Melting point: 132-135 °C (dec.) (lit.)
Boiling point: 140℃ (decomposition)
Density: 1.619 g/cm3 at 25 °C
Refractive index: 1.4780
Flash point: 157℃
Malonic acid, also known as malic acid, is an organic acid that can dissolve in water, alcohol, ether, acetone and pyridine. It exists in the form of calcium salt in beet roots and is deposited in the concentrated tank of sugar beet. Scale is calcium malonate. Malonic acid is a colorless flake crystal. Malonic acid loses carbon dioxide when heated to generate acetic acid. By using this property to decarboxylate substituted malonic acid, various carboxylic acids can be synthesized. The methylene group in the malonic acid molecule is activated by two carboxyl groups, and various types of reactions can occur. In industry, the method of hydrolyzing cyanoacetic acid or diethyl malonate is commonly used to prepare malonic acid. Since malonic acid itself is not very stable, its application in organic synthesis is carried out through diethyl malonate.
Mainly used in pharmaceutical intermediates, also used in spices, adhesives, resin additives, electroplating polishing agents, etc.; used as a complexing agent, also used in the preparation of barbitur salts, etc.; malonic acid is a fungicide rice blasting The intermediate of indole is also the intermediate of plant growth regulator indole. ; Malonic acid and its esters are mainly used in perfumes, adhesives, resin additives, pharmaceutical intermediates, electroplating polishing agents, explosion control agents, thermal welding flux additives, etc. In the pharmaceutical industry, it is used to produce luminal, barbital, vitamin B1, vitamin B2, vitamin B6, phenylbutazone, amino acids, etc. Malonic acid is used as an aluminum surface treatment agent. Since only water and carbon dioxide are generated during thermal decomposition, there is no pollution problem. In this regard, it has great advantages compared with acid-type treatment agents such as formic acid used in the past. ; Mainly used in pharmaceutical intermediates, as well as spices, adhesives, resin additives, electroplating polishing agents, etc.; used in the production of barbiturates and other drugs.
In industry, the method of hydrolyzing cyanoacetic acid or diethyl malonate is commonly used to prepare malonic acid.
It can also be prepared from acetic acid as a raw material. Acetic acid reacts with chlorine gas to obtain chloroacetic acid, which is then treated with sodium carbonate to generate sodium salt, which undergoes nucleophilic substitution reaction with sodium cyanide to obtain cyanoacetic acid. The sodium hydroxide solution is hydrolyzed, and the cyano group is converted into carboxylate ion, which is then acidified to obtain malonic acid.