Nomenclature in organic chemistry. The Wonderful World of Organics

Even in the middle of the XIX century. individual chemists tried to create such a nomenclature that would speak about the structure of the named substances; such a nomenclature is called rational. In this case, for example, the names of hydrocarbons were derived from the names of the first representative of this group of hydrocarbons. So, for a number of methane, the name of methane served as the basis for the name. For example, one of the isomers of pentane can be called dimethylethylmethane, i.e. this substance can be represented as a derivative of methane, in which two hydrogen atoms are replaced by CH3 methyl groups, and one hydrogen atom is replaced by a C 2 H 5 ethyl group.

International nomenclature

Desiring to create the most rational nomenclature of organic compounds that would be accepted in all countries of the world, the largest chemists - representatives of chemical societies from different countries - gathered in 1892 in Geneva (Switzerland). At this meeting, a systematic scientific nomenclature was developed, which is now usually called the Geneva or international nomenclature.

In order to name any compound according to the Geneva nomenclature, the following rules are followed.

Considering the structural formula of the compound, the longest chain of carbon atoms is chosen and the atoms are numbered, starting from the end to which the substituent is closer (side branch).

The compound is considered according to the principles of Geneva nomenclature as a derivative of a normal hydrocarbon having the same corresponding renumbered chain.

The place of the substituent (chain branch) is indicated by a number corresponding to the number of the carbon atom at which the substituent is located, then the substituent is called, and finally the hydrocarbon from which the entire compound is produced along the longest renumbered chain.

In cases where there are several branches in the chain, the position of each is indicated separately by the corresponding numbers, and each substituent is named separately. If the compound has several identical substituents, for example, two methyl groups, then after two numbers denoting their places, they say “dimethyl” (from the Greek di - “two”); in the presence of three methyl groups, they say "tri-methyl", etc.

After the creation of the Geneva nomenclature, they repeatedly tried to improve it - to supplement, correct it. Thus, in the city of Liege (Belgium), the "Liège rules" were considered, which, however, were not accepted by many chemists.

In 1957, and then in 1965, the International Union of Pure and Applied Chemisty, abbreviated as IUPAC (or IUPAC), approved the rules for the nomenclature of organic compounds. These rules basically correspond to the Geneva nomenclature, but make some amendments to it. In the future, when presenting the International Nomenclature of various classes of compounds, IUPAC recommendations were also taken into account.

Organic compounds are the largest class of chemical compounds. The variety of organic compounds is associated with the unique property of carbon to form chains of atoms, which in turn is due to the high stability of the carbon-carbon bond. The carbon-carbon bond can be either single or multiple - double, triple. With an increase in the multiplicity of the carbon-carbon bond, its energy increases, that is, stability, and the length decreases. The high valency of carbon - 4, as well as the ability to form multiple bonds, allows the formation of various structures.

The main provisions of the theory of chemical structure of A.M. Butlerov

Atoms in molecules are connected to each other in a certain sequence according to their valencies. The sequence of interatomic bonds in a molecule is called its chemical structure and is reflected by one structural formula (structural formula).
The chemical structure can be established by chemical methods. (Currently modern physical methods are also used).
The properties of substances depend on their chemical structure.
By the properties of a given substance, one can determine the structure of its molecule, and by the structure of the molecule, one can predict the properties.
Atoms and groups of atoms in a molecule interact with each other.

Butlerov's theory was the scientific foundation of organic chemistry and contributed to its rapid development. Based on the provisions of the theory, A.M. Butlerov gave an explanation for the phenomenon of isomerism, predicted the existence of various isomers, and obtained some of them for the first time.

Classification of organic compounds

The classification of organic substances is carried out according to various criteria.

1. According to the structure of the carbon chain (skeleton):

acyclic

cyclic (carbocyclic, heterocyclic)

By the presence of a side chain (radical)

unbranched,

branched

2. According to the degree of saturation (multiplicity) of carbon-carbon bonds:

limiting (alkanes, cycloalkanes);

unsaturated (alkenes, arenes, alkynes, dienes, etc.).

According to the presence of functional groups:

· hydrocarbons;

heterofunctional organic compounds (hydroxy acids, amino acids).

All classes of organic compounds are interconnected. The transition from one class of compounds to another is carried out mainly due to the transformation of functional groups without changing the carbon skeleton. Compounds of each class constitute a homologous series.

Nomenclature of organic compounds

For naming organic compounds, the trivial, rational and systematic, or international (IUPAC) nomenclature is used.

The trivial (historically established) nomenclature in the name of the compound usually indicates the primary source of its discovery or preparation (formic acid, salicylic acid, etc.), any of the characteristic properties. Such a nomenclature does not reflect the structure of the substance and does not allow one to draw up a formula by its name.

According to rational nomenclature, any organic compound of a given homologous series is called as a derivative of the simplest.

According to international nomenclature, the defining fragment underlying (at the root) the name of acyclic compounds is the longest carbon chain, and for cyclic compounds, the cycle.

The names of the first four saturated hydrocarbons are trivial (historical names) - methane, ethane, propane, butane. Starting from the fifth, the names are formed by Greek numerals corresponding to the number of carbon atoms in the molecule, with the addition of the suffix "-an", with the exception of the number "nine", when the Latin numeral "nona" serves as the root.

