Group precedence in organic chemistry. What is the name of organic compounds? Suffixes in the names of organic compounds

In the topics of the site, I have already considered the question of how to name or how to decipher the names of organic compounds, but let's dwell on this again in more detail!

IUPAC (naming system chemical compounds and descriptions of the science of chemistry in general), also called the nomenclature of organic compounds, allows you to absolutely accurately reflect the structure of the molecule of organic matter in the name! Thanks to this, chemists of all countries can accurately understand what kind of substance they have in front of them only by name.

To compile the names of the compounds, it is necessary to follow the following algorithm step by step:

1. Find the longest chain of C atoms.

For example, I took a hypothetical substance:

Let's find the longest - the main chain, and it should not only be the longest, but should contain as many functional groups and unsaturated bonds as possible:

2. Sequentially number the carbon atoms of the main chain, proceeding as follows:

If there are functional groups, then they are numbered from the side of the nearest and highest functional group.
If there is no first point and there are unsaturated bonds, then they are numbered from the side closest to such a bond.
If there is no second point, but there is a branched chain, then they are numbered from the end of the one closest to the branch.

Seniority of functional groups:

*The carbon atom enclosed in brackets is part of the main carbon chain

So, the oldest of the vinyl, amino, methyl and hydroxy groups is the hydroxy group *, it will be the end of the name and it is from the end closest to the hydroxy groups that the chain numbering will begin. (*Methyl-, ethyl-, vinyl-, isopropyl-, etc. radicals are always lower in order of precedence of the groups listed in the table).

3. The name of the alkane consists of the names of the side radicals, listed in alphabetical order, indicating the position in the main chain, and the name of the main chain.

Let's start naming:

a) Main chain, nine carbons:

nonan

b) Triple bond at the eighth carbon atom:

non -8-in

c) The highest functional group goes to the end, indicate the position of both hydroxy groups and add "di", since there are two groups:

non-8-in -2,2-diol

e) We list the remaining radicals in alphabetical order:

5-amino-4-methyl-6-vinylnon-8-in -2,2-diol

Deciphering the names of organic compounds

Names are deciphered in a similar way, for example:

3-hydroxyhex-4-enoic acid

a) We draw six carbon atoms in the main chain, and the chain ends in -ovaya, therefore, the extreme atom will be, in combination, a functional group of a carboxylic acid!

b) We number the chain starting from the main functional group:

c) Now let's pay attention to the suffix -en-, it says that there is a double bond at the fourth carbon atom:

d) The prefix hydroxy- remains at the third carbon atom, we add the -OH group and we get our compound:

Features of the nomenclature of various classes of compounds

For carboxylic acids, there is a nomenclature for the alpha (α), beta (β), and gamma (γ) positions, according to the first, second, and third carbon atom after the carboxy group.

For example:

For compounds with a double bond, or a bond around which rotation is impossible, there is a cis(Z)-, trans(E)-nomenclature. If the same substituents are on the same side of the double bond, then this is cis- or Z-isomerism, if they are different, then this is trans- or E-isomerism.

For aromatic compounds, the second, third and fourth positions relative to the senior substituent are called ortho- (o-), meta- (m-) and para (p-) positions:

For carbohydrates, there are a number of trivial names (glucose, ribose, maltose, etc.), with the designations D- or L-.

D- or L- designations refer to the right (D) or left (L) direction of the penultimate hydroxyl:

Also, in the cyclic form of carbohydrates, there is the designation alpha (α) or beta (β) for hemiacetal hydroxyl, so if it “looks” down, then this is an alpha carbohydrate, up - beta:

3. Nomenclature of organic compounds

Nomenclature in chemistry is, figuratively speaking, the professional language of chemists. Ideally, it should accurately and clearly reflect the chemical structure, spatial structure of substances and their chemical transformations.

Organic substances are diverse and numerous. However each compound must have its own name, and only one structural formula must correspond to the name of the compound. Even in the last quarter XIX in. organic substances were mainly named according to the trivial (empirical) nomenclature, later rational names began to be used. However, the rational nomenclature is not official and modern scientific nomenclature does not recommend its use. Therefore, in modern textbooks of the Saami, rational names have been preserved only for a narrow number of compounds, for example, alkyl - and dialkylacetylenes.

In 1919 With the aim of standardization chemical nomenclature, chemical terms, atomic masses, methods of conducting the experiment and presenting the results obtained was organized by the International Union for Pure and Applied Chemistry - IUPAC (from the English. International Union of Pure and Appied Chemistry - IUPAC)

After the IUPAC Congress in London, which took place in 1947, a lot of work to expand and correct the rules was carried out by the IUPAC Commission on the Nomenclature of Organic Compounds. IUPAC Congresses in 1957 and 1965 recommended the nomenclature she developed for use, and it became known as the IUPAC nomenclature. The rules of this nomenclature were published in different years in separate editions, and in 1979 they were collected in the Blue Book, which is the most complete set of modern rules for the nomenclature of organic compounds.

