Let's look at the example of an alkane C 6 H 14.
1. First, we depict the linear isomer molecule (its carbon skeleton)
2. Then we shorten the chain by 1 carbon atom and attach this atom to any carbon atom of the chain as a branch from it, excluding extreme positions:
(2) or (3)
If you attach a carbon atom to one of the extreme positions, the chemical structure of the chain does not change:
In addition, you need to ensure that there are no repetitions. Yes, the structure
identical to structure (2).
3. When all positions of the main chain have been exhausted, we shorten the chain by another 1 carbon atom:
Now there will be 2 carbon atoms in the side branches. The following combinations of atoms are possible here:
A side substituent may consist of 2 or more carbon atoms connected in series, but for hexane there are no isomers with such side branches, and the structure
identical to structure (3).
A side substituent - C-C can only be placed in a chain containing at least 5 carbon atoms and can only be attached to the 3rd and further atom from the end of the chain.
4. After constructing the carbon skeleton of the isomer, it is necessary to supplement all carbon atoms in the molecule with hydrogen bonds, given that carbon is tetravalent.
So, the composition C 6 H 14 corresponds to 5 isomers:
2) 
3) 
4) 
5) 
Rotational isomerism of alkanes
A characteristic feature of s-bonds is that the electron density in them is distributed symmetrically relative to the axis connecting the nuclei of the bonded atoms (cylindrical or rotational symmetry). Therefore, the rotation of atoms around the s-bond will not lead to its breaking. As a result of intramolecular rotation along C–C s-bonds, alkane molecules, starting with ethane C 2 H 6, can take on different geometric shapes.
Various spatial forms of a molecule that transform into each other by rotating around C–C s-bonds are called conformations or rotary isomers(conformers).
Rotational isomers of a molecule are its energetically unequal states. Their interconversion occurs quickly and constantly as a result of thermal movement. Therefore, rotary isomers cannot be isolated in individual form, but their existence has been proven by physical methods. Some conformations are more stable (energetically favorable) and the molecule remains in such states for a longer time.
Let's consider rotary isomers using ethane H 3 C–CH 3 as an example:
When one CH 3 group rotates relative to another, many different forms of the molecule arise, among which two characteristic conformations are distinguished ( A And B), characterized by a rotation of 60°:
These rotary isomers of ethane differ in the distances between the hydrogen atoms connected to different carbon atoms.
In conformation A The hydrogen atoms are close together (obscure each other), their repulsion is great, the energy of the molecule is maximum. This conformation is called “eclipsed”, it is energetically unfavorable and the molecule goes into the conformation B, where the distances between H atoms of different carbon atoms are greatest and, accordingly, repulsion is minimal. This conformation is called “inhibited” because it is energetically more favorable and the molecule remains in this form for more time.
As the carbon chain lengthens, the number of distinguishable conformations increases. Thus, rotation along the central bond in n-butane
leads to four rotary isomers:
The most stable of them is conformer IV, in which the CH 3 groups are maximally distant from each other. Construct the dependence of the potential energy of n-butane on the angle of rotation with students on the board.
Optical isomerism
If a carbon atom in a molecule is bonded to four different atoms or atomic groups, for example:
then the existence of two compounds with the same structural formula, but differing in spatial structure, is possible. The molecules of such compounds relate to each other as an object and its mirror image and are spatial isomers.
This type of isomerism is called optical; isomers are called optical isomers or optical antipodes:
Molecules of optical isomers are incompatible in space (like left and right hands); they lack a plane of symmetry.
Thus, optical isomers are spatial isomers whose molecules are related to each other as an object and a mirror image incompatible with it.
Optical isomers have the same physical and chemical properties, but differ in their relationship to polarized light. Such isomers have optical activity (one of them rotates the plane of polarized light to the left, and the other by the same angle to the right). Differences in chemical properties are observed only in reactions with optically active reagents.
Optical isomerism manifests itself in organic substances of various classes and plays a very important role in the chemistry of natural compounds.
Okay, maybe not so much.
