How to get alkane from alkane? What else can you get from an alkane?

The study of the structure of organic compounds, the chemical properties that they exhibit in reactions, allow the production of various types of products and goods from the same raw materials. Processing of produced hydrocarbons solves many problems. To the question: "How to get an alkane from an alkane?" The chemical science and practice of oil cracking give exhaustive answers. Let's look at the problem of the relationship between different classes of hydrocarbons, as well as their derivatives. The main attention will be paid to industrial methods of processing of carbon-containing raw materials.

Genetic relationship of organic substances

In the early stages of studying and obtaining hydrocarbons and derivatives of chemists, it seemed that these groups were isolated from each other. Gradually accumulated information shedding light on the genetic relationship of the main classes of substances. The main efforts were aimed at finding ways to change the structure, increasing the multiplicity of communication. The most important problems of theoretical research and experiments:

• How to get alkane from alkane;
• How to process coal, crude oil and natural gas;
• How to carry out the dehydrogenation of the ultimate hydrocarbons;
• As from the alkane to obtain alkyne (acetylene).

Researchers and practitioners were convinced that there are many reciprocal transitions from one hydrocarbon to another.

The practical importance of genetic connections of the main types of compounds

The unity of hydrocarbon compounds was proved in the process of the formation of organic chemistry as a science and a branch of production. In the development of this problem - how to get an alkane from an alkane - Russian and Soviet organic chemists made a significant contribution. Many of the reaction-transformations used for this purpose are catalytic processes, carried out using complex technologies. Close ties and mutual transformations of organic compounds are used to solve a variety of practical problems, among which:

• Obtaining from one type of raw materials of different types of substances;
• Production of complex products with simple compounds and vice versa;
• Release of a variety of goods that are in high demand;
• Economy of severely depleted natural hydrocarbon resources;
• Rational use of oil and gas bearing strata, coal tar, combustible shales, peat.

Composition of natural carbon sources

Hydrocarbons of all types are found in nature in significant quantities. They serve as starting materials for processing and obtaining organic compounds of different composition. The most important sources of alkanes and alkenes:

1. Natural gas. The content of the ultimate methane hydrocarbon in different deposits reaches 80-98%. Other compounds: nitrogen, carbon dioxide, ethane, propane, butane.
2. Oil. The natural mixture of isomeric hydrocarbons from different deposits differs in composition. In some types of "black gold" alkanes predominate, others consist of cycloparaffins and arenas. Dome associated petroleum gases also contain paraffins.
3. Coke. The production of coal necessary for metallurgy is accompanied by the production of coal tar containing more than 400 components, the main ones being arenas.
4. Vegetable and food raw materials are a large and diverse group, including wood, seeds and fruits of industrial crops, animal fats.

Possible transitions between organic compounds

In the "black gold" deposits, cycloalkanes or naphthenes are often present. Processing of raw materials gives the ultimate cyclic hydrocarbons containing 5-7 C atoms in the ring, they have the greatest practical significance. How from alkane to get cycloalkane, if the reserves of naphthenes are depleted? To obtain limiting cyclic hydrocarbons from saturated acyclic compounds, a dehydrocyclization method is used. Chains of 4 or more C atoms are closed, a stable cycle arises. Other typical transformations of organic substances can be reflected in simple schemes:

• Oil → hydrocarbons → alkanes → carboxylic acids.
• Natural gas → marginal hydrocarbons → carboxylic acids.
• Hard coal → hydrocarbons → alkanes → unsaturated hydrocarbons → polymers.
• Oil → hydrocarbons → arenas → benzene → isopropyl-benzene → acetone, phenol.
• Natural gas → unsaturated hydrocarbons → ethanol.
• Coal → methanol.
• Oil → hydrocarbons → alkenes → butadiene and isoprene.

Let us consider in more detail which chemical compounds can be obtained due to the genetic relationship of organic substances.

How to get alkane from alkane

In industry, almost all types of marginal hydrocarbons are derived from oil and gas. Oil refining is a modern method for obtaining alkanes from alkanes:

A) Liquid limiting hydrocarbons gives direct distillation of oil (low yield of target products).

B) Thermal and catalytic oil cracking is used to increase the percentage of light fractions, improve the quality of the hydrocarbons produced (gasoline, kerosene). In the solar fraction of oil, hexadecane is present, which during decay gives dodecane and butylene. Dodecane already under the kerosene fraction undergoes further decomposition, from it the limiting hydrocarbon nonane and propene (alkene) are obtained. Continuation of cracking can lead to the formation of heptane and ethylene.

Isomerization and alkylation

Catalytic isomerization reactions allow the alkanes of the normal structure to obtain branched: H3C- (CH2) 3-CH3 → CH (CH3) 2-CH2-CH3. The product of this process is isopentane. Normal butane, which is contained in the cracking gases, is converted to isobutane in a catalytic isomerization reaction. The resulting product can be alkylated with isobutylene in the presence of a catalyst and isooctane-a high-quality fuel. If ethylene is used as an alkylating agent, a synthetic neohexane fuel is obtained in the reaction with isobutane.