3.1 Trivial or empirical nomenclature

Trivial or empirical names for substances are random names. They usually reflect natural source, a getter, or some connection property. For example, urea is found in urine, formic acid in ant secretions, oxalic acid in sorrel, lactic acid in sour milk, malic acid in apple, citric acid in lemon, tartaric acid in grapes; pyruvic acid and pyrogallol are obtained by pyrolysis of tartaric and gallic acids; glycerin, glycols, glycine or glycocol are sweet tasting substances.

H 2 NCONH 2 - urea,

HCOOH - formic acid,

HOOSCOOH - oxalic acid,

CH3CH(OH)COOH - lactic acid,

HOOSCH(OH)CH2COOH - malic acid,

HOCH2CH(OH)CH2OH - glycerol,

HOCH2CH2OH - ethylene glycol,

H2NCH2COOH - glycocol, glycine.

3.2 Rational nomenclature.

Before considering the basics of this nomenclature, let's get acquainted with several important concepts in organic chemistry. Carbon atoms in a chain can differ in the number of bonds with neighboring carbon atoms. If the number of such bonds is four, then carbon is called Quaternary (quarter), three - tertiary (third), two - secondary (sec.), one primary (first).

When a carbon atom is removed from a hydrocarbon molecule, a hydrocarbon radical is formed. The names of limiting acyclic radicals are obtained by replacing the suffix -an in the name of the hydrocarbon –silt. Based on the number of carbon bonds with free valence with neighboring carbon atoms, primary, secondary, tertiary radicals are distinguished. An unbranched primary radical is called a normal radical and is denoted by a lowercase letter n-, which is written with a hyphen before the general name of the radical.

Substances that are similar in structure and very similar in chemical properties, but differ in molecular composition by only one or more methylene groups CH 2 , called homologues. Homologues form homologous series, where each subsequent homologue differs from the previous one by one methylene group. The homologous series of hydrocarbons got their name from the names of the first representatives - the ancestors of the series. For example, saturated hydrocarbons are called methane, and unsaturated hydrocarbons are called ethylene or acetylene. According to rational nomenclature, all homologues are considered as substances obtained by replacing one or more hydrogen atoms in the ancestor of the series with hydrocarbon radicals. Therefore, the methane carbon or the ethylene or acetylene fragment is first found and the radicals associated with them are determined. In the acyclic saturated hydrocarbon, I take primarily quaternary carbon for methane, in its absence - tertiary, etc. First, hydrocarbon radicals with multiplying prefixes are listed, and then the name of the ancestor of the series is added.

CH3 CH 2CH3 - dimethylmethane,

CH3 With(CH3)2CH2CH(CH3)CH3 - trimethylisobutylmethane,

CH3CH2 CH=CH 2 - ethylene,

CH3 C≡CH- methylacetylene.

3.3 Scientific nomenclature

The IUPAC nomenclature for organic compounds is a system of several scientific nomenclatures and naming conventions. To compose the name of the substance as a whole, the IUPAC substitution nomenclature is used predominantly, less often the radical-functional one. A main acyclic chain containing several non-terminal heteroatoms, heterocycles can be named by substitutive nomenclature. AT organic chemistry non-carbon element other than hydrogen is called heteroelement . Oxygen, nitrogen, sulfur, phosphorus, silicon are heteroelements most often found in organic compounds. If a heteroatom is at the end of an acyclic chain, it is called terminal , if it is inside this chain, then non-terminal . If in a closed chain of atoms, i.e., in a cycle, there is at least one atom of a heteroelement, then such a cycle is called heterocycle , and the connection is heterocyclic .

A special method of naming has been developed for heterocycles. extended Hantzsch-Widmann system , and names of heterocycles according to this system are preferred over names according to substitute nomenclature. The names of polynuclear carbocils containing the maximum number of non-cumulated double bonds, as well as complex systems, consisting of carbo - and heterocycle or several heterocycles, are composed according to condensation method .

3.3.1 Substitutive nomenclature

Substitutive nomenclature considers any organic compound as consisting of parental structure and deputies. There is also the concept characteristic structural elements connections, which include substituents and types of bonds or degree of saturation. The degree of saturation of the parent structure of the compound and hydrocarbon radicals is conveyed by suffixes –an(saturated, single bonds only), -en(double bond), -in(triple bond). If there are several identical unsaturated bonds, then multiplying prefixes are used; di-, tri-, tetra-, etc., for example diene, diyne, triene, triyne.

The deputies are divided into hydrocarbon radicals and characteristic groups. The latter, in turn, are formally divided into functional groups(FG) and non-functional groups(NFG). For FG there is a series of seniority:

RnN + H 3- n, COOH, SO 3 H, COOR, COHlg, CONH 2, CN, CHO, > C \u003d O, OH, SH, OOH, NH 2.

