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formalin

Product name formalin
GOST no data
CAS 50-00-0

Formaldehyde is a colorless gas with a pungent odor. It is soluble in water, methanol, ethanol and other polar solvents. At low temperature it fully miscible in non-polar solvents such as toluene, diethyl ether, ethyl acetate, chloroform. Formaldehyde is most commonly sold as a 37-40% methanol stabilized aqueous solution with trade names such as formalin or formol. Pure gaseous formaldehyde is stable at 80-100°C, below it slowly polymerizes. Upon evaporation of water solution it forms linear polymer paraform CH2O)n (n=8-10). Formaldehyde can be easily released from paraform upon heating. Formaldehyde also reversibly polymerizes to produce its cyclic trimer, 1,3,5-trioxane and tetramer, tetraoximethylene.

Formaldehyde was first synthesized by the Russian chemist Aleksandr Butlerov in 1859. Formaldehyde exhibits most of the chemical properties of the aldehydes. It reduces by hydrogen in the presence of metal catalyst resulting in methanol. Reaction with acetaldehyde in the presence of calcium hydroxide Ca(OH)2 yields to pentaerythritol; interaction with isobutylene results in isoprene. Liquid-phase condensation of formaldehyde with propylene leading in the presence of BF3 or sulfuric acid results in butadiene. Interaction of two formaldehyde molecules with acetylene results in 2-butine-1,4-diol, commercial butadiene precursor. Formaldehyde easily reacts with compounds containing labile hydrogen atom (polycondensation process) to form polymers.

Production.

Industrially formaldehyde is produced by oxidative methanol dehydrogenation.

  • in vapour phase on silver catalyst at 680-720°C. Methanol conversion is 97-98%;
  • on silver catalyst at 600-650°C with methanol conversion 77-87%. Unreacted methanol is recycled;
  • with excess of air on iron-molibdenum-tungsten oxide catalyst at 250-400°C. Methanol conversion is 98-99%;

    2CH3OH + O2 --> 2H2CO + 2H2O

    Uses.

    Formaldehyde is one of the principal industrial chemicals. It is applied:

  • in the production of polymers and resins. When combined with phenol, urea, or melamine, formaldehyde produces a hard thermoset resin.
  • in low concentrations for process C-41 (color negative film);
  • as an intermediate in butadiene preparation;
  • to produce beta-propiolactone (reaction with ketene);
  • as a raw material in making pentaerythritol, methylene diphenyl diisocyanate, hexamine and other industrial chemicals;
  • as an intermediate in manufacturing pharmaceuticals, dyes and paints;
  • in medicine as a disinfectant and as a preservative in vaccinations;

  • Manufacturer(s) JSC AZOT
    Chemical structure of formaldehyde

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