There are several definitions of what organic substances are, how they differ from another group of compounds - inorganic. One of the most common explanations comes from the name "hydrocarbons". Indeed, at the heart of all organic molecules are chains of carbon atoms bonded to hydrogen. There are other elements that have received the name "organogenic".
Organic chemistry before the discovery of urea
Since ancient times, people have used many natural substances and minerals: sulfur, gold, iron and copper ore, table salt. Throughout the existence of science - from ancient times to the first half of XIX century - scientists could not prove the connection between animate and inanimate nature at the level of microscopic structure (atoms, molecules). It was believed that organic substances owe their appearance to the mythical life force - vitalism. There was a myth about the possibility of growing a little man "homunculus". To do this, it was necessary to put various waste products into a barrel, wait a certain time until the vital force was born.
A crushing blow to vitalism was dealt by the work of Weller, who synthesized the organic substance urea from inorganic components. So it was proved that there is no life force, nature is one, organisms and inorganic compounds are formed by atoms of the same elements. The composition of urea was known even before Weller's work; the study of this compound was not difficult in those years. Remarkable was the very fact of obtaining a substance characteristic of metabolism outside the body of an animal or a person.
Theory of A. M. Butlerov
The role of the Russian school of chemists in the development of the science that studies organic substances is great. The names of Butlerov, Markovnikov, Zelinsky, Lebedev are associated with entire epochs in the development of organic synthesis. The founder of the theory of the structure of compounds is A. M. Butlerov. The famous chemist in the 60s of the XIX century explained the composition organic matter, the reasons for the diversity of their structure, revealed the relationship that exists between the composition, structure and properties of substances.
On the basis of Butlerov's conclusions, it was possible not only to systematize knowledge about already existing organic compounds. It became possible to predict the properties of substances not yet known to science, to create technological schemes for their production in industrial conditions. Many of the ideas of leading organic chemists are being fully implemented today.
When hydrocarbons are oxidized, new organic substances are obtained - representatives of other classes (aldehydes, ketones, alcohols, carboxylic acids). For example, large volumes of acetylene are used to produce acetic acid. Part of this reaction product is further consumed to obtain synthetic fibers. An acid solution (9% and 6%) is in every home - this is ordinary vinegar. Oxidation of organic substances is the basis for obtaining very a large number compounds of industrial, agricultural, medical importance.
aromatic hydrocarbons
Aromaticity in organic molecules is the presence of one or more benzene nuclei. A chain of 6 carbon atoms closes into a ring, a conjugated bond appears in it, so the properties of such hydrocarbons are not similar to other hydrocarbons.
Aromatic hydrocarbons (or arenes) have a huge practical value. Many of them are widely used: benzene, toluene, xylene. They are used as solvents and raw materials for the production of drugs, dyes, rubber, rubber and other products of organic synthesis.
Oxygen compounds
Oxygen atoms are present in a large group of organic substances. They are part of the most active part of the molecule, its functional group. Alcohols contain one or more hydroxyl species —OH. Examples of alcohols: methanol, ethanol, glycerin. In carboxylic acids, there is another functional particle - carboxyl (-COOOH).
Other oxygen-containing organic compounds are aldehydes and ketones. Carboxylic acids, alcohols and aldehydes are present in large quantities in various plant organs. They can be sources for obtaining natural products (acetic acid, ethyl alcohol, menthol).
Fats are compounds of carboxylic acids and the trihydric alcohol glycerol. In addition to alcohols and acids of a linear structure, there are organic compounds with benzene ring and functional group. Examples of aromatic alcohols: phenol, toluene.
Carbohydrates
The most important organic substances of the body that make up the cells are proteins, enzymes, nucleic acids, carbohydrates and fats (lipids). Simple carbohydrates - monosaccharides - are found in cells in the form of ribose, deoxyribose, fructose and glucose. The last carbohydrate in this short list is the main substance of metabolism in cells. Ribose and deoxyribose are constituents of ribonucleic and deoxyribonucleic acids (RNA and DNA).
When glucose molecules are broken down, the energy necessary for life is released. First, it is stored in the formation of a kind of energy transfer - adenosine triphosphoric acid (ATP). This substance is carried by the blood, delivered to tissues and cells. With the successive cleavage of three phosphoric acid residues from adenosine, energy is released.
Fats
Lipids are substances of living organisms that have specific properties. They do not dissolve in water, are hydrophobic particles. The seeds and fruits of some plants, nervous tissue, liver, kidneys, blood of animals and humans are especially rich in substances of this class.
Human and animal skin contains many small sebaceous glands. The secret secreted by them is displayed on the surface of the body, lubricates it, protects it from moisture loss and the penetration of microbes. The layer of subcutaneous fatty tissue protects internal organs from damage, serves as a reserve substance.
