Absolute ethyl alcohol has found its application in industry. This substance is necessary to ensure the reaction of organic synthesis. Such a liquid is currently often used in laboratories. For the first time, technical specifications dedicated to this substance were published in the 37th year. Currently, there are specialized GOSTs and standards that regulate the quality of the liquid and the nuances of its preparation.
general information
As defined in 1937, absolute alcohol is a liquid whose strength is estimated at 99.7% or more. In every 100 grams, up to 5 mg of aldehydes is allowed. When examining a substance for organic acids, all such compounds must be converted to acetic acid. Concentration cannot exceed milliliter per 100 ml of finished product.
A distinctive feature of absolute alcohol is the absence of any dry residue. In this substance there can be no alkaline compounds, mineral acids. The inclusion of furfural is not allowed. Alcohol must be transparent, without any shade or color. Foreign odors are not inherent in it, the presence of a specific taste is not allowed.
Nuances of terminology
Modern chemists know not only absolute alcohol, but also anhydrous. These two terms cannot be equated. In the absolute variety, as can be concluded from the above, water can be, but in small quantities.
The chemical compound in question is capable of forming stable bonds during a chemical reaction with gasoline. Due to this, absolute alcohol in a number of countries is used to produce motor fuel. As studies have shown, if this fluid is mixed with gasoline, the antiknock properties of the fuel used to operate the motor become more significant. Therefore, greater compression is possible.
Features and Forms
About how the distillate differs from the rectified, can tell a qualified chemist. The distillate is obtained by fermentation and distillation, and the rectified product is a product purified from impurities. In addition, using the rectification method, you can achieve ready-made ethanol, the concentration of the main substance in which is up to 95.7%. Such parameters are due to the presence of ethyl alcohol in azeotropic compounds that appear during chemical interaction with water under normal atmospheric pressure.
Usually, ethyl alcohol advising GOST 5964-93 is currently used. It is he who is most in demand in the national economy. In such a liquid, water is contained in a concentration of 4.43% or slightly more. In certain cases, for the course of the reaction, it is necessary to ensure the presence of alcohol, in which there is practically no water, then resort to the absolute variety. This is necessary in the manufacture of pharmaceutical products, varnishes and paints. The absolute variety is in demand in the manufacture of cosmetics, perfumes. Absolute reactions have been developed for the manufacture of the substance.
Mistakes and fallacies
It so happened that the alcohol presented in pharmacies is the very product that comes to mind first, it is worth mentioning at least some kind of alcohol. If ordinary people talk about ethanol, as a rule, the topic boils down to discussing the strength of the liquid, and some regret that there is no absolute, real alcohol, that is, one that would be 100% alcohol proper, without special diluents and additives. Many are convinced that the maximum strength is 95.6%. In fact, absolute alcohol exists, it’s just chemists who know about it, since it was in this industry that it found application.
Some think: say, does some Itkul distillery use an absolute product in its work? Do not be mistaken in this regard: absolute liquid is not intended for food purposes, it is used in the manufacturing industry, but not for the manufacture of drinks.
About terms and phenomena
Before you understand how the products of the same Itkul distillery differ from an industrial product, it is reasonable to orient yourself in the term “strength” as applied to alcohol-containing liquids. This parameter was introduced to reflect the presence of ethanol in a mixture of alcohol and water. What people are used to calling alcohol is normally a compound with water, and any alcohol used in the food industry must have water in its composition. The content of this substance varies.
The concentration of absolute ethyl alcohol, as follows from the current standards, should be 99.7% or even more, that is, thousandths of a percent are allocated to the total volume of water. For real use, such a product is usually not required; it is unjustified to use it because of the complexity of manufacture. Even for medical purposes, 95% strength is enough, not to mention food use. In rare cases, it is necessary to use hydrolysis alcohol.
Where to get?
Experienced chemists can tell how to make alcohol. Specialized enterprises responsible for this process daily produce large volumes of product of varying degrees of concentration. Several methods for preparing alcohol are known, and the most popular option is the natural fermentation reaction. For its implementation, it is necessary to have at its disposal plant products enriched with carbohydrates. Another approach is the hydrolysis reaction using cellulose extracted from straw and wood.
Based on whether hydrolysis alcohol is needed or not, you can resort to the hydration reaction of ethylene. This word denotes gas. Orthophosphoric or sulfuric acid is used for the reaction. The chemical interaction proceeding with a combination of these substances is rather complex, the reaction requires the participation of a catalyst, but its effectiveness is high enough for the method to become industrially widespread.
