Glycerin is a trihydric alcohol. It is used in medicine, food industry, cosmetology, and even for the preparation of dynamites. What properties does glycerin have? Is it possible to get it at home?
What is glycerin?
Glycerin is an organic substance and is a trihydric alcohol. Its chemical form looks like C 3 H 8 O 3 or HOCH 2 —CH (OH) —CH 2 OH. The meaning of the word glycerin is directly related to its properties. The name comes from the ancient Greek word “glycos,” or “sweet,” because of the sweet taste of the substance.
Glycerin is a clear liquid, quite viscous and completely odorless. It is non-toxic and non-toxic, therefore it poses no danger in direct contact with the skin. In the natural environment, glycerin is part of animal fats, and is also found in most oils of plant origin. An insignificant part of it is in the blood of animals.
Glycerin was first discovered in 1783, when the chemist Karl Scheele was engaged in the saponification of fats using lead oxide. While heating the oxide with olive oil, a soapy solution began to form. After evaporation, a viscous sweetish syrup was formed.
The properties
The substance has increased 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 self-ignite. 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 it is highly soluble in water and alcohols. When added to water, the solution contracts or decreases, and the temperature rises. In such a mixture, the freezing temperature of water decreases.
When interacting with mineral and carboxylic acids, glycerol forms esters. At its core, these are fats that participate in the metabolism process and perform important biological functions in the animal body. One of them are, for example, phospholipids.
Trinitroglycerin is also an ester. The substance is formed from the combination of glycerol with nitrous acid. It is an oily toxic and highly explosive liquid, sensitive to the slightest manipulation.
Glycerin and copper hydroxide form a dark blue solution with complete dissolution of the precipitate, which indicates the acid properties of alcohol. Glycerin is able to dissolve aromatic alcohols, alkalis, sugars, salts and other organic and inorganic compounds.
Production methods
The first ever glycerol production method 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. Then glycerin needs to be thickened and purified by distillation or activated carbon.
Another method 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, for example, starch, cane sugar. But then not a pure liquid is formed, but a mixture with various glycols.
All these methods help to obtain the so-called food glycerin. It is harmless to humans and is added to make certain foods. In contrast to it, there is also technical glycerin. This substance is obtained not from plant 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 for the manufacture of synthetic resins. Nitroglycerin is used for the production of dynamites and other explosives. In medicine, the same substance is great for vasodilator drugs.
In industry, it is used for the manufacture of paper, detergents. In the manufacture of electrical and radio equipment during soldering, it serves as a flux. Glycerin is used for the manufacture of plastics, construction varnishes and paints.
In the food industry, it is registered as additive E422. This is an emulsifier, which is needed to increase the viscosity, as well as to create various mixtures. The substance is part of numerous medications, is used for cartridges of electronic cigarettes, for the manufacture of candles. In biology, glycerin is necessary for the preservation of tissues, organs, organisms and anatomical preparations.
Glycerin in cosmetics
Due to the fact that glycerol retains moisture, it is often used in various cosmetics for skin and hair care. It is present in soap, in nourishing and moisturizing creams.
The substance penetrates the epidermis, trapping water in the cells. Thus, it prevents the skin from becoming too dry and lifeless. But he has also disadvantages. The fact is that in an atmosphere with very dry air (less than 65% humidity), glycerin begins to absorb moisture from the skin, additionally draining it.
Typically, cosmetologists do not recommend using it in the winter. In addition, 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 home recipes for masks and lotions. For example, in combination with orange and water to tone and cleanse the skin, it is used for hair along with eggs, honey, castor oil and other ingredients.
How to make glycerin?
Optionally buy glycerin. It can be cooked at home. To do this, you need animal fat (1.9 kg), alkali (342 mg), water (995 mg) and salt. Fat can be taken from the meat of any animal, cleansing it of all veins and blood vessels. And then we act like this:
- melt slices of fat over low heat;
- leave it to cool to 35 degrees;
- in a separate bowl, prepare the alkali, pouring it into the water;
- the alkali temperature should also reach 35 degrees, then gently pour it gently into the pan with fat;
- stir the ingredients quickly while adding salt;
- continue to “salt” and stir until the mixture begins to divide into a clear liquid at the bottom and a cloudy solution at the top;
- we catch the entire upper layer - this is soap, the lower layer - glycerin;
- filter glycerin through a sieve or gauze to remove small pieces of soap.
Engage in the preparation of glycerin yourself should be very careful. When diluted with water, the alkali heats up above 90 degrees. You need to work with gloves, glasses (from vapors), and dilute alkali in a special container.