Preparation of ethanol from chloroethane. How to obtain chloroethane from ethane in organic chemistry. Mechanism of radical displacement reaction
Ethane – C2H6 – is an odorless and colorless gas, a class of alkanes. In nature, it is found in oil, natural gas, and other hydrocarbons, and therefore belongs to organic compounds. From ethane allowed to get ethyl alcohol. True, this process is quite labor-intensive, therefore alcohol usually obtained in a different way.
Instructions
1. Ethyl alcohol are obtained preferably as a result of fermentation of sugar-containing products, grains, fruits, berries, and vegetables. For this purpose, distillation units, heating, and distillation are used.
2. Get Ethyl alcohol from ethane a mild reaction is allowed in the process of catalytic oxidation when heated to 2000 degrees in the presence of a catalyst.
3. Another method of acquiring ethyl alcohol and from ethane consists in carrying out the following reactions: 1. halogenation at a temperature of 1000°C and in the presence of ultraviolet light: C2H6 + Cl2 = C2H5Cl2. Next, carry out the reaction with alkali: C2H5Cl + NaOH = C2H5OH + NaCl
4. Ethyl alcohol from ethane You can get it by one more method. Carry out dehydrogenation ethane at 400-5000°C in the presence of catalysts platinum Pt, nickel Ni, Al2O3:C2H6 = C2H4 + H2
6. Ethane is flammable, approximately insoluble in water, explosive when mixed with air, and non-toxic. When heated ethane up to a temperature of 575-10000°C it decomposes into acetylene and hydrogen, subsequent heating leads to charring and the formation of aromatic hydrocarbons.
7. Industrially, ethane is used to produce ethylene, a colorless gas with the same chemical formula as ethane. In the last century, in combination with oxygen, ethylene was used for anesthesia. Today, ethylene is the raw material for the purchase of polyethylene, vinyl acetate, ethylene oxide, acetic acid and much more. Ethylene is also a phytohormone that affects the health and growth of many living organisms.
Ethyl alcohol, or ethanol is a liquid with the chemical formula C2H5OH. When interacting with air, ethanol forms an explosive mixture. It is widely used in technology in the form of an azeotropic mixture; it is an excellent but flammable solvent. Also used in the food and medical industries. Purchase of ethyl alcohol a is a rather complicated process that requires great knowledge in the field of synthesis of similar substances.
Instructions
1. One of the methods for acquiring ethyl alcohol a – fermentation of potato starch by yeast enzymes. This method is still in use, but due to growing consumption it can no longer satisfy the needs of industry; in addition, the disadvantage of this method is the need for large expenditures of food raw materials.
2. Another method of acquiring ethanol is wood hydrolysis. This method is also associated with the use of vegetable oil. Wood contains about 50% cellulose, from which glucose is obtained using water and sulfuric acid, which is then fermented. One of the production methods for this is sulfuric acid hydrolysis of ethylene. Direct hydration of ethylene using water and phosphoric acid is also used.
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Note!
Preparing pure ethyl alcohol at home is virtually impossible; it will invariably contain impurities of poisonous methyl alcohol.
Chloroethane(other names: ethyl chloride, ethyl chloride) is a colorless gas with the chemical formula C2H5Cl. Miscible with ethyl alcohol and diethyl ether, approximately immiscible with water. How is it possible to obtain this substance?
Instructions
1. There are two main industrial methods for the synthesis of chlorine ethane:1) By hydrochlorination of ethylene (ethene). 2) By chlorination of ethane.
2. Currently, the 2nd method is recognized as more promising and economically feasible. The reaction proceeds as follows: C2H6 + Cl2 = C2H5Cl + HCl
3. Like any standard reaction of halogenation of alkanes, it proceeds according to the so-called. "radical mechanism". In order to initiate its preface, a mixture: alkane (in in this case, ethane) – a halogen (in this case, chlorine) must be exposed to saturated ultraviolet irradiation.
4. When exposed to light, the chlorine molecule breaks down into radicals. These radicals immediately interact with ethane molecules, taking away a hydrogen atom from them, as a result of which ethyl radicals C2H5 are formed, which, in turn, destroy chlorine molecules, forming new radicals. That is, a “chain reaction” occurs, so to speak.
5. Increasing temperature increases the rate of chlorination of ethane. However, because the “yield” of other chlorine-containing ethane derivatives also increases, which is undesirable, this reaction is carried out at low temperatures in order to maximize the potential acquisition of the target product.
