Many processes without which it is impossible to imagine our life (such as respiration, digestion, photosynthesis and the like) are associated with various chemical reactions of organic compounds (and inorganic). Let's look at their main types and dwell in more detail on a process called connection.
What is called a chemical reaction
First of all, it is worthwhile to give a general definition of this phenomenon. The phrase under consideration means various reactions of substances of varying complexity, resulting in the formation of products different from the original ones. The substances involved in this process are referred to as “reagents”.
In a letter, the chemical reaction of organic compounds (and inorganic) is recorded using specialized equations. Outwardly, they slightly resemble mathematical examples of addition. However, instead of the equal sign ("="), arrows are used ("→" or "⇆"). In addition, sometimes there may be more substances on the right side of the equation than on the left. All that is before the arrow is the substances before the start of the reaction (the left side of the formula). All that follows (the right side) is compounds formed as a result of a chemical process.
As an example of a chemical equation, we can consider the reaction of decomposition of water into hydrogen and oxygen under the influence of an electric current: 2 2 → 2 2 ↑ + 2 ↑. Water is the starting reagent, and oxygen and hydrogen are the products.
As yet another, but already more complex example of the chemical reaction of compounds, we can consider a phenomenon familiar to every housewife who at least once baked sweets. It's about quenching baking soda with table vinegar. The action that is taking place is illustrated by the following equation: NaHCO 3 + 2 CH 3 COOH → 2CH 3 COONa + 2 ↑ + 2 . It is clear from it that during the interaction of sodium bicarbonate and vinegar the sodium salt of acetic acid, water and carbon dioxide are formed .
By their nature, chemical processes take an intermediate place between physical and nuclear.
Unlike the former, the compounds involved in chemical reactions are able to change their composition. That is, from the atoms of one substance, several others can be formed, as in the above equation for the decomposition of water.
Unlike nuclear reactions, chemical does not affect the nuclei of atoms of interacting substances.
What are the types of chemical processes
The distribution of reactions of compounds by species occurs according to different criteria:
- Reversibility / Irreversibility.
- The presence / absence of catalytic substances and processes.
- By absorption / heat generation (endothermic / exothermic reaction).
- By the number of phases: homogeneous / heterogeneous and their two hybrid varieties.
- By changing the degrees of oxidation of interacting substances.
Types of chemical processes in inorganic chemistry by the method of interaction
This criterion is special. With its help, four types of reactions are distinguished: compound, substitution, decomposition (decomposition) and exchange.
The name of each of them corresponds to the process that it describes. That is, in the compound, the substances combine, in substitution, change into other groups, in decomposition several are formed from one reagent, and in exchange the reaction participants are changed by atoms.
Types of processes by the method of interaction in organic chemistry
Despite the great complexity, the reactions of organic compounds occur according to the same principle as inorganic ones. However, they have slightly different names.
So, the reactions of compound and decomposition are called “addition”, as well as “cleavage” (elimination) and directly organic decomposition (in this section of chemistry there are two types of splitting processes).
Other reactions of organic compounds are substitution (the name does not change), rearrangement (exchange), and redox processes. Despite the similarity of the mechanisms of their course, in organics they are more multifaceted.
Chemical reaction compounds
Having considered the various types of processes in which substances enter into organic and inorganic chemistry, it is worthwhile to dwell in more detail on the compound.
This reaction differs from all others in that, regardless of the number of reagents at its beginning, in the final they all combine into one.
As an example, we can recall the process of slaking lime: CaO + H 2 O → Ca (OH) 2 . In this case, the compound of calcium oxide (quicklime) reacts with hydrogen oxide (water). As a result, calcium hydroxide (hydrated lime) is formed and warm steam is released. By the way, this means that this process is truly exothermic.
The reaction equation of the compound
Schematically considered process can be represented as follows: A + BV → ABV. In this formula, ABV is a newly formed complex substance, A is a simple reagent, and BV is a variant of a complex compound.
It is worth noting that this formula is also characteristic of the process of joining and joining.
Examples of the reaction under consideration are the interaction of sodium oxide and carbon dioxide (NaO 2 + 2 ↑ (t 450-550 ° ) → Na 2 CO 3 ), as well as sulfur oxide with oxygen (2SO 2 + O 2 ↑ → 2SO 3 ) .
