Ketone fragrance

An organic compound in which both ends of the carbonyl group are bonded to a hydrocarbon group is called a ketone. When the hydrocarbon group attached to both ends of the carbonyl group is an aliphatic hydrocarbon group, it is an aliphatic ketone; when the carbonyl group has at least one end to which an aromatic hydrocarbon group is attached, it is called an aromatic ketone. The ketone can be further classified into a monoketone, a diketone, and the like according to the number of carbonyl groups contained in the molecule. A saturated monohydric aldehyde having the same number of carbon atoms and a ketone are mutually isomers. There are nearly 100 kinds of ketone fragrances, and the chemical properties are generally stable. But there are different degrees of discoloration. Among them, the aliphatic ketone has a strong aroma, and the individual varieties are used only in a small amount in the blending of daily flavors. Aromatic ketones are only used in small amounts in individual flavors. Among the varieties of cyclic ketones composed of 5 or 6 carbons or a plurality of carbons, ionone, methyl ionone, and damasone are widely used. Macrocyclic ketones of fifteen or more carbons are components of natural animal flavors and are used only in high-grade perfume fragrances due to their high price. Low-grade aliphatic ketones (both hydrocarbons are aliphatic hydrocarbons) are liquids with a special odor. High-grade ketones have a fragrant smell, are easily soluble in water, ether and ethanol. As the carbon number increases, the solubility decreases and the viscosity decreases. The addition of a ketone of more than six carbon atoms is substantially insoluble in water; the higher aliphatic ketone is a solid; the aromatic ketone (both of which are aromatic) is mostly solid. The simplest mono-fatty ketone is acetone; the simplest monoaryl ketone is benzophenone. The lower boiling point of the lower ketone is much lower than the boiling point of the alcohol which is similar to the molecular weight. This is mainly because the ketone molecules cannot form hydrogen bonds and there is no association. However, the boiling point of the higher ketone gradually approaches the boiling point of the alcohol having a similar molecular mass. The ketone is more chemically active because the carbon-oxygen double bond of the carbonyl group is an α bond and a π bond is an unsaturated polar bond. The oxygen atom is more electronegative than carbon and strongly attracts electrons. The electron cloud density on the oxygen atom is increased, and the electron cloud density on the carbon atom is low, so a certain polarity is generated, the carbon atom becomes a positive carbon, and the oxygen atom becomes a negative oxygen ion. The former is more active than the latter. It is susceptible to the attack of a nucleophile with a charge or a lone pair of electrons, and an addition reaction occurs. Therefore, the addition of a ketone is mostly a nucleophilic addition. For example, a ketone with a nucleophile such as HCN, NH2OH or NH2NH2 is easily added. Reactions, these addition reactions are mostly reversible.