Alkanes (paraffins, saturated hydrocarbons) are biocompounds consisting only of C and H atoms in which all atoms are connected by simple sigma bonds. The simplest saturated hydrocarbon is methane. Each subsequent hydrocarbon of this series differs from the previous one by the CH2 group. In the indicated series of compounds, the neighboring members differ from each other by the homological difference (CH2); similar series are called homologous. Such series are characterized by close chemical properties and regularly changing physical properties.
The main source of alacne synthesis is oil. It should be noted that its biochemical composition depends on the field. Unsaturated hydrocarbons are a valuable source for the production of formaldehyde, methanol, chloroform, plastics, synthetic resins, esters, acetone, glycerol, propylene, polypropylene, synthetic butanediene rubber, acetate, etc. In industry, alkanes are obtained from shales of brown and coal. Under ordinary conditions, alkanes are chemically inert substances. At room temperature, they do not interact with concentrated sulfate acid, or with alkali metals, or with caustic alkalis. Paraffins easily enter into substitution reactions, which proceed according to a radical mechanism. Under thermal conditions, they can oxidize and undergo decomposition.
Heptane isomers can be obtained both by conventional methods for the synthesis of alkanes, and by isolation from synthetic gasoline or oil. n-Heptane is a colorless liquid with a weak specific odor; it is highly soluble in organic solvents (ethanol, chloroform, diethyl ether). Isomers of heptane, in particular, tryptane (2,2,3-trimethylbutane - 3- (3) 2- (3) -CH3) have practical use. The specified compound is used as an additive to motor fuel. Heptane isomers are found in gasoline fractions of oil and gas condensates. n-Heptane is the primary standard in determining the detonation properties of carburetor fuel. During the reforming process, n-Hexane is converted to heptane isomers, then dehydrocyclized to an aromatic compound - toluene.
The phenomenon of isomerism is widespread in organic chemistry. There are two main types of isomerism - structural and stereoisomerism. Each type can be divided into types: isomerism of the hydrocarbon chain, arrangement of double bonds and functional groups in the carbon radical, metamerism, isomerism of the arrangement of substituents in the benzene core. A special place among stereoisomers is occupied by optical isomerism. This type is associated with the ability of certain groups of organic substances in solutions to exhibit optical activity. Substances that are capable of exhibiting optical activity are called optically active substances. The isomerism of organic compounds is determined using a special device - a polarimeter. The device is equipped with two Nicolas prisms, an analyzer, and a polarimetric tube.
Optically active substances, as a rule, exist in the form of two optical isomers. They are called optical antipodes, or enantiomers. A mixture that contains equimolecular amounts of enantiomers that is optically inactive is called a racemate or racemic compound. Racemates are indicated by ±. The simplest optically active substance is lactic acid, in the molecule of which there is one asymmetric carbon atom, the valencies of which are associated with four different substituents - hydrogen, hydroxyl, methyl and carboxyl groups.
Each organic compound in the molecule of which there is an asymmetric carbon atom exists in the form of spatial forms (models) with the same number of the same atoms and atomic groups arranged around asymmetric carbon so that when they (forms, models) are combined in space it is impossible reach their full match. These models are similar as the right and left hand of a person or as an object and its mirror image. Therefore, they are called chiral isomers, and isomerism is called optical or mirror.