For UFH and radicals, only prefix names are characteristic (in the example below 1: 3-methyl-5-chloro-..; in example 2: 5-bromo-...). FG is characterized by two names: 1) for use in a suffix (suffix designation or name), when FG is the senior one (in example 3: OH is the senior FG, suffix new designation -ol; in example 4: N H2 - senior FG, suffixtitle -amine); 2) for use in a prefix (prefix designation or name) when the FG is the youngest (example re 2: OH - junior FG, prefix notation hydroxy-; in example 1: N H2 - junior FG, prefix name amino-).

Example 1:

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Locations of substituents and unsaturated bonds in ro the pre-initial structure is indicated by the numbers that received n title locants. The location of locants obeys simply mu rule: locants are placed before prefixes, but after suffix owls. Lokants are separated from each other by commas, and from the prefix, suffix and the name of the parent structure - dashes (see examples 1-4). Condensation locants for two or more systems are enclosed in square brackets; they belong to the original components (in example 3), and not to the final condenser bathroom system. Numbers in square brackets in spiral names new, bicyclic and polycyclic compounds are not locants, since they indicate the number of atoms in a particular link (in example 4), and not their numbers.

If the same or different atoms of the parent structure has several identical substituents, then, sob put them together, use multiplying prefixes, for example: 2,3,3-three methyl-2,4- di hydroxy-, 2,3- di oxo-1 .5-di chloro -, .~di a - min-1.3, .- three ol - 1,3,4, .-di carboxylic-1,4 acid. Substituent prefixes are listed in the compound name in alphabetical order, but multiplier prefixes are not taken into account: CH3C(CH3)2CH(CH3)CH(C l )CH(С l )COOH -4,5,5-trimethyl-2,3-dichlorohexanoic acid.

In the examples 2-4 above, the carbon atoms in the cycles are not shown. A similar notation of formulas is also used inacyclic systems. for example

The same notation can be used to denote hydrocarbon radicals. As an example, alkyl-substituted benzenes are given:

In modern chemical literature, hydrocarbon radiols are designated by two letters of their English names:

CH 3 - Me, C 2 H 5 - Et, n-C 3 H 7 - n - Pr, iso- C 3 H 7 - i - Pr, n- C 4 H 9 - n - Bu, sec-C 4 H 9 - s - Bu, iso- C 4 H 9 - i - Bu, tert.- C 4 H 9 - t - Bu, C 6 H 5 - Ph, C 6 H 5 CH 2 - Bz.

Substituents are also simple(CH3, CH3 (CH2) 3CH2-, C6H5, F , C l , J , N H2 , CN, OH, NO, NO 2 ), composite, consisting oftwo or more simple ones, and complex- from the simple, with whichare compound substituents. Both compound and complex have common prefix names, including multiplying prefixes di-, three - etc., and they are arranged in alphabetical order by the first letters: d imethylamino-, m ethylamino-, X loromethyl, d ichloromethyl, t richloromethyl, a minocarbonyl-(CO N H2), a alkoxycarbonyl-(COO R ), b romocarbonyl - (BrCO), 3- G idroxy-2-( t richloromethyl)propyl [-CH2CH(CC l 3 )CH2OH], 2-( d ichloromethyl)-1-(trifluoromethyl)-3,3,3-trichloropropyl [CC l 3 CH (CHS l 2) CH (C F 3 )-]. For compound and complex substituents, the name of which, as a rule, is enclosed in brackets, multiplying prefixes are used bis-, tris-, tetrakis- etc., which are not taken into account when listing prefixes in alphabetical order.

4-(d imethylamino)-2,3,5-tri m ethyl-2,3-bis( t rifluoromethyl)hexanoic acid.

According to the rules of substitutional nomenclature, the name of an organic compound consists of the name of the parent structure, prefixes and suffixes with the corresponding locants.

Name connections
Perfixes of radicals, minor FG, UFG, hydro, i.e. defined prefixes in alphabetical order with locants in front	The name of the parent structure = inseparable prefixes + root + saturation degree suffix	Senior FG suffix

Prefixes that are an integral part of the name of the parent structure, for example cyclo-(examples 2, 4), iso-,a-element designations (oxa-, thia ~, aza-, phospha-, etc., see example 4, oksa-), name of the attached structure according to the method condensation (benzo-, naphtho-, anthra-, thieno-, pyrano- etc., see example 3, imidazo-), as well as epoxy - and epithio-, indicating to join, are called inseparable, while prefixes of radicals, characteristic groups and prefix hydro-- separable. First, the separable prefixes are placed in al in alphabetical order, and then insert multiplying prefixes and locants.

