Obtaining chloroethane from ethanol. How to get ethanol from ethane
Chemical formula ethyl alcohol (ethanol) - C2H5OH. And the substance chloroethane, used as a refrigerant and for anesthesia in medical purposes, has the formula C2H5Cl. These substances are similar in composition, only in the first case, a hydroxyl group is attached to the ethyl radical C2H5, and in the second case, a chlorine ion. It is possible to chemically obtain both ethanol from chloroethane and chloroethane from ethanol.
Instruction
There are a number of ways to chemically convert chloroethane from ethyl alcohol. For example, you can subject a container of ethanol to high heat in the presence of concentrated sulfuric acid. And then the resulting ethylene gas is combined with gaseous hydrogen chloride. Here is the scheme of the first stage of the reaction: С2Н5ОН=С2Н4+Н2О.
The resulting water is absorbed by concentrated sulfuric acid, which is very hygroscopic. Gaseous ethylene is collected in another container connected to the reaction flask with a glass adapter.
When the resulting ethylene reacts with gaseous hydrogen chloride, chloroethane is formed. Here is the scheme of the second stage of the reaction: С2Н4+НCl=С2Н5Сl.
This reaction takes place in the presence of a catalyst, iron trichloride. By the way, in industry, chloroethane is obtained in this way (of course, without using ethyl alcohol as a feedstock).
You can get chloroethane using the reaction of the interaction of ethyl alcohol with phosphorus pentachloride. After mixing these substances, the reaction mixture is poured into water, and using a separating funnel, the organic part (chloroethane) is separated from the inorganic part due to the fact that chlorethane is very poorly miscible with water. The reaction proceeds as follows: C2H5OH + PCl5 = C2H5Cl + HCl + POCl3.
There is another popular laboratory method for obtaining chloroethane from ethyl alcohol. When ethanol reacts with thionyl chloride, chloroethane is obtained, hydrochloric acid and gaseous sulfur dioxide. You can separate the organic phase from the inorganic phase, as in the previous example, using a separating funnel. The reaction proceeds according to the following scheme: C2H5OH + SOCl2 = C2H5Cl + HCl + SO2.
In the second case, the reaction is completely unprofitable in the economic sense, and is only of practical interest.
Halogen derivatives of hydrocarbons are products of substitution of hydrogen atoms in hydrocarbons for one or more halogen atoms.
Most halogenated hydrocarbons (haloalkyls) are highly reactive compounds. Substitution and elimination reactions are of the greatest importance for compounds of this class. The chemical properties of haloalkyls are determined primarily by the C-X bond (X = F, Cl, Br, I). The C-X bond in haloalkyls is characterized by increased polarity. This is explained by the greater electronegativity of the halogen atom compared to the carbon with which it is bonded.
The shift of the electron density occurs towards the halogen atom (-I- effect). Such a redistribution of the electron density leads to the fact that a partial negative charge (-) appears on the halogen atom, and a partial positive charge (+) appears on the carbon atom:
As a result, the C-X bond becomes polarized. The reduced electron density on the carbon atom determines the high, in contrast to saturated hydrocarbons, the reactivity of halogen derivatives, which easily enter into the reactions of nucleophilic substitution (SN) and elimination (elimination) (E).
Laboratory work
Objective: study of methods for obtaining and chemical properties of halogen derivatives of hydrocarbons.
Reagents and equipment: 2N NaOH; H 2 SO 4 conc.; 0.2n AgNO 3 ;I 2 in KI solution; chlorobenzene; ethanol; NaCl (solid); chloral hydrate (crystal).
rack with test tubes; holder for test tubes; glass slides; spirit lamp, microscope.
