What Is Paraformaldehyde?
Paraformaldehyde, an organic compound, results from the dehydration and polymerization of formaldehyde. This linear polymer is recognized by its CAS registration number 30525-89-4 and has the chemical formula (CH2O)n. Also known as “paraform” and “1,3,5-trioxane,” paraformaldehyde belongs to the class of polymers known as polyacetals or polyoxymethylenes, characterized by the oxymethylene (-CH2O-) structure in their units. Due to its potent effects, it is regulated as a powerful drug under related laws, highlighting its significant toxicity.
Applications of Paraformaldehyde
As a versatile agent, paraformaldehyde is deployed as a fumigant for pest control and disinfection. Its high reactivity makes it a preferred raw material in the synthesis of various products, including paints, adhesives, preservatives, and resins (phenolic, urea, and vinylon acetalization applications), as well as in the production of ion exchange resins, pharmaceuticals, water-resistant glues, and protein glue coagulants. Specifically, it serves as a crucial ingredient for methylol and methylene compounds, which enhance the properties of paints and adhesives by providing UV protection and improving their durability and heat resistance. Notably, methylene chloride, a primary methylene compound, is widely used as a paint stripper and remover.
Properties of Paraformaldehyde
This polymer, denoted as (CH2O)n, appears as a white solid (in various forms like flakes, granules, or crystalline powder) and decomposes at temperatures between 120-180°C, depending on its polymerization degree. It emits a distinct formaldehyde odor and is insoluble in water, ethanol, and ether, yet dissolves in sodium hydroxide solution. Its density stands at 1.42g/mL. Notably, paraformaldehyde can revert to formaldehyde when dissolved in water or upon heating, highlighting its dynamic nature as it releases flammable formaldehyde gas when dried.
Types of Paraformaldehyde
Available for research and industrial applications, paraformaldehyde is often utilized as a crosslinking and immobilization reagent due to its ability to convert back to formaldehyde upon heating with sodium hydroxide. Its laboratory forms include manageable quantities like 100g, 500g, 1kg, and 2kg, facilitating easy handling. Industrially, it’s packaged in larger quantities, such as 20kg paper bags or flexible containers, supporting its use in manufacturing paints, adhesives, fiber processing resins, and phenolic resins.
Other Information about Paraformaldehyde
1. Generation of Paraformaldehyde
Paraformaldehyde naturally precipitates as a white solid from formaldehyde solutions, especially upon cooling. Formaldehyde, its monomer, is typically produced by the air oxidation of methanol in the presence of a catalyst or by the carbonization of calcium formate.
2. Paraformaldehyde Safety Information
Recognized as a flammable and combustible solid, paraformaldehyde poses risks of dust explosions when its particles are airborne. It can react vigorously with oxidizing agents, acids, and bases, potentially leading to the generation of heat or the release of formaldehyde gas. Its ingestion or inhalation is harmful, causing skin and eye irritation, along with possible lung damage.
3. Legal and Regulatory Information on Paraformaldehyde
Given its hazards, paraformaldehyde is subject to stringent regulations. It is classified as a combustible substance and is also designated as a deleterious substance under various health and safety laws. Compliance with these regulations is crucial for its safe handling and use.