3.3.2 Substitute nomenclature

Substitutive nomenclature is used to form scientific names heterocyclic systems, as well as the acyclic parent structure of the compound, consisting of a number of unequal fragments connected to each other through heteroatoms. The basis of the name of the ancestral structure according to this nomenclature is the name of a hypothetical open or cyclic carbon chain (heptaneor cyclopentadiene, see examples 1 and 2 below), which are obtained

replacement of heteroatoms by carbon atoms. Moreover, in an acyclic system, only non-terminal heteroatoms are replaced by carbon atoms (example 1). Inseparable prefixes are added to this name in descending order of precedence, indicating the nature of heteroatoms (a-designation of elements) and their locants ( 3,6-oxase + heptane → 3,6-oxazaheptanein example 1; 1,3-thiase + cyclopentadiene-2,4 → 1,3-thiazacyclopentadiene-2,4 in example 2); a-designations of elements are formed by replacing the ending in their Latin name with "a". The precedence of heteroelements in Periodic system elements decrease from top to bottom in groups and from right to left in periods (oxygen is the oldest, aluminum is the youngest in this fragment of the system), as shown below:

Lecture #1

CLASSIFICATION, NOMENCLATURE and isomerism of ORGANIC COMPOUNDS

1. Classification of organic compounds.

2. Nomenclature of organic compounds.

3. Structural isomerism.

1. Classification of organic compounds.

Organic compounds are classified according to two main features: the structure of the carbon skeleton and functional groups.

According to the structure of the carbon skeleton, acyclic, carbocyclic and heterocyclic compounds are distinguished.

Acyclic compounds- contain an open chain of carbon atoms.

Carbocyclic compounds- contain a closed chain of carbon atoms and are divided into alicyclic and aromatic. To alicyclic include all carbocyclic compounds, except aromatic ones. aromatic the compounds contain a cyclohexatriene fragment (benzene nucleus).

Heterocyclic compounds- contain cycles, including, along with carbon atoms, one or more heteroatoms.

By the nature of the functional groups organic compounds divide by classes.

Table 1. Main classes of organic compounds.

Functional group	Connection class	General formula
Is absent	hydrocarbons
F, -Cl, -Br, -I (–Hal)	Halogen derivatives
Hydroxyl	Alcohols and phenols
Alkoxy	Ethers
NH2, >NH, >N-
	Nitro compounds
Carbonyl >c=o<="" center=""> >c=o>	Aldehydes and ketones
Carboxyl	carboxylic acids
Alkoxycarbonyl	Esters
carboxamide	carboxylic acids
thiol
	Sulphonic acids

2. Nomenclature of organic compounds.

At present, it is generally accepted in organic chemistry systematic nomenclature, developed by the International Union of Pure and Applied Chemistry ( IUPAC). Along with it, preserved and used trivial and rational nomenclature.

Trivial nomenclature consists of historically established names that do not reflect the composition and structure of the substance. They are random and reflect the natural source of the substance (lactic acid, urea, caffeine), characteristic properties(glycerin, fulminic acid), production method (pyruvic acid, sulfuric ester), name of the discoverer (Michler's ketone, Chichibabin hydrocarbon), field of application (ascorbic acid). The advantage of trivial names is their conciseness, so the use of some of them is allowed by IUPAC rules.

Systematic nomenclature is scientific and reflects the composition, chemical and spatial structure of the compound. The name of the compound is expressed using a compound word, the constituent parts of which reflect certain structural elements of the substance molecule. IUPAC nomenclature rules are based on the principles replacement nomenclature, according to which the molecules of compounds are considered as derivatives of hydrocarbons, in which hydrogen atoms are replaced by other atoms or groups of atoms. When constructing a name in a compound molecule, the following structural elements are distinguished.

ancestral structure- main chain carbon chain or cyclic structure in carbo- and heterocycles.

Hydrocarbon radical- the remainder of the formula designation of a hydrocarbon with free valences (see table 2).

characteristic group- a functional group associated with the parent structure or included in its composition (see table 3).

When compiling the name, the following rules are consistently followed.

1. Determine the senior characteristic group and indicate its designation in the suffix (see table 3).

2. The ancestral structure is determined according to the following criteria in descending order of precedence: a) contains a senior characteristic group; b) contains the maximum number of characteristic groups; c) contains the maximum number of multiple bonds; d) has a maximum length. The ancestral structure is designated at the root of the name in accordance with the length of the chain or the size of the cycle: C1 - “met”, C2 - “et”, C3 - “prop”, C4 - “but”, C5 and further - the roots of Greek numerals.

3. Determine the degree of saturation and reflect it in the suffix: “an” - no multiple bonds, “en” - double bond, “in” - triple bond.

4. Set the remaining substituents (hydrocarbon radicals and minor characteristic groups) and list their names in the prefix in alphabetical order.

5. Multiplying prefixes are set - “di”, “three”, “tetra”, indicating the number of identical structural elements (when listing substituents in alphabetical order, they are not taken into account).

