What is acetaldehyde formula structure preparation reactions and uses
It is an organic chemical compound with the chemical name Acetaldehyde. Acetaldehyde is also called MeCHO. It is a colourless organic liquid having a molecular formula C2H4O, also known as CH3CHO. IUPAC name of Acetaldehyde is ethanal. It has a pungent odor.
It is soluble in water and has a suffocating smell. It is non-corrosive to many metals but when it has a narcotic action and can cause mucous irritation. It can damage our liver. When we drink alcohol it breaks and forms Acetaldehyde. It is completely soluble in water.
Acetaldehyde is usually used as an intermediate in the production of acetic acid, also it is used in the manufacturing of perfumes, drugs, flavouring agents, dyes, etc. When Acetaldehyde is applied externally for prolonged periods it is toxic.
Properties of Acetaldehyde- C2H4O or CH3CHO
Molecular weight: 44.05 g/mol
Density: 0.784 g/cm3
Boiling point: 20.2 °C
Melting point: -123.5 °C
Colour: Colourless
Odor: Pungent odor
Solubility: It is soluble in water, ethanol, benzene, acetone, and slightly soluble in Chloroform.
Acetaldehyde Structure(C2H4O-Structure)
C- Carbon, H- Hydrogen, O- Oxygen
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Acetaldehyde (C2H4O OR CH3CHO) Occurrence
Acetaldehyde can be found in many plants and ripe fruits. Also, it is an intermediate in the ethanol metabolism, through the action of enzymes alcohol dehydrogenase that changes ethanol to acetaldehyde.
Uses of Acetaldehyde(C2H4O or CH3CHO)
Acetaldehyde is primarily used to produce other chemicals.
It is used to produce acetic acid.
It is used to manufacture resin.
It is used to manufacture disinfectants, drugs, and perfumes.
It is used to produce polyvinyl acetate.
It is used as a precursor to pyridine derivatives, crotonaldehyde, and pentaerythritol.
Acetaldehyde is also used as a preservative for fruit and fish in the manufacture of vinegar, yeast, etc.
It is used as a solvent in some industrial processes such as the manufacturing of paper, tanning, and rubber.
Also, we use it in the production of n-butyraldehyde.
It is used in leather tanning, as a denaturant for alcohol, in fuel mixtures, as a hardener for gelatin fibres, in glue and casein products.
Solved Examples
1. How to prepare acetaldehyde by dehydrogenation of ethanol?
Solution: Acetaldehyde can be prepared acetaldehyde from the dehydrogenation of ethanol by using copper as a catalyst in this reaction. At 260-28000C, the ethanol reacts over the catalyst to form acetaldehyde:
CH3CH2OH + ½ O2 → CH3CHO + H2O
2. How to prepare Acetaldehyde?
One of the methods of preparation of Acetaldehyde is the hydration of acetylene or ethylene by the Wacker process in which copper or palladium is the catalyst:
2CH2=CH2 + O2 → 2CH3CHO
Acetaldehyde was produced by the hydration of acetylene in which mercury (II) salts serve as a catalyst Before the Wacker process,
C2H2+ H2O + Hg2 → CH3CHO + Hg
Temperature maintained during the reaction is 90-950C, and the formed acetaldehyde is separated from water and mercury and cooled to 25-300C
Oxidation of ethanol is another method where partial dehydrogenation of ethanol produces acetaldehyde in the presence of copper as a catalyst:
CH3CH2OH → CH3CHO + H2
Ethanol vapour is passed at a temperature of 260-2900C in this process.
Fun Facts
Acetaldehyde is a clear liquid that burns easily. Acetaldehyde has a strong fruity odour that in high concentration can make breathing difficult.
If acetaldehyde can be in contact with your eyes, flush them with large amounts of water for at least 15 minutes. Lift the lower and upper lids from time to time. Get medical attention. If acetaldehyde can be in contact with your skin, gently wash the skin with soap and water for 15 minutes. If this does not help, get medical attention.
Acetaldehyde can hurt our heart and blood vessels. Other studies on animals show that breathing acetaldehyde can severely damage the lungs and cause cancer. Repeated exposure to acetaldehyde in the air may cause cancer in humans. When we drink alcohol, our liver transforms acetaldehyde into an acid. It can damage our liver.
It is very interesting that Acetaldehyde is completely soluble in water and tends to form a long chain.
