Ethanol is also known as acetaldehyde. Acetaldehyde is a chemical compound that has the formula CH3CHO. Chemists sometimes abbreviate it as MeCHO, where ‘Me’ stands for methyl. Acetaldehyde is a very significant aldehyde. It is manufactured on a big scale in a variety of sectors. Acetaldehyde is found in a variety of foods, including coffee, bread, and ripe fruit, and is produced by plants. It also contributes to the cause of hangovers after consuming alcohol. Acetaldehyde exposure can occur through the air, water, soil, or groundwater, as well as through drink and smoking. Acetaldehyde dehydrogenase is inhibited by disulfiram use. It is the enzyme that is responsible for acetaldehyde metabolism.
Acetaldehyde dissolves quickly in naphtha, gasoline, xylene, ether, turpentine, alcohol, and benzene. It’s a colorless, flammable liquid with a stifling odor. Although acetaldehyde is non-corrosive to many metals, its narcotic impact might provoke mucosal irritation.
Acetaldehyde Formula
Acetaldehyde has the chemical formula CH3CHO or C2H40. 44.053 g mL-1 is the molar mass. The acetaldehyde molecule contains the normal functional group of an aldehyde H-C=O linked to a methyl group (-CH3), making it the second most simple aldehyde after formaldehyde. Furthermore, the C atom from the aldehyde has a hybridization sp2, whereas the methyl group has sp3, resulting in a molecule with planar-trigonal and tetrahedral geometry.
Structure of Acetaldehyde
The Structure of Acetaldehyde is given below:
Physical Properties of Acetaldehyde
- Acetaldehyde is a white liquid with a strong odor.
- Furthermore, its boiling point is 20.20°C, and its melting point is -123°C.
- It has a density of 0.784 g mL-1.
- Acetaldehyde, on the other hand, is soluble in miscible water, ethanol, benzene, acetone, and toluene.
- It is also mildly soluble in chloroform.
Chemical Properties of Acetaldehyde
- Acetaldehyde has chemical characteristics comparable to formaldehyde.
- It is used as an electrophile precursor in organic synthesis.
- Condensation reactions provide intermediates such as pentaerythritol, which can be utilized in chemical synthesis.
- It may also be used to make hydroxyethyl derivatives via a reaction with a Grignard reagent.
- Acetaldehyde is a building block used in the production of heterocyclic compounds such as imines and pyridines.
Preparation of Acetaldehyde
- The approach used nowadays is the Wacker process, which uses copper or palladium as a catalyst to hydrate acetylene or ethylene :
2CH2=CH2 + O2 → 2CH3CHO
Before the Wacker method, acetaldehyde was synthesized by the hydration of acetylene with the use of mercury (II) salts as a catalyst :
C2H2 + Hg2+ + H2O → CH3CHO + Hg
The reaction is carried out at 90-95°C, and the produced acetaldehyde is isolated from water and mercury and cooled to 25-30°C.
- Another approach is ethanol oxidation, which involves partial dehydrogenation of ethanol in the presence of copper as a catalyst to yield acetaldehyde,
CH3CHO + H2 + CH3CH2OH
Ethanol vapor is carried through this process at temperatures ranging from 260 to 290°C.
Uses of Acetaldehyde
- Acetaldehyde is largely utilized in the manufacture of other chemicals.
- It is utilized in the production of acetic acid.
- It is used in the production of resin.
- It is used in the production of disinfectants, pharmaceuticals, and fragrances.
- It is used in the production of polyvinyl acetate.
- It is used to make pyridine derivatives, crotonaldehyde, and pentaerythritol.
- Acetaldehyde is also employed as a preservative for fruit and fish in the production of vinegar, yeast, and other products.
- It is employed as a solvent in several industrial processes such as papermaking, tanning, and rubber production.
- It is also used in the manufacture of n-butyraldehyde.
- It is used in the tanning of leather, as an alcohol denaturant, in fuel mixes, and as a hardener for gelatin fibers, glue, and casein products.
Sample Questions
Question 1: What are the health consequences of acetaldehyde?
Answer:
The health consequences of acetaldehyde are Acute (short-term) exposure to acetaldehyde causes eye, skin, and respiratory system irritation. The symptoms of chronic (long-term) acetaldehyde poisoning are similar to those of alcoholism.
Question 2: What effect does acetaldehyde have on the liver?
Answer:
Acetaldehyde, a significant toxic metabolite, is one of the key culprits in mediating the fibrogenic and mutagenic effects of alcohol in the liver. Acetaldehyde stimulates the production of adducts, which results in functional impairments of essential proteins, including enzymes, as well as DNA damage, which promotes mutagenesis .
Question 3: What basically is the difference between formaldehyde and acetaldehyde?
Answer:
The iodoform test is used to distinguish between formaldehyde and acetaldehyde. Methyl ketones react with yellow precipitate to produce iodine and potassium hydroxide, whereas acetaldehyde binds to carboxylic acid to produce sodium salt with iodine and KOH. It is worth noting that formaldehyde does not test for iodoformity.
Question 4: What beverages contain a lot of acetaldehyde?
Answer:
Tea and fizzy drinks, for example, contain significant acetaldehyde contents. Soft drinks (0.2–0.6ppm), beer (0.6–24ppm), wine (0.7–290ppm), and spirits (0.5–104ppm) are examples .
Question 5: What’s the distinction between ethanol and ethanal?
Answer:
Ethanol is a two-carbon molecule with a hydroxyl (–OH) functional group, whereas Ethanal has an aldehyde (–CHO) functional group.
Ethanol has the chemical formula CH3CH2OH, whereas Ethanal has the chemical formula CH3C=O.
Question 6: Is acetaldehyde water soluble?
Answer:
Water dissolves formaldehyde, acetaldehyde, and acetone. The solubility of carbon chains in water decreases as they become longer. At around four carbon atoms per oxygen atom, the solubility boundary is reached.
Question 7: In acetaldehyde, how many single bonds are there?
Answer:
Acetaldehyde is another name for ethanal. It’s a carbon-based aldehyde molecule with two carbon atoms. Five single bonds and one carbon-oxygen double bond make up ethanal.