To go through everything and not miss a single one, you can come up with several approaches. I like this one: Take ethene (ethylene) CH2 = CH2. It differs from heptene by 5 carbon atoms (C5H10). To sort through all possible isomers, you need to take one hydrogen atom from ethene and give it to the C5H10 fragment. The result is an alkyl C5H11, and it must be added to the ethene residue (ethenyl CH2=CH-) in place of the removed hydrogen.
1) The C5H11 alkyl itself can have several isomers. The simplest one with a straight chain is CH2-CH2-CH2-CH2-CH3 (pentyl or amyl). From it and ethenyl, heptene-1 (or 1-heptene, or hept-1-ene) is formed, which is simply called heptene CH2=CH-CH2-CH2-CH2-CH2-CH3.
2a) If in a pentyl we move one hydrogen from the C2 atom to the C1 atom, we get pentyl-2 (or 2-pentyl, or pent-2-yl) CH3-CH(-)-CH2-CH2-CH3. The dash in parentheses means that the stick needs to be drawn up or down, and that there is an unpaired electron here, and this is where the pentyl-2 will attach to the ethenyl. The result is CH2=CH-CH(CH3)-CH2-CH2-CH3 3-methylhexene-1 or 3-methyl-1-hexene or 3-methylhex-1-ene. I hope you understand the principle of the formation of alternative names, so for the compounds mentioned below I will give only one name.
2b) If in a pentyl we move one hydrogen from the C3 atom to the C1 atom, we get pentyl-3 CH3-CH2-CH(-)-CH2-CH3. Combining it with ethenyl we get CH2=CH-CH(CH2-CH3)-CH2-CH3 3-ethylpentene-1
3a, b) Pentyl is isomerized into a chain of 4 carbon atoms (butyl) having one methyl group. This methyl group can be attached to the C2 or C3 atom of the butyl. We obtain, respectively, 2-methylbutyl -CH2-CH(CH3)-CH2-CH3 and 3-methylbutyl -CH2-CH2-CH(CH3)-CH3, and adding them to ethenyl we obtain two more isomers C7H14 CH2=CH-CH2-CH( CH3)-CH2-CH3 4-methylhexene-1 and CH2=CH-CH2-CH2-CH(CH3)-CH3 5-methylhexene-1.
4a, b) Now in butyl we move the line to the C2 atom, we get 2-butyl CH3-CH(-)-CH2-CH3. But we need to add one more carbon atom (replace H with CH3). If we add this methyl to one of the terminal atoms, we get the pentyl-3 and pentyl-2 already discussed. But the addition of methyl to one of the middle atoms will give two new alkyls CH3-C(CH3)(-)-CH2-CH3 2-methyl-2-butyl- and CH3-CH(-)-CH(CH3)-CH3 2 -methyl-2-butyl-.
By adding them to ethenyl we get two more isomers C7H14 CH2=CH-C(CH3)2-CH2-CH3 3,3-dimethylpentene-1 and CH2=CH-CH(CH3)-CH(CH3)-CH3 3.4 -dimethyl-pentene-1.
5) Now, when building an alkyl, we will leave a chain of 3 carbon atoms -CH2-CH2-CH3. The missing 2 carbon atoms can be added either as ethyl or as two methyls. In the case of addition in the form of ethyl, we obtain the already considered options. But two methyls can be attached either both to the first, or one to the first, one to the second carbon atoms, or both to the second. In the first and second cases we get the already considered options, and in the last we get a new alkyl -CH2-C(CH3)2-CH3 2,2-dimethylpropyl, and adding it to ethenyl we get CH2=CH-CH2-C(CH3)2- CH3 4,4-dimethylpentene-1.
Thus, 8 isomers have already been obtained. Note that in these isomers the double bond is at the end of the chain, i.e. binds atoms C1 and C2. Such olefins (with a double bond at the end are called terminal). Terminal olefins do not exhibit cis-trans isomerism.
Next, we divide the C5H10 fragment into two fragments. This can be done in two ways: CH2 + C4H8 and C2H4 + C3H6. From the CH2 and C2H4 fragments, only one variant of alkyls can be constructed (CH3 and CH2-CH3). From the C3H6 fragment, propyl -CH2-CH2-CH3 and isopropyl CH3-CH(-)-CH3 can be formed.