Squirrels
Proteins make up more than half of all organic substances of the cell, in some tissues their content reaches 80%. All types of proteins are characterized by high molecular weights, the presence of primary, secondary, tertiary and quaternary structures. When heated, they are destroyed - denaturation occurs. The primary structure is a huge chain of amino acids for the microcosm. Under the action of special enzymes in the digestive system of animals and humans, the protein macromolecule breaks down into its constituent parts. They enter the cells, where the synthesis of organic substances takes place - other proteins specific to each living being.
Enzymes and their role
Reactions in the cell proceed at a rate that is difficult to achieve under industrial conditions, thanks to catalysts - enzymes. There are enzymes that act only on proteins - lipases. The hydrolysis of starch occurs with the participation of amylase. Lipases are needed to decompose fats into their constituent parts. Processes involving enzymes occur in all living organisms. If a person does not have any enzyme in the cells, then this affects the metabolism, in general, health.
Nucleic acids
Substances, first discovered and isolated from cell nuclei, perform the function of transmitting hereditary traits. The main amount of DNA is contained in chromosomes, and RNA molecules are located in the cytoplasm. With the reduplication (doubling) of DNA, it becomes possible to transfer hereditary information sex cells - gametes. When they merge, the new organism receives genetic material from the parents.
Organic matter is a chemical compound containing carbon. The only exceptions are carbonic acid, carbides, carbonates, cyanides and oxides of carbon.
History
The term "organic substances" itself appeared in the everyday life of scientists at the stage early development chemistry. At that time, vitalistic worldviews dominated. It was a continuation of the traditions of Aristotle and Pliny. During this period, pundits were busy dividing the world into living and non-living. At the same time, all substances, without exception, were clearly divided into mineral and organic. It was believed that for the synthesis of compounds of "living" substances, a special "strength" was needed. It is inherent in all living beings, and organic elements cannot be formed without it.
It's funny for modern science the assertion dominated for a very long time, until in 1828 Friedrich Wöhler experimentally refuted it. He was able to obtain organic urea from inorganic ammonium cyanate. This pushed chemistry forward. However, the division of substances into organic and inorganic has been preserved in the present. It underlies the classification. Almost 27 million are known organic compounds.
Why are there so many organic compounds?
Organic matter is, with a few exceptions, a carbon compound. In fact, this is a very curious element. Carbon is able to form chains from its atoms. It is very important that the connection between them is stable.
In addition, carbon in organic substances exhibits a valency - IV. It follows from this that this element is able to form bonds with other substances not only single, but also double and triple. As their multiplicity increases, the chain of atoms will become shorter. At the same time, the stability of the connection only increases.
Also, carbon has the ability to form flat, linear and three-dimensional structures. That is why there are so many different organic substances in nature.
Composition
As mentioned above, organic matter is carbon compounds. And this is very important. arise when it is associated with almost any element periodic table. In nature, most often their composition (in addition to carbon) includes oxygen, hydrogen, sulfur, nitrogen and phosphorus. The rest of the elements are much rarer.
Properties
So, organic matter is a carbon compound. However, there are several important criteria that it must meet. All substances of organic origin have common properties:
1. The different typology of bonds existing between atoms inevitably leads to the appearance of isomers. First of all, they are formed by the combination of carbon molecules. Isomers are different substances that have the same molecular weight and composition, but different chemical-physical properties. This phenomenon is called isomerism.
2. Another criterion is the phenomenon of homology. These are series of organic compounds, in which the formula of neighboring substances differs from the previous ones by one CH 2 group. This important property used in materials science.
What are the classes of organic substances?
There are several classes of organic compounds. They are known to everyone. lipids and carbohydrates. These groups can be called biological polymers. They are involved in the metabolism of cellular level in any organism. Also included in this group are nucleic acids. So we can say that organic matter is what we eat every day, what we are made of.
Squirrels
Proteins are made up of structural components - amino acids. These are their monomers. Proteins are also called proteins. About 200 types of amino acids are known. All of them are found in living organisms. But only twenty of them are components of proteins. They are called basic. But less popular terms can also be found in the literature - proteinogenic and protein-forming amino acids. The formula of this class of organic matter contains amine (-NH 2) and carboxyl (-COOH) components. They are connected to each other by the same carbon bonds.
Functions of proteins
Proteins in the body of plants and animals perform many important functions. But the main one is structural. Proteins are the main components of the cell membrane and the matrix of organelles in cells. In our body, all the walls of arteries, veins and capillaries, tendons and cartilage, nails and hair consist mainly of different proteins.
