On the properties of diethyl malonate, diethyl malonate is an important agent for organic synthesis. Looking at its physical properties, it is colorless and transparent, has a fragrant taste, and has good fluidity. Its boiling point is moderate, about 199.3 ° C. At this temperature, it gradually changes from liquid to gaseous state. The melting point is -48.9 ° C. When the ambient temperature drops to this temperature, it condenses into a solid state. The density is slightly smaller than that of water, about 1.0551g/cm ³, so it floats on water. Its solubility also has characteristics, and it can be miscible with organic solvents such as alcohols and ethers. In water, its solubility is limited, which is due to the molecular structure.
In terms of chemical properties, diethyl malonate has high activity. There is methylene in the molecule, which is affected by the ester groups at both ends. Methylene hydrogen is acidic and can interact with strong bases to form carbon negative ions. This carbon negative ion is a nucleophilic reagent, which can undergo nucleophilic substitution or addition reactions with halogenated hydrocarbons, aldons, ketones and many other compounds. For example, when reacting with halogenated hydrocarbons, carbon negative ions attack the carbon atoms of halogenated hydrocarbons, and the halogenated atoms leave to form substituted products. This is an important way to increase the carbon chain. Reacting with aldons and ketones can build complex organic structures and provide various possibilities for organic synthesis.
The preparation method of its preparation often uses chloroacetic acid as the starting material. Chloroacetic acid first reacts with sodium carbonate, and the carboxyl group forms a sodium salt, Then nucleophilic substitution occurs with sodium cyanide, and chlorine is replaced by cyanyl to form sodium cyanoacetate. Sodium cyanoacetate is hydrolyzed, and the cyanyl group is converted into a carboxyl group to obtain malonic acid. Malonic acid and ethanol are esterified under the catalysis of concentrated sulfuric acid, and diethyl malonate can be obtained. During the reaction, concentrated sulfuric acid acts as a catalyst and a water-absorbing agent to promote the right shift of the esterification equilibrium to improve the yield.
In the industrial field, diethyl malonate is widely used. In the synthesis of medicine, it is a key intermediate for a variety of drugs. For example, to synthesize barbiturates, use it to react with urea under the catalysis of sodium alcohol to construct the parent nuclear structure of barbituric acid. After subsequent modification, various drugs with sedative and hypnotic effects can In terms of fragrance synthesis, through a series of reactions, fragrances with unique aromas can be prepared and the fragrance of the product can be added. In the synthesis of agricultural chemicals, it participates in the synthesis of pesticides, fungicides, etc., which contributes greatly to the protection of crop growth.
However, when diethyl malonate is used, safety cannot be ignored. It is toxic to a certain extent. It can be harmful to human health by inhalation, ingestion or absorption through the skin. It has irritating effects on the eyes, respiratory tract and skin. After contact, the eyes may feel tingling, redness and swelling, and the skin may have erythema and itching. During operation, it is advisable to wear protective equipment, such as gas masks, protective gloves and protective clothing, in a well-ventilated environment to prevent contact and inhalation. If you come into contact accidentally, rinse with plenty of water immediately, and in severe cases, send to the doctor immediately. When storing, it should be placed in a cool and ventilated place, away from fire and heat sources, and stored separately from oxidants and acids to prevent dangerous reactions.
Diethyl malonate is of great significance in organic synthesis and industrial production. However, when using and storing, it is necessary to strictly abide by safety regulations in order to make the best use of it and ensure personal and environmental safety.