6. Carry out the numbering of the parent structure so that the highest characteristic group has the smallest serial number. Lokants (numbers) are placed before the name of the parent structure, before prefixes and before suffixes.

Table 2. Names of alkanes and alkyl radicals adopted by the IUPAC systematic nomenclature.

	Name	Alkyl radical	Name



	Isopropyl
	n-butane		n-Butyl
	sec-Butyl
	Isobutane		Isobutyl
	tert-Butyl
CH3CH2CH2CH2CH3	n-Pentane	CH3CH2CH2CH2CH2-	n-Pentyl
	Isopentane		Isopentyl
	Neopentane		Neopentyl

Table 3. Names of characteristic groups (listed in descending order of precedence).

*The carbon atom enclosed in brackets is part of the parent structure.

**Alkoxy groups and all those following them are listed alphabetically in the prefix and have no order of precedence.

Rational (radical-functional) nomenclature used for the names of simple mono- and bifunctional compounds and some classes of natural compounds. The name is based on the name this class compounds or one of the members of the homologous series, indicating substituents. As a rule, Greek letters are used as locants.

3. Structural isomerism.

Isomers are substances that have same composition and molecular weight but different physical and chemical properties. Differences in the properties of isomers are due to differences in their chemical or spatial structure.

Under chemical structure understand the nature and sequence of bonds between atoms in a molecule. Isomers whose molecules differ in chemical structure, called structural isomers.

Structural isomers may differ:

on the structure of the carbon skeleton

according to the position of multiple bonds and functional groups

by type of functional groups

1. Isomerism

The concept of "isomers" was introduced by Berzelius in 1830. He defined "isomers" as substances that have the same composition (molecular formula) but different properties. The concept of isomers was introduced by Berzelius after he found that cyanic acid HOCN is identical in composition to fulminant or isocyanic acid O=C=NH.

There are two main types of isomerism: structural and spatial(stereoisomerism).

Structural isomers differ from each other in the order of bonds between atoms in a molecule; stereoisomers - the arrangement of atoms in space with the same order of bonds between them.

2. Structural isomerism

Structural isomerism is divided into several varieties.

Isomerism of the carbon skeleton due to the different bond order between the carbon atoms that form the skeleton of the molecule. So, there can be only one non-cyclic saturated hydrocarbon with three C atoms - propane (I). There may already be two hydrocarbons of the same type with four C atoms: n-butane (II) and isobutane (III), and with five C atoms - three: n-pentane (IV), isopentane (V) and neopentane (VI): ammonia, while 1,3-dinitrobenzene (XI) does not react with NH3.

In the series of aliphatic ethers, sulfides and amines, there is special kind isomerism - metamerism, due to the different position of the heteroatom in the carbon chain. Metamers are, for example, methylpropyl (XII) and diethyl (XIII) ethers:

The isomerism of unsaturated compounds can be caused by different positions of the multiple bond, as, for example, in butene-1 (XIV) and butene-2 (XV), in vinylacetic (XVI) and crotonic (XVII) acids:

In most cases, structural isomers combine the features of skeletal isomerism and position isomerism, contain different functional groups and belong to different classes of substances, as a result of which they differ from each other much more than the isomers of substances of the same type considered above. For example, propylene (XVIII) and cyclopropane (XIX), ethylene oxide (XX) and acetaldehyde (XXI), acetone (XXII) and propionaldehyde (XXIII), dimethyl ether (XXIV) and ethanol(XXV), allene (XXVI) and methylacetylene (XXVII):

special kind structural isomerism is an tautomerism(equilibrium dynamic isomerism) - the existence of a substance in two or more isomeric forms, easily passing into each other. So, acetoacetic ester exists in the form of an equilibrium mixture of ketone (XXVIII) and enol (XXIX) forms:

There are many organic compounds, but among them there are compounds with common and similar properties. Therefore, they are all classified according to common characteristics, combined into separate classes and groups. The classification is based on hydrocarbons – compounds that are made up of only carbon and hydrogen atoms. The rest of the organic matter is "Other Classes of Organic Compounds".

Hydrocarbons are divided into two broad classes: acyclic and cyclic compounds.

Acyclic compounds (fatty or aliphatic) – compounds whose molecules contain an open (not closed in a ring) unbranched or branched carbon chain with single or multiple bonds. Acyclic compounds are divided into two main groups:

saturated (limiting) hydrocarbons (alkanes), in which all carbon atoms are interconnected only by simple bonds;

unsaturated (unsaturated) hydrocarbons, in which between carbon atoms, except for single simple connections There are also double and triple bonds.

Unsaturated (unsaturated) hydrocarbons are divided into three groups: alkenes, alkynes and alkadienes.