Helpful advice
More recently, it was from this substance that tetraethyl lead Pb(C2H5)4 was produced - a well-known thermal power plant, an additive to motor fuel that increases its octane number and reduces the likelihood of detonation. Due to the exceptional harmfulness of this additive, due to the toxicity of lead and all its compounds, the use of leaded gasoline is now severely limited, and in a number of countries, completely prohibited. Only the addition of thermal power plants to aviation fuel is allowed. Chloroethane is also used in the production of cellulose acetate, in organosilicon synthesis, as a solvent for a number of resins, fats, etc. It is also used in medicine, as a fast-acting anesthetic for local anesthesia, a “freezing agent”.
Ethanol – colorless organic matter, which has a cool specific smell. It is used in industry, in laboratories - as the best organic solvent, in medicine - as a beautiful antiseptic. Ethyl alcohol also used for the production of alcoholic beverages. It is obtained by different methods.
Instructions
1. In the first place is the purchase of ethanol during the fermentation process. Glucose or grape sugar is fermented, resulting in the formation alcohol And carbon dioxide. The release of gas bubbles indicates the incompleteness of the process. Only when carbon dioxide ceases to be produced can we say that the process is complete, more alcohol will not be formed. Schematic acquisition alcohol and from glucose can be represented in the form of the reaction: C?H??O? = fermentation = C?H?OH +CO?.
2. To purchase grape wine with a table of contents of ethyl alcohol and 16%, it is allowed to use grape juice, because It contains glucose in free form. An equally well-known method is fermentation. Potatoes are used to implement this method. It is brewed, cooled and malt is added; it contains a mixture of enzymes, under the influence of which, when yeast is added, it forms alcohol .
3. There are a number of other chemical methods in which ethanol can be obtained from more primitive substances, such as ethane and ethylene, through metamorphosis. Method 1 – ethylene hydration. Treat ethylene with sulfuric acid. As a result, you should get ethyl sulfuric acid: CH? = CH? +H?SO? = CH?-CH?-OSO?OH.Next, ethyl sulfuric acid is subjected to hydrolysis: CH?-CH?-OSO?OH + H?O = C?H?OH + H?SO?.The intermediate product will be diethyl ether, consequently obtained the mixture needs further purification. Purification of reaction products is based on the difference in boiling points of ethanol and diethyl ether.
4. Method 2 – ethylene hydration. Hydration is carried out under pressure at a temperature of 300°C: CH?=CH? + H?O = C?H?OH.
5. Method 3 – purchasing ethanol from ethane in an alkaline medium with further purification. At the first stage, bromoethane is formed, at the 2nd stage - ethyl alcohol:CH?-CH? + HBr = CH?-CH?Br + HBr;CH?-CH?Br + H?O =NaOH= C?H?OH +HBr.
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Acetylene belongs to unsaturated hydrocarbons. Its chemical properties are determined triple bond. It is capable of undergoing oxidation, substitution, addition and polymerization reactions. Ethane– a saturated hydrocarbon for which radical substitution reactions, dehydrogenation and oxidation occur. At a temperature of about 600 degrees Celsius, it decomposes into hydrogen and ethene.
You will need
- – chemical equipment;
- – catalysts;
- – bromine water.
Instructions
1. Acetylene, ethylene and ethane are colorless flammable gases under normal conditions. Therefore, first familiarize yourself with safety precautions when working with volatile substances. Don’t forget to review the molecular structure and chemical properties of alkynes (unsaturated hydrocarbons), alkenes and alkanes. See how they are similar and how they differ. To purchase ethane you will need acetylene and hydrogen.
2. In order to produce acetylene in laboratory conditions, carry out the decomposition of calcium carbide CaC2. You can take it ready-made or get it by sintering the quicklime with coke: CaO+3C=CaC2+CO - the process occurs at a temperature of 2500°C, CaC2+2H2O=C2H2+Ca(OH)2. Carry out a good reaction with acetylene - decolorization of bromine water or potassium permanganate solution.
3. You can obtain hydrogen using several methods: - by the interaction of metals with acid: Zn+2 HCl=ZnCl2+H2? - during the reaction of alkali with metals whose hydroxides have amphoteric properties: Zn+2 NaOH+2 H2O=Na2+H2? - electrolysis water, to increase the electrical conductivity of which alkali is added. In this case, hydrogen is formed at the cathode, and oxygen is formed at the anode: 2 H2O = 2 H2 + O2.
4. To purchase from acetylene ethane, it is necessary to carry out a hydrogen addition reaction (hydrogenation), while considering the properties of chemical bonds: first, from acetylene ethylene is obtained, and then, during subsequent hydrogenation, ethane is obtained. To visually express the processes, compose and write down the reaction equations: C2H2 + H2 = C2H4C2H4 + H2 = C2H6 The hydrogenation reaction occurs at room temperature in the presence of catalysts - finely crushed palladium, platinum or nickel.
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Note!