Nomenclature of homologues of a number of saturated hydrocarbons

FORMULA	TITLE	FORMULA	TITLE
CH 4	methane	C 6 H 14	hexane
C 2 H 6	ethane	C 7 H 16	heptane
C 3 H 8	propane	C 8 H 18	octane
C 4 H 10	butane	C 9 H 20	nonan
C 5 H 12	pentane	C 10 H 22	dean

Monovalent radicals formed from saturated unbranched saturated hydrocarbons by removing hydrogen from the final carbon atom are called by replacing the suffix "-an" in the name of the hydrocarbon with the suffix "-yl". (- CH 3 methyl, etc.)

When compiling the name of a substance according to its structural formula, it is necessary to sequentially perform the following steps:

1. Select the main carbon chain (cycle), including the main characteristic group, and number it from the end of the chain, closer to which the senior group is located. If there are several such possibilities, then you need to consider the presence of:

a) other characteristic groups (by seniority);

b) double bond;

c) triple bond;

d) other substituents (in alphabetical order).

2. Compose a name from three parts;

· Using a prefix (prefix), designate the substituents (side chains, junior characteristic groups) and arrange them alphabetically. The position of the substitute must be indicated by a number before the prefix.

· In the basis (root), name the main carbon chain, taking into account its type, length. Add a suffix to the name of the main chain, indicating the degree of saturation of the bonds. If there are several multiple bonds in the molecule, their number must be indicated in the suffix, and after the suffix - their position in the carbon chain in Arabic numerals.

· The ending includes the name of the senior characteristic group with an indication of its position.

3. Place punctuation marks: separate all numbers from words with a hyphen, and from each other with commas.

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

For example: name compounds according to the rules of systematic (IUPAC) nomenclature:

2,4-dimethylheptane 4,6-dimethylheptene-1

Classes of organic compounds

hydrocarbons	class formula	class name	Representatives	Nomenclature
	Alkanes Cycloalkanes Alkene Dienes Alkyne Arenas	, , , , ,	[-an] [cyclo----an] [-ene] [-diene] [-yne] Benzene Methylbenzene (toluene) Xylene
Functional classes of organic substances
Function formula. groups	Group name	class formula	class name	Representatives	Nomenclature
	Carbox - strong	R-COOH	carboxylic acids	HCOOH C COOH	[-oic acid]
	Aldehyde-naya	COH CHO O	Aldehydes	HCOH CCOH	[-al]
	Okso	R-C-R \|\| o(COO	Ketones	C-C-CH 3 \|\| O	[-he]
-OH	Hydroxy	Oh O ArOH	Alcohols Phenols	C-OH OH OH	[-ol]phenol
-NH 2	Amino	N(NH(N	Amines Primary Secondary Tertiary	C-N ( C) 2 NH ( C) 3 N	-amine

test questions

1. The subject of bioorganic chemistry, its significance for biology and medicine.

2. Structure and classification of organic compounds according to the type of carbon chain. bonds and the nature of functional groups.

3. Nomenclature of organic compounds. Substitutive IUPAC nomenclature.

a) nomenclature terms: ancestral structure, characteristic group, substitute;

b) the sequence of drawing up the name of the organic compound according to the general scheme.

4. Trivial and radical-functional nomenclature of organic compounds.

Typical tasks

1. NAME THE COMPOUNDS ACCORDING TO THE RULES OF THE SYSTEMATIC (IUPAC) NOMENCLATURE:

2-oxobutanediol-1,4 4-amino-2-thiopentanoic acid

2-isopropylcyclohexanediol-1,4 4-hydroxy-2,2-dimethylhexadiene-2,5-al -

2. MATCH THE NAME OF THE COMPOUND AND THE CLASS TO WHICH IT BELONS

COMPOUND NAME COMPOUND CLASS

A) fructose 1) arenas

B) 2-methylbutene-1 2) alkenes

B) toluene 3) alkadienes

D) propyne 4) monosaccharides

Well, to complete our acquaintance with alcohols, I will give another formula of another well-known substance - cholesterol. Not everyone knows that it is a monohydric alcohol!

|`/`\\`|<`|w>`\`/|<`/w$color(red)HO$color()>\/`|0/`|/\<`|w>|_q_q_q<-dH>:a_q|0<|dH>`/<`|wH>`\|dH; #a_(A-72)<_(A-120,d+)>-/-/<->`\

I marked the hydroxyl group in it in red.

carboxylic acids

Any winemaker knows that wine must be kept out of the air. Otherwise it will sour. But chemists know the reason - if you add one more oxygen atom to alcohol, you get an acid.
Let's look at the formulas of acids that are obtained from alcohols already familiar to us:

Substance			Skeletal formula
Methanoic acid (formic acid)	H/C`\|O\|\OH	HCOOH	O//\OH
Ethanoic acid (acetic acid)	H-C-C\O-H; H\|#C\|H	CH3-COOH	/`\|O\|\OH
propanoic acid (methylacetic acid)	H-C-C-C\O-H; H\|#2\|H; H\|#3\|H	CH3-CH2-COOH	\/`\|O\|\OH
Butanoic acid (butyric acid)	H-C-C-C-C\O-H; H\|#2\|H; H\|#3\|H; H\|#4\|H	CH3-CH2-CH2-COOH	/\/`\|O\|\OH
Generalized formula	(R)-C\O-H	(R)-COOH or (R)-CO2H	(R)/`\|O\|\OH

A distinctive feature of organic acids is the presence of a carboxyl group (COOH), which gives such substances acidic properties.

Everyone who has tried vinegar knows that it is very sour. The reason for this is the presence of acetic acid in it. Typically, table vinegar contains 3 to 15% acetic acid, with the rest (mostly) water. Eating undiluted acetic acid is life-threatening.