Alkenes(olefins, ethylene hydrocarbons) – acyclic unsaturated hydrocarbons, which contain one double bond between carbon atoms, form a homologous series with the general formula C n H 2n . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-en". For example, propene, butene, isobutylene or methylpropene.

Alkynes(acetylene hydrocarbons) – hydrocarbons that contain a triple bond between carbon atoms form a homologous series with the general formula C n H 2n-2 . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-in". For example, ethin (acylene), butin, peptin.

Alkadienes – organic compounds that contain two carbon-carbon double bonds. Depending on how the double bonds are arranged relative to each other, dienes are divided into three groups: conjugated dienes, allenes and dienes with isolated double bonds. Typically, dienes include acyclic and cyclic 1,3-dienes, forming with the general formulas C n H 2n-2 and C n H 2n-4 . Acyclic dienes are structural isomers of alkynes.

Cyclic compounds, in turn, are divided into two large groups:

carbocyclic compounds – compounds whose rings consist only of carbon atoms; Carbocyclic compounds are subdivided into alicyclic – saturated (cycloparaffins) and aromatic;
heterocyclic compounds – compounds whose cycles consist not only of carbon atoms, but of atoms of other elements: nitrogen, oxygen, sulfur, etc.

In molecules of both acyclic and cyclic compounds hydrogen atoms can be replaced by other atoms or groups of atoms, thus, by introducing functional groups, derivatives of hydrocarbons can be obtained. This property further expands the possibilities of obtaining various organic compounds and explains their diversity.

The presence of certain groups in the molecules of organic compounds determines the generality of their properties. This is the basis for the classification of derivatives of hydrocarbons.

"Other classes of organic compounds" include the following:

Alcohols are obtained by replacing one or more hydrogen atoms with hydroxyl groups – Oh. It is a compound with the general formula R – (OH) x, where x – number of hydroxyl groups.

Aldehydes contain an aldehyde group (C = O), which is always at the end of the hydrocarbon chain.

carboxylic acids contain one or more carboxyl groups – COOH.

Esters – derivatives of oxygen-containing acids, which are formally the products of substitution of hydrogen atoms of hydroxides – OH acid function per hydrocarbon residue; are also considered as acyl derivatives of alcohols.

Fats (triglycerides) – natural organic compounds, complete esters glycerin and one-component fatty acids; belong to the class of lipids. Natural fats contain in their composition three acid radicals with an unbranched structure and, usually, even number carbon atoms.

Carbohydrates – organic substances containing a straight chain of several carbon atoms, a carboxyl group and several hydroxyl groups.

Amines contain an amino group – NH2

Amino acids– organic compounds, the molecule of which simultaneously contains carboxyl and amine groups.

Squirrels – high-molecular organic substances, which consist of alpha-amino acids connected in a chain by a peptide bond.

Nucleic acids – high-molecular organic compounds, biopolymers formed by nucleotide residues.

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The simplest classification is that all known substances are divided into inorganic and organic. The organic substances are hydrocarbons and their derivatives. All other substances are inorganic.

inorganic substances divided by composition into simple and complex.

Simple substances consist of atoms of one chemical element and are divided into metals, non-metals, noble gases. Compounds are made up of atoms of different elements that are chemically bonded to each other.

Complex inorganic substances according to their composition and properties are divided into the following major classes: oxides, bases, acids, amphoteric hydroxides, salts.

