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 "indigophera anil", which contains indigo. Phenylamine was previously created using this substance. Consider the properties and application of aniline.
The substance belongs to the simplest aromatic amines. Its formula is C 6 H 5 NH 2 .
Physical properties of aniline
Toxic substance whose fumes are toxic. It is an oily liquid that has no color. The smell is weak, characteristic of this substance. When it ignites, the flame is bright, smoky.
Partially soluble in water (at boiling point, solubility 6.4%). Mineralized water reduces its solubility, with the exception 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. At the same time, it becomes more viscous. Otherwise, this process is called "autooxidation." Oxidation can be slowed by the addition of antioxidants - oxalic acid, sodium hydro- and thiosulfate.
The following are the characteristics of aniline at normal atmospheric pressure:
- boiling point - 184.4 ° C;
- melting / freezing point - minus 5.89 ° ;
- density at a temperature of 20 ° C - 1.02 g / cm3;
- auto-ignition temperature in air - 562 ° C;
- flash point in air - 79 ° C.
The main areas of application of aniline
In Russia, the substance is mainly used for the synthesis of dyes and medicines, in the textile and pharmaceutical industries. Using aniline, sulfamide group preparations are obtained that have an antibacterial effect, and sugar substitutes are also synthesized.
There are other areas of application of aniolin. In chemistry, it is used to produce hydroquinone - a substance used in cosmetics, mainly as a part of skin whitening products. The substance is also used in the creation of explosives, adhesives, sealants.
Using aniline, metal corrosion slows down: its phosphates are added to solutions of strong electrolytes, as a result of which carbon steel corrosion is inhibited.
Aniline is also used to increase the antiknock fuel (automotive, rocket, aviation). The octane number of gasoline at a one percent content of aniline increases by 3 units or more. But they try not to use the substance in its pure form, since with prolonged storage, the quality of gasoline with aniline decreases, as well as the toxicity of its gases. Derivatives are more commonly used. In a number of Western countries, there are restrictions on the use of aniline in fuel.
In the world, most of the obtained aniline is used in the production of polyurethanes, as well as synthetic rubbers, paints, and weed control products.
Aniline dyes
The main area of application of aniline has been and remains the production of dyes. They are made using the oxidation of aniline and its salts.
Initially, aniline paints were only available in powder form. In the USSR, they were used in everyday life, restoring and remodeling things through their coloring. But the painted things quickly faded when sunlight hit, 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 preparation of the fabric. But, despite tangible progress and improvement of dyes, fabrics dyed by them, still quickly fade in the sun.
Aniline toxicity
Aniline is a toxic substance. It can inhibit the nervous system, when it enters the bloodstream it causes oxygen starvation of tissues. It can enter the body in the form of vapors, as well as penetrate the skin and mucous membranes.
Now aniline poisoning is rare. This substance is dangerous mainly for those who work with it. In order to avoid the ingress of toxin into the body, the established safety measures must be observed. When painting things at home with aniline dyes, especially powder ones, you need to protect them from children, ventilate the room in which they are painted, do not swallow the substance, if it gets on parts of the body, immediately wash it off with water and stain it with gloves. If aniline was accidentally swallowed, you should immediately consult a doctor.