The next function is enzymatic. Proteins act as enzymes. They catalyze chemical reactions in the body. They are responsible for the breakdown of nutrients in the digestive tract. In plants, enzymes fix the position of carbon during photosynthesis.
Some carry various substances in the body, such as oxygen. Organic matter is also able to join them. This is how the transport function works. Proteins carry metal ions through the blood vessels fatty acid, hormones and, of course, carbon dioxide and hemoglobin. Transport also occurs at the intercellular level.
Protein compounds - immunoglobulins - are responsible for the protective function. These are blood antibodies. For example, thrombin and fibrinogen are actively involved in the process of coagulation. Thus, they prevent large blood loss.
Proteins are also responsible for the contraction function. Due to the fact that myosin and actin protofibrils constantly perform sliding movements relative to each other, muscle fibers contract. But similar processes occur in unicellular organisms. The movement of bacterial flagella is also directly related to the sliding of microtubules, which are of a protein nature.
Oxidation of organic substances releases a large amount of energy. But, as a rule, proteins are consumed for energy needs very rarely. This happens when all stocks are exhausted. Lipids and carbohydrates are best suited for this. Therefore, proteins can perform an energy function, but only under certain conditions.
Lipids
Organic matter is also a fat-like compound. Lipids belong to the simplest biological molecules. They are insoluble in water, but decompose in non-polar solutions such as gasoline, ether, and chloroform. They are part of all living cells. Chemically, lipids are alcohols and carboxylic acids. The most famous of them are fats. In the body of animals and plants, these substances perform many important functions. Many lipids are used in medicine and industry.
Functions of lipids
These organic chemicals, together with proteins in cells, form biological membranes. But their main function is energy. When fat molecules are oxidized, it is released great amount energy. She goes to education ATP cells. In the form of lipids, a significant amount of energy reserves can accumulate in the body. Sometimes they are even more than necessary for the implementation of normal life. With pathological changes in the metabolism of "fat" cells, it becomes more. Although in fairness it should be noted that such excessive reserves are simply necessary for hibernating animals and plants. Many people believe that trees and shrubs feed on soil during the cold period. In reality, they use up the reserves of oils and fats that they made over the summer.
In humans and animals, fats can also perform a protective function. They are deposited in the subcutaneous tissue and around organs such as the kidneys and intestines. Thus, they serve as good protection against mechanical damage, that is, shock.
In addition, fats have low level thermal conductivity, which helps retain heat. This is very important, especially in cold climates. In marine animals, the subcutaneous fat layer also contributes to good buoyancy. But in birds, lipids also perform water-repellent and lubricating functions. The wax coats their feathers and makes them more elastic. Some types of plants have the same plaque on the leaves.
Carbohydrates
The formula of organic matter C n (H 2 O) m indicates that the compound belongs to the class of carbohydrates. The name of these molecules refers to the fact that they contain oxygen and hydrogen in the same amount as water. In addition to these chemical elements, compounds may contain, for example, nitrogen.
Carbohydrates in the cell are the main group of organic compounds. These are primary products. They are also the initial products of the synthesis in plants of other substances, for example, alcohols, organic acids and amino acids. Carbohydrates are also part of the cells of animals and fungi. They are also found among the main components of bacteria and protozoa. So, in an animal cell they are from 1 to 2%, and in a plant cell their number can reach 90%.
To date, there are only three groups of carbohydrates:
Simple sugars (monosaccharides);
Oligosaccharides, consisting of several molecules of consecutively connected simple sugars;
Polysaccharides, they include more than 10 molecules of monosaccharides and their derivatives.
Functions of carbohydrates
All organic substances in the cell perform certain functions. So, for example, glucose is the main energy source. It is broken down in all cells during cellular respiration. Glycogen and starch constitute the main energy reserve, with the former in animals and the latter in plants.
Carbohydrates also perform a structural function. Cellulose is the main component of the plant cell wall. And in arthropods, chitin performs the same function. It is also found in the cells of higher fungi. If we take oligosaccharides as an example, then they are part of the cytoplasmic membrane - in the form of glycolipids and glycoproteins. Also, glycocalyx is often detected in cells. Pentoses are involved in the synthesis of nucleic acids. When is included in DNA, and ribose is included in RNA. Also, these components are found in coenzymes, for example, in FAD, NADP and NAD.
Carbohydrates are also able to perform a protective function in the body. In animals, the substance heparin actively prevents rapid blood clotting. It is formed during tissue damage and blocks the formation of blood clots in the vessels. Heparin in in large numbers found in mast cells in granules.