oxides- This complex substances, consisting of two chemical elements, one of which is oxygen with an oxidation state of (-2). The general formula of oxides is: E m O n, where m is the number of atoms of the element E, and n is the number of oxygen atoms. Oxides, in turn, are classified into salt-forming and non-salt-forming. Salt-forming substances are divided into basic, amphoteric, acidic, which correspond to bases, amphoteric hydroxides, acids, respectively.
Basic oxides are metal oxides in oxidation states +1 and +2. These include:
- metal oxides of the main subgroup of the first group ( alkali metals ) Li-Fr
- metal oxides of the main subgroup of the second group ( Mg and alkaline earth metals) Mg-Ra
- oxides transition metals in lower oxidation states
Acid oxides- form non-metals with S.O. more than +2 and metals with S.O. from +5 to +7 (SO 2, SeO 2, P 2 O 5, As 2 O 3, CO 2, SiO 2, CrO 3 and Mn 2 O 7). Exception: for NO oxides 2 and ClO 2 there are no corresponding acid hydroxides, but they are considered acidic.
Amphoteric oxides-formed by amphoteric metals with S.O. +2, +3, +4 (BeO, Cr 2 O 3 , ZnO, Al 2 O 3 , GeO 2 , SnO 2 and PbO).
Non-salt-forming oxides- oxides of non-metals with С.О.+1, +2 (СО, NO, N 2 O, SiO).
Foundations- these are complex substances consisting of metal atoms and one or more hydroxo groups (-OH). The general formula of the bases is: M (OH) y, where y is the number of hydroxo groups equal to the oxidation state of the metal M (usually +1 and +2). Bases are divided into soluble (alkali) and insoluble.
acids- (acid hydroxides) are complex substances consisting of hydrogen atoms that can be replaced by metal atoms, and acid residues. The general formula of acids: H x Ac, where Ac is an acid residue (from the English "acid" - acid), x is the number of hydrogen atoms equal to the charge of the ion of the acid residue.
Amphoteric hydroxides are complex substances that exhibit both the properties of acids and the properties of bases. Therefore the formulas amphoteric hydroxides can be written in both acid and base forms.
salt- These are complex substances consisting of metal cations and anions of acid residues. This definition applies to medium salts.
Medium salts- these are the products of the complete replacement of hydrogen atoms in the acid molecule by metal atoms or the complete replacement of hydroxo groups in the base molecule by acidic residues.
Acid salts- hydrogen atoms in the acid are partially replaced by metal atoms. They are obtained by neutralizing a base with an excess of an acid. To properly name acid salt, it is necessary to add the prefix hydro- or dihydro- to the name of the normal salt, depending on the number of hydrogen atoms that make up the acid salt. For example, KHCO 3 is potassium bicarbonate, KH 2 PO 4 is potassium dihydroorthophosphate. It must be remembered that acid salts can only form two or more basic acids.
Basic salts- hydroxo groups of the base (OH -) are partially replaced by acidic residues. To name basic salt, it is necessary to add the prefix hydroxo- or dihydroxo- to the name of the normal salt, depending on the number of OH groups that make up the salt. For example, (CuOH) 2 CO 3 is copper (II) hydroxocarbonate. It must be remembered that basic salts can only form bases containing two or more hydroxo groups.
double salts- in their composition there are two different cations, they are obtained by crystallization from a mixed solution of salts with different cations, but the same anions. For example, KAl(SO 4) 2, KNaSO 4.
mixed salts- in their composition there are two different anions. For example, Ca(OCl)Cl.
Hydrate salts (crystal hydrates) - they include molecules of crystallization water. Example: Na 2 SO 4 10H 2 O.

Classification of organic substances

Compounds containing only hydrogen and carbon atoms are called hydrocarbons. Before starting this section, remember, to simplify the record, chemists do not paint carbons and hydrogens in chains, but do not forget that carbon forms four bonds, and if in the figure carbon is bound by two bonds, then it is bound by two more bonds to hydrogens, although the last and not specified:

Depending on the structure of the carbon chain, organic compounds are divided into compounds with an open chain - acyclic(aliphatic) and cyclic- with a closed chain of atoms.

Cyclic are divided into two groups: carbocyclic connections and heterocyclic.

Carbocyclic compounds, in turn, include two series of compounds: alicyclic and aromatic.

aromatic compounds the structure of molecules is based on flat carbon-containing cycles with a special closed system of π-electrons. forming a common π-system (a single π-electron cloud).

Both acyclic (aliphatic) and cyclic hydrocarbons can contain multiple (double or triple) bonds. These hydrocarbons are called unlimited(unsaturated), as opposed to marginal(saturated) containing only single bonds.

Pi-bond (π-bond) - covalent bond, formed by the overlap of p-atomic orbitals. In contrast to the sigma bond, which occurs by overlapping s-atomic orbitals along the atomic bonding line, pi bonds occur when p-atomic orbitals overlap on either side of the atomic bonding line.

In the case of the formation of an aromatic system, for example, benzene C6H6, each of the six carbon atoms is in the state of sp2 - hybridization and forms three sigma bonds with bond angles 120°. The fourth p-electron of each carbon atom is oriented perpendicular to the plane of the benzene ring. In general, a single bond arises, extending to all carbon atoms of the benzene ring. Two regions of pi bonds of high electron density are formed on both sides of the plane of sigma bonds. With such a bond, all carbon atoms in the benzene molecule become equivalent and, therefore, such a system is more stable than a system with three localized double bonds.

Limit aliphatic hydrocarbons are called alkanes, they have the general formula C n H 2n + 2, where n is the number of carbon atoms. Their old name is often used today - paraffins:

Unsaturated aliphatic hydrocarbons with one triple bond are called alkynes. Their general formula C n H 2n - 2

Limit alicyclic hydrocarbons - cycloalkanes, their general formula is C n H 2n:

We have considered the classification of hydrocarbons. But if in these molecules one or more hydrogen atoms are replaced by other atoms or groups of atoms (halogens, hydroxyl groups, amino groups, etc.), derivatives of hydrocarbons are formed: halogen derivatives, oxygen-containing, nitrogen-containing and other organic compounds.

The atoms or groups of atoms that determine the most characteristic properties of a given class of substances are called functional groups.

Hydrocarbons in their derivatives with the same functional group form homologous series.