Carboxylic acids may have several carboxyl groups. In this case they are called: dibasic, tripartite etc...

Food products contain many other organic acids. Here are just a few of them:

The name of these acids corresponds to those food products in which they are contained. By the way, note that there are acids here that also have a hydroxyl group characteristic of alcohols. Such substances are called hydroxycarboxylic acids(or hydroxy acids).
Below each of the acids is signed, specifying the name of the group of organic substances to which it belongs.

Radicals

Radicals are another concept that has influenced chemical formulas. The word itself is probably known to everyone, but in chemistry, radicals have nothing to do with politicians, rebels and other citizens with an active position.
Here they are just fragments of molecules. And now we will figure out what is their peculiarity and get acquainted with a new way of writing chemical formulas.

Above in the text, generalized formulas have already been mentioned several times: alcohols - (R) -OH and carboxylic acids - (R) -COOH. Let me remind you that -OH and -COOH are functional groups. But R is the radical. No wonder it is depicted in the form of the letter R.

More specifically, a univalent radical is a part of a molecule devoid of one hydrogen atom. Well, if you take away two hydrogen atoms, you get a divalent radical.

Radicals in chemistry have their own names. Some of them even received Latin designations, similar to the designations of the elements. And besides, sometimes radicals in formulas can be indicated in an abbreviated form, more reminiscent of gross formulas.
All this is shown in the following table.

Name	Structural formula	Designation	Short Formula	alcohol example
Methyl	CH3-()	Me	CH3	(Me)-OH	CH3OH
Ethyl	CH3-CH2-()	Et	C2H5	(Et)-OH	C2H5OH
Propil	CH3-CH2-CH2-()	Pr	C3H7	(Pr)-OH	C3H7OH
Isopropyl	H3C\CH(`/H3C)-()	i-Pr	C3H7	(i-Pr)-OH	(CH3)2CHOH
Phenyl	`/`=`\//-\\-{}	Ph	C6H5	(Ph)-OH	C6H5OH

I think that everything is clear here. I just want to draw your attention to the column that gives examples of alcohols. Some radicals are written in a form that resembles an empirical formula, but the functional group is written separately. For example, CH3-CH2-OH is converted to C2H5OH.
And for branched chains like isopropyl, constructions with brackets are used.

There is another phenomenon free radicals. These are radicals that for some reason separated from functional groups. In this case, one of the rules with which we began the study of formulas is violated: the number of chemical bonds no longer corresponds to the valency of one of the atoms. Well, or you can say that one of the links becomes open from one end. Usually, free radicals live for a short time, because the molecules tend to return to a stable state.

Introduction to nitrogen. Amines

I propose to get acquainted with another element that is part of many organic compounds. it nitrogen.
It is denoted by the Latin letter N and has a valency of three.

Let's see what substances are obtained if nitrogen is added to familiar hydrocarbons:

Substance	Expanded structural formula	Simplified structural formula	Skeletal formula
Aminomethane (methylamine)	H-C-N\H;H\|#C\|H	CH3-NH2	\NH2
Aminoethane (ethylamine)	H-C-C-N\H;H\|#C\|H;H\|#3\|H	CH3-CH2-NH2	/\NH2
Dimethylamine	H-C-N<`\|H>-C-H; H\|#-3\|H; H\|#2\|H	$L(1.3)H/N<_(A80,w+)CH3>\dCH3	/N<_(y-.5)H>\
Aminobenzene (Aniline)	H\N\|C\\C\|C<\H>`//C<\|H>`\C<`/H>`\|\|C<`\H>/	NH2\|C\\CH\|CH`//C<_(y.5)H>`\HC`\|\|HC/	NH2\|\\|`/`\`\|/_o
Triethylamine	$slope(45)H-C-C/N\C-C-H;H\|#2\|H; H\|#3\|H; H\|#5\|H;H\|#6\|H; #N`\|C<`-H><-H>`\|C<`-H><-H>`\|H	CH3-CH2-N<`\|CH2-CH3>-CH2-CH3	\/N<`\|/>\\|

As you probably guessed from the names, all these substances are combined under the common name amines. The functional group ()-NH2 is called amino group. Here are some general formulas for amines:

In general, there are no special innovations here. If these formulas are clear to you, then you can safely engage in further study of organic chemistry using some textbook or the Internet.
But I would like to talk more about formulas in inorganic chemistry. You will see how easy it will be to understand them after studying the structure of organic molecules.

Rational formulas

It should not be concluded that inorganic chemistry is simpler than organic. Of course, inorganic molecules tend to look much simpler because they don't tend to form the complex structures that hydrocarbons do. But on the other hand, one has to study more than a hundred elements that make up the periodic table. And these elements tend to combine according to their chemical properties, but with numerous exceptions.

So, I won't say any of this. The topic of my article is chemical formulas. And with them, everything is relatively simple.
The most commonly used in inorganic chemistry are rational formulas. And now we will figure out how they differ from those already familiar to us.

First, let's get acquainted with another element - calcium. This is also a very common item.
It is designated Ca and has a valency of two. Let's see what compounds it forms with carbon, oxygen and hydrogen known to us.

Substance	Structural formula	rational formula
calcium oxide	Ca=O	CaO
calcium hydroxide	H-O-Ca-O-H	Ca(OH)2
Calcium carbonate	$slope(45)Ca`/O\C\|O`\|/O`\#1	CaCO3
Calcium bicarbonate	HO/`\|O\|\O/Ca\O/`\|O\|\OH	Ca(HCO3)2
Carbonic acid	H\|O\C\|O`\|/O`\|H	H2CO3

At first glance, one can see that the rational formula is something in between the structural and gross formulas. But so far it is not very clear how they are obtained. To understand the meaning of these formulas, you need to consider the chemical reactions in which substances participate.

