Naphthenic hydrocarbons are part of oil. Their composition, properties, preparation and application will be discussed in this article. Here are examples of naphthenic compounds, the 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. Briefly reviewed the issue of safety 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 molecules, closed cycles. They got their name in 1883. It was introduced into organic chemistry by scientistsV. V. Markovnikov and V. N. Ogloblin. Naphthenes also include hydrocarbons with several five- and six-membered rings (including condensed ones, for example, decalin). It is not entirely correct to classify all cycloalkanes (cyclanes) as naphthenes.
Physical and chemical properties of naphthenes
By 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 special Naftalan mud, with the help of which many skin diseases are treated.
In terms of chemical properties, naphthenic hydrocarbons are similar to saturated acyclic hydrocarbons of the methane series. The exception is cyclopropane, which behaves like an unsaturated hydrocarbon in some reactions, adding atoms with a ring gap. In most chemical reactions, naphthenic hydrocarbons act as saturated hydrocarbons with a linear chain of carbon atoms. However, the use of chemical reactions with cycle breaking makes it possible to use naphthenic hydrocarbons as an excellent raw material for chemical synthesis: obtaining aromatic hydrocarbons and other valuable products for the chemical industry in various industries through catalytic reforming.
The general formula and the most important representatives of the series
The formula for naphthenic hydrocarbons is common to all cycloalkanes: CnH2n, where n is the number of atoms in the molecule, usually five or six. The planar formula of molecules is a circle or a closed cycle. The volumetric formula is quite complex, allows you to have several optionsarrangement of atoms in a molecule.
Examples of naphthenic hydrocarbons can be such chemical compounds as cyclopentane (five carbon atoms in the ring), cyclohexane (six carbon atoms in the ring) and their alkyl derivatives. A special group is naphthenic acids. Let's take a closer look at all these connections.
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 С5Н10. It is a saturated hydrocarbon of the alicyclic series, one of the simplest cycloalkanes. It is a colorless liquid with a characteristic odor, density 0.745 g/cm3, insoluble in water, miscible with benzene, ether, acetone (dissolution according to the "like in like" principle). The main amount of cyclopentane is obtained by secondary distillation of oil. Most cyclopentane is used in the organic synthesis of valuable chemicals such as dyes.
Cyclohexane - raw material for polyamide production
Cyclohexane (or cyclohexylene), like cyclopentane, is a saturated hydrocarbon containing six carbon atoms in a closed cycle. Its formula is С6Н12.
Its physical properties are colorless liquid under normal conditions, density 0.778g/cm3, insoluble in water. Like cyclopentane, we will dissolve in benzene, ethers, acetone. It is contained in almost all types of oil, but in very small quantities, therefore it is obtained by catalytic hydrogenation of benzene.It 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, are used to obtain polyamides.
Naphthenic acids: properties and uses
These are carboxylic acids of the alicyclic series, mostly monobasic. They contain one or more five- or six-membered carbon cycles. It is naphthenic acids that make up most of the acid-containing components of various oils. They are extracted with an alkali solution, the so-called "s alting out" of naphthenates.
Under normal conditions, naphthenic acids are viscous, colorless liquids that turn yellow on standing, practically insoluble in water. They themselves are good solvents for resins and gums. Miscible with most organic solvents, has all the chemical properties of carboxylic acids.
S alts of naphthenic acids are most widely used. Alkali metal s alts (soap-naphths or naphthenates) are used as emulsifiers and disinfectants, as well as wool washing agents. Copper s alts are widely used as a disinfectant for the impregnation of sleepers, ropes, fabrics, aluminum and lead s alts - as special additives, additives to lubricating oils and fuels.
In addition, soap naphthas are used as additives to concrete mixtures andmortars, make them water-repellent, which is very important, since they allow mortar mixtures to be made plastic due to lubrication with obtaining a peculiar effect of special films, called finely oriented.
S alts of naphthenic acids as driers
Lead, cob alt, manganese and zinc, which are s alted out by hydroxides from the acids (soaphta) contained in oil, are widely used as desiccants for oil paints. Desiccant (in late Latin means "drying") - a substance used to speed up the drying of paints. From a chemical point of view, it is a catalyst for the oxidative polymerization of solutions of vegetable oils and their derivatives.
Mylonaphths, or naphthenates, among desiccants are the cheapest, most stable during storage, but, unfortunately, they 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 an odor perceived by humans as pungent and unpleasant. To protect the respiratory organs of people working with paints, it is necessary to use protection against vapors of solvents and desiccants. This is easily handled by ordinary water curtains and wet absorbers: napkins, dressings, etc. With small amounts of work and intermittent contact with paints, this will be enough.
During long and constant work with paints, especially those containing many desiccants, deeper protection is needed - asrespiratory organs, as well as eyes, skin and mucous membranes. Metals contained in desiccants, especially lead, tend to accumulate in the liver and other human organs, causing serious illness.
It is impossible to work metalworking machines without the use of cutting fluids - coolant. Most coolants are emulsions that make extensive use of 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 component parts, emulsifiers and stabilizers are used. The presence of water in the emulsion makes them non-volatile and practically harmless. Therefore, many people who work with oils wash their hands with an emulsion containing naphthenes. This property of the coolant is very often used by both locksmiths and drivers. The emulsion with naphthenes not only helps to easily wash off dried dirt, but also disinfects the skin of the hands, softens, and eliminates the need to use vaseline oil as a skin softener.
Oil cannot be used as fuel
Dmitry Mendeleev's famous statement that oil is not fuel, but it is possible to heat with banknotes, acquires more and more meaning over time. Oil, gas and coal are the best raw materials for the huge amount of materials needed by man today, but their reserves are very limited and irreplaceable. Among such raw materials there are also naphthenic hydrocarbons, one of the most valuable components of oil -black gold, not yet fully appreciated by mankind.