When working, follow safety precautions. Remember that these gases burn well and are explosive when mixed with air or oxygen.
Helpful advice
Please note that hydrogen is lighter than air, so it must be collected in a test tube turned upside down. You can determine the acquisition of ethane by exposing it to bromine water (its color will remain constant).
Ethan and propane– gases, the simplest representatives of a number of saturated hydrocarbons – alkanes. Their chemical formulas C2H6 and C3H8 respectively. Ethane serves as a feedstock for the production of ethylene. Propane is used as a fuel, both in pure form and in a mixture with other hydrocarbons.
Instructions
1. In order to receive propane, you will need two simple hydrocarbons: methane and ethane. Subject them separately from each other to halogenation (or rather, chlorination) under the influence of ultraviolet irradiation. This is necessary in order for the reaction starters, free radicals, to form. As a result, the following reactions occur: – CH4 + Cl2 = CH3Cl + HCl, that is, methane chloride and hydrogen chloride are formed; – C2H6 + Cl2 = C2H5Cl + HCl, that is, ethane chloride and hydrogen chloride are formed.
2. Subsequently, expose methane chloride and ethane chloride to the presence of sodium metal. As a result of the ongoing reaction, propane and sodium chloride. The reaction proceeds according to the following scheme: - C2H5Cl + CH3Cl + 2Na = C3H8 + 2NaCl. This kind of reaction is called the “Wurtz reaction”, named after the famous German chemist, who was the first to synthesize a symmetrical hydrocarbon by reacting sodium with halogen derivatives of alkanes .
3. In halogenation reactions, you can use bromine instead of chlorine. Primitively, if you use more energetic chlorine, the reaction proceeds faster and easier.
4. In industry propane from ethane do not receive: this process is absolutely unprofitable. Such reactions are of purely educational interest; they are used to practice and consolidate laboratory skills.
Helpful advice
Ethane is found in oil and gases and is also produced during the cracking of oil and the dry distillation of coal. Propane is contained in natural gases. Also, this agent of alkanes is used as a component of low-temperature solvents, when purchasing monomers used in the production of polypropylene, as a raw material for petrochemical synthesis, etc.
In order to understand how to obtain chloroethane from ethane, let’s first analyze the characteristics of ethane.
Brief characteristics of ethane
This hydrocarbon has the formula C2H6. The carbons in its molecule are in the sp3 hybrid state. This affects physical and chemical properties of this substance. Under normal conditions, ethane is a gaseous substance slightly soluble in water. Like all other representatives of the class of alkanes, ethane has saturated single bonds. This is reflected in the chemical properties of this hydrocarbon. It is not capable of undergoing addition reactions; only radical substitution is permissible for it.
Feature of the course
Let's 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 homolytic bond cleavage, chlorine radicals are formed. Education requires a certain amount of energy.
It can be purchased different 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 sufficient to break the bonds. The second way to form active radicals is the use of ultraviolet radiation.
Mechanism of radical displacement reaction
Let's look at how to get chloroethane from ethane. proceeds through the mechanism of SR-action of halogens with alkanes. In the gas phase, when ethane reacts with chlorine, chlorine first dissociates under the influence of UV. This stage is called initiation; it is characterized by the appearance of active chlorine radical species. The resulting particles attack the ethane molecule, forming hydrogen chloride, as well as the ethyl radical C2H5.
Let's continue the conversation about how to obtain chloroethane from ethane. At the next stage, the ethyl radical reacts with a chlorine molecule, forming ethane chloride and another chlorine radical. It is he who is able to react again, continuing the chain reaction cycle. This stage is called chain growth. The number of active radicals at this stage of interaction does not change, but is retained in full. The completion of the cycle is 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 obtain chloroethane from ethane. Let's focus on application. The resulting chloroethyl is a serious narcotic substance. It is used as anesthesia for surgical operations. Two to three seconds are enough to minimize physical activity.
As the main disadvantage of this substance, we note the possibility of overdose. Even a slight increase in the permissible limit causes serious problems for the human body. Nowadays, 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. Once 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.
This substance is also used to reduce skin itching, treat thermal burns, neuromyositis, and cryotherapy for inflammation. The ampoule is first heated in the palm of the hand, then the stream is directed onto the skin. For therapeutic purposes, the procedure is carried out once a day for 7-10 days.
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, due to which anesthesia occurs very quickly, literally within a few minutes. The main disadvantage of this chemical is its 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.
IN organic chemistry exist Various types chemical reactions:
1. Cleavage (elimination)
These are chemical reactions that result in the formation of molecules of several new substances from a molecule of the original compound. Among the elimination reactions, the reaction of thermal splitting of carbons is very important.