Nucleic acids
Proteins, carbohydrates and lipids are not all known classes of organic substances. Chemistry also includes nucleic acids. These are phosphorus-containing biopolymers. They, being in the cell nucleus and cytoplasm of all living beings, ensure the transmission and storage of genetic data. These substances were discovered thanks to the biochemist F. Miescher, who studied salmon spermatozoa. It was an "accidental" discovery. A little later, RNA and DNA were also found in all plant and animal organisms. Nucleic acids have also been isolated in the cells of fungi and bacteria, as well as viruses.
In total, two types of nucleic acids have been found in nature - ribonucleic (RNA) and deoxyribonucleic (DNA). The difference is clear from the name. deoxyribose is a five-carbon sugar. Ribose is found in the RNA molecule.
Organic chemistry is the study of nucleic acids. Topics for research are also dictated by medicine. There are many genetic diseases hidden in the DNA codes, which scientists have yet to discover.
In the past, scientists divided all substances in nature into conditionally inanimate and living ones, including the animal and plant kingdoms among the latter. Substances of the first group are called mineral. And those that entered the second, began to be called organic substances.
What is meant by this? The class of organic substances is the most extensive among all chemical compounds known to modern scientists. The question of which substances are organic can be answered as follows - this is chemical compounds containing carbon.
Please note that not all carbon-containing compounds are organic. For example, corbides and carbonates, carbonic acid and cyanides, carbon oxides are not among them.
Why are there so many organic substances?
The answer to this question lies in the properties of carbon. This element is curious in that it is able to form chains from its atoms. And at the same time, the carbon bond is very stable.
In addition, in organic compounds, it exhibits a high valence (IV), i.e. the ability to form chemical bonds with other substances. And not only single, but also double and even triple (otherwise - multiples). As the bond multiplicity increases, the chain of atoms becomes shorter, and the bond stability increases.
And carbon is endowed with the ability to form linear, flat and three-dimensional structures.
That is why organic substances in nature are so diverse. You can easily check it yourself: stand in front of a mirror and carefully look at your reflection. Each of us is a walking guide to organic chemistry. Think about it: at least 30% of the mass of each of your cells is organic compounds. The proteins that built your body. Carbohydrates, which serve as "fuel" and a source of energy. Fats that store energy reserves. Hormones that control organ function and even your behavior. Enzymes that start chemical reactions inside you. And even the "source code," the strands of DNA, are all carbon-based organic compounds.
Composition of organic substances
As we said at the very beginning, the main building material for organic matter is carbon. And practically any elements, combining with carbon, can form organic compounds.
In nature, most often in the composition of organic substances are hydrogen, oxygen, nitrogen, sulfur and phosphorus.
The structure of organic substances
The diversity of organic substances on the planet and the diversity of their structure can be explained by the characteristic features of carbon atoms.
You remember that carbon atoms are able to form very strong bonds with each other, connecting in chains. The result is stable molecules. The way in which carbon atoms chain together (arrange in a zigzag pattern) is one of the key features her buildings. Carbon can combine both into open chains and into closed (cyclic) chains.
It is also important that the structure chemical substances directly affects their chemical properties. A significant role is also played by how atoms and groups of atoms in a molecule affect each other.
Due to the peculiarities of the structure, the number of carbon compounds of the same type goes to tens and hundreds. For an example, consider hydrogen compounds carbon: methane, ethane, propane, butane, etc.
For example, methane - CH 4. Such a combination of hydrogen with carbon under normal conditions is in gaseous state of aggregation. When oxygen appears in the composition, a liquid is formed - methyl alcohol CH 3 OH.
Not only substances with different qualitative composition (as in the example above) exhibit different properties, but substances of the same qualitative composition are also capable of this. An example is the different ability of methane CH 4 and ethylene C 2 H 4 to react with bromine and chlorine. Methane is capable of such reactions only when heated or under ultraviolet light. And ethylene reacts even without lighting and heating.
Let's consider this option: qualitative composition chemical compounds are the same, quantitative - different. Then the chemical properties of the compounds are different. As in the case of acetylene C 2 H 2 and benzene C 6 H 6.
Not the last role in this variety is played by such properties of organic substances, "tied" to their structure, as isomerism and homology.
Imagine that you have two seemingly identical substances - same composition and the same molecular formula to describe them. But the structure of these substances is fundamentally different, hence the difference in chemical and physical properties. For example, the molecular formula C 4 H 10 can be written two various substances: butane and isobutane.
We are talking about isomers- compounds that have the same composition and molecular weight. But the atoms in their molecules are located in a different order (branched and unbranched structure).
Concerning homology- this is a characteristic of such a carbon chain in which each next member can be obtained by adding one CH 2 group to the previous one. Each homologous series can be expressed by one general formula. And knowing the formula, it is easy to determine the composition of any of the members of the series. For example, methane homologues are described by the formula C n H 2n+2 .