A homologous series is a series of compounds belonging to the same class (homologs), differing from each other in composition by an integer number of -CH 2 - groups (homologous difference), having a similar structure and, therefore, similar chemical properties.

similarity chemical properties homologues greatly simplifies the study of organic compounds.

Substituted hydrocarbons

Halogen derivatives of hydrocarbons can be considered as products of substitution in hydrocarbons of one or more hydrogen atoms by halogen atoms. In accordance with this, there can be limiting and unlimiting mono-, li-, tri- (in general case poly-) halogen derivatives. The general formula of halogen derivatives of saturated hydrocarbons is R-G. Oxygen-containing organic substances include alcohols, phenols, aldehydes, ketones, carboxylic acids, ethers and esters.
Alcohols- derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by hydroxyl groups. Alcohols are called monohydric if they have one hydroxyl group, and saturated if they are derivatives of alkanes. The general formula of saturated monohydric alcohols: R-OH.
Phenols- derivatives of aromatic hydrocarbons (benzene series), in which one or more hydrogen atoms in the benzene ring are replaced by hydroxyl groups.
Aldehydes and ketones- derivatives of hydrocarbons containing a carbonyl group of atoms (carbonyl). In aldehyde molecules, one carbonyl bond goes to the connection with a hydrogen atom, the other - with a hydrocarbon radical. In the case of ketones, the carbonyl group is bonded to two (generally different) radicals.
Ethers are organic substances containing two hydrocarbon radicals connected by an oxygen atom: R=O-R or R-O-R 2 . The radicals can be the same or different. The composition of ethers is expressed by the formula C n H 2n +2O.
Esters- compounds formed by substitution of a hydrogen atom of the carboxyl group in carboxylic acids to a hydrocarbon radical.
Nitro compounds- derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by a nitro group -NO 2 .
Amines- compounds that are considered as derivatives of ammonia, in which hydrogen atoms are replaced by hydrocarbon radicals. Depending on the nature of the radical, amines can be aliphatic. Depending on the number of hydrogen atoms replaced by radicals, primary, secondary, and tertiary amines are distinguished. In a particular case, secondary as well as tertiary amines may have the same radicals. Primary amines can also be considered as derivatives of hydrocarbons (alkanes) in which one hydrogen atom is replaced by an amino group. Amino acids contain two functional groups connected to a hydrocarbon radical - an amino group -NH 2 and a carboxyl -COOH.

Other important organic compounds are known that have several different or identical functional groups, long linear chains associated with benzene rings. In such cases, a strict definition of whether a substance belongs to a particular class is impossible. These compounds are often isolated into specific groups of substances: carbohydrates, proteins, nucleic acids, antibiotics, alkaloids, etc. At present, many compounds are also known that can be classified as both organic and inorganic. They are called organoelement compounds. Some of them can be considered as derivatives of hydrocarbons.

Nomenclature

Two nomenclature is used to name organic compounds - rational and systematic (IUPAC) and trivial names.

Compilation of names according to the IUPAC nomenclature:

1) The basis of the name of the compound is the root of the word, denoting saturated hydrocarbon with the same number of atoms as the main chain.

2) A suffix is added to the root, characterizing the degree of saturation:

An (limiting, no multiple bonds);

Yong (in the presence of a double bond);

Ying (in the presence of a triple bond).

If there are several multiple bonds, then the number of such bonds (-diene, -triene, etc.) is indicated in the suffix, and after the suffix, the position of the multiple bond must be indicated in numbers, for example:

CH 3 -CH 2 -CH \u003d CH 2 CH 3 -CH \u003d CH -CH 3

butene-1 butene-2

CH 2 \u003d CH - CH \u003d CH 2

Groups such as nitro-, halogens, hydrocarbon radicals that are not included in the main chain are taken out to the prefix. They are listed in alphabetical order. The position of the substituent is indicated by a number before the prefix.

The title order is as follows:

1. Find the longest chain of C atoms.

2. Sequentially number the carbon atoms of the main chain, starting from the end closest to the branch.

3. The name of the alkane consists of the names of the side radicals, listed in alphabetical order, indicating the position in the main chain, and the name of the main chain.

Naming order

Chemical language, which, as one of the most specific parts, includes chemical symbolism (including and chemical formulas), is an important active means of learning chemistry and therefore requires a clear and conscious application.

Chemical formulas- these are conditional images of the composition and structure of chemically individual substances through chemical symbols, indices and other signs. When studying the composition, chemical, electronic and spatial structure of substances, their physical and chemical properties, isomerism and other phenomena, chemical formulas of various types are used.

Especially many types of formulas (the simplest, molecular, structural, projection, conformational, etc.) are used in the study of substances molecular structure- majority organic matter and a relatively small part inorganic substances under normal conditions. Much fewer species formulas (the simplest) are used in the study of non-molecular compounds, the structure of which is more clearly reflected by ball-and-stick models and diagrams of crystal structures or their unit cells.