From the C4H8 fragment, the following alkyls can be constructed -CH2-CH2-CH2-CH3 - butyl-1, CH3-CH(-)-CH2-CH3 - butyl-2, -CH2-CH(CH3)-CH3 - isobutyl (2-methylpropyl ) and -C(CH3)2-CH3 - tert-butyl (2,2-dimethylethyl).
To add them to alkyls, we remove two hydrogen atoms from the ethene molecule. This can be done in three ways: by removing both hydrogen atoms from the same carbon atom (this will produce terminal olefins), or by removing one from each. In the second option, these two hydrogen atoms can be removed from the same side of the double bond (cis isomers are obtained), and from different sides (trans isomers are obtained).
CH2=C(CH3)-CH2-CH2-CH2-CH3 - 2-methylhexene-1;
CH2=C(CH3)-CH(CH3)-CH2-CH3 - 2,3-dimethylpentene-1;
CH2=C(CH3)-CH2-CH(CH3)-CH3 - 2,4-dimethylpentene-1;
CH2=C(CH3)-C(CH3)2-CH3 - 2,3,3-trimethyl butene-1.
CH2=C(CH2CH3)-CH2-CH2-CH3 - 2-ethylpentene-1 or 3-methylenehexane;
CH2=C(CH2CH3)-CH(CH3)-CH3 - 2-ethyl-3-methylbutene-1 or 2-methyl-3-methylenepentane.
CH3-CH=CH-CH2-CH2-CH2-CH3 - heptene-2 (cis and trans isomers);
CH3-CH=CH-CH(CH3)-CH2-CH3 - 4-methylhexene-2 (cis and trans isomers);
CH3-CH=CH-CH2-CH(CH3)-CH3 - 5-methylhexene-2 (cis and trans isomers);
CH3-CH=CH-C(CH3)2-CH3 - 4,4-dimethylpentene-2 (cis and trans isomers);
CH3-CH2-CH=CH-CH2-CH2-CH3 - heptene-3 (cis and trans isomers);
CH3-CH2-CH=CH-CH(CH3)-CH3 - 2-methylhexene-3 (cis and trans isomers).
Well, with olefins it seems like everything. What remains are the cycloalkanes.
In cycloalkanes, several carbon atoms form a ring. Conventionally, it can be considered as a flat cycle. Therefore, if two substituents are attached to the ring (at different carbon atoms), then they can be located on the same side (cis-isomers) or on opposite sides (trans-isomers) of the ring plane.
Draw a heptagon. Place CH2 at each vertex. The result was cycloheptane;
Now draw a hexagon. Write CH2 at five vertices, and CH-CH3 at one. The result was methylcyclohexane;
Draw a pentagon. Draw CH-CH2-CH3 at one vertex, and CH2 at the other vertices. ethylcyclopentane;
Draw a pentagon. Draw CH-CH3 at two vertices in a row, and CH2 at the remaining vertices. The result was 1,2-dimethylpentane (cis- and trans-isomers);
Draw a pentagon. At two vertices, draw CH-CH3 through one, and CH2 at the remaining vertices. The result was 1,3-dimethylpentane (cis- and trans-isomers);
Draw a quadrilateral. Draw CH2 at three vertices, and CH at one, and attach -CH2-CH2-CH3 to it. The result was propylcyclobutane;
Draw a quadrilateral. Draw CH2 at three vertices, and CH at one, and attach -CH(CH3)-CH3 to it. The result is isopropylcyclobutane;
Draw a quadrilateral. Draw CH2 at three vertices, and C at one, and attach the CH3 and CH2-CH3 groups to it. The result was 1-methyl-1-ethylcyclobutane;
Draw a quadrilateral. Draw CH2 at two vertices in a row, and CH at the other two. Add CH3 to one CH, and CH2-CH3 to the other. The result was 1-methyl-2-ethylcyclobutane (cis- and trans-isomers);
Draw a quadrilateral. At two vertices, draw CH2 through one, and at the other two, CH. Add CH3 to one CH, and CH2-CH3 to the other. The result was 1-methyl-3-ethylcyclobutane (cis and trans isomers);
Draw a quadrilateral. At two vertices in a row, draw CH2, at one CH, at one C. Draw CH3 to CH, and to C two groups of CH3. The result was 1,1,2-dimethylcyclobutane;
Organic chemistry is not that easy.