As the “homologous difference” CH 2 is added, the bond between the atoms of the substance is strengthened. Let's take the homologous series of methane: its first four terms are gases (methane, ethane, propane, butane), the next six are liquids (pentane, hexane, heptane, octane, nonane, decane), and then substances in the solid state of aggregation follow (pentadecane, eicosan, etc.). And the stronger the bond between carbon atoms, the higher the molecular weight, boiling and melting points of substances.
What classes of organic substances exist?
Organic substances of biological origin include:
- proteins;
- carbohydrates;
- nucleic acids;
- lipids.
The first three points can also be called biological polymers.
A more detailed classification of organic chemicals covers substances not only of biological origin.
The hydrocarbons are:
- acyclic compounds:
- saturated hydrocarbons(alkanes);
- unsaturated hydrocarbons:
- alkenes;
- alkynes;
- alkadienes.
- cyclic compounds:
- carbocyclic compounds:
- alicyclic;
- aromatic.
- heterocyclic compounds.
- carbocyclic compounds:
There are also other classes of organic compounds in which carbon combines with substances other than hydrogen:
- alcohols and phenols;
- aldehydes and ketones;
- carboxylic acids;
- esters;
- lipids;
- carbohydrates:
- monosaccharides;
- oligosaccharides;
- polysaccharides.
- mucopolysaccharides.
- amines;
- amino acids;
- proteins;
- nucleic acids.
Formulas of organic substances by classes
Examples of organic substances
As you remember, in the human body, various kinds of organic substances are the basis of the foundations. These are our tissues and fluids, hormones and pigments, enzymes and ATP, and much more.
In the bodies of humans and animals, proteins and fats are prioritized (half of the dry weight of an animal cell is protein). In plants (about 80% of the dry mass of the cell) - for carbohydrates, primarily complex - polysaccharides. Including for cellulose (without which there would be no paper), starch.
Let's talk about some of them in more detail.
For example, about carbohydrates. If it were possible to take and measure the masses of all organic substances on the planet, it would be carbohydrates that would win this competition.
They serve as a source of energy in the body, are building materials for cells, and also carry out the supply of substances. Plants use starch for this purpose, and glycogen for animals.
In addition, carbohydrates are very diverse. For example, simple carbohydrates. The most common monosaccharides in nature are pentoses (including deoxyribose, which is part of DNA) and hexoses (glucose, which is well known to you).
Like bricks, at a large construction site of nature, polysaccharides are built from thousands and thousands of monosaccharides. Without them, more precisely, without cellulose, starch, there would be no plants. Yes, and animals without glycogen, lactose and chitin would have a hard time.
Let's look carefully at squirrels. Nature is the greatest master of mosaics and puzzles: from just 20 amino acids, 5 million types of proteins are formed in the human body. Proteins also have many vital functions. For example, construction, regulation of processes in the body, blood coagulation (there are separate proteins for this), movement, transport of certain substances in the body, they are also a source of energy, in the form of enzymes they act as a catalyst for reactions, provide protection. Antibodies play an important role in protecting the body from negative external influences. And if a discord occurs in the fine tuning of the body, antibodies, instead of destroying external enemies, can act as aggressors to their own organs and tissues of the body.
Proteins are also divided into simple (proteins) and complex (proteins). And they have properties inherent only to them: denaturation (the destruction that you noticed more than once when you boiled a hard-boiled egg) and renaturation (this property has found wide application in the manufacture of antibiotics, food concentrates, etc.).
Let's not ignore and lipids(fats). In our body, they serve as a reserve source of energy. As solvents, they help the course of biochemical reactions. Participate in the construction of the body - for example, in the formation of cell membranes.
And a few more words about such curious organic compounds as hormones. They are involved in biochemical reactions and metabolism. These small hormones make men men (testosterone) and women women (estrogen). They make us happy or sad (thyroid hormones play an important role in mood swings, and endorphins give a feeling of happiness). And they even determine whether we are “owls” or “larks”. Are you ready to study late or do you prefer to get up early and do homework before school, decides not only your daily routine, but also some adrenal hormones.
Conclusion
The world of organic matter is truly amazing. It is enough to delve into its study just a little to take your breath away from the feeling of kinship with all life on Earth. Two legs, four or roots instead of legs - we are all united by the magic of mother nature's chemical laboratory. It causes carbon atoms to join in chains, react and create thousands of such diverse chemical compounds.
You now have a short guide to organic chemistry. Of course, not all possible information is presented here. Some points you may have to clarify on your own. But you can always use the route we have planned for your independent research.
You can also use the definition of organic matter given in the article, the classification and general formulas of organic compounds and general information about them to prepare for chemistry lessons at school.
