Acetaldehyde Formula

Ethanal (also known as acetaldehyde) is an organic chemical compound having the formula CH\[_{3}\]CHO, which is commonly written as MeCHO (Me = methyl) by chemists. It's one of the most important aldehydes, with widespread natural occurrence and widespread industrial production. Acetaldehyde is produced by plants and can be found in coffee, bread, and ripe fruit. It's also created when the liver enzyme alcohol dehydrogenase partially oxidises ethanol, and it's a contributing cause of hangovers after drinking.

Air, water, soil, or groundwater, as well as drink and smoke, are all potential sources of exposure.  Disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for acetaldehyde metabolism, allowing acetaldehyde to build up in the body.

This article will study the acetaldehyde formula (ethanal formula) and ethanal structure in detail.

Ethanal Formula and Properties

Ethanal Structure/Acetaldehyde Structural Formula

Given below is the ethanal structural formula: 

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History of Acetaldehyde

Acetaldehyde was initially discovered in 1774 by Swedish pharmacist/chemist Carl Wilhelm Scheele; it was later studied by French scientists Antoine François, comte de Fourcroy and Louis Nicolas Vauquelin (1800), as well as German chemists Johann Wolfgang Döbereiner (1821, 1822, 1832) and Justus von Liebig (1821, 1822, 1832). (1835). Liebig named it "aldehyde" in 1835, but it was later changed to "acetaldehyde."

Preparation of Ethanal

1. Hydration of Acetylene

The hydration of acetylene created acetaldehyde prior to the Wacker method and the availability of inexpensive ethylene. Mercury(II) salts are catalysts in this reaction:

C\[_{2}\]H\[_{2}\] + Hg\[^{2+}\] + H\[_{2}\]O → CH\[_{3}\]CHO + Hg

The intermediacy of vinyl alcohol, which tautomerizes acetaldehyde, is involved in the mechanism. The reaction is carried out at 90–95 degrees Celsius, and the acetaldehyde produced is separated from the water and mercury before being cooled to 25–30 degrees Celsius. Iron(III) sulphate is employed in the wet oxidation process to re-oxidize mercury back to mercury(II) salt. In a separate reactor, the iron(II) sulphate is oxidised with nitric acid.

2. Dehydrogenation of Ethanol

Acetaldehyde was traditionally made by partially dehydrogenating ethanol:

CH\[_{3}\]CH\[_{2}\]OH → CH\[_{3}\]CHO + H\[_{2}\]

Ethanol vapour is passed through a copper-based catalyst at temperatures between 260 and 290 degrees Celsius in this endothermic process. Because of the value of the hydrogen coproduct, the process was previously appealing, but it is no longer commercially viable.

3. Hydroformylation of Methanol

Methanol can be hydroformylation with catalysts such as cobalt, nickel, or iron salts to create acetaldehyde, albeit this is a non-industrial process. Acetaldehyde, which is also non-competitive, is produced with moderate selectivity from synthesis gas.

Biochemistry of Acetaldehyde

Alcohol dehydrogenase in the liver converts ethanol to acetaldehyde, which is ultimately converted to harmless acetic acid by acetaldehyde dehydrogenase. The reduction of NAD+ to NADH is associated with these two oxidation processes. Catalase is the enzyme that converts ethanol to acetaldehyde in the brain, with alcohol dehydrogenase playing a small role. In bacteria, plants, and yeast, the enzyme pyruvate decarboxylase converts pyruvate to acetaldehyde and carbon dioxide, followed by the conversion of acetaldehyde to ethanol. Alcohol dehydrogenase catalyses the latter reaction as well.

Applications of Acetaldehyde

Acetaldehyde was primarily employed as an acetic acid precursor. Because the Monsanto and Cativa technologies make acetic acid more effectively from methanol, its application has dropped. Acetaldehyde is a precursor to pyridine derivatives, pentaerythritol, and crotonaldehyde, among others. When urea and acetaldehyde are combined, a useful resin is formed. When acetic anhydride is combined with acetaldehyde, ethylidene diacetate is formed, which is a precursor to vinyl acetate, which is used to make polyvinyl acetate.

Conclusion

Ethanal also known as acetaldehyde is an organic chemical molecule with the formula CH\[_{3}\]CHO, which scientists write as MeCHO (Me = methyl). It's one of the most important aldehydes, with a wide range of natural occurrences and industrial applications. Plants create acetaldehyde, which can be found in coffee, bread, and ripe fruit. It's also produced when the liver enzyme alcohol dehydrogenase partially oxidises ethanol, and it's one of the main causes of hangovers.