Oksiminointi

Oksiminointi, also known as oximation, is a chemical reaction where a carbonyl compound, such as an aldehyde or ketone, reacts with a hydroxylamine derivative to form an oxime. This reaction is a type of condensation reaction, where a molecule of water is eliminated. The general formula for the reaction can be represented as R1R2C=O + R-NHOH → R1R2C=N-OR + H2O, where R1 and R2 are hydrogen atoms or alkyl/aryl groups, and R is typically hydrogen.

The mechanism of oximation involves the nucleophilic attack of the nitrogen atom of the hydroxylamine on the electrophilic carbon of the carbonyl group. This is followed by proton transfer and dehydration to yield the oxime product. The reaction is usually carried out in a mildly acidic or neutral medium. The properties of the resulting oxime, such as its melting point and solubility, can be used for characterization and purification of the original carbonyl compound.

Oximes are versatile intermediates in organic synthesis. They can be hydrolyzed back to the original carbonyl compounds or reduced to amines. The Beckmann rearrangement is a well-known reaction of oximes, where they are converted to amides under acidic conditions. Oximation is also employed in analytical chemistry for the detection and quantification of carbonyl compounds. For example, it is used in the determination of aldehydes and ketones in food and environmental samples.