Basic Information
Chemical Name: Dehydroacetic acid, also known as 3 - Acetyl - 6 - methyl - 2H - pyran - 2,4(3H) - dione.
Chemical Formula:
Molecular Weight: 168.15
CAS Registry Number: 520 - 45 - 6
Physical and Chemical Properties
Appearance: It is colorless to white, needle - like or flake - like crystals, or white crystalline powder.
Melting Point: 109 - 111°C
Boiling Point: 269.9°C
Solubility: It is sparingly soluble in water, with a solubility of 0.1g/100mL (at 25°C), and is easily soluble in organic solvents such as ethanol, ether, and acetone. The solubility in ethanol is 33g/100mL (at 25°C).
Stability: It is relatively stable to light and heat, and is not easily decomposed when heated in aqueous solution. It has a certain chemical stability under acidic and basic conditions, but will undergo a hydrolysis reaction under strong alkaline conditions.
Product Quality Standards
Purity Requirements: The purity of industrial - grade products is generally required to be above 98%, and the purity of food - grade and pharmaceutical - grade products is even higher, usually above 99%.
Impurity Restrictions: The content of heavy metals (such as lead and mercury) is strictly limited. The content of heavy metals in food - grade products is generally required to be below a few ppm (parts per million). The content of other impurities such as water content is also strictly controlled, and the water content is generally required to be below 0.5%.
Production Process
Chemical Synthesis Method
Raw Materials: Mainly ethyl acetoacetate.
Steps: Dehydroacetic acid is synthesized through a series of chemical steps such as condensation reactions. For example, ethyl acetoacetate undergoes an intramolecular condensation reaction under the action of a basic catalyst (such as sodium ethoxide) to form an intermediate, and then through acidification, dehydration and other steps, dehydroacetic acid is finally obtained. The advantage of this method is high yield and suitability for large - scale production, but it has high requirements for reaction conditions and equipment, and parameters such as reaction temperature, pressure and catalyst dosage need to be strictly controlled.
Application Fields
Food Industry
Preservative Function: Dehydroacetic acid is a highly effective preservative that can inhibit the growth and reproduction of molds, yeasts and bacteria. It has a wide antibacterial spectrum and has a good inhibitory effect on common microorganisms that cause food spoilage, such as Aspergillus niger, Aspergillus flavus and Saccharomyces cerevisiae. The addition amount in food is generally 0.03% - 0.05% (by mass), and it can be used for the preservation of various foods such as bread, pastries, fruit juice beverages and pickles. For example, in bread - making, the addition of dehydroacetic acid can effectively extend the shelf life of bread and prevent bread from getting moldy and deteriorating during storage.
Cosmetics Industry
Preservation Function: In cosmetics, it can prevent the growth of microorganisms and ensure the quality and safety of cosmetics within the shelf - life. The usual addition amount is relatively low, generally around 0.1% - 0.3%, and it is used in products such as creams, lotions and shampoos. It can be used in combination with other preservatives (such as phenoxyethanol) to enhance the preservative effect.
Pharmaceutical Industry
Drug Intermediate: Dehydroacetic acid can be used as an intermediate for the synthesis of certain drugs. For example, it plays a role in the synthesis of some drugs with antibacterial and anti - inflammatory effects. Through chemical modification methods, the chemical structure of dehydroacetic acid is converted into a compound with specific pharmacological activities.
Safety and Precautions
Toxicity: Dehydroacetic acid has low toxicity and generally does not harm human health within the specified usage range. However, long - term or excessive intake may have certain adverse effects on the human body, such as causing allergic reactions.
Usage Regulations: The use in food is strictly regulated by laws and regulations. Different countries and regions have clear regulations on the maximum usage amount and usage range of dehydroacetic acid in food. For example, in China, the Standards for the Use of Food Additives stipulate the specific usage limits of dehydroacetic acid in various foods, and producers must strictly abide by these regulations to ensure food safety. There are also corresponding quality and safety standards in the cosmetics and pharmaceutical industries to regulate its use.
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