Naphthenic hydrocarbons are part of the oil. Their composition, properties, preparation and application will be discussed in this article. Here are examples of naphthenic compounds, formulas of the most famous of them. The concept of desiccants is presented and the use of naphthenes in the form of desiccants for the paint and varnish industry is considered. The safety issue is briefly considered when working with substances containing naphthenes.
Naphthenic hydrocarbons: application, properties, formula
These compounds are organic substances obtained in large quantities from oil. They got their name from the word oil (Greek naphtha).
Naphthenic hydrocarbons include compounds of the alicyclic series of saturated hydrocarbons, i.e., having round-shaped molecules, closed cycles. They got their name in 1883. It was introduced into organic chemistry by scientists V.V. Markovnikov and V.N. Ogloblin. Naphthenes also include hydrocarbons with several five- and six-membered cycles (including condensed ones, for example, decalin). It is not entirely correct to attribute all cycloalkanes (cyclanes) to naphthenes in a row.
Physical and chemical properties of naphthenes
By their physical properties, naphthenic hydrocarbons are liquids, sometimes with very sharp unpleasant odors, which crude oil is famous for. It is naphthenes that have a therapeutic effect in a special Naftalan mud, with the help of which many skin diseases are treated.
The chemical properties of naphthenic hydrocarbons are similar to saturated acyclic hydrocarbons of a number of methane. The exception is cyclopropane, which behaves in some reactions as an unsaturated hydrocarbon, attaching atoms with a ring break. In most chemical reactions, naphthenic hydrocarbons appear as saturated, with a linear chain of carbon atoms. However, the use of chemical reactions with breaking cycles makes it possible to use naphthenic carbons as an excellent raw material for chemical synthesis: the production of aromatic hydrocarbons and other valuable products for the chemical industry of various industries through catalytic reforming.
General formula and the most important representatives of a number
The formula for naphthenic hydrocarbons is common to all cycloalkanes: CnH 2 n, where n is the number of atoms in a molecule, usually five or six. The planar formula of molecules is a circle or a closed cycle. The volumetric formula is quite complex, it allows you to have several options for the arrangement of atoms in the molecule.
Examples of naphthenic hydrocarbons include chemical compounds such as cyclopentane (five carbon atoms in the ring), cyclohexane (six carbon atoms in the ring) and their alkyl derivatives. A special group is made up of naphthenic acids. Let's take a closer look at all of these compounds.
Cyclopentane for Organic Synthesis
Cyclopentane (or cyclopentylene) is a cyclic saturated hydrocarbon containing five carbon atoms in one closed chain. The formula of cyclopentane is C 5 H 10 . This is a saturated alicyclic hydrocarbon, one of the simplest cycloalkanes. It is a colorless liquid with a characteristic odor, density 0.745 g / cm 3 , insoluble in water, miscible with benzene, ether, acetone (dissolution according to the principle of “like in like”). The main amount of cyclopentane is obtained by secondary distillation of oil. Most cyclopentane is used for the organic synthesis of valuable chemicals, such as dyes.
Cyclohexane - raw materials for polyamides
Cyclohexane (or cyclohexylene), like cyclopentane, is a saturated hydrocarbon containing six carbon atoms in a closed cycle. Its formula is C 6 H 12 .
Its physical properties are a colorless liquid under normal conditions, density 0.778 g / cm 3 , insoluble in water. Like cyclopentane, soluble in benzene, ethers, acetone. It is contained in almost all types of oil, but in very small quantities, so it is obtained by the catalytic hydrogenation of benzene. Finds, like cyclopentane, a very wide application in the chemical industry in the production of cyclohexanol and cyclohexanone, nitrocyclohexane, cyclohexanoxime - intermediates in the production of caprolactam and adipic acid, which, in turn, serve to produce polyamides.
Naphthenic acids: properties and applications
These are alicyclic carboxylic acids, mostly monobasic. They contain one or more five- or six-membered carbon cycles. It is naphthenic acids that make up the bulk of the acid-containing components of various oils. They are extracted with a solution of alkali, the so-called "salting out" of naphthenates.
Under normal conditions, naphthenic acids are viscous, colorless, yellowing liquids upon standing, and practically insoluble in water. They are good solvents for resins and gums. Miscible with most organic solvents, have all the chemical properties of carboxylic acids.
The most widely used salts are naphthenic acids. Alkali metal salts (soap or naphthenates) are used as emulsifiers and disinfectants, as well as a means for washing wool. Copper salts are widely used as a disinfectant for the impregnation of sleepers, ropes, fabrics, aluminum and lead salts - as special additives, additives for lubricating oils and fuels.
In addition, soap muffins are used as additives to concrete mixtures and solutions, make them water-repellent, which is very important, since they allow you to make mortar mixes plastic due to lubrication to obtain a peculiar effect of special films called thin-oriented.
Salts of naphthenic acids as desiccants
Salts of lead, cobalt, manganese and zinc salted with hydroxides from the acids contained in oil (soap-oil) are widely used as desiccants for oil paints. Desiccant (in late Latin means “drying”) - a substance used to accelerate the drying of paints. From a chemical point of view, it is a catalyst for oxidative polymerization of solutions of vegetable oils and their derivatives.
Milk naphtha, or naphthenates, among driers are the cheapest, most stable during storage, but, unfortunately, have impurities and a characteristic unpleasant odor, therefore they are not used for oil painting.
Protection of the human body when working with desiccants
Naphthenic hydrocarbons often have a smell that people perceive as pungent and unpleasant. To protect the respiratory organs of people working with paints, it is necessary to apply protection against solvent vapors and desiccants. Ordinary water curtains and wet absorbers: wipes, dressings, etc. can easily cope with this. With small amounts of work and intermittent contact with paints, this will be quite enough.
With long-term and constant work with paints, especially those containing many desiccants, a deeper protection is needed - both the respiratory organs, and eyes, skin and mucous membranes. Metals contained in desiccants, especially lead, tend to accumulate in the liver and other organs of a person, cause serious illness.
Cutting fluids
It is impossible to work metalworking machines without the use of cutting fluids - coolant. Most coolants are emulsions that use fairly cheap crude oil products, such as naphthenic hydrocarbons, as well as mineral oils mixed with water.
In order for the emulsion not to separate into its constituent parts, emulsifiers and stabilizers are used. The presence of water in the emulsion makes them non-volatile and practically harmless. Therefore, many who work with oils, wash their hands with severe impurities with an emulsion containing naphthenes. This property of coolant is very often used by both locksmith and drivers. An emulsion with naphthenes not only helps to easily wash dried impurities, but also disinfects the skin of the hands, softens, eliminates the need for petroleum jelly as a skin softener.
Oil cannot be used as fuel
Dmitry Mendeleev’s famous statement that oil is not fuel, but can be drowned with banknotes, becomes more and more meaningful over time. Oil, gas and coal are the best raw materials for the huge amount of materials that a person needs today, but their reserves are very limited and non-recoverable. Among such raw materials there are naphthenic hydrocarbons, one of the most valuable components of oil - black gold, not yet fully estimated by mankind.