Ketone is a compound in which the carbonyl group is attached to two hydrocarbyl groups. According to the different molecular alkyl, ketones can be divided into aliphatic ketones, alicyclic ketones, aromatic ketones, saturated ketones and unsaturated ketones. The carbonyl of the aromatic ketone is directly attached to the aromatic ring; the carbonyl is embedded in the ring and is known as a cyclic ketone such as cyclohexanone. According to the number of carbonyl can be divided into a ketone, two ketones and ketones. The carbonyl is embedded in the ring and is known as a cyclic ketone, such as cyclohexanone. In a monohydric ketone, the two hydrocarbon groups to which the carbonyl group is attached are the same as the monoketone, for example, acetone (dimethyl ketone). Different from each other for the ketone, such as acetophenone (phenyl methyl ketone). Ketone molecules can not form hydrogen bonds, the boiling point is lower than the corresponding alcohol, but carbonyl oxygen and water molecules to form hydrogen bonds, so low-carbon ketone (lower ketone) soluble in water. The lower ketone is a liquid with a pleasant odor, and the higher ketone (higher ketone) is a solid.

The definition of ketone

The chemical nature of lively, easy and hydrocyanic acid, Grignard reagents, hydroxylamine, alcohol and other nucleophilic addition reaction; can be reduced to alcohol. By the carbonyl polarization, α-H ketones can occur halogenated reaction; in alkaline conditions, with a methyl ketone can occur haloform reaction. By secondary alcohol oxidation, aromatics acylation and carboxylic acid derivatives and organometallic compounds prepared by the reaction. Acetone, cyclohexanone is an important chemical raw materials.

The structure and nomenclature of ketone

Ketone molecules contain carbonyl, carbon atoms and carbon atoms on its two hydrocarbon groups

Ketones can be divided into two kinds of aliphatic and aromatic, the following principles:

A. Select the carbon chain containing the longest carbon chain as the main chain;

B Combine the names of the same substituents, indicating the position, in front of the ketone name.

The physical properties of ketones

The boiling point of the ketone (degrees Celsius)

Acetone: 56.2

Butanone: 79.6

2-pentanone: 102.4

Propiophenone: 216.5

Chemical properties of ketones

If the C = O of the α-C associated with three different groups of different volume, it will cause carbonyl plane on both sides of the space obstruction to the nucleophilic attack attack carbonyl to create a spatial selectivity, we use L, M, S, respectively, α-C on the volume of large, medium and small three groups.

Addition reaction

Nucleophilic addition reaction

The nucleophilic addition of α, β-unsaturated aldehydes (ketones) is also divided into two cases, 1,2-addition

And 1,4-addition. The 1,4-addition of the α, β-unsaturated aldehyde (ketone) actually corresponds to 3,4-addition.

Michael Additions

The nucleophilic addition of carbon-carbon double bonds to α, β-unsaturated carbonyl compounds is an important method for the alkylation of active methylene compounds, which is known as the formation of carbon anions by the active methylene compounds,Michael reaction. The most important application of Michael addition is the Robinson annelation reaction. If the ring ketone as a Michael reaction donor, with methyl vinyl ketone (receptor) role, the product 1,5-dione, which by the intramolecular aldol condensation and dehydration can be in the original ring And a new six-membered ring is added. This process is called Robinson ring-extension reaction.

Robinson made the ring

From the point of view of modern organic synthesis, Robinson ring reaction is actually a series reaction. Is a Michael addition and aldol condensation formed in series reaction. At the beginning of the reaction, the enolate formed by a carbonyl compound nucleophiles attacking an α, β-unsaturated ketone, resulting in the Michael addition. The product was then subjected to intramolecular aldol condensation to give the Robinson ring-forming product.

Nucleophilic addition with oxygen-containing sulfur

1. Reaction with H2O - to produce diol

2. Reaction with ROH to form acetal (ketone)

Features:

A. Acetal (ketone) structure is characterized by containing O-C-O bond;

B. Acetal (ketone) reaction can be used to protect the carbonyl;

C. Acetal (ketone) reaction occurs only in the aldehyde (ketone) carbonyl, for other carbonyl compounds do not occur this reaction;

D. Molecules containing both hydroxyl and aldehyde (ketone) carbonyl, can occur within the acetal (ketone), the formation of five, six-membered ring;

E. Nucleophilic addition with RSH

F. Nucleophilic addition with NaHSO3

Intramolecular molecules containing strong alkaline group-ONa and strong acid-SO3H, the occurrence of acid-base in the reaction of the irreversible, sodium α-hydroxy sulfonate crystals precipitated from the organic phase, α-hydroxy sulfonic acid Sodium in the acidic conditions can be hydrolyzed to the original aldehyde (ketone). Therefore, the reaction can be used for aldehyde (ketone) separation. -SO3H is a good leaving group, can be replaced by nucleophilic substitution reaction other groups.

Reduction reaction

1. Catalytic hydrogenation

2. Reducing agent method

3. Wolff-Kishner-Huang Minglong reduction

4. Carnnizzarro reaction

5. benzoin condensation

Oxidation reaction

1. Oxidation of Tollens reagents, Fehling reagents and Benedit reagents

2. Baeyer-Villiger oxidation - RCOOOH oxidation

other

1.Perkin reaction

2.Knoevenagel reaction

3.Wittig reaction

4.Mannich reaction

And nitrogen-containing nucleophile addition

The nucleophilic addition of the nitrogen-containing nucleophile (G-NH2) to the aldehydes and ketones eliminates H2O, resulting in the C = N bond of C = N-G:

The imines produced by the different G have their respective names:

1. Nucleophilic addition to NH3

2. Nucleophilic addition to RNH2 and ArNH2

3. Nucleophilic addition to hydrazine derivatives

4. Nucleophilic addition to H2NOH and Beckmann rearrangement

5. nucleophilic addition with R2NH to form enamine