Formic aldehyde, or formaldehyde, is a colorless gas with a pungent, unpleasant, specific odor. It is highly soluble in water, as well as in alcohols. Formaldehyde is very toxic and can cause pathological changes in the human body. In addition, it is considered a carcinogen.
Formaldehyde is the first member of a whole homologous series, which includes aliphatic formic aldehyde. Formic acid also exhibits the properties of this group.
Chemical properties
Formaldehyde is able to enter into all reactions that are characteristic of the homologous series of aliphatic aldehydes. Including nucleophiles. It also binds to reducing agents. This is mainly due to the fact that formaldehyde has a low electron density on carbon atoms. Due to this structural feature, it very easily enters into chemical reactions even with the weakest nucleophiles. This explains the fact that in aqueous solutions, formic aldehyde is found in a hydrated state.
Production receipt
This substance has a fairly simple formula. In chemical language, formic aldehyde looks like this: HCHO. The main industrial method for its preparation is the oxidation of methanol. This reaction is carried out using a silver catalyst. The required temperature is 650 degrees. Methanol oxidation occurs at atmospheric pressure.
This process has been used universally for quite some time. It is well mastered. About 80% of formaldehyde is obtained due to the oxidative reaction of methanol. However, this is not the only way. Recently an even more promising method has been developed. It is based on the use of iron-molybdenum catalysts. In this case, the level of the required temperature is reduced to 300 degrees, and this is almost half as much.
Another industrial process is also known - the oxidation of methane. This reaction has a rather simple formula: formic aldehyde is obtained at a pressure of 1-2 MPa at a temperature of 450 degrees. As a catalyst, aluminum phosphate is taken.
Application
Methandiol is an aqueous solution of formaldehyde that causes protein denaturation. This quality makes it possible to use this substance as a tanning agent in the manufacture of leather goods. He also found wide application in the manufacture of film. Due to its strong tanning properties, formaldehyde is known as an antiseptic. It is widely used in medicine. On its basis, such antiseptic preparations as Formagel and Formidron are produced. For a long time, ant aldehyde has been used in biology to store biomaterials, for example, organs or corpses of animals.
At present, the production of formic aldehyde is beneficial for the woodworking and, of course, furniture industry. It is used for the production of melamine urea formaldehyde resins. They are used in the manufacture of chipboard, plywood and other building materials.
When storing formic aldehyde, it should be borne in mind that at temperatures below 10 degrees the solution becomes cloudy and a white precipitate appears. Formaldehyde also interacts with oxygen. As a result, additional chain initiators are formed due to degenerate branching.
Toxic properties
So, formaldehyde is obtained by the oxidation of methanol and methane. Undoubtedly, it has a fairly high degree of toxicity. Formic aldehyde primarily affects genetic material. Reproductive organs also suffer from this substance. But, of course, damage to the respiratory tract, skin and mucous membranes of the eyes is more often noted.
Formaldehyde is also dangerous in that it has a negative effect on the central nervous system.
Formic aldehyde is not just toxic - 60-90 ml of a substance (depending on body weight), ingested, will cause death. Symptoms of poisoning are as follows:
- general breakdown;
- pallor of the skin ;
- unconsciousness;
- depression of the central nervous system;
- labored breathing;
- Strong headache;
- cramps, especially at night.
The effect of formic aldehyde on the human body
The use of formic aldehyde in production often causes varying degrees of poisoning among employees. With severe inhalation damage, that is, by inhalation of the substance, conjunctivitis and an acute form of bronchitis are observed, which sometimes leads to pulmonary edema. Symptoms with prolonged exposure to formaldehyde will only increase. After a short time, signs of damage and depression of the central nervous system will appear. This will be expressed in constant dizziness, a feeling of fear will arise, a gait will become shaky, and at night a person may even have cramps.
If poisoning occurred through the mouth, the first symptom will be a burn of the mucous membrane of the digestive tract. It will manifest itself in the form of pain, burning in the throat and along the esophagus. A person feels strong vomiting, the mass rejected by the stomach will contain blood. In severe cases, laryngeal edema develops and a reflex respiratory arrest is observed.
In chronic poisoning with low concentrations in humans, severe weight loss, mental agitation, visual disturbances, insomnia and persistent headaches are noted .
Formaldehyde vapor poisoning
Formic aldehyde is most often found in the air. Employees of enterprises engaged in the manufacture of artificial resins, in the presence of constant and prolonged contact with formaldehyde vapors, may be poisoned. Often, in the first working days, a person develops noticeable dermatitis on his face and hands. The presence of formaldehyde in the body can be seen by the deterioration of the condition of the nails - they soften and become brittle.
Eczema and dermatitis can be allergic. After a person has suffered poisoning, he develops a strong sensitivity to formic aldehyde. There is evidence that formaldehyde adversely affects the functioning of the reproductive system of the female body.
The use of formaldehyde in cosmetics
The formaldehyde content is allowed as a preservative in cosmetics, but its concentration should not exceed 0.1%. Formic aldehyde may be present in toothpaste, body, face, and hand creams.
Also in pharmacology, in some drugs that prevent excessive sweating, formaldehyde can be found. Its permissible concentration is 0.5%. This substance is a good antiseptic, even in such small quantities it is able to destroy microorganisms. It is strictly forbidden to apply any ointment to the face if it contains 5% formaldehyde. This is fraught with the appearance of dermatitis and allergic reactions. Formic aldehyde is also not used to preserve cosmetics if they are sold as aerosols and sprays.
All products on their labels should contain information on the content of this dangerous substance, even if its amount is 0.05%. In fact, until today it has not been clarified how formaldehyde solution affects the skin, but it is known that in animals it reddens and flakes.
Carcinogenicity of formic aldehyde
Formaldehyde is known to interact with selenium with the participation of highly concentrated sulfuric acid. As a result, sulfoether-4-tetradecylidioxane is formed. This compound with a complex name after treatment with barium oxide hydrate becomes an excellent detergent. It would seem, what is the danger? But formaldehyde is listed as a carcinogen. Although its degree of danger has not yet been established, one cannot but take into account the fact that formic aldehyde is deadly for animals. According to official data from many scientific centers of the world, the connection between the use of formaldehyde in the manufacture of paints, resins, textiles, plastics and the occurrence of cancerous tumors in humans has been proven. The risk of developing nasopharyngeal cancer is particularly high.