Experience 3.1 Obtaining chloroethane from ethanol
Small crystals of sodium chloride are poured into a test tube to a height of about 3 mm and 3-4 drops of ethyl alcohol are added so that all the salt is moistened with alcohol. Then 3-4 drops of sulfuric acid are added and heated over the flame of an alcohol lamp, avoiding too rapid release of hydrogen chloride. To control the progress of the formation of chloroethane, bring the opening of the test tube to the flame of an alcohol lamp and set it on fire (chloroethane burns with the formation of a characteristic green ring). After the initial heating, as soon as even a faint green ring of chloroethane is noticed, the heating is stopped. It is necessary to write the reaction equations.
Note. The test tube should not be heated unnecessarily, as a significant amount of hydrogen chloride is released during the reaction. For this reason, no attempt should be made to determine the smell of chloroethane.
Experience 3.2 Obtaining chloroform from chloral hydrate
Place 3-4 crystals of chloral hydrate in a test tube, add 6-8 drops of 2n. NaOH and slightly warm the liquid, which has become cloudy already at room temperature. What is happening? You should pay attention to the smell of the resulting liquid, comparing it with the smell of chloroform from a bottle. It is necessary to write the reaction equations.
Experience 3.3 Obtaining iodoform from ethanol
Place 2 drops of ethanol, 3 drops of a solution of iodine in potassium iodide and 3 drops of 2N sodium hydroxide into a test tube. NaOH. With slight heating, (sometimes even from the warmth of the hands), a white turbidity appears with a characteristic very persistent odor of iodoform. When the turbidity is dissolved, another 3-5 drops of iodine solution should be added to the warm solution. Wait 2-3 minutes for crystals to form. Then, using a pipette, 2 drops of liquid with iodoform crystals are taken from the bottom of the test tube, transferred to a glass slide under a microscope, and the shape of the resulting crystals is drawn in a journal. Write reaction equations.
Note. Heat the mixture of iodine with alcohol and alkali to a boil, but do not boil, as the resulting iodoform will decompose.
Experience 3.4Comparative mobility of the halogen in the benzene ring
Chloroethane is a flammable volatile liquid that has a peculiar odor and colorless color. Chloroethane is very often used in medical practice for anesthesia or inhalation anesthesia. This is a fairly powerful narcotic drug, due to which anesthesia occurs very quickly, literally within a few minutes. The main disadvantage of this chemical, is the short duration of action, that is, after anesthesia, awakening occurs after 20 minutes, so it can only be used for short-term surgical interventions. It can also be used as a local analgesic for dermatitis, sports injuries, bruises, insect bites, inflammation, etc.
There are different types of chemical reactions in organic chemistry:
1. Cleavage (elimination)
These are chemical reactions, as a result of which molecules of several new substances are formed from the molecule of the original compound. Of great importance among elimination reactions is the reaction of thermal splitting of carbons.
2. Accession
As a result of these reactions, several molecules of reacting substances are combined into one. This is the main feature of addition reactions.
3. Substitution
During these reactions, one atom or a whole group of atoms is replaced by another atom or another group of atoms.
4. Rearrangement (isomerization)
As a result of these reactions, molecules of one substance form molecules of other substances.
How to get chloroethane from ethylene
In this case, we will use the addition reaction - hydrohalogenation (addition of hydrogen halide). So, chloroethane from ethylene can be obtained by the following reaction:
C2H4 + HCI = C2H5Cl
How to get ethanol from chloroethane
Now we need to use chemical reaction- substitution with alkali, as a result of which we get alcohol and salt:
C2H5Cl + NaOH = C2H5OH + NaCl
How to get chloroethane from ethane
In order to obtain chloroethane from ethane, we use the usual halogenation of alkanes. Only, you need to remember one important condition, the reactions must be carried out in the presence of light. Here chemical equation, given by the reaction.
In order to understand how to get chloroethane from ethane, we first analyze the features of ethane.
