, there is also technical glycerin. This substance is not obtained from vegetable and animal raw materials, but from propylene, a combustible gas with a strong narcotic effect.
Application
Both food and technical glycerin is widely used in our lives. It is often used to make synthetic resins. Nitroglycerin is used to make dynamites and other explosives. In medicine, the same substance is excellent for drugs that dilate blood vessels.
In industry, it is used to make paper, detergents. In the production of electrical and radio engineering during soldering, it serves as a flux. Glycerin is used to make plastics, building varnishes and paints.
In the food industry, it is registered as an additive E422. It is an emulsifier that is needed to increase viscosity, as well as to create various mixtures. The substance is part of numerous medicines, used for electronic cigarette cartridges, for the manufacture of candles. In biology, glycerol is necessary for the preservation of tissues, organs, organisms and anatomical preparations.
Glycerin in cosmetics
Due to its ability to retain moisture, glycerin is often used in various skin and hair care products. It is present in soaps, nourishing and moisturizing creams.
The substance penetrates the epidermis, retaining water in the cells. Thus, it prevents the skin from becoming too dry and lifeless. But he also has disadvantages. The fact is that in an atmosphere with very dry air (less than 65% humidity), glycerin begins to absorb moisture from the skin, further drying it out.
Usually beauticians do not recommend using it in winter. Also, proportions are important. In small amounts, the presence of glycerin in the cream only improves the properties of the skin. Together with other products, it is used in homemade recipes for masks and lotions. For example, in combination with orange and water fortoning and cleansing the skin, hair is used together with egg, honey, castor oil and other ingredients.
How to make glycerin?
You don't have to buy glycerin. It can also be prepared at home. To do this, you need animal fat (1.9 kg), alkali (342 mg), water (995 mg) and s alt. Fat can be taken from the meat of any animal, having cleaned it of all veins and vessels. And then we act like this:
- melt pieces of fat over low heat;
- leave it to cool down to 35 degrees;
- in a separate bowl we prepare the lye, pouring it into the water;
- the temperature of the lye should also reach 35 degrees, then gently carefully pour it into the pan with fat;
- quickly stir ingredients while adding s alt;
- continue to "s alt" and stir until the mixture begins to separate into a clear liquid at the bottom and a cloudy solution at the top;
- fishing out the entire top layer is soap, the bottom layer is glycerin;
- filter the glycerin through a sieve or gauze to remove small particles of soap.
You should be very careful when preparing glycerin yourself. When diluted with water, alkali heats up above 90 degrees. You need to work with gloves, glasses (from fumes), and dilute the alkali in a special container.