Several complex compounds are also capable of reacting with each other: AB + HB → ABVG. For example, the same sodium oxide and hydrogen oxide: NaO 2 + H 2 O → 2NaOH.
Reaction conditions in inorganic compounds
As was shown in the previous equation, substances of various degrees of complexity are capable of entering into the interaction under consideration.
Moreover, for simple reagents of inorganic origin, redox reactions of the compound (A + B → AB) are possible.
As an example, we can consider the process of obtaining ferric iron chloride. For this, the reaction of the compound between chlorine and ferum (iron) is carried out: 3Cl 2 ↑ + 2Fe → 2FeCl 3.
If we are talking about the interaction of complex inorganic substances (AB + HB → ABVH), the processes in them can occur, both affecting and not affecting their valency.
As an illustration of this, it is worth considering an example of the formation of calcium hydrogen carbonate from carbon dioxide, hydrogen oxide (water) and white food coloring E170 (calcium carbonate): 2 ↑ + 2 + 3 → Ca (CO 3 ) 2. In this case, a classical compound reaction takes place. During its implementation, the valency of the reagents does not change.
The slightly more advanced (than the first) chemical equation 2FeCl 2 + Cl 2 ↑ → 2FeCl 3 is an example of the redox process in the interaction of simple and complex inorganic reagents: gas (chlorine) and salt (iron chloride).
Types of addition reactions in organic chemistry
As already indicated in the fourth paragraph, in substances of organic origin the reaction in question is called “addition”. As a rule, complex substances with a double (or triple) bond take part in it.
For example, the reaction between dibrom and ethylene leading to the formation of 1,2-dibromoethane: (C 2 H 4 ) CH 2 = CH 2 + Br 2 → (C₂H₄Br₂) BrCH 2 - CH 2 Br. By the way, signs similar to equal and minus ("=" and "-"), in this equation show the bonds between the atoms of a complex substance. This is a feature of writing formulas of organic substances.
Depending on which of the compounds act as reagents, several varieties of the joining process under consideration are distinguished:
- Hydrogenation (hydrogen molecules H are added via a multiple bond).
- Hydrohalogenation (hydrogen halide attached).
- Halogenation (addition of Br 2 halogens, Cl 2 ↑ and the like).
- Polymerization (the formation of substances with a high molecular weight from several low molecular weight compounds).
Examples of the addition reaction (compound)
After listing the varieties of the process in question, it is worthwhile to find out in practice some examples of the reaction of the compound.
As an illustration of hydrogenation, you can pay attention to the equation of interaction of propene with hydrogen, which will result in propane: (C 3 H 6 ↑) CH 3 —CH = CH 2 ↑ + H 2 ↑ → (C 3 H 8 ↑) CH 3 —CH 2 —CH 3 ↑ .
In organic chemistry, the reaction of a compound (addition) can occur between hydrochloric acid (inorganic substance) and ethylene with the formation of chloroethane: (C 2 H 4 ↑) CH 2 = CH 2 ↑ + HCl → CH 3 - CH 2 —Cl (C 2 H 5 Cl). The presented equation is an example of hydrohalogenation.
As for halogenation, it can be illustrated by the reaction between dichloro and ethylene leading to the formation of 1,2-dichloroethane: (C 2 H 4 ↑) CH 2 = CH 2 + Cl 2 ↑ → (C₂H₄Cl₂) ClCH 2 -CH 2 Cl.
Many useful substances are formed due to organic chemistry. The reaction of the compound (addition) of ethylene molecules with a radical initiator of polymerization under the influence of ultraviolet radiation is a confirmation of this: n CH 2 = CH 2 (R and UV light) → (-CH 2 -CH 2 -) n. The substance formed in this way is well known to everyone under the name of polyethylene.
Various types of packages, bags, dishes, pipes, insulation materials and much more are made from this material. A feature of this substance is the possibility of its secondary processing. Its popularity is due to the fact that polyethylene does not decompose, which is why environmentalists have a negative attitude towards it. However, in recent years, a method has been found for the safe disposal of polyethylene products. For this, the material is treated with nitric acid (HNO 3 ). After that, certain types of bacteria are able to decompose this substance into safe components.
The reaction of the compound (accession) plays an important role in nature and human life. In addition, it is often used by scientists in laboratories to synthesize new substances for various important studies.