Tell us in the comments which section of chemistry (organic or inorganic) you like best and why. Don't forget to share the article in social networks so your classmates can use it too.
Please report if you find any inaccuracy or error in the article. We are all human and we all make mistakes sometimes.
blog.site, with full or partial copying of the material, a link to the source is required.
Classification of organic substances
Depending on the type of structure of the carbon chain, organic substances are divided into:
- acyclic and cyclic.
- marginal (saturated) and unsaturated (unsaturated).
- carbocyclic and heterocyclic.
- alicyclic and aromatic.
Acyclic compounds are organic compounds in whose molecules there are no cycles and all carbon atoms are connected to each other in straight or branched open chains.
In turn, among acyclic compounds, limiting (or saturated) compounds are distinguished, which contain only single carbon-carbon (C-C) bonds in the carbon skeleton and unsaturated (or unsaturated) compounds containing multiples - double (C \u003d C) or triple (C ≡ C) communications.
Cyclic compounds are chemical compounds in which there are three or more bonded atoms forming a ring.
Depending on which atoms the rings are formed, carbocyclic compounds and heterocyclic compounds are distinguished.
Carbocyclic compounds (or isocyclic) contain only carbon atoms in their cycles. These compounds are in turn divided into alicyclic compounds (aliphatic cyclic) and aromatic compounds.
Heterocyclic compounds contain one or more heteroatoms in the hydrocarbon cycle, most often oxygen, nitrogen, or sulfur atoms.
The simplest class of organic substances are hydrocarbons - compounds that are formed exclusively by carbon and hydrogen atoms, i.e. formally do not have functional groups.
Since hydrocarbons do not have functional groups, they can only be classified according to the type of carbon skeleton. Hydrocarbons, depending on the type of their carbon skeleton, are divided into subclasses:
1) Limiting acyclic hydrocarbons are called alkanes. The general molecular formula of alkanes is written as C n H 2n+2, where n is the number of carbon atoms in a hydrocarbon molecule. These compounds do not have interclass isomers.
2) Acyclic unsaturated hydrocarbons are divided into:
a) alkenes - they contain only one multiple, namely one double C \u003d C bond, the general formula of alkenes is C n H 2n,
b) alkynes - in alkyne molecules there is also only one multiple, namely triple C≡C bond. The general molecular formula of alkynes is C n H 2n-2
c) alkadienes - in the molecules of alkadienes there are two double C=C bonds. The general molecular formula of alkadienes is C n H 2n-2
3) Cyclic saturated hydrocarbons are called cycloalkanes and have the general molecular formula C n H 2n.
The rest of the organic substances in organic chemistry are considered as derivatives of hydrocarbons formed upon the introduction of the so-called functional groups into hydrocarbon molecules, which contain other chemical elements.
Thus, the formula of compounds with one functional group can be written as R-X, where R is a hydrocarbon radical, and X is a functional group. A hydrocarbon radical is a fragment of a hydrocarbon molecule without one or more hydrogen atoms.
According to the presence of certain functional groups, the compounds are divided into classes. The main functional groups and classes of compounds in which they are included are presented in the table:
Thus, various combinations of types of carbon skeletons with different functional groups give a wide variety of variants of organic compounds.
Halogen derivatives of hydrocarbons
Halogen derivatives of hydrocarbons are compounds obtained by replacing one or more hydrogen atoms in a molecule of any initial hydrocarbon with one or more atoms of a halogen, respectively.
Let some hydrocarbon have the formula C n H m, then when replacing in its molecule X hydrogen atoms on X halogen atoms, the formula for the halogen derivative will look like C n H m-X Hal X. Thus, monochlorine derivatives of alkanes have the formula C n H 2n+1 Cl, dichloro derivatives C n H 2n Cl 2 etc.
Alcohols and phenols
Alcohols are derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by the hydroxyl group -OH. Alcohols with one hydroxyl group are called monatomic, with two - diatomic, with three triatomic etc. For example:
Alcohols with two or more hydroxyl groups are also called polyhydric alcohols.General formula saturated monohydric alcohols C n H 2n + 1 OH or C n H 2n + 2 O. The general formula for limiting polyhydric alcohols C n H 2n+2 O x , where x is the atomic number of alcohol.
Alcohols can also be aromatic. For example:
benzyl alcoholThe general formula of such monohydric aromatic alcohols is C n H 2n-6 O.
However, it should be clearly understood that derivatives of aromatic hydrocarbons in which one or more hydrogen atoms at the aromatic nucleus are replaced by hydroxyl groups do not apply to alcohols. They belong to the class phenols . For example, this given compound is an alcohol:
And this is phenol:
The reason why phenols are not classified as alcohols lies in their specific chemical properties ah, strongly distinguishing them from alcohols. It is easy to see that monohydric phenols are isomeric to monohydric aromatic alcohols, i.e. also have the general molecular formula C n H 2n-6 O.