You can guess something using logical reasoning.
And somewhere logic will not help, you need to cram.
As, for example, in this question.
Here's a look at the formulas:
Hydrocarbons corresponding to the formula C17H14 belong to both alkenes and cycloalkanes. Therefore, as Rafail told you in the comment, there are a lot of them. In alkenes (intraclass isomerism) there are three types of isomerism: 1). isomerism of double bond position; 2). carbon skeleton isomerism; 3). and some alkenes have spatial cis- and trans-isomers. And cycloalkanes within this class have closed ring isomerism, and some cycloalkanes have cis and trans isomers. It is necessary to decide on the class of connections.
In fact, there are quite a lot of them, so I won’t list them all:
Here are some of their representatives:
But there are still many of them and, frankly speaking, it is very difficult to remember all the representatives of all isomers of this composition.
Not a very simple task, or rather not a very quick one. I can’t give you all, but more than 20 isomers for the indicated composition:
If your task is to compose drawings, then I sympathize with you, but I found several images with compiled isomer chains:
In general, be strong!
Hexane is an organic compound known as a hydrocarbon. The hexane molecule consists of only carbon and hydrogen atoms in a chain structure. The article provides the structural formula and isomers of hexane, as well as the reactions of hexane with other substances.
Most often, the substance is extracted by refining crude oil. Thus, it is a common component of gasoline used in automobiles and other internal combustion engines. Additionally, it has many uses in home, laboratory or industrial settings. To understand what hexane is, learn more about its properties and abilities.
Hexane is usually a colorless liquid, best known as a solvent.
Hexane is a substance composed of carbon and hydrogen that is most commonly released as a byproduct of petroleum or crude oil refining. It is a colorless liquid at room temperature and has many industrial uses. For example, it is a very popular solvent and is often used in industrial cleaners; it is also often used to extract oils from vegetables, especially soybeans. Most gasoline contains gasoline. While most experts say the compound is non-toxic and poses only low risks to animals, there is still a lot of controversy in many places when it comes to how often it is included, sometimes without full disclosure, in consumer products.
Physical properties of hexane
Hexane appears as a colorless liquid with a petroleum odor that is stable at room temperature. There are several different types of hexane, but their properties are similar. Its melting point occurs at -139.54 degrees Fahrenheit and its boiling point is 154.04 degrees Fahrenheit. Melting points and boiling points vary depending on the type of hexane. Hexane has a molar mass of 86.18 g per mole. It is a non-polar molecule and does not dissolve in water.
Hexane: formula
It is generally considered a relatively simple molecule.As the hexadecimal prefix indicates, it has six carbon atoms, which are accompanied by 14 hydrogen atoms, giving it the molecular formula C6H14.Carbohydrates are connected in chains, one after the other.Each carbon has at least two hydrogen atoms attached to it, except for the first and last carbon, which have three.Due to its exclusive carbon-hydrogen composition and the fact that it only has bonds, it can be classified as a straight-chain alkane. The formula for hexane is denoted as CH3CH2CH2CH2CH2CH3, but is more often written as C6H14.
Hexane has 6 carbon atoms (black) and 14 hydrogen atoms (white).
Structural formula of hexane
The structure of hexane is such that the prefix "hex" in the name of hexane indicates that the hexane molecule has six carbon atoms. These atoms are arranged in a chain and linked together with single bonds. Each carbon atom has at least two hydrogen atoms attached to the terminal carbon atoms, which have three. This chain structure with carbon and hydrogen atoms means that it is classified as an alkane, which is where its name suffix comes from. Hexane is expressed as CH3CH2CH2CH2CH2CH3, but is more commonly expressed as C6H14. Other isomers of hexane have different structures. They are usually branched rather than having a long hexagonal chain.Where does hexane come from and how to extract it?
Hexane is produced in several different places in nature, but is usually most readily available in oil fields. This is often due to the fact that gasoline contains it in high concentrations. When petroleum and petroleum-based oils are extracted and refined, chemists can often isolate a compound that can then be purified and sold commercially.
Hexane is a naturally occurring compound that occurs in several places in nature. However, hexane is most often extracted from oil by refining crude oil. Industrial hexane is extracted into a fraction boiling at temperatures of 149 degrees Fahrenheit to 158 degrees Fahrenheit. Differences in temperatures and purification processes account for the different types of hexane and their different properties.