Calcium in its purest form is a soft white metal. It does not occur in nature. But it is quite possible to buy it in a chemical store. It is usually stored in special jars without air access. Because it reacts with oxygen in air. In fact, that is why it does not occur in nature.
So, the reaction of calcium with oxygen:

2Ca + O2 -> 2CaO

The number 2 before the formula of a substance means that 2 molecules are involved in the reaction.
Calcium oxide is formed from calcium and oxygen. This substance also does not occur in nature because it reacts with water:

CaO + H2O -> Ca(OH2)

It turns out calcium hydroxide. If you look closely at its structural formula (in the previous table), you can see that it is formed by one calcium atom and two hydroxyl groups, with which we are already familiar.
These are the laws of chemistry: if a hydroxyl group is attached to an organic substance, alcohol is obtained, and if to a metal, then hydroxide.

But calcium hydroxide is not found in nature due to the presence of carbon dioxide in the air. I think that everyone has heard about this gas. It is formed during the breathing of people and animals, the combustion of coal and petroleum products, during fires and volcanic eruptions. Therefore, it is always present in the air. But it also dissolves quite well in water, forming carbonic acid:

CO2 + H2O<=>H2CO3

Sign<=>indicates that the reaction can proceed in both directions under the same conditions.

Thus, calcium hydroxide dissolved in water reacts with carbonic acid and turns into poorly soluble calcium carbonate:

Ca(OH)2 + H2CO3 -> CaCO3"|v" + 2H2O

The down arrow means that the substance precipitates as a result of the reaction.
Upon further contact of calcium carbonate with carbon dioxide in the presence of water, a reversible reaction occurs to form an acid salt - calcium bicarbonate, which is highly soluble in water.

CaCO3 + CO2 + H2O<=>Ca(HCO3)2

This process affects the hardness of the water. As the temperature rises, the bicarbonate turns back into carbonate. Therefore, in regions with hard water, scale forms in kettles.

Chalk, limestone, marble, tuff and many other minerals are largely composed of calcium carbonate. It is also found in corals, mollusk shells, animal bones, etc...
But if calcium carbonate is heated on a very high heat, it will turn into calcium oxide and carbon dioxide.

This short story about the calcium cycle in nature should explain why rational formulas are needed. So, rational formulas are written in such a way that functional groups are visible. In our case, this is:

In addition, individual elements - Ca, H, O (in oxides) - are also independent groups.

ions

I think it's time to get acquainted with ions. This word is probably familiar to everyone. And after studying the functional groups, it doesn’t cost us anything to figure out what these ions are.

In general, the nature of chemical bonds is usually that some elements donate electrons while others receive them. Electrons are particles with a negative charge. An element with a full set of electrons has zero charge. If he gave an electron, then its charge becomes positive, and if he accepted it, then it becomes negative. For example, hydrogen has only one electron, which it gives up quite easily, turning into a positive ion. For this, there is a special record in chemical formulas:

H2O<=>H^+ + OH^-

Here we see that as a result electrolytic dissociation water breaks down into a positively charged hydrogen ion and a negatively charged OH group. The OH^- ion is called hydroxide ion. It should not be confused with the hydroxyl group, which is not an ion, but part of a molecule. The + or - sign in the upper right corner shows the charge of the ion.
But carbonic acid never exists as an independent substance. In fact, it is a mixture of hydrogen ions and carbonate ions (or bicarbonate ions):

H2CO3 = H^+ + HCO3^-<=>2H^+ + CO3^2-

The carbonate ion has a charge of 2-. This means that two electrons have joined it.

Negatively charged ions are called anions. Usually these include acidic residues.
Positively charged ions cations. Most often it is hydrogen and metals.

And here you can probably fully understand the meaning of rational formulas. The cation is written in them first, and then the anion. Even if the formula does not contain any charges.

You probably already guess that ions can be described not only by rational formulas. Here is the skeletal formula of the bicarbonate anion:

Here, the charge is indicated directly next to the oxygen atom, which received an extra electron, and therefore lost one line. Simply put, each extra electron reduces the number of chemical bonds depicted in the structural formula. On the other hand, if some node of the structural formula has a + sign, then it has an additional wand. As always, this fact needs to be demonstrated with an example. But among the substances familiar to us, there is not a single cation that would consist of several atoms.
And such a substance is ammonia. Its aqueous solution is often called ammonia and is part of any first aid kit. Ammonia is a compound of hydrogen and nitrogen and has the rational formula NH3. Consider the chemical reaction that occurs when ammonia is dissolved in water:

NH3 + H2O<=>NH4^+ + OH^-

The same, but using structural formulas:

H|N<`/H>\H + H-O-H<=>H|N^+<_(A75,w+)H><_(A15,d+)H>`/H + O`^-# -H

On the right side we see two ions. They were formed as a result of the fact that one hydrogen atom moved from a water molecule to an ammonia molecule. But this atom moved without its electron. The anion is already familiar to us - it is the hydroxide ion. And the cation is called ammonium. It exhibits properties similar to metals. For example, it can combine with an acid residue. The substance formed by the combination of ammonium with a carbonate anion is called ammonium carbonate: (NH4)2CO3.
Here is the reaction equation for the interaction of ammonium with a carbonate anion, written in the form of structural formulas:

2H|N^+<`/H><_(A75,w+)H>_(A15,d+)H + O^-\C|O`|/O^-<=>H|N^+<`/H><_(A75,w+)H>_(A15,d+)H`|0O^-\C|O`|/O^-|0H_(A-15,d-)N^+<_(A105,w+)H><\H>`|H

But in this form, the reaction equation is given for demonstration purposes. Usually equations use rational formulas:

2NH4^+ + CO3^2-<=>(NH4)2CO3

Hill system

So, we can assume that we have already studied the structural and rational formulas. But there is another issue worth considering in more detail. What is the difference between gross formulas and rational ones?
We know why the rational formula for carbonic acid is written H2CO3 and not otherwise. (Two hydrogen cations come first, followed by the carbonate anion.) But why is the gross formula written as CH2O3?

