There are many organic compounds, but among them there are compounds with common and similar properties. Therefore, they are all classified according to common characteristics, combined into separate classes and groups. The classification is based on hydrocarbons – compounds that are made up of only carbon and hydrogen atoms. The rest of the organic matter is "Other Classes of Organic Compounds".
Hydrocarbons are divided into two broad classes: acyclic and cyclic compounds.
Acyclic compounds (fatty or aliphatic) – compounds whose molecules contain an open (not closed in a ring) unbranched or branched carbon chain with single or multiple bonds. Acyclic compounds are divided into two main groups:
saturated (limiting) hydrocarbons (alkanes), in which all carbon atoms are interconnected only by simple bonds;
unsaturated (unsaturated) hydrocarbons, in which between carbon atoms, in addition to single simple bonds, there are also double and triple bonds.
Unsaturated (unsaturated) hydrocarbons are divided into three groups: alkenes, alkynes and alkadienes.
Alkenes(olefins, ethylene hydrocarbons) – acyclic unsaturated hydrocarbons that contain one double bond between carbon atoms form a homologous series with the general formula C n H 2n . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-en". For example, propene, butene, isobutylene or methylpropene.
Alkynes(acetylene hydrocarbons) – hydrocarbons that contain a triple bond between carbon atoms form a homologous series with the general formula C n H 2n-2 . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-in". For example, ethin (acylene), butin, peptin.
Alkadienes – organic compounds that contain two carbon-carbon double bonds. Depending on how the double bonds are arranged relative to each other, dienes are divided into three groups: conjugated dienes, allenes and dienes with isolated double bonds. Typically, dienes include acyclic and cyclic 1,3-dienes, forming with the general formulas C n H 2n-2 and C n H 2n-4 . Acyclic dienes are structural isomers of alkynes.
Cyclic compounds, in turn, are divided into two large groups:
- carbocyclic compounds – compounds whose rings consist only of carbon atoms; Carbocyclic compounds are subdivided into alicyclic – saturated (cycloparaffins) and aromatic;
- heterocyclic compounds – compounds whose cycles consist not only of carbon atoms, but of atoms of other elements: nitrogen, oxygen, sulfur, etc.
In molecules of both acyclic and cyclic compounds hydrogen atoms can be replaced by other atoms or groups of atoms, thus, by introducing functional groups, derivatives of hydrocarbons can be obtained. This property further expands the possibilities of obtaining various organic compounds and explains their diversity.
The presence of certain groups in the molecules of organic compounds determines the generality of their properties. This is the basis for the classification of derivatives of hydrocarbons.
"Other classes of organic compounds" include the following:
Alcohols are obtained by replacing one or more hydrogen atoms with hydroxyl groups – Oh. It is a compound with the general formula R – (OH) x, where x – number of hydroxyl groups.
Aldehydes contain an aldehyde group (C = O), which is always at the end of the hydrocarbon chain.
carboxylic acids contain one or more carboxyl groups – COOH.
Esters – derivatives of oxygen-containing acids, which are formally the products of substitution of hydrogen atoms of hydroxides – OH acid function per hydrocarbon residue; are also considered as acyl derivatives of alcohols.
Fats (triglycerides) – natural organic compounds, full esters of glycerol and monocomponent fatty acids; belong to the class of lipids. Natural fats contain three linear acid radicals and usually an even number of carbon atoms.
Carbohydrates – organic substances containing a straight chain of several carbon atoms, a carboxyl group and several hydroxyl groups.
Amines contain an amino group – NH2
Amino acids– organic compounds, the molecule of which simultaneously contains carboxyl and amine groups.
Squirrels – high-molecular organic substances, which consist of alpha-amino acids connected in a chain by a peptide bond.
Nucleic acids – high-molecular organic compounds, biopolymers formed by nucleotide residues.
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In the history of the development of organic chemistry, two periods are distinguished: empirical (from the middle of the 17th to the end of the 18th century), in which the knowledge of organic substances, methods for their isolation and processing took place empirically, and analytical (the end of the 18th - the middle of the 19th century), associated with the emergence of methods for establishing composition of organic matter. During the analytical period, it was found that all organic substances contain carbon. Among other elements that make up organic compounds, hydrogen, nitrogen, sulfur, oxygen and phosphorus were found.
Of great importance in the history of organic chemistry is the structural period (second half of the 19th - early 20th centuries), marked by the birth of the scientific theory of the structure of organic compounds, the founder of which was A.M. Butlerov.
