Aldehydes and ketones are part of the carbonyl groupcompounds, and are hydrocarbon molecules. Simply put, aldehydes are a combination of carbon and hydrogen atoms, and ketones are a combination of carbonyl carbon with residues of aldehydes. As a rule, the combination of a carbonyl group and hydrogen is called an aldehyde group, and the aldehydes and ketones themselves are oxidative compounds.
Except for formaldehyde, which hasgaseous form, all other kinds of aldehydes and ketones are mobile liquid, the boiling point of which is much lower than the temperature of carbon with the same number of atoms. Hydrogen, which is part of the aldehydes, allows them to completely dissolve in water.
The preparation of aldehydes occurs in variousmethods differing in complexity and substance with which the hydrocarbon is oxidized. The simplest form of aldehyde, called formaldehyde, is obtained by combining oxygen and methane, with a small addition of copper-zinc material. The production of aldehydes and ketones depends on the combination of different chemicals, and on the number of atoms participating in the oxidation.
The acids that are obtained after the compoundaldehyde and other substances, have the same carbon base. The names of the aldehydes obtained most often use Russian trivial names, corresponding to the name of the final acids into which the aldehyde is converted. Here, for example, several names of aldehydes: formic, acetic, propionic, butyric and isobutyric aldehydes. And each of them differs from each other in the number of atoms. The production of aldehydes is mainly due to the oxidation of primary alcohols. This is the most important of all known methods of obtaining this substance.
Acetic aldehyde is obtained by combining alcoholand potassium dichromate, and this procedure is almost always carried out in the laboratory. The second way, due to which the aldehydes are produced, is to combine the atoms of alcohol, oxygen and metal. Most often it is platinum, since this metal has the most active effect. Copper powder can also be used, although it is more difficult to work with it. To connect it, it is necessary to heat copper to high temperatures.
Reactions involving oxygen canrepeat an unlimited number of times. When copper is oxidized with oxygen, methyl alcohol is obtained. And in the production of benzoic aldehyde, halogens from the atoms, as a result of a chemical reaction, to hydroxyl.
Each individual aldehyde has its ownchemical properties, which, in turn, react with other substances. These reactions can be divided into several groups, with the corresponding groups of atoms. First, it is a compound with silver oxide. When the silver oxide and aldehyde are combined and the mixture is heated, a metallic coating can be seen on the test tube. If, however, copper oxide is added to the aldehyde and heated at high temperature, the blue precipitate of copper hydroxide turns to yellow. That is, the substance turns into an acid. It is also worth noting that if you heat the yellow mixture, then in the end it will turn red.
The preparation of aldehydes with aromatic properties, and its oxidation occurs over time, and, eventually, leads to the formation of overbenzoic acid.
Among other things, you can pay attention to the reactionThe aldehyde, called the Cannizzaro reaction. In the process of this reaction, one of the two molecules of the aldehyde turns into an acid, and the second - back into alcohol. All the above methods for obtaining aldehydes are somewhat confusing and, perhaps, incomprehensible for an ignorant person, however, it is important to remember that almost all aldehydes are very toxic and can accumulate in the human body.