Amines
Amines called ammonia derivatives in which one, two or all three hydrogen atoms are replaced by a hydrocarbon radical.
Amines in which only one hydrogen atom is replaced by a hydrocarbon radical, i.e. having the general formula R-NH 2 are called primary amines.
Amines in which two hydrogen atoms are replaced by hydrocarbon radicals are called secondary amines. The formula for a secondary amine can be written as R-NH-R'. In this case, the radicals R and R' can be either the same or different. For example:
If there are no hydrogen atoms at the nitrogen atom in amines, i.e. all three hydrogen atoms of the ammonia molecule are replaced by a hydrocarbon radical, then such amines are called tertiary amines. IN general view the formula for a tertiary amine can be written as:
In this case, the radicals R, R', R'' can be either completely identical, or all three are different.
The general molecular formula of primary, secondary and tertiary limiting amines is C n H 2 n +3 N.
Aromatic amines with only one unsaturated substituent have the general formula C n H 2 n -5 N
Aldehydes and ketones
Aldehydes called derivatives of hydrocarbons, in which, at the primary carbon atom, two hydrogen atoms are replaced by one oxygen atom, i.e. derivatives of hydrocarbons in the structure of which there is an aldehyde group –CH=O. The general formula for aldehydes can be written as R-CH=O. For example:
Ketones called derivatives of hydrocarbons, in which two hydrogen atoms at the secondary carbon atom are replaced by an oxygen atom, i.e. compounds in the structure of which there is a carbonyl group -C (O) -.
The general formula for ketones can be written as R-C(O)-R'. In this case, the radicals R, R' can be either the same or different.
For example:
| propane is he | butane is he |
As you can see, aldehydes and ketones are very similar in structure, but they are still distinguished as classes, since they have significant differences in chemical properties.
The general molecular formula of saturated ketones and aldehydes is the same and has the form C n H 2 n O
carboxylic acids
carboxylic acids called derivatives of hydrocarbons in which there is a carboxyl group -COOH.
If an acid has two carboxyl groups, the acid is called dicarboxylic acid.
Limit monocarboxylic acids (with one -COOH group) have a general molecular formula of the form C n H 2 n O 2
Aromatic monocarboxylic acids have the general formula C n H 2 n -8 O 2
Ethers
Ethers - organic compounds in which two hydrocarbon radicals are indirectly connected through an oxygen atom, i.e. have a formula of the form R-O-R'. In this case, the radicals R and R' can be either the same or different.
For example:
The general formula of saturated ethers is the same as for saturated monohydric alcohols, i.e. C n H 2 n +1 OH or C n H 2 n +2 O.
Esters
Esters are a class of compounds based on organic carboxylic acids, in which the hydrogen atom in the hydroxyl group is replaced by the hydrocarbon radical R. The general form of esters can be written as:
For example:
Nitro compounds
Nitro compounds- derivatives of hydrocarbons, in which one or more hydrogen atoms are replaced by a nitro group -NO 2.
Limit nitro compounds with one nitro group have the general molecular formula C n H 2 n +1 NO 2
Amino acids
Compounds that simultaneously have two functional groups in their structure - amino NH 2 and carboxyl - COOH. For example,
NH 2 -CH 2 -COOH
Limiting amino acids with one carboxyl and one amino group are isomeric to the corresponding limiting nitro compounds i.e. like they have the general molecular formula C n H 2 n +1 NO 2
IN USE assignments for the classification of organic substances, it is important to be able to write down general molecular formulas homologous series different types compounds, knowing the structural features of the carbon skeleton and the presence of certain functional groups. In order to learn how to determine the general molecular formulas of organic compounds of different classes, it will be useful material on this topic.
Nomenclature of organic compounds
Features of the structure and chemical properties of compounds are reflected in the nomenclature. The main types of nomenclature are systematic And trivial.
Systematic nomenclature actually prescribes algorithms, according to which one or another name is compiled in strict accordance with the structural features of an organic substance molecule or, roughly speaking, its structural formula.
Consider the rules for naming organic compounds according to systematic nomenclature.
When naming organic substances according to systematic nomenclature, the most important thing is to correctly determine the number of carbon atoms in the longest carbon chain or count the number of carbon atoms in a cycle.
Depending on the number of carbon atoms in the main carbon chain, compounds will have a different root in their name:
| Number of C atoms in the main carbon chain | Name root |
| prop- |
|
| pent- |
|
| hex- |
|
| hept- |
|
| dec(c)- |
The second important component taken into account when compiling names is the presence / absence of multiple bonds or a functional group, which are listed in the table above.