The main provisions of the theory of the structure of organic compounds:
- atoms in molecules are interconnected in a certain order by chemical bonds in accordance with their valency. Carbon in all organic compounds is tetravalent;
- the properties of substances depend not only on their qualitative and quantitative composition, but also on the order in which atoms are combined;
- atoms in a molecule mutually influence each other.
The order of connection of atoms in a molecule is described by a structural formula in which chemical bonds are represented by dashes.
Characteristic properties of organic substances
There are several important properties that distinguish organic compounds into a separate, unlike any other class of chemical compounds:
- Organic compounds are usually gases, liquids, or low-melting solids, in contrast to inorganic compounds, which are mostly solids with a high melting point.
- Organic compounds are mostly built covalently, and inorganic compounds - ionically.
- The different topology of the formation of bonds between the atoms that form organic compounds (primarily carbon atoms) leads to the appearance of isomers - compounds that have the same composition and molecular weight, but have different physicochemical properties. This phenomenon is called isomerism.
- The phenomenon of homology is the existence of series of organic compounds in which the formula of any two neighbors of the series (homologues) differs by the same group - the homological difference CH 2 . Organic matter burns.
Classification of organic substances
The classification takes as a basis two important features - the structure of the carbon skeleton and the presence of functional groups in the molecule.
In the molecules of organic substances, carbon atoms combine with each other, forming the so-called. carbon skeleton or chain. Chains are open and closed (cyclic), open chains can be unbranched (normal) and branched:
According to the structure of the carbon skeleton, there are:
- alicyclic organic substances having an open carbon chain, both branched and unbranched. For example,
CH 3 -CH 2 -CH 2 -CH 3 (butane)
CH 3 -CH (CH 3) -CH 3 (isobutane)
- carbocyclic organic substances in which the carbon chain is closed in a cycle (ring). For example,
- heterocyclic organic compounds containing in the cycle not only carbon atoms, but also atoms of other elements, most often nitrogen, oxygen or sulfur:
A functional group is an atom or group of non-hydrocarbon atoms that determines whether a compound belongs to a particular class. The sign according to which an organic substance belongs to one class or another is the nature of the functional group (Table 1).
Table 1. Functional groups and classes.
Compounds may contain more than one functional group. If these groups are the same, then the compounds are called polyfunctional, for example, chloroform, glycerin. Compounds containing various functional groups are called heterofunctional, they can be simultaneously attributed to several classes of compounds, for example, lactic acid can be considered as a carboxylic acid and as an alcohol, and colamine as an amine and an alcohol.
Purpose of the lecture: familiarity with the classification and nomenclature of organic compounds
Plan:
1. Subject and tasks of organic chemistry. Its significance for pharmacy.
2. Classification of organic compounds.
3. Principles of trivial and rational nomenclature.
4. Principles of IUPAC nomenclature.
Subject and tasks of organic chemistry.
Organic chemistry is a branch of chemistry devoted to the study of the structure, methods of synthesis and chemical transformations of hydrocarbons and their functional derivatives.
The term "organic chemistry" was first introduced by the Swedish chemist Jens Jakob Berzellius in 1807.
Due to the peculiarities of their structure, organic substances are very numerous. Today their number reaches 10 million.
At present, the state of organic chemistry is such that it makes it possible to scientifically plan and carry out the synthesis of any complex molecules (proteins, vitamins, enzymes, drugs, etc.).
Organic chemistry is closely related to pharmacy. It allows the isolation of individual medicinal substances from plant and animal raw materials, synthesizes and purifies medicinal raw materials, determines the structure of the substance and the mechanism of chemical action, and allows determining the authenticity of a particular drug. Suffice it to say that 95% of medicines are organic in nature.
Classification of organic compounds
In the classification, two most important features are taken as a basis: structure carbon skeleton and the presence in the molecule functional groups.
According to the structure of the carbon skeleton, organic. compounds are divided into three large groups.
I Acyclic(aliphatic) compounds having an open carbon chain, both straight and branched.
The parent compounds in organic chemistry are recognized hydrocarbons consisting only of carbon and hydrogen atoms. A variety of organic compounds can be considered as derivatives of hydrocarbons obtained by introducing functional groups into them.
A functional group is a structural fragment of a molecule that is characteristic of a given class of organic compounds and determines its chemical properties.
For example, the properties of alcohols are determined by the presence of a hydroxo group ( - HE), properties of amines - amino groups ( - NH2), carboxylic acids by the presence of a carboxyl group in the molecule (- UNSD) and so on.
