Jan. 06, 2025
Industrial preparation of acetic acid is the important data of preparation of acetic acid, the ingredients of its reaction with ethanol, and the synthesis process. The raw materials are ethanol and oxygen which is required under various conditions. The synthesis process of acetic acid is primarily divided into two stages, namely, the dehydration reaction and the oxidation-reduction reaction; each stage produces acetic acid itself. preparation of acetic acid steps includes;
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1. Dehydration of Ethanol
This is the first step of the industrial preparation of acetic acid. Ethanol is metered into a reactor, and it is passed through a series of crystallizer, drum filter and granulating filter to remove the impurities. After being dried in dryer, ethanol is heated to various temperatures until this process is complete. The acetic ester of dehydrated ethanol is then precipitated from the solution by filtering and decanting. Now the dehydrated ethanol is transferred to the oxidation-reduction stage.
2. Oxidation-Reduction of Ethanol
This stage includes two reactions, that is, oxidation of ethanol and reduction of acetic ester. The oxidation reaction mainly uses air or oxygen as the oxidant. Air or oxygen is introduced into the reactor with a certain amount of ethanol, subsequently heated to a certain temperature, and then passed through a catalyst bed to achieve complete oxidation of ethanol. In this process, oxygen is consumed and acetic acid is produced as carbon dioxide gas by the reaction between acetic acid and carbon dioxide with heat discharge in a large quantity. Therefore, the process is an exothermic reaction and requires cooling. The dehydration of acetic ester is an endothermal reaction, that is, the production of acetic acid and carbon dioxide gas partially consumes oxygen and heat is produced in a large quantity. The amount of heat produced here should be discharged by water at a certain temperature to achieve the required temperature for the oxidation-reduction of acetic ester in a certain state.
The reduction reaction of acetic ester involves hydrogen as reducing reagent, which reacts with acetic ester simultaneously to form acetic acid. The hydrogen donor can be concentrated sulfuric acid or molecular hydrogen gas. The reaction products of ethanol oxidation and reduction of acetic ester are then combined, heated to a certain temperature, and then discharged into the liquid-liquid extractor for separation. The bottom product of this process is concentrated acetic acid (with less than 70% H3COOH), which is pumped into the vacuum evaporation stage.
3. Concentration of Acetic Acid by Vacuum Evaporation
Vacuum evaporation is one of the common methods in industrial preparation of acetic acid with strong corrosion resistance and high selectivity. Usually, acetic acid is concentrated under a vacuum of 0.8-1.5 MPa at a temperature of 120-160', and the endothermic process produced by the reaction is carried out with liquid nitrogen or oil cooling. It is an ideal way to concentrate acetic acid, which has good atom economy, high concentration factor and low energy consumption. The concentrated acetic acid obtained through this process should be stored in a sealed container with anti-corrosion measures to prevent it from being oxidized during storage.
4. Distribution of Acetic Acid
An important part of the preparation of acetic acid is that it should be stored in sealed containers and not oxidized, which can protect its quality. Preparation of acetic acid will be delivered to end users in the form of pellets, while they will be combined with other raw materials as required by the end users.
Some of the uses acetic acid
Acetic acid has been widely used in such manufacture as plastic, rubber, agricultural chemicals, medicine and so on. In the manufacture of plastic, from acetic acid derivative such as vinyl acetate or ethylene acetic acid is prepared. The reaction can make the ready-made plastics softer and more flexible, which is why its use in the manufacture of artificial leather was widespread. Vinyl acetate is mainly used to produce polyvinyl alcohol, polyvinyl chloride and so on. Acetylene terephthalic fiber is also known as "green fiber", because of its lower energy consumption and harmless to environment when compared with synthetic fiber; it has become one of the most widely used materials in clothing.
Acetic acid also plays a vital role in the protective and preserving of agricultural products. It is used to make anti-oxidants, anti-fungal, anti-bacterial, insecticide and so on. Acetic acid is a very useful product for chemical industry. Since it is an important raw material in the manufacture of chemicals such as acetic ester, acetone and so on, preparation of acetic acid has become an indispensable step in this industry. It is the most important raw material used in the manufacture of dyes and xylol based products.
Acetic acid is one of the commonly used domestic items which is generally used in all Indian households, it is more commonly known as Vinegar when used in a 5%-8% concentration. Acetic acid with the chemical formula of CH3COOH is also known as ethanoic acid. It is a colourless liquid that has a characteristic pungent smell. This organic compound is soluble in water and is more acidic than H'O but significantly less acidic than mineral acids.
The structure of CH3COOH in the solid-state exists in a chain of molecules, and they are connected through intramolecular hydrogen bonds with each other. The undiluted version of acetic acid is also known as glacial acetic acid because it has a melting point of 16' C and hence gets frozen in winter when the weather is cold.
Acetic acid is generally referred to as the second simplest form of a carboxylic acid-containing methyl group with a CH3 chemical formula and is connected to the carboxylic acid group (COOH). In a way, we can say that it is the acetyl group (CH3CO) connected to the hydroxyl group (OH).
The structure of Acetic acid reveals that it contains sp² hybridization in the molecule. It has been observed that in the solid state, there is a chain of molecules of acetic acid that are connected to each other via hydrogen bonds. The Acetic acid molecule has two carbon atoms, while one carbon atom is having a double bond with Oxygen, the other carbon atom has three bonded hydrogen molecules and both the carbon atoms are bonded to each other by a single bond.
