Synthesis of 3‐methylcyclohex‐2‐enone


Synthesis of 3‐methylcyclohex‐2‐enone -general reaction scheme
Synthesis of 3‐methylcyclohex‐2‐enone

In this experiment, the condensation of two molecules of ethyl 3-oxobutanoate with formaldehyde is catalyzed by a base to yield 4,6-diethoxycarbonyl-3-methylcyclohex-2-enone. This product is then subjected to hydrolysis and decarboxylation, resulting in the formation of 3-methylcyclohex-2-enone.


3-methylcyclohex-2-enone is a chemical compound with the molecular formula C8H12O. It is a colorless liquid with a distinct odor and is commonly used as a building block in organic synthesis.

The structure of 3-methylcyclohex-2-enone consists of a cyclohexene ring with a methyl group and a carbonyl group attached to it. This molecule is classified as an enone, which is a type of organic compound containing a double bond between a carbon and an oxygen atom.

One of the most significant applications of 3-methylcyclohex-2-enone is in the synthesis of various chemicals, including pharmaceuticals and agrochemicals. It is used as a key building block for the production of many drugs, such as anti-inflammatory agents and antibiotics. This molecule is also used as a precursor for the synthesis of insecticides, herbicides, and other agrochemicals.

In addition to its use in the production of various chemicals, 3-methylcyclohex-2-enone also has several applications in the fragrance and flavor industry. It is used as a flavoring agent in foods and beverages and is a component of many perfumes and colognes. Its unique odor and flavor profile make it a popular choice in the fragrance and flavor industry.

One of the most interesting properties of 3-methylcyclohex-2-enone is its ability to undergo a range of chemical reactions. For example, it can react with aldehydes and ketones to form enones, which are important intermediates in organic synthesis. It can also undergo Diels-Alder reactions, which are commonly used in the synthesis of various organic compounds.

Experimental procedure

Firstly, grind the paraformaldehyde into a fine powder and transfer it to a 250 mL round-bottom flask. Next, add ethyl 3-oxobutanoate and piperidine to the flask. The reaction will begin shortly, causing the contents of the flask to heat up rapidly and resulting in the dissolution of the solid paraformaldehyde. If necessary, the reaction can be moderated by cooling the flask in an ice bath. Once the initial reaction is completed and the mixture is homogeneous, heat it at 100 °C for 1 hour. The flask will now contain crude 4,6-diethoxycarbonyl-3-methylcyclohex-2-enone, which can be used without purification.

To perform the experiment, begin by dissolving 30 mL of glacial acetic acid in 20 mL of water in a reaction flask. Carefully add 3 mL of concentrated sulfuric acid H2SO4 to the solution. Once mixed, attach a reflux condenser to the flask and heat the mixture under reflux for approximately 5 hours. Afterward, allow the mixture to cool to room temperature before carefully adding a sodium hydroxide NaOH solution in 70 mL of water.

Transfer the resulting mixture to a separatory funnel and extract the product using 3×20 mL portions of diethyl ether. Combine the ether extracts and dry them over magnesium sulfate MgSO4. Filter off the drying agent by gravity and then evaporate the filtrate using a rotary evaporator. Transfer the remaining residue to a small distillation set and distill it at atmospheric pressure, collecting the fraction that boils at approximately 200 ºC. Once you have collected the desired fraction, calculate the boiling point of the product.