In principle, the rational formula of carbonic acid may well be considered a true formula, because there are no repeating elements in it. Unlike NH4OH or Ca(OH)2 .
But an additional rule is often applied to gross formulas, which determines the order of the elements. The rule is pretty simple: put carbon first, then hydrogen, and then the rest of the elements in alphabetical order.
So CH2O3 comes out - carbon, hydrogen, oxygen. This is called the Hill system. It is used in almost all chemical reference books. And in this article too.

A little about the easyChem system

Instead of concluding, I would like to talk about the easyChem system. It is designed so that all those formulas that we discussed here can be easily inserted into the text. Actually, all the formulas in this article are drawn using easyChem.

Why do we need any system for the derivation of formulas? The thing is that the standard way to display information in Internet browsers is Hypertext Markup Language (HTML). It is focused on text processing.

Rational and gross formulas can be depicted with the help of text. Even some simplified structural formulas can also be written in text, for example alcohol CH3-CH2-OH. Although for this you would have to use this notation in HTML: CH ₃-CH ₂-OH.
This of course creates some difficulties, but you can put up with them. But how to represent the structural formula? In principle, one can use a monospaced font:

H H | | H-C-C-O-H | | H H It certainly doesn't look very nice, but it's also feasible.

The real problem arises when trying to represent benzene rings and when using skeletal formulas. There is no other way but to connect the bitmap. Rasters are stored in separate files. Browsers can include gif, png or jpeg images.
To create such files, a graphical editor is required. For example, Photoshop. But I have been familiar with Photoshop for more than 10 years and I can say for sure that it is very poorly suited for depicting chemical formulas.
Molecular editors are much better at this task. But with a large number of formulas, each of which is stored in a separate file, it is quite easy to get confused in them.
For example, the number of formulas in this article is . They are displayed in the form of graphic images (the rest using HTML tools).

easyChem allows you to store all formulas directly in an HTML document in text form. I think it's very convenient.
In addition, the gross formulas in this article are calculated automatically. Because easyChem works in two stages: first, the textual description is converted into an information structure (graph), and then various actions can be performed with this structure. Among them, the following functions can be noted: calculation of molecular weight, conversion to a gross formula, checking for the possibility of output as text, graphic and text rendering.

Thus, for the preparation of this article, I used only a text editor. Moreover, I did not have to think which of the formulas would be graphical and which would be textual.

Here are some examples that reveal the secret of article text preparation: Descriptions from the left column are automatically converted into formulas in the second column.
In the first line, the description of the rational formula is very similar to the displayed result. The only difference is that the numeric coefficients are output as interlinear.
In the second line, the expanded formula is given as three separate strings, separated by a symbol; I think it's easy to see that a text description is a lot like what would be required to draw a formula with a pencil on paper.
The third line demonstrates the use of slanted lines using the characters \ and /. The ` (backtick) sign means that the line is drawn from right to left (or from bottom to top).

There is much more detailed documentation on using the easyChem system here.

On this, let me finish the article and wish you good luck in studying chemistry.

Brief explanatory dictionary of terms used in the article

Hydrocarbons Substances composed of carbon and hydrogen. They differ from each other in the structure of molecules. Structural formulas are schematic representations of molecules, where atoms are denoted by Latin letters, and chemical bonds are dashes. Structural formulas are expanded, simplified and skeletal. Expanded structural formulas - such structural formulas, where each atom is represented as a separate node. Simplified structural formulas are such structural formulas where hydrogen atoms are written next to the element with which they are associated. And if more than one hydrogen is attached to one atom, then the amount is written as a number. It can also be said that groups act as nodes in simplified formulas. Skeletal formulas are structural formulas where carbon atoms are shown as empty nodes. The number of hydrogen atoms bonded to each carbon atom is 4 minus the number of bonds that converge at the site. For non-carbon knots, the rules of simplified formulas apply. Gross formula (aka true formula) - a list of all chemical elements that make up a molecule, indicating the number of atoms as a number (if the atom is one, then the unit is not written) Hill's system - a rule that determines the order of atoms in the gross formula: carbon comes first, then hydrogen, and then the rest of the elements in alphabetical order. This is a system used very often. And all the gross formulas in this article are written according to the Hill system. Functional groups Stable combinations of atoms that are preserved during chemical reactions. Often functional groups have their own names, affect the chemical properties and the scientific name of the substance.