How to get alkene and alkadiene from an alkane

In the industry, unsaturated acyclic hydrocarbons with one double bond are obtained with oil cracking. At high temperature, alkanes decompose (pyrolysis). Alkenes are isolated from the total mass of intermediate and final reaction products. Ethylene is produced by dehydrogenation of ethane on a nickel catalyst: C2H6 → C2H4 + H2 ↑. Butane under similar conditions gives 2-butene, at the same time the formation of ethane and ethylene. Dehydrogenation allows us to find solutions to the problem of how to get alkadiene from an alkane. With the stepwise removal of two hydrogen molecules from a hydrocarbon of 4 carbon atoms, the following transformations occur: butane → butene → butadiene. The final product is important for the production of synthetic rubber. Similarly to butadiene, another polymer is obtained that mimics the valuable qualities of a natural analog: isopentane → isoprene → isoprene rubber.

How to get acetylene from an alkane

Hydrocarbon with one triple bond - acetylene - is very important in the industrial sector, construction and other areas of economic activity. The oldest method of obtaining this simplest alkyne is due to the action of water on solid pieces of calcium carbide. This method was replaced by cracking of natural gas. Now in the chemical industry, they know how to get the alkyne from the alkane with the least cost. In special technological apparatuses at high temperature or under the influence of an electric discharge dehydrogenation of methane - the prevailing substance of natural gas: 2CH4 → HC≡CH + 3H2 takes place. Acetylene is widely used, acetaldehyde is obtained from it, which is further used in the production of acetic acid, artificial resins, plastics, synthetic fibers, rubbers and rubbers.

How to get arenas from the ultimate hydrocarbons

From paraffins, the chains of transformation lead to benzene and its derivatives. The process of aromatization was studied by Russian and Soviet chemists in the 20th century. The essence of their work on the topic "How to get benzene from benzene and its homologues" is reduced to the dehydrocyclization of hexane, heptane and other saturated hydrocarbons: C6H14 → C6H6 + 4H2; C7H16 → C6H5-CH3 + 4H2. Another way is the synthesis of cycloparaffins from acyclic hydrocarbons followed by dehydrogenation: hexane → cyclohexane → benzene.

How to get ethyl and other alcohols from alkanes

In ancient times over the question: "How to get alcohol from an alkane?" Did not reflect, our ancestors used only the method of alcoholic fermentation of sugar-containing products under the action of yeast enzymes. The growth of the technical value of ethyl alcohol led to the search for new types of non-food raw materials for ethanol production. In the first half of the last century, the substance became an indispensable raw material for the production of rubber by the method of Lebedev. One of the methods was predicted by A. Butlerov, who dreamed that a cheap method of obtaining ethylene would open the way "for obtaining alcohol." Sources of unsaturated hydrocarbons are oil cracking products and catalytic dehydrogenation of alkanes. Ethane is obtained from ethane, which is oxidized in the presence of sulfuric acid: C2H6 → C2H4 → C2H5OH. Hydration of other alkenes, which are also obtained during the processing of oil, gives homologues of synthetic ethyl alcohol. Disadvantages of the method are expressed in the costs of regenerating the acid and protecting the apparatus from its corrosive effects. The industry switched to the method of direct hydration of alkenes, in which solid catalysts are used. Methanol is produced by oxidation of methane. Ethylene and its homologues serve as raw materials for the production of alcohols.

How from alkanes to obtain aldehydes and carboxylic acids

After solving the problem of cheap raw materials for the alcohol industry, chemists know how to get the aldehyde from the alkane with the least cost. One of the ways of obtaining acetaldehyde is the hydration of acetylene. The whole process follows the scheme: natural gas → CH4 → C2H2 → CH3-SON. The use of natural hydrocarbons for the production of ethyl alcohol has increased. The substance is the raw material for the production of carbonyl and carboxyl compounds. Acetaldehyde can be obtained by ethane dehydrogenation, followed by the formation of ethyl alcohol in the reaction, its oxidation or dehydrogenation. One of the options is the oxidation of ethylene: C2H6 → C2H4 → C2H4O. How to get carboxylic acid from an alkane? The question that for a long time was in the category of problematic. Acetic acid is formed by fermenting food raw materials, with dry distillation of wood. The availability of available sources of alkanes allows the oxidation of butane and obtain cheap acetic acid: C4H10 + 2 ½ O2 → 2CH3COOH + H2O. The release of other carboxylic acids from the limiting and unsaturated hydrocarbons is established.

Modern world economy is difficult to imagine without natural gas, oil and coal raw materials. Of these natural mixtures, various alkanes are isolated that are used to produce a large number of organic synthesis products.