The most common use of hexane is as an industrial cleaner. Because it is insoluble in water, it is effective in separating from other substances as well as breaking down molecules. This makes it effective as a degreaser. This is not a common additive found in household cleaning products, and users are most likely to find it in heavy equipment and industrial cleaning products. In addition, it is also effective in bonding materials together and is a common ingredient in adhesives for various purposes.
Exposure to hexane without the correct safety equipment can cause long-term damage and even...
Laboratory use
Hexane is also used in laboratory settings. In particular, it is used as a solvent in chromatography. This is a popular separation used by scientists to identify the different components of a compound or unidentified substance. In addition to chromatography, hexane is a popular solvent for use in a variety of reactions and processes. In addition, hexane is used to separate oil and grease in soil and water analysis.Oil refining
Another use of hexane is required for petroleum refining. Manufacturers extract oils from peanuts, soybeans and corn to make vegetable oil. Manufacturers treat vegetables with hexane, which effectively breaks down the produce to extract oil.Many types of plants and vegetables are treated with this chemical to extract their oils and proteins for use in other products. Soybeans, peanuts and corn are some of the most common. The compound is often able to break down these products very effectively, and the resulting oils are usually ready to be repackaged and either sold or used in finished products with very little additional processing.
Other common uses of hexane
Just as good at breaking down compounds, hexane in combination with other non-aqueous soluble compounds can help to enhance the property of the substance. For example, it is often listed as an ingredient in leather and shoe adhesives, and is sometimes also used in roofing or tile adhesives.
Despite its use in the food industry, hexane is a toxic substance. Therefore, users should handle this component with care and take proper precautions. Inhalation of hexane is one of the most common problems. When cleaning with hexane or using hexane in the laboratory, wear a respirator and work in a well-ventilated area.In addition, users should avoid getting the product into . Finally, users should always wear gloves when handling hexane. When proper safety precautions and handling are used, hexane is generally safe to use. The EPA has classified hexane as Group D or has not classified its carcinogenicity for .
Hexane is generally considered to be toxic, or at least harmful when inhaled, and there have been workplace incidents and even deaths where hours each day were spent inhaling its fumes. This is most common in plants where oil waste is processed, industrial refining, or some other industrial processes take place. Long-term exposure to hexane can cause dizziness and nausea, which gets worse over time.
There have also been questions about hexane residues that linger in vegetable oils, especially when they appear in foods available on the general market. Some advocates argue that the presence of this chemical is unacceptable and dangerous, while others say it should not be a cause. In most cases, the amount that actually ends up in food is very, very small, but still not much is known about how the body behaves in relation to even this amount. Most toxicity studies that have been conducted have focused on inhalation and topical dermal exposure.
Some people who are exposed to hexane experience dizziness and nausea that get worse over time.
How to buy products with hexane ?
The store for industrial cleaners, adhesives and other products containing hexane will offer you any modifications and specifications. Use the basic and advanced search functions to find the products you need by entering keywords into the search bar found on any page of the construction site. Use the refine menu to narrow your lists and make them easier to sort. Hexane is a natural compound with a variety of commercial, industrial and residential needs. Formulas of hexane isomers
Question: What are the isomers of *hexane*? (Please draw them...)Answer:
I have listed 5 possible hydrocarbon isomers of hexane below.
Explanation:
Recall that isomers have the same chemical formula (in this case C6H14), but different structural formulas and, therefore, different physical and chemical properties.
Structural isomers of hexane
For example, let's take hydrocarbons of the saturated and unsaturated series.
Definition
First, let's find out what the phenomenon of isomerism is. Depending on the number of carbon atoms in the molecule, the formation of compounds that differ in structure, physical and chemical properties is possible. Isomerism is a phenomenon that explains the diversity of organic substances.
Isomerism of saturated hydrocarbons
How to compose isomers, name representatives of this class of organic compounds? In order to cope with the task, let us first highlight the distinctive characteristics of this class of substances. Saturated hydrocarbons have the general formula SpH2n+2; their molecules contain only simple (single) bonds. Isomerism for representatives of the methane series presupposes the existence of different organic substances that have the same qualitative and quantitative composition, but differ in the sequence of arrangement of atoms.