MOSCOW STATE

UNIVERSITY OF ENVIRONMENTAL ENGINEERING

Moscow - 2006

Ministry of Education of the Russian Federation

MOSCOW STATE UNIVERSITY

ENVIRONMENTAL ENGINEERING

Department of General and Physical Chemistry

NOMENCLATURE OF ORGANIC COMPOUNDS

Guidelines

Under the editorship of Doctor of Chemistry, prof. V.S. Pervova

Moscow - 2006

Approved by the editorial and publishing council

Compiled by: G.N. Bespalov, G.S. Isaeva, I.V. Yaroshenko, E.D. Streltsova

UDC. 5.4.7.1

Nomenclature of organic compounds. Guidelines. / Compiled by: G.N. Bespalov, G.S. Isaeva, I.V. Yaroshenko, E.D. Streltsova

M.: MGUIE, 2006, 28 p., 2 tab.

The guidelines are intended for students studying in the specialties 1705, 1705.06: 1705.07, 1712.03, studying organic chemistry. The paper discusses the basics of the naming system of substances according to rational nomenclature and IUPAC nomenclature. To check the assimilation of the material, fifteen options for tasks are offered.

Reviewers: Department of Chemical Technology of Plastic Masses of the Moscow Chemical Technology Institute. D.I. Mendeleev.

Doctor of Chemistry, Prof. A.L. Rusanov, INEOS RAS.

INTRODUCTION

Nomenclature is a naming system for substances. The main requirement for scientific nomenclature is that it unambiguously define one or another chemical compound, excluding the possibility of mixing this compound with another, be simple and allow one to construct its structural formula by the name of the compound.

There are several different systems. One of the first is trivial nomenclature. Until now, many organic compounds have random historical names. Some of them are associated with being in nature, others with the method of obtaining, others reflect the physical state, and so on. Benzene, alcohol, methane, fulminic acid, formic acid, acetone, ether are trivial names for organic substances. These names are not united according to a certain feature into a coherent system and do not reflect the structure of the molecules of organic substances. However, many natural and synthetic substances of complex structure still have trivial names due to their brevity and expressiveness.

The emergence of the theoretical foundations of organic chemistry led to the creation of new classification systems and, consequently, new ways of naming organic compounds, reflecting the chemical structure. This means that the name can uniquely compose the structural formula of the substance and the structural formula to give the name of the substance. So there was rational nomenclature and Geneva nomenclature, the further development of which led to the creation of a system IUPAC, proposed by the International Union of Pure Applied Chemistry, recommended for the name of all organic substances. However, in practice one has to deal with different systems of names for organic substances.

To compile the names of organic substances, both according to rational nomenclature and according to the IUPAC system, it is necessary to know the names of hydrocarbon radicals. Hydrocarbon radicals- These are particles that are obtained by detaching one or more hydrogen atoms from a hydrocarbon molecule. In hydrocarbon molecules, one should distinguish between primary, secondary, tertiary and quaternary carbon atoms, which is determined by the number of its bonds with neighboring carbon atoms. Primary has one bond to a carbon atom, secondary- two bonds to a carbon atom or atoms, tertiary- three, quaternary- four.

When a hydrogen atom is detached from the primary carbon atom, primary radical(that is, the primary carbon atom has a free unit of valence), from the secondary - secondary radical, from the tertiary - tertiary radical.

Table 1 shows the formulas of saturated hydrocarbons and the radicals formed from them, as well as their names. As can be seen from the table, only one radical can be formed from methane and ethane. From propane, a hydrocarbon with three carbon atoms, it is already possible to form two isomeric radicals - propyl and isopropyl, depending on which carbon atom (primary or secondary) a hydrogen atom is detached. Starting with butane, hydrocarbons have isomers. In accordance with this, the number of isomeric radicals also increases: n.butyl, sec. butyl, isobutyl, tert. butyl.

The name of the subsequent hydrocarbons is made up of the Greek numeral corresponding to the number of carbon atoms in the molecule and the suffix "an".

With an increase in the number of carbon atoms in a hydrocarbon, the number of isomers increases, and the number of radicals that can be formed from them also increases.

Most of the isomers do not have special names. However, according to rational nomenclature and IUPAC nomenclature, any arbitrarily complex compound can be named using the names of simple radicals.

Table 1.

Limit hydrocarbons and their radicals.

Hydrocarbon


CH 3 -CH 2 -CH 3		CH 3 -CH 2 -CH 2 -	isopropyl (sec. propyl)
CH 3 - _ CH 2 - CH 2 -CH 3		CH 3 -CH 2 -CH 2 -CH 2 - CH 3 -CH 2 -CH	sec-butyl
	isobutane	CH 3 - CH - CH 2 -	isobutyl tert.butyl

Table 2. shows some unsaturated and aromatic hydrocarbons and their corresponding radicals Table 2.Unsaturated and aromatic hydrocarbons and their radicals.

hydrocarbons		Radicals

CH 2 \u003d CH-CH 3	propylene	CH 2 \u003d CH-CH 2 - CH \u003d CH-CH 3 CH 2 \u003d C-CH 3	propenyl isopropenyl
	acetylene		acetylenyl or ethynyl

			p(pair)-tolyls

RATIONAL NOMENCLATURE

Rational nomenclature is based on type theory. This system is based on the names of the simplest members of homologous series: methane if there are no double bonds, ethylene if there is one double bond, and acetylene if there is one triple bond in the compound. All other hydrocarbons are considered as derivatives of these simplest hydrocarbons, obtained by replacing one or more hydrogen atoms with hydrocarbons. radicals. In order to name a particular compound, you need to list the substituent radicals, and then name the corresponding hydrocarbon. The listing of radicals should start with the simplest methyl, and then, as it becomes more complex, ethyl, propyl, etc. Branched radicals are considered more complex than normal ones with the same number of carbon atoms. Such
connection can be called methylethylisopropylmethane. If the compound contains several identical radicals, then you should indicate how many of these radicals are contained in the compound, using multiplying prefixes - Greek numerals: 2 - di, 3 - three, 4 - tetra, so the compound will be called trimethylethylmethane.