Reactions and Products
By resorting to the previously described methods of how to make alcohol, you can get at your disposal a product of relatively low concentration. The finished fluid will contain a variety of impurities. To purify the substance and increase the percentage of alcohol, it is necessary to organize distillation. To do this, you can use a traditional distillation unit or distillation column. A similar installation is used if necessary to process oil. Following the results of such events, it is possible to produce alcohol, whose strength is up to 95.6%.
The alcohol presented in the pharmacy is just such a product, but for some operations and reactions it is not enough, and absolute must be made. There are several well-known methods, but they are all quite complicated. You can bind water included in the alcohol, glycerol. Another option is chemical reactions with metals. Sometimes resort to gypsum or potassium salts. The reaction with quicklime has a certain effectiveness. You can use calcium chloride. In practice, all these methods are rare, since it is difficult to implement them on an industrial scale, despite the good outcome of the interaction.
What to do?
From the above it is clear why the price of absolute alcohol is high. To obtain this difficult product, it is necessary to use plants for azeotropic dehydration. For the system to work, it is necessary to use a high-percentage solution of alcohol in water. The substance is mixed with benzene in liquid form, then the obtained compounds are distilled in the intended columns. Several azeotropic techniques have been developed. The result of the process is a rather large amount of ethyl alcohol, the strength of which varies between 99.9-100%.
Although the price of absolute alcohol is high, the need to use this compound in a number of chemical processes causes considerable demand, so domestic and foreign enterprises produce quite large volumes of absolute product. The finished liquid is included in the fuel for space transport, used in cars and in the manufacture of a number of products used by ordinary people in everyday life. But in ordinary life, a person who is far from chemistry and production will hardly have to meet with absolute alcohol.
The nuances of getting
Ethyl alcohol is now widely used in biology. This substance is necessary for preserving a variety of drugs. Often, biologists use the absolute form. At the same time, it is taken into account that it is impossible to purify the product to the required level by conventional distillation, since a boiling mixture is formed, which cannot be separated when a classical distillation unit is used. The boiling point of alcohol with a strength of 95.6% is 78.15 degrees Celsius, and for absolute this indicator is 78.37 degrees.
It is noted that alcohol, which is practically devoid of water, is sometimes obtained for biological purposes, for a long time insisting the rectification on copper sulfate powder - such a product is made by calcining copper sulfate. Thanks to salt, water almost completely leaves the main mixture, while the powder does not dissolve in alcohol. If you take calcined lime and boil it in alcohol for several hours, the reaction result will be even better. The final stage of such a process is distillation, during which it is necessary to exclude interaction with air containing moisture.
Technical points
Ethanol is an odorless and colorless liquid. It has a burning taste and a peculiar smell. Ethanol boils when heated to 78.4 on the Celsius scale, melts at -114.15 on the same measurement scale. The density of the substance is estimated at 0.794 t / m.
It will not be difficult to mix ethyl alcohol and water, glycerin and various other alcohols, some ethers and organic solvents. Substances can be mixed in any concentration and ratio. With certain substances, methylcarbinol forms an azeotropic mixture. This is observed when interacting not only with water, but also with chloroform. An azeotropic compound is generated if ethyl alcohol is mixed with ethyl acetate, benzene. The ability to form alcoholates is inherent in ethanol if the substance interacts with magnesium and calcium salts.
Alcohol: and what happens?
It is customary to divide alcohol into food, technical. The determination of the category depends on what was used to obtain the liquid. Chemists responsible for the manufacture of the substance are well aware of the difference between distillate and rectified product, about the characteristics of different categories. Rectified is a cleaner product, unlike distillate, which has a characteristic odor.
The possibilities of using alcohol are determined by its strength and the quality of rectification. Absolute alcohol, necessary for technical purposes, was considered above, but a rather interesting topic is food. Such a liquid is made from plant products, food. To obtain ethyl alcohol, potatoes, some berries and fruits are used. Cereals can be used. The cheapest option is alcohol obtained from potatoes.
For industrial alcohol, wood can be taken as a raw material. Sometimes it is obtained when working with oil transformation products. In the manufacture of industrial alcohol, the feedstock is placed in a plant where hydrolysis proceeds. In industrial alcohol in abundance are impurities hazardous to human health. For this reason, it cannot be used in the food industry.
Features of the production process
High-quality alcohol is obtained if the working process proceeds using reliable raw materials, if the technology is followed and the distillation is carried out qualitatively, during which harmful compounds are seized. The degree of purification is the basis for classifying a product as a specific grade.
The higher the grade of alcohol, the less harmful compounds in it. In addition, it shows his strength. Ethyl alcohol used in the food industry is obtained by diluting the rectified product that has passed the purification procedure with highly effective methods. For dilution, softened water is used.