Ethanoic acid behaves as a dimer while in liquid and vapour state because of intermolecular hydrogen bonding. Now, to draw the Lewis structure of acetic acid, firstly you have to figure out the number of valence electrons. As for this particular organic compound, carbon, oxygen, and hydrogen have 4, 6, and 1 valence electrons, respectively. Therefore the total number of valence electrons will be= 2(4) +2(6) +4(1) = 24. So, if you look at the Lewis structure, you will see that there is one double bond and six single bonds in the molecule. You will notice that each oxygen molecule contains two lone pairs of electrons.
Acidity (Reaction with metals, Alkalis)
Ethanoic acid is known to react with active metals like Na to liberate hydrogen. This reaction is similar to that of ethanol.
\[ CH_{3}COOH + Na \rightarrow CH_{3}COONa + H_{2} \]
Acetic acid reacts with NaOH to form salt and water.
\[ CH_{3}COOH + NaOH \rightarrow CH_{3}COONa + H_{2}O \]
CH3COOH also reacts with sodium carbonate and sodium hydrogen carbonate, which are weaker bases and release CO2.
\[ Na_{2}CO_{3} + 2 CH_{3}COOH \rightarrow 2 CH_{3}COONa + CO_{2} + H_{2}O \]
\[ CH_{3}COOH + NaHCO_{3} \rightarrow CH_{3}COONa + H_{2}O + CO_{2} \]
Acid Chlorides
It reacts with thionyl chloride and produces acetyl chloride.
\[CH_{3}COOH + SOCl_{2} \] ' \[ CH_{3}COCl + HCl + SO_{2} \]
Acid Anhydride
Acetic acid reacts with an acid chloride in the presence of a base and releases acetic anhydride.
\[ CH_{3}CO_{2}H \rightarrow CH_{2}=C=O + H_{2}O \]
\[CH_{3}CO_{2}H + CH_{2}=C=O \rightarrow (CH_{3}CO)_{2}O\]
Ester
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When alcohol reacts with any carboxylic acid, it produces esters. When acetic acid reacts with ethyl alcohol, it leads to the formation of ethyl ethanoate.
\[ CH_{3}COOH + C_{2}H_{5}OH \rightarrow CH_{3}COOC_{2}H_{5} + H_{2}O \]
CH3COOH as Solvent
Acetic acid is a polar protic solvent. It is an acid solvent as it can donate an H+ ion to the substance to be dissolved. It is often used in reactions like Friedel-Crafts Alkylation. Using it, terephthalic acid can be produced.
Ethanoic acid is prepared industrially primarily via carbonylation. This process takes place in the following steps
\[ CH_{3}OH + HI \rightarrow CH_{3}I + H_{2}O \]
\[ CH_{3}I + CO \rightarrow CH_{3}COI \]
\[ CH_{3}COI + H_{2}O \rightarrow CH_{3}COOH + HI \]
Acetaldehyde Oxidation
\[ 2 CH_{2}CHO + O_{2} \rightarrow 2 CH_{3}CO_{2}H \]
Under some conditions and using catalysts, acetic acid can be formed. In this reaction, several significant by-products are produced, for example, formic acid, ethyl acetate, etc.
Ethylene Oxidation
In the presence of palladium catalyst, we can get acetic acid from ethylene.
\[ C_{2}H_{4} + O_{2} \rightarrow CH_{3}CO_{2}H \]
Oxidative Fermentation
In the presence of sufficient oxygen, acetic acid bacteria can produce ethanoic acid from foodstuffs.
\[ C_{2}H_{5}OH + O_{2} \rightarrow CH_{3}COOH + H_{2}O \]
Anaerobic Fermentation
\[ C_{6}H_{12}O_{6} \rightarrow 3 CH_{3}COOH \]
Some anaerobic bacteria like Acetobacterium can transform sugar directly into acetic acid.
Apart from these methods, researchers are also trying to produce acetic acid through the oxidation of waste gases from industrial processes.
The reaction between sodium bicarbonate and acetic acid produces carbon dioxide gases. It is usually used in chemical volcanoes.
The overall chemical equation is as follows:
\[ NaHCO_{3}(s) + CH_{3}COOH (l) \rightarrow CO_{2}(g) + H_{2}O(l) + Na^{+}(aq) + CH_{3}COO^{-}(aq) \]
Where, s = solid, g = gas, l = liquid, aq = aqueous or water solution.
You can write this reaction in another way as well,
\[ NaHCO_{3} + HC_{2}H_{3}O_{2} \rightarrow NaC_{2}H_{3}O_{2} + H_{2}O + CO_{2} \]
However, this reaction is not responsible for the dissociation of the NaC2H3O2 in water.
The chemical reaction typically takes place in two steps. In which the first one is a double displacement reaction where the acetic acid of the vinegar reacts with sodium bicarbonate to produce carbonic acid and sodium acetate
\[ NaHCO_{3} + HC_{2}H_{3}O_{2} \rightarrow NaC_{2}H_{3}O_{2} + H_{2}CO_{2} \]
Since Carbonic acid is unstable, it goes through a decomposition reaction to release carbon dioxide gas
\[ H_{2}CO_{3} \rightarrow H_{2}O + CO_{2} \]
This is all about acetic acid, its physical and chemical properties. Focus on the reactions given here to prepare acetic acid and those displaying its chemical properties to understand its features well.
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