For the central methane atom, it is better to choose the carbon atom at which there is the largest number of substituents. Depending on which carbon atom is chosen for the central methane atom, several different names can be given to the same substance according to rational nomenclature.

Compounds with double and triple bonds are also called similarly:

Two methods can be used to distinguish between two isomeric compounds. In the first compound, substituent radicals are located at two different carbon atoms linked by a double bond, symmetrically with respect to the double bond. In the second compound, both radicals are located at the same carbon atom, i.e. asymmetrical about the double bond.

Therefore, they are called so: the first is symmetrical methylethylene, and the second is asymmetrical methylethyl-ethylene. In the second method, one carbon atom connected to a simpler radical is denoted by the Greek letter , the other - . When naming such compounds, indicate at which carbon atom which radical is located. So the first connection will be called  -methyl- -ethylethylene, and the second -  -methyl- -ethylethylene.

The name of hydrocarbons whose molecule has a symmetrical structure, i.e., consists of two identical radicals, is made up of the names of these radicals and the prefix di-

Cyclic hydrocarbons in rational nomenclature are considered as polymethylenes and are named according to the number of methylene groups included in the ring, and Greek numerals are used:

If there are substituents in the cycle, they are listed before the name of the main cycle. Such

connection will be called methylhexamethylene.

Rational nomenclature is still used when naming relatively simple compounds, especially when one wants to emphasize the functional type of a compound. However, the name of highly branched hydrocarbons causes difficulties, since there are no names for complex radicals.

IUPAC NOMENCLATURE

The IUPAC nomenclature (IUPAC), proposed by the International Union of Pure and Applied Chemistry, makes it possible to name any arbitrarily complex compound. This nomenclature is a development and streamlining of the Geneva nomenclature, with which it has much in common.

In this nomenclature, the first four saturated normal hydrocarbons have trivial names: methane, ethane, propane and butane. The names of subsequent normal (unbranched) hydrocarbons are formed from the basis of Greek numerals with the addition of the ending -an: C 5 H 12 - pentane, C 6 H 14 - hexane, C 7 H 16 -heptane, etc. (see table 1)

For the name of branched hydrocarbons, it is necessary to choose the longest normal chain. If several chains of the same length can be distinguished in a hydrocarbon, then one should choose the most branched chain. The name of this hydrocarbon corresponding to the longest chain is taken as the basis for the name of this hydrocarbon. Therefore, a hydrocarbon having the structure

will be considered as a derivative of heptane. This longest chain number, and the direction of numbering is chosen so that the numbers indicating the position of the side chains would be the smallest. For each lateral substituent, an Arabic numeral indicates its location in the chain and gives a name. If there are several identical substituents in the compound, then along with indicating the location of each substituent using multiplying prefixes (Greek numerals) di-, tri-, tatra-, and so on, their number is indicated. Side substituents are listed in order of increasing complexity: methyl CH 3 - less complex than ethyl C 2 H 5 -, i.e. a radical with fewer carbon atoms is less complex than one with more atoms. With the same number of carbon atoms, the radical in which the main chain

longer: sec. butyl
less complex than tert. butyl

Thus, the previously given connection will be called 2,2,5-trimethyl-3-ethylheptane.

In the presence of multiple bonds in the hydrocarbon, the longest chain, which contains a double or triple bond, is taken as the main chain. If the hydrocarbon has one double bond, then the ending –en in the name of the saturated hydrocarbon corresponding in this chain is replaced by the ending - en and an Arabic numeral indicates the number of the carbon atom at which the double chain begins. So connection

will be called heptin-3.

If the compound contains two double or triple bonds, then the endings of the hydrocarbon names should be – diene or - diin respectively, indicating the numbers of atoms in which multiple bonds begin:

In the presence of double and triple bonds, the ending in the name of the hydrocarbon will be –en-in indicating the numbers of atoms at which the corresponding multiple bonds begin:

In the case of branched unsaturated hydrocarbons, the main chain is chosen in such a way that the positions of double and swarm bonds are indicated by the smallest numbers.

The names of cyclic hydrocarbons are formed by adding the prefix to the name of the saturated hydrocarbon with the same number of carbon atoms cyclo-

In the presence of side substituents, their location, number and name are indicated, after which the cyclic hydrocarbon is called.

If the cycle contains multiple bonds, then this is reflected in the change of the ending to -en in the presence of a double bond or ending in –in with one triple bond.

The simplest monocyclic aromatic compound retains its trivial name, benzene. In addition, the trivial names of some substituted aromatic hydrocarbons are retained.

Monocyclic aromatic hydrocarbons are considered as derivatives of benzene obtained by replacing hydrogen atoms with hydrocarbon radicals. In order to name this or that aromatic compound, one should number the carbon atoms of the benzene ring, indicate the positions of the substituents in the ring, indicate how many of them, name these radicals, and then name the aromatic hydrocarbon. The positions of the substituents should be indicated by the smallest numbers. Thus the connection

will be called 1,4-dimethyl-2-ethylbenzene.

If there are only two substituents in the benzene ring, then instead of numbers 1,2-, 1,3- and 1,4- one can use the notation ortho (o-), meta (m-) and para (p-)

The names of some fused and polycyclic aromatic hydrocarbons and the numbering of carbon atoms are given below.

BIBLIOGRAPHICAL LIST.

Pavlov B.A., Terentiev A.P. Course of organic chemistry. M.-L.