Let's try to give a name to a substance that has a structural formula:
1. The main (and only) carbon chain of this molecule contains 4 carbon atoms, so the name will contain the root but-;
2. There are no multiple bonds in the carbon skeleton, therefore, the suffix to be used after the root of the word will be -an, as for the corresponding saturated acyclic hydrocarbons (alkanes);
3. The presence of a functional group -OH, provided that there are no more senior functional groups, adds after the root and suffix from paragraph 2. another suffix - "ol";
4. In molecules containing multiple bonds or functional groups, the numbering of carbon atoms of the main chain starts from the side of the molecule to which they are closer.
Let's look at another example:
The presence of four carbon atoms in the main carbon chain tells us that the root “but-” is the basis of the name, and the absence of multiple bonds indicates the suffix “-an”, which will follow immediately after the root. Senior group in this compound - carboxylic acid, it determines whether this substance belongs to the class of carboxylic acids. Therefore, the ending at the name will be "-ovoic acid". At the second carbon atom is an amino group NH2 -, therefore, this substance belongs to amino acids. Also at the third carbon atom we see the hydrocarbon radical methyl ( CH 3 -). Therefore, according to the systematic nomenclature, this compound is called 2-amino-3-methylbutanoic acid.
Trivial nomenclature, in contrast to the systematic, as a rule, has no connection with the structure of the substance, but is due for the most part to its origin, as well as chemical or physical properties.
| Formula | Name according to systematic nomenclature | Trivial name |
| hydrocarbons | ||
| CH 4 | methane | marsh gas |
| CH 2 \u003d CH 2 | ethene | ethylene |
| CH 2 \u003d CH-CH 3 | propene | propylene |
| CH≡CH | ethin | acetylene |
| CH 2 \u003d CH-CH \u003d CH 2 | butadiene-1,3 | divinyl |
| 2-methylbutadiene-1,3 | isoprene | |
| methylbenzene | toluene | |
| 1,2-dimethylbenzene | ortho-xylene (about-xylene) |
|
| 1,3-dimethylbenzene | meta-xylene (m-xylene) |
|
| 1,4-dimethylbenzene | pair-xylene (P-xylene) |
|
| vinylbenzene | styrene | |
| Alcohols | ||
| CH3OH | methanol | methyl alcohol, wood alcohol |
| CH 3 CH 2 OH | ethanol | ethanol |
| CH 2 \u003d CH-CH 2 -OH | propen-2-ol-1 | allyl alcohol |
| ethanediol-1,2 | ethylene glycol | |
| propanetriol-1,2,3 | glycerol | |
| phenol (hydroxybenzene) | carbolic acid | |
| 1-hydroxy-2-methylbenzene | ortho-cresol (about-cresol) |
|
| 1-hydroxy-3-methylbenzene | meta-cresol (m-cresol) |
|
| 1-hydroxy-4-methylbenzene | pair-cresol (P-cresol) |
|
| phenylmethanol | benzyl alcohol | |
| Aldehydes and ketones | ||
| methanal | formaldehyde | |
| ethanal | acetaldehyde, acetaldehyde | |
| propenal | acrylic aldehyde, acrolein | |
| benzaldehyde | benzoic aldehyde | |
| propanone | acetone | |
| carboxylic acids | ||
| (HCOOH) | methane acid | formic acid (salts and esters - formates) |
| (CH3COOH) | ethanoic acid | acetic acid (salts and esters - acetates) |
| (CH 3 CH 2 COOH) | propanoic acid | propionic acid (salts and esters - propionates) |
| C 15 H 31 COOH | hexadecanoic acid | palmitic acid (salts and esters - palmitates) |
| C 17 H 35 COOH | octadecanoic acid | stearic acid (salts and esters - stearates) |
| propenoic acid | acrylic acid (salts and esters - acrylates) |
|
| HOOC-COOH | ethanedioic acid | oxalic acid (salts and esters - oxalates) |
| 1,4-benzenedicarboxylic acid | terephthalic acid | |
| Esters | ||
| HCOOCH 3 | methylmethanoate | methyl formate, formic acid methyl ester |
| CH 3 COOK 3 | methyl ethanoate | methyl acetate, acetic acid methyl ester |
| CH 3 COOC 2 H 5 | ethyl ethanoate | ethyl acetate, acetic acid ethyl ester |
| CH 2 \u003d CH-COOCH 3 | methyl propenoate | methyl acrylate, acrylic acid methyl ester |
| Nitrogen compounds | ||
| aminobenzene, phenylamine | aniline | |
| NH 2 -CH 2 -COOH | aminoethanoic acid | glycine, aminoacetic acid |
| 2-aminopropionic acid | alanine | |