2. Joining
As a result of these reactions, several molecules of reacting substances combine into one. This is the main feature of addition reactions.
3. Substitution
When carrying out 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 other substances are formed from molecules of one substance.
How to obtain chloroethane from ethylene
In this case, we will use an addition reaction - hydrohalogenation (addition of a hydrogen halo). So, chloroethane can be obtained from ethylene by the following reaction:
C2H4 + HCI = C2H5Cl
How to get ethanol from chloroethane
Now we need to use chemical reaction– substitution with an 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: reactions must be carried out in the presence of light. Here is the chemical equation given to the reaction.
The chemical formula of ethyl alcohol (ethanol) is C2H5OH. And the substance chloroethane, used as a refrigerant and for anesthesia for 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 is attached. It is possible to chemically obtain both ethanol from chloroethane and chloroethane from ethanol.
Instructions
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 combine the resulting ethylene gas with hydrogen chloride gas. Here is the scheme of the first stage of the reaction: C2H5OH = C2H4 + H2O.
The resulting water is absorbed by concentrated sulfuric acid, which is very hygroscopic. Ethylene gas is collected in another container connected to the reaction flask using a glass adapter.
When the resulting ethylene reacts with hydrogen chloride gas, chloroethane is formed. Here is the scheme for the second stage of the reaction: C2H4 + HCl = C2H5Cl.
This reaction occurs in the presence of a catalyst - iron trichloride. By the way, in industry, chloroethane is produced in exactly this way (of course, without using ethyl alcohol as a feedstock).
You can get chloroethane using the reaction 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 chloroethane mixes very poorly with water. The reaction proceeds as follows: C2H5OH + PCl5 = C2H5Cl + HCl + POCl3.
There is another popular laboratory method for producing chloroethane from ethyl alcohol. When ethanol reacts with thionyl chloride, it produces chloroethane, hydrochloric acid and sulfur dioxide gas. 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 an economic sense and is of only practical interest.
Halogen derivatives of hydrocarbons are products of the replacement of hydrogen atoms in hydrocarbons with one or more halogen atoms.
Most halogenated hydrocarbons (haloalkyls) are highly reactive compounds. Substitution and elimination reactions are of 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 to which it is bonded.
The electron density shifts towards the halogen atom (-I- effect). This redistribution of 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 -bond C – X becomes polarized. The reduced electron density on the carbon atom determines the high, in contrast to saturated hydrocarbons, reactivity of halogen derivatives, which easily enter into reactions of nucleophilic substitution (SN) and elimination (E).
Laboratory work
Goal of the work: study of methods of production and chemical properties of halogenated hydrocarbons.
Reagents and equipment: 2N NaOH;H 2 SO 4 conc.; 0.2 N AgNO 3 ;I 2 in solution KI; chlorobenzene; ethanol; NaCl(sol); chloral hydrate (crist).
rack with test tubes; test tube holder; glass slides; alcohol lamp, microscope.
Experiment 3.1 Preparation of chloroethane from ethanol
Pour small crystals of sodium chloride into a test tube to a height of about 3 mm and add 3-4 drops of ethyl alcohol so that all the salt is moistened with alcohol. Then add 3-4 drops of sulfuric acid and heat over the flame of an alcohol lamp, preventing the release of hydrogen chloride too quickly. To monitor the progress of chloroethane formation, 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 at least a faint green ring of chloroethane is noticed, the heating is stopped. It is necessary to write reaction equations.
Note. Do not heat the test tube unnecessarily, as the reaction releases a significant amount of hydrogen chloride. For this reason, you should not try to detect the smell of chloroethane.
Experiment 3.2 Preparation of chloroform from chloral hydrate
3-4 crystals of chloral hydrate are placed in a test tube, 6-8 drops of 2N are added. NaOH and slightly heat the liquid, which has already become cloudy at room temperature. What happens? 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 reaction equations.
Experiment 3.3 Preparation of iodoform from ethanol
Place 2 drops of ethanol, 3 drops of a solution of iodine in potassium iodide and 3 drops of 2N into a test tube. NaOH. With low heating (sometimes even from the warmth of your hands), a white cloud appears with a characteristic, very persistent odor of iodoform. When the turbidity dissolves, another 3-5 drops of iodine solution must be added to the warm solution. Wait 2-3 minutes until crystals form. Then, using a pipette, take 2 drops of liquid with iodoform crystals from the bottom of the test tube, transfer them to a glass slide under a microscope, and sketch the shape of the resulting crystals in a journal. Write the reaction equations.
Note. Heat a mixture of iodine with alcohol and alkali to a boil, but do not boil, since the resulting iodoform will decompose.
Experience 3.4Comparative mobility of halogen in the benzene ring