Homework 1

Option 1.16

a) (CH 3) 2 (CH) 2 (C 2 H 5) 2,

b) (CH 3) 2 CCH(CH 3)

a) methylisopropyl tert.butylmethane,

b) methylethylacetylene.

a) 2,2,3-trimethylbutane,

b) 3,4-dimethylhexene-3.

Option 2.17

1. Write in expanded form the structural formulas of the following hydrocarbons and name them according to rational nomenclature and IUPAC nomenclature. Indicate how many primary, secondary, tertiary and quaternary carbon atoms are in each compound:

a) (CH 3) 3 CCH(CH 3)CH(CH 3)(C 2 H 5)

b) (CH 3) (C 2 H 5) C 2 (C 2 H 5) 2.

2. Write the structural formulas of the following compounds

and name them according to the IUPAC nomenclature:

b) -methyl- -ethyl- -sec.butylethylene.

3. Write the structural formulas of the following compounds and name them according to rational nomenclature:

a) 2,2,3,4-tetramethyl-3-ethylpentane,

b) 2,5-dimethylhexine-3.

: Option 3.18

a) (CH 3) 3 CCH (C 2 H 5) CH (CH 3) (C 2 H 5),

b) (CH 3) 2 CHС 2 CH (CH 3) 2.

2. Write the structural formulas of the following compounds and name them according to the IUPAC nomenclature

a) ethyldifluorobutylmethane,

b) isopropyl tertiary butylacetylene.

3. Write the structural formulas of the following compounds and name them according to rational nomenclature:

a) 2,2-dimethyl-3-ethylpentane,

b) 2,2,5,5-tetramethylhexene-3

Option 4.19

a) (CH 3) 2 (CH) 4 (CH 3) (C 2 H 5),

b) (CH 3) 3 C 2 (CH 3) (C 2 H 5) CH (CH 3) 2.

a) methylisopropyl tert.butylmethane,

b) sym.sec.butyltert.butylethylene.

3. Write the structural formulas of the following compounds and name them according to rational nomenclature:

a) 2,2,4,4-tetramethyl-3-ethylpentane,

b) 2,2,5-trimethylhexine-3.

Option 5.20

a) CH 3 (CH 2) 2 CH (C 2 H 5) CH (CH 3) (C 2 H 5),

b) (CH 3) 3 C 4 (CH 3) 3.

2. Write the structural formulas of the following compounds and name them according to the IUPAC nomenclature

a) ethylisopropylisobutylmethane,

b) -ethyl- -isopropyl- -sec.butylethylene.

3. Write the structural formulas of the following compounds and name them according to rational nomenclature:

a) 2-methyl-3,3-diethylpentane,

b) butadiene-1,3

Option 6, 21

a) (CH 3) 3 C (CH 2) 2 CH (CH 3) 2,

b) CH 2 C (CH 3) CHCH 2.

2. Write the structural formulas of the following compounds and name them according to the IUPAC nomenclature

a) methylethylisopropyltert.butylmethane,

b) ,-dimethyl- -sec-butylethylene.

Organic chemistry is the chemistry of carbon compounds, or, in other words, the chemistry of hydrocarbons and their derivatives. What is the classification and nomenclature of organic compounds?

What are organic compounds?

By composition, organic compounds are divided into classes - hydrocarbons and functional derivatives of hydrocarbons.

Hydrocarbons are organic compounds that contain only carbon and hydrogen atoms (and are based on a chain built from carbon atoms).

Rice. 1. Table of hydrocarbons.

Functional derivatives of hydrocarbons have one or more functional (active) groups that contain atoms of other elements (except carbon and hydrogen) and determine the properties of this class of compounds. The composition of functional groups includes atoms of such elements as oxygen, nitrogen, sulfur. The main classes of organic compounds are characterized by the type of functional groups.

According to the shape of the carbon chain, organic compounds are divided into compounds of normal and isostructure, as well as compounds with an open carbon chain (acyclic) and with a closed carbon chain (cyclic).

Compounds with a normal structure have a carbon chain without branches, and compounds with an isostructure have branches in the carbon chain

Rice. 2. Types of carbon chains.

According to the type of chemical bond between carbon atoms, organic compounds are divided into saturated (limiting) and unsaturated (unsaturated). Saturated ones contain only simple carbon-carbon bonds, while unsaturated ones contain at least one multiple bond.

Compounds with an open chain - saturated and unsaturated - are called compounds of the fatty series., or aliphatic.

Cyclic compounds (saturated and unsaturated) are called alicyclic.

There are compounds with a special type of bond, which are called aromatic.

Nomenclature of organic compounds

Currently, organic compounds are named according to the rules of the International Systematic Nomenclature. For compounds common in everyday life and industry, especially natural ones, a trivial nomenclature is used, including historical names. For some, especially monofunctional, compounds, a type of MCH is used - the radical-functional nomenclature.

Basic principles for compiling the name of the compound according to the MCH:

the molecule is considered as a derivative of a saturated hydrocarbon;
in the molecule choose the longest carbon chain containing a functional group or a multiple bond, if any. the chain is named as the corresponding saturated hydrocarbon;
the main chain is numbered from its end, which is closer to the older group in the molecule;
if there is a multiple bond in the main chain, then in the name of the saturated hydrocarbon, the ending -an changes to the corresponding one;
if there is a functional group in the main chain, then the corresponding ending is added to the name of the main chain;
before the name of the main chain, list the names of radicals that are not included in the main chain, but associated with it, with the addition of one locant for each radical.