What Is Desoximetasone?
Oxime (wò), an organic compound produced by the interaction of aldehydes and ketones containing carbonyl groups with hydroxylamine, can participate in many organic chemical reactions. For example, the classic Beckmann rearrangement is the product of oxime as a substrate and rearrangement to form an amide (lactam) under acidic conditions.
- Oxime is an important class of organic compounds. The English name is oxime, and its general formula can be written as RC = NOH. Benzyl
- An oxime can be tautomeric with a nitroso compound, and the following equilibrium exists:
- Under the catalysis of acidic catalysts such as sulfuric acid, polyphosphoric acid, and strong acids such as phosphorus pentachloride, phosphorus trichloride, benzenesulfonyl chloride and thionyl chloride, ketooximes can undergo Beckmann rearrangement reactions to form amides. The general formula of the reaction is shown in the figure:
- Beckmann rearranged formula
- The reaction mechanism is as follows:
- Reaction mechanism of Beckmann rearrangement
- The above reaction mechanism shows that the catalysis of acid helps the hydroxyl group to leave. This reaction has three characteristics:
- One is that the leaving group and the migrating group are in the trans form, which is inferred from the structure of the product.
- The second is that the departure of the group is synchronized with the migration of the group. If it is not synchronized, the hydroxyl group leaves in the form of water to form a nitrogen positive ion. At this time, two groups on adjacent carbons can migrate to obtain a mixture. However, the experimental results have only one product, so the reaction is synchronous. [1]
- Third, the configuration of the migrating group is unchanged before and after migration. (Example shown below)
- The oxime rearrangement configuration remains unchanged
- In addition, the industrial production of caprolactam is the use of this reaction, and caprolactam is the raw material for the production of nylon-6. The configuration of the starting oxime can also be inferred from the hydrolysis product by this reaction. The preparation process is shown in the following figure:
- Synthesis of Caprolactam
- Lactam is the product of dehydration of carboxyl and amino groups in the molecule. Caprolactam can undergo ring-opening polymerization under the action of sulfuric acid or phosphorus trichloride to obtain nylon-6. Since amide hydrolysis can obtain carboxylic acid and amine, this rearrangement reaction also provides a way to prepare carboxylic acid and amine from ketone. Since only the groups that are in the opposite position to the hydroxyl group can migrate, the groups that are always in the opposite position to the hydroxyl group eventually form amines, and the groups in the cis position to the hydroxyl group finally form carboxylic acids. (As shown below). The oxime can also be reduced by sodium amalgam or hydrogenation to form an amine. [2]