If saturated hydrocarbons contain four or more carbon atoms, isomerism of the carbon skeleton is observed for representatives of this class. For example, you can create a formula for substances of isomers of the composition C5H12 in the form of normal pentane, 2-methylbutane, 2,2-dimethylpropane.
Subsequence
Structural isomers characteristic of alkanes are composed using a specific algorithm of actions. In order to understand how to compose isomers of saturated hydrocarbons, let us dwell on this issue in more detail. First, a straight carbon chain with no additional branches is considered. For example, if there are six carbon atoms in a molecule, you can create the formula for hexane. Since all alkanes have single bonds, only structural isomers can be written for them.
Structural isomers
To compose the formulas of possible isomers, the carbon skeleton is shortened by one C atom, it turns into an active particle - a radical. The methyl group can be located at all atoms in the chain, excluding the outermost atoms, thereby forming various organic derivatives of alkanes.
For example, you can formulate the formula 2-methylpentane, 3-methylpentane. Then the number of carbon atoms in the main (main) chain is reduced by one more, resulting in two active methyl groups. They can be placed at the same or adjacent carbon atoms, resulting in various isomeric compounds.
For example, you can create formulas for two isomers: 2,2-dimethylbutane, 2,3-dimethylbutane, which differ in physical characteristics. With subsequent shortening of the main carbon skeleton, other structural isomers can be obtained. So, for hydrocarbons of the limiting series, the phenomenon of isomerism is explained by the presence of single (simple) bonds in their molecules.
Features of alkene isomerism
In order to understand how to compose isomers, it is necessary to note the specific features of this class of organic substances. We have the general formula SpN2n. In the molecules of these substances, in addition to a single bond, there is also a double bond, which affects the number of isomeric compounds. In addition to the structural isomerism characteristic of alkanes, for this class one can also distinguish isomerism of the position of a multiple bond, interclass isomerism.
For example, for a hydrocarbon with the composition C4H8, you can create formulas for two substances that will differ in the location of the double bond: butene-1 and butene-2.
To understand how to form isomers with the general formula C4H8, you need to understand that, in addition to alkenes, cyclic hydrocarbons also have the same general formula. Examples of isomers belonging to cyclic compounds include cyclobutane and methylcyclopropane.
In addition, for unsaturated compounds of the ethylene series, the formulas for geometric isomers can be written: cis and trans forms. Hydrocarbons that have a double bond between carbon atoms are characterized by several types of isomerism: structural, interclass, geometric.
Alkynes
Compounds that belong to this class of hydrocarbons have a general formula - SpN2n-2. Among the distinctive characteristics of this class is the presence of a triple bond in the molecule. One of them is simple, formed by hybrid clouds. Two bonds are formed when non-hybrid clouds overlap; they determine the features of isomerism of this class.
For example, for a hydrocarbon with the composition C5H8, you can create formulas for substances that have an unbranched carbon chain. Since there is a multiple bond in the parent compound, it can be positioned differently, forming pentine-1, pentine-2. For example, you can write an expanded and abbreviated formula for a compound with a given qualitative and quantitative composition, in which the carbon chain will be reduced by one atom, which will be represented in the compound as a radical. In addition, for alkynes there are also interclass isomers, which are diene hydrocarbons.
For hydrocarbons that have a triple bond, you can create isomers of the carbon skeleton, write formulas for dienes, and also consider compounds with different arrangements of the multiple bond.
Conclusion
When composing the structural formulas of organic substances, oxygen and carbon atoms can be arranged in different ways, obtaining substances called isomers. Depending on the specific class of organic compounds, the number of isomers may vary. For example, hydrocarbons of the limiting series, which include compounds of the methane series, are characterized only by structural isomerism.
For ethylene homologues, which are characterized by the presence of a multiple (double) bond, in addition to structural isomers, it is also possible to consider isomerism of the position of the multiple bond. In addition, other compounds that belong to the class of cycloalkanes have the same general formula, that is, interclass isomerism is possible.
For oxygen-containing substances, for example, for carboxylic acids, the formulas of optical isomers can also be written.