Aniline is an organic substance. It was first received in 1826. Other names are phenylamine, aminobenzene. The name "aniline" comes from the name of the plant "indigofera anil", which contains indigo. Previously, phenylamine was created with the participation of this substance. Consider the properties and uses of aniline.
The substance belongs to the simplest aromatic amines. Its formula is C6H5NH2.
Physical properties of aniline
Poisonous substance whose vapors are toxic. It is an oily liquid that has no color. The smell is weak, characteristic of this particular substance. When ignited, the flame is bright, smoky.
Partially soluble in water (solubility 6.4% at boiling point). Mineralized water reduces its solubility, except for the content of lithium and cesium bromides, as well as cesium iodide. The latter, on the contrary, increases the solubility of aniline.
During storage, the substance darkens, especially quickly when exposed to air and light. This makes it more viscous. Otherwise, this process is called "autoxidation". Oxidation can be slowed down with the addition of antioxidants - oxalic acid, sodium hydro- and sodium thiosulfate.
The following are the characteristics of aniline at normal atmospheric pressure:
- boiling point - 184.4 °C;
- melting/freezing point minus 5.89°C;
- density at 20 °C - 1.02 g/cm3;
- auto-ignition temperature in air - 562 °C;
- flash point in air - 79 °C.
Main applications of aniline
In Russia, the substance is mainly used for the synthesis of dyes and medicines, in the textile and pharmaceutical industries. With the help of aniline, preparations of the sulfa group with antibacterial action are obtained, and sugar substitutes are also synthesized.
There are other uses for anioline. In chemistry, it is used to produce hydroquinone, a substance used in cosmetics, mainly in skin whitening products. Also, the substance is used in the creation of explosives, adhesives, sealants.
Aniline slows down the corrosion of metals: its phosphates are added to solutions of strong electrolytes, as a result of which the corrosion of carbon steel is inhibited.
Aniline is also used to increase the antiknock properties of fuel (automobile, rocket, aviation). The octane number of gasoline with a one percent content of aniline increases by 3 units or more. But in its pure form, they try not to use the substance, since during long-term storage the quality of gasoline with aniline decreases, as well as the toxicity of its gases. Derivatives are more commonly used. ATa number of Western countries have restrictions on the use of aniline in the composition of the fuel.
Worldwide, most of the aniline produced is used in the production of polyurethanes, as well as synthetic rubbers, paints, weed control.
Aniline dyes
The most important area of application of aniline was and remains the production of dyes. They are made by oxidizing aniline and its s alts.
Initially, aniline paints were produced only in powder form. In the USSR, they were used in everyday life, restoring and remaking things through their coloring. But the dyed things quickly faded when exposed to sunlight, the paint was washed out during the washing process. Currently, aniline dyes are also produced in the form of solutions, and some manufacturers produce concentrated solutions, which, unlike powders, do not require special fabric preparation. But, despite the tangible progress and improvement in dyes, fabrics dyed with them still quickly fade in the sun.
Aniline toxicity
Aniline is a toxic substance. It can depress the nervous system, when it enters the blood, it causes oxygen starvation of tissues. It can enter the body in the form of vapors, and also penetrate the skin and mucous membranes.
Now aniline poisoning is rare. This substance is dangerous mainly for those who work with it. To avoid the entry of toxin into the body, it is necessary to comply with the establishedsecurity measures. When painting things at home with aniline dyes, especially powder ones, you need to keep them away from children, ventilate the room in which the dyeing is done, do not swallow the substance, if it gets on parts of the body, immediately wash it off with water and stain with gloves. If aniline is accidentally swallowed, seek medical attention immediately.
