What is formaldehyde ?
Formaldehyde or methanal is a gas with a very strong and unpleasant smell. It is the simplest organic compound from the substance class of aldehydes.
Features
A solution of 37% formaldehyde in water is called formalin or formol. Formaldehyde is also supplied in polymerized form under the name of paraformaldehyde, a white fine powder. This form has the advantage that it is a less volatile compound, and longer shelf life. The disadvantage is that the compound, in certain circumstances (for example, if the carbonyl substrate in Wittig reaction) is too little reactive. Further, as for comes formaldehyde trimer, trioxane. This is a solid with a melting point of 64 ° C.
In a concentrated aqueous solution of formaldehyde to formic acid reacts. This solution is - in diluted form - used as a disinfectant and to prepare and store biological samples. It denatures protein and makes them insoluble, and a long shelf life, but also much harder, a process that is akin to tanning. Biologicals that have been fixed in formalin are hard and difficult to handle.
Formaldehyde is a gas and can also be stored as a more easily storable, and editable chemical compound. Reaction with ammonia provides hexamine, a cyclic aminal which by heating and treatment with an acid can be converted back to formaldehyde. The reaction with sodium hydrogen sulphite gives the corresponding bisulfite adduct, which is readily soluble in water. This can be converted back in formaldehyde by hydrolysis.
Applications
Formaldehyde is used in include chipboard, MDF, UF insulation and textiles (clothing, curtains and drapes). It can also be used to make polymers: together with urea is formed, for example urea formaldehyde.
Formaldehyde is widely used as a preservative in cosmetics, sometimes in the form of formalin, but more often by the use of so-called formaldehyde donors are substances which slowly release formaldehyde. Examples of formaldehyde donors are bronopol, imidazolidinyl urea, DMDM hydantoin and Benzylhemiformal. In the cosmetic industry is widely used as a disinfectant formaldehyde plant and packaging, making many types of cosmetics contain small amounts of formaldehyde, even if it is not mentioned in the INCI ingredients declaration.
Formaldehyde is used in various industries:
- reaction agent in production processes (inter alia, in the preparation of chemicals)
- leather, textile and carpet factories
- paper and wood processing industry
- medical sector:
- hospitals (disinfectant in hospital rooms)
- Laboratories (disinfectant against viruses)
- in the preparation of vaccines
- simple drug testing (Marquis reagent)
- agricultural companies
- beverage industry
Toxicology and safety
Formaldehyde is toxic. Methanol is toxic in that this substance by the enzyme alcohol dehydrogenase in the liver is converted to formaldehyde.
Formaldehyde has been proven human carcinogen. The carcinogenic effect has been clearly demonstrated in animal studies but epidemiological studies in humans were no formal conclusions. The IARC ranked formaldehyde and 2004 in group 2A (probably carcinogenic). In June 2004 an international working group of experts decided to place on the basis of existing epidemiological studies formaldehyde in Group 1, therefore carcinogenic to humans.
One of the warnings indicated on packets of cigarettes, tobacco and other tobacco is tobacco smoke includes formaldehyde.
Formaldehyde can irritate the eyes, nose and throat. There may also be headache and skin irritation occur. It is even possible to develop a occupational asthma on this substance.