Acetic aldehyde: properties, preparation, use
Today, millions of chemical compounds are known. And most of them are organic. These substances are divided into several large groups, the name of one of them - aldehydes. Today we will consider a representative of this class - acetaldehyde.
Acetic aldehyde is an organic compound of the aldehyde class. It can also be called differently: acetaldehyde, ethanal or methyl formaldehyde. Acetaldehyde Formula - CH3-Cho.
The substance in question has the appearance of a colorless liquid with a sharp, suffocating odor, which is readily soluble by water, ether, and alcohol. Since the boiling point of the compound under discussion is low (about 20aboutC), it is possible to store and transport only its trimer - paraldehyde. Acetic aldehyde is obtained by heating the above-mentioned substance with an inorganic acid. This is a typical aliphaticheskogo azdegid, and it can take part in all reactions that are characteristic of this group of compounds. The substance tends to tautomerize.This process ends with the formation of an enol-vinyl alcohol. Due to the fact that acetaldehyde is available as an anhydrous monomer, it is used as an electrophile. Both he and his salts can react. The latter, for example, when interacting with the Grignard reagent and lithium-organic compounds, form hydroxyethyl derivatives. Acetic aldehyde during condensation is distinguished by its chirality. So, during the Strecker reaction, it can condense with ammonia and cyanide, and the hydrolysis product will be the amino acid alanine. Acetic aldehyde also reacts with other compounds, amines, of the same type, then imins are the product of the interaction. In the synthesis of heterocyclic compounds, acetaldehyde is a very important component, the basis of all ongoing experiments. The paraldehyde — the cyclic trimer of this substance — is obtained by the condensation of three molecules of ethanal. Also, acetaldehyde can form stable acetals. This occurs during the interaction of the chemical in question with ethyl alcohol, passing under anhydrous conditions.
In general, acetaldehyde is obtained by the oxidation of ethylene (the Wacker process). Palladium chloride acts as an oxidizing agent. This substance can also be obtained during the hydration of acetylene, in which mercury salts are present. The reaction product is an enol, which is isomerized into the desired substance. Another way to obtain acetaldehyde, which was the most popular long before the Wacker process became known, is the oxidation or dehydration of ethanol in the presence of copper or silver catalysts. During dehydration, in addition to the desired substance, hydrogen is formed, and during oxidation - water.
Butadiene, aldehyde polymers and some organic substances, including the acid of the same name, are obtained using the compound under discussion. It is formed during its oxidation. The reaction looks like this: "oxygen + acetaldehyde = acetic acid". Ethanal is an important precursor to many derivatives, and this property is widely used in the synthesis
many substances. In humans, animals and plants, acetaldehyde is involved in some complex reactions. It also forms part of cigarette smoke.
Acetaldehyde can be both beneficial and harmful. It has a bad effect on the skin, is an irritant and, possibly, a carcinogen. Therefore, its presence in the body is undesirable. But some people themselves provoke acetaldehyde by smoking cigarettes and drinking alcohol. Think it over!