FAQs on Acetaldehyde Chemistry Structure and Key Reactions
1. What is acetaldehyde?
Acetaldehyde is a volatile organic compound with the chemical formula CH3CHO and is the simplest aldehyde after formaldehyde. It is also known as ethanal in IUPAC nomenclature.
- Functional group: –CHO (aldehyde group)
- Molecular formula: C2H4O
- Physical state: Colorless liquid with a pungent odor
- Common occurrence: Intermediate in alcohol metabolism and industrial chemical production
2. What is the structural formula of acetaldehyde?
The structural formula of acetaldehyde is CH3–CHO, showing a methyl group attached to an aldehyde group.
- Expanded structure: H3C–C(=O)H
- Contains a carbonyl group (C=O)
- The carbonyl carbon is bonded to one hydrogen and one methyl group
- Belongs to the class of aldehydes
3. How is acetaldehyde prepared in the laboratory?
Acetaldehyde is commonly prepared by the controlled oxidation of ethanol using acidified potassium dichromate. The balanced reaction is 3C2H5OH + K2Cr2O7 + 4H2SO4 → 3CH3CHO + Cr2(SO4)3 + K2SO4 + 7H2O.
- Ethanol is gently heated with acidified K2Cr2O7
- Distillation prevents further oxidation to ethanoic acid
- Oxidizing agent changes color from orange to green
4. What are the physical properties of acetaldehyde?
Acetaldehyde is a colorless, highly volatile liquid with a boiling point of about 20.2°C.
- Molar mass: 44.05 g mol-1
- Highly soluble in water due to hydrogen bonding
- Has a strong, fruity or pungent odor
- Low boiling point due to absence of intermolecular hydrogen bonding between its own molecules
5. What are the chemical properties of acetaldehyde?
Acetaldehyde shows typical aldehyde reactions such as oxidation, reduction, and nucleophilic addition.
- Oxidation: CH3CHO + [O] → CH3COOH (forms ethanoic acid)
- Reduction: CH3CHO + H2 → CH3CH2OH (in presence of Ni catalyst)
- Gives positive Tollens’ test and Fehling’s test
- Undergoes nucleophilic addition due to polar C=O bond
6. Why does acetaldehyde give a positive Tollens’ test?
Acetaldehyde gives a positive Tollens’ test because it contains the aldehyde (–CHO) group, which reduces Tollens’ reagent to metallic silver. The balanced reaction is CH3CHO + 2[Ag(NH3)2]+ + 3OH- → CH3COO- + 2Ag(s) + 4NH3 + 2H2O.
- Silver mirror forms on the test tube
- Aldehyde is oxidized to acetate ion
- Ketones generally do not give this test
7. What happens when acetaldehyde is oxidized?
When acetaldehyde is oxidized, it forms ethanoic acid (CH3COOH). The reaction is: 2CH3CHO + O2 → 2CH3COOH.
- Occurs with mild oxidizing agents like acidified dichromate
- Industrial oxidation may use oxygen and catalysts
- Demonstrates typical aldehyde oxidation behavior
8. How is acetaldehyde formed in the human body?
Acetaldehyde is formed in the human body by the oxidation of ethanol in the liver by the enzyme alcohol dehydrogenase.
- Step 1: Ethanol → Acetaldehyde
- Step 2: Acetaldehyde → Acetic acid (via aldehyde dehydrogenase)
- Acetaldehyde accumulation causes hangover symptoms
- It is toxic and classified as a probable carcinogen
9. What is the difference between acetaldehyde and acetone?
The main difference between acetaldehyde and acetone is that acetaldehyde is an aldehyde (CH3CHO) while acetone is a ketone (CH3COCH3).
- Acetaldehyde has a hydrogen attached to the carbonyl carbon
- Acetone has two alkyl groups attached to the carbonyl carbon
- Acetaldehyde gives positive Tollens’ and Fehling’s tests
- Acetone does not give these aldehyde-specific tests
10. What are the industrial uses of acetaldehyde?
Acetaldehyde is widely used as an intermediate in the production of chemicals such as acetic acid, perfumes, and plastics.
- Manufacture of acetic acid (CH3COOH)
- Production of perfumes and flavoring agents
- Used in synthesis of dyes and drugs
- Precursor in the manufacture of pyridine derivatives