Brief description of ethane
This hydrocarbon has the formula C2H6. The carbons in its molecule are in the sp3 hybrid state. This affects the physical and chemical properties of this substance. Under normal conditions, ethane is gaseous substance sparingly soluble in water. Like all other representatives of the alkane class, ethane has saturated simple bonds. This is reflected in the chemical properties of this hydrocarbon. It is not capable of entering into addition reactions; only radical substitution is permissible for it.
flow feature
Find out how to get chloroethane from ethane. To do this, it is necessary to carry out a reaction between ethane and chlorine in the presence of a quantum of light (elevated temperature). Due to the homolytic bond cleavage, chlorine radicals are formed. Education requires a certain amount of energy.
It can be purchased in a variety of ways. Thermal pyrolysis can be considered as one of the options for the formation of radicals. To obtain chloroethane from ethane, the equation is written at a temperature of about 500 0 C. The energy that will be released in this case is enough to break bonds. The second method for the formation of active radicals is the use of ultraviolet radiation.
Mechanism of the radical substitution reaction
Consider how to get chloroethane from ethane. proceeds by the mechanism of the SR action of halogens with alkanes. In the gas phase, during the reaction of ethane with chlorine, chlorine is first dissociated under the action of UV. This stage is called initiation, it is it that is characterized by the appearance of active particles-radicals of chlorine. The resulting particles attack the ethane molecule, forming hydrogen chloride, as well as the ethyl C2H5 radical.
Let's continue the conversation about how to get chloroethane from ethane. At the next stage, the ethyl radical interacts with a chlorine molecule, forming ethane chloride and another chlorine radical. It is he who is able to re-enter the reaction, continuing the cycle of a chain reaction. This stage is called chain growth. The number of active radicals at this stage of the interaction does not change, but remains in full. The cycle is completed by the third stage of the reaction, which is called chain termination. It involves the collision of free particles, resulting in the formation of reaction products.
Application
The answer to the question of how to get chloroethane from ethane. Let's take a look at the application. The resulting chloroethyl is a serious narcotic substance. It is used as an anesthetic during surgical operations. Two or three seconds are enough to minimize motor activity.
As the main disadvantage of this substance, we note the possibility of an overdose. Even a slight increase in the permissible norm causes serious problems for the human body. Today, chloroethane is used only in some cases as a narcotic substance.
To a greater extent, it is in demand as a local remedy for short-term superficial anesthesia of the skin. Getting on the skin, the substance evaporates, hypothermia of the skin occurs, its sensitivity decreases, as a result of which it becomes possible to make incisions, that is, to carry out minor superficial operations.
Also, this substance is used to reduce skin itching, treat thermal burns, neuromyositis, and cryotherapy for inflammation. The ampoule is first heated in the palm of your hand, then the jet is directed to the skin. For medicinal purposes, the procedure is carried out once a day for 7-10 days.
a) Ethane can be obtained from methane in two steps. When methane is chlorinated, chloromethane is formed:
When chloromethane reacts with sodium, ethane is formed (Wurtz reaction):
Ethanol can be obtained from ethane in two steps. When ethane is chlorinated, chloroethane is formed:
When an aqueous solution of alkali acts on chloroethane, the chlorine atom is replaced by a hydroxyl group and ethanol is formed.
Ethane can also be obtained from ethanol in two steps. When ethanol is heated with sulfuric acid, dehydration occurs and ethylene is formed:
b) When ethanol is heated with sulfuric acid, dehydration occurs and ethylene is formed:
When ethylene is hydrogenated over a catalyst, ethane is formed:
When ethane is chlorinated, chloroethane is formed:
Acetaldehyde can be obtained from chloroethane in two steps. Under the action of an aqueous solution of alkali on chloroethane, ethanol is formed.
When heated, ethanol is oxidized by copper oxide to acetaldehyde:
c) Butadiene can be obtained directly from ethyl alcohol when heated in the presence of a catalyst, with simultaneous dehydrogenation (hydrogen splitting) and dehydration (water splitting):
d) When calcium carbonate is heated strongly with carbon, calcium carbide is formed:
When calcium carbide is reacted with water, acetylene is obtained:
Ethyl alcohol can be obtained from acetylene in two steps. When acetylene is hydrogenated in the presence of a catalyst, ethylene is formed.