Table 1. Main classes of organic compounds
This classification is important because the functional groups largely determine the chemical properties of this class of compounds.
If the compounds contain several functional groups and they are the same, then such compounds are called polyfunctional (CH 2 HE- CH HE- CH 2 HE- glycerol), if the molecule contains different functional groups, then this heterofunctional compound (CH 3 - CH ( HE)- UNSD- lactic acid). Heterofunctional compounds can be immediately attributed to several classes of compounds.
There are many organic compounds, but among them there are compounds with common and similar properties. Therefore, they are all classified according to common characteristics, combined into separate classes and groups. The classification is based on hydrocarbons – compounds that are made up of only carbon and hydrogen atoms. The rest of the organic matter is "Other Classes of Organic Compounds".
Hydrocarbons are divided into two broad classes: acyclic and cyclic compounds.
Acyclic compounds (fatty or aliphatic) – compounds whose molecules contain an open (not closed in a ring) unbranched or branched carbon chain with single or multiple bonds. Acyclic compounds are divided into two main groups:
saturated (limiting) hydrocarbons (alkanes), in which all carbon atoms are interconnected only by simple bonds;
unsaturated (unsaturated) hydrocarbons, in which between carbon atoms, in addition to single simple bonds, there are also double and triple bonds.
Unsaturated (unsaturated) hydrocarbons are divided into three groups: alkenes, alkynes and alkadienes.
Alkenes(olefins, ethylene hydrocarbons) – acyclic unsaturated hydrocarbons that contain one double bond between carbon atoms form a homologous series with the general formula C n H 2n . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-en". For example, propene, butene, isobutylene or methylpropene.
Alkynes(acetylene hydrocarbons) – hydrocarbons that contain a triple bond between carbon atoms form a homologous series with the general formula C n H 2n-2 . The names of alkenes are formed from the names of the corresponding alkanes with the suffix "-an" replaced by the suffix "-in". For example, ethin (acylene), butin, peptin.
Alkadienes – organic compounds that contain two carbon-carbon double bonds. Depending on how the double bonds are arranged relative to each other, dienes are divided into three groups: conjugated dienes, allenes and dienes with isolated double bonds. Typically, dienes include acyclic and cyclic 1,3-dienes, forming with the general formulas C n H 2n-2 and C n H 2n-4 . Acyclic dienes are structural isomers of alkynes.
Cyclic compounds, in turn, are divided into two large groups:
- carbocyclic compounds – compounds whose rings consist only of carbon atoms; Carbocyclic compounds are subdivided into alicyclic – saturated (cycloparaffins) and aromatic;
- heterocyclic compounds – compounds whose cycles consist not only of carbon atoms, but of atoms of other elements: nitrogen, oxygen, sulfur, etc.
In molecules of both acyclic and cyclic compounds hydrogen atoms can be replaced by other atoms or groups of atoms, thus, by introducing functional groups, derivatives of hydrocarbons can be obtained. This property further expands the possibilities of obtaining various organic compounds and explains their diversity.
The presence of certain groups in the molecules of organic compounds determines the generality of their properties. This is the basis for the classification of derivatives of hydrocarbons.
"Other classes of organic compounds" include the following:
Alcohols are obtained by replacing one or more hydrogen atoms with hydroxyl groups – Oh. It is a compound with the general formula R – (OH) x, where x – number of hydroxyl groups.
Aldehydes contain an aldehyde group (C = O), which is always at the end of the hydrocarbon chain.
carboxylic acids contain one or more carboxyl groups – COOH.
Esters – derivatives of oxygen-containing acids, which are formally the products of substitution of hydrogen atoms of hydroxides – OH acid function per hydrocarbon residue; are also considered as acyl derivatives of alcohols.
Fats (triglycerides) – natural organic compounds, full esters of glycerol and monocomponent fatty acids; belong to the class of lipids. Natural fats contain three linear acid radicals and usually an even number of carbon atoms.
Carbohydrates – organic substances containing a straight chain of several carbon atoms, a carboxyl group and several hydroxyl groups.
Amines contain an amino group – NH2
Amino acids– organic compounds, the molecule of which simultaneously contains carboxyl and amine groups.
Squirrels – high-molecular organic substances, which consist of alpha-amino acids connected in a chain by a peptide bond.
Nucleic acids – high-molecular organic compounds, biopolymers formed by nucleotide residues.
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