Cyclohexenone

Cyclohex -2-enone

Colorless liquid

Liquid

0.99 g · cm -3 ( 20 ° C)

-53 ° C

167-169 ° C

1011 hPa ( 168 ° C)

Soluble in water

1.4883 (20 ° C)

Risk

220 mg · kg -1 ( LD50, rat, oral)

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2-cyclohexen -1-one is a chemical compound from the group of enones, i.e., a ketone having C = C double bond. The substance is a colorless liquid in a pure state; the commercially available product is usually yellowish.

Production and representation

For the preparation of 2-cyclohexen -1-one, there are several different synthetic routes, only some of which are mentioned here:

A well-developed on a laboratory scale method is the reduction and acid hydrolysis of 3- ethoxy-2- cyclohexen-1 -one, which over the 1,3-cyclohexanedione in turn accesses of resorcinol:

Liquid ammonia is available, there is, starting from anisole by Birch reduction, followed by acid hydrolysis and rearrangement of the C- C double bond, obtained by:

Also quite good, it is available from cyclohexanone by α - bromination and elimination, or from 3-chloro cyclohexene by hydrolysis and oxidation.

Technically, 2-cyclohexen -1-one by the catalytic oxidation of cyclohexene, for example, with hydrogen peroxide to the vanadium catalysts. There are several patented process variants with different oxidizing agents or catalysts.

Properties

Physical Properties

2-cyclohexen -1-one is a mobile, clear liquid which is similar to having 0.993 g · cm - 3, a density of water having a melting point of -53 ° C and a boiling point of about 170 ° C at room temperature.

It is compatible with many solvents, such as alcohols (methanol, ethanol), ethers (diethyl ether, tetrahydrofuran, 1,4 -dioxane, tert- butyl methyl ether ), halogenated alkanes (dichloromethane, chloroform), esters (ethyl acetate) and polar aprotic solvents ( N, N -dimethylformamide, dimethyl sulfoxide) miscible.

The solubility in water is 41.3 g · l-1 at pH 7 and 25 ° C.

Chemical Properties

2-cyclohexen -1-one can enter both normal reactions of ketones (eg acetal ) and alkenes (eg, electrophilic additions, cycloadditions, epoxidation ). As a typical representative of the α, β -unsaturated carbonyl compounds, it has an electron-poor carbon-carbon double bond, which may also function as the electrophile. With strong bases can ( two CH2 - groups of the carbonyl or of the carbon-carbon double bond adjacent ) are deprotonated at the positions 4 and 6.

Use

It is a frequently used synthetic building block in organic chemistry as it offers many different ways the molecular framework extensions. For example, it can be readily with nucleophiles (such as enolates or silyl enol ethers ) or in a Diels -Alder reaction reacted in a Michael addition with electron- rich dienes. In addition, it reacts with organocopper compounds from 1,4- addition ( Michael addition ), or with Grignard compounds with 1,2-addition, i.e., attack of the nucleophile on the carbonyl carbon atom. It is used for example in multi-step syntheses in the construction of polycyclic natural products.