[Chemistry Class Notes] Formaldehyde Pdf for Exam

Formaldehyde is also referred to as methanal. It is an organic compound, which is the simplest of the aldehydes and used in large amounts in diverse chemical manufacturing processes. It can be principally produced by the vapor-phase oxidation of methanol, and it is commonly sold as formalin, a 37% aqueous solution. Dehydrating formalin to a crystalline trimer, trioxane, or an amorphous paraformaldehyde, polymer, which is a convenient source of gaseous formaldehyde, is an option.

HCHO name or the HCHO chemical name is Formaldehyde.

About Formaldehyde

Hexamethylenetetramine, or methenamine, is a urinary antiseptic made from ammonia and formaldehyde. Methenamine nitration gives explosive RDX or cyclonite. In the presence of calcium hydroxide, acetaldehyde and formaldehyde react to form pentaerythritol, whose tetranitrate is the explosive PETN. In the production of phenol-formaldehyde resin, urea-formaldehyde resin, and acetal resin, large amounts of formaldehyde are used (polyoxymethylene). The HCHO common name is the formaldehyde.

The formaldehyde reaction with the proteins leads to its use in the tanning industry and also in treating multiple vegetable proteins to render them fibrous. Because of its reactivity with proteins, formaldehyde is used as an embalming agent, disinfectant, and soil sterilant.

Pure formaldehyde is a flammable and colorless gas having a strong, pungent odor. It can be extremely irritating to the mucous membranes and associated with certain cancer types in humans and also other animals. Formaldehyde can be classified as a human carcinogen (which means cancer-causing substance).

Forms

Formaldehyde is more complex than a few basic carbon compounds because it can take several different forms. These compounds are often used interchangeably and are interconverted.

• Molecular Formaldehyde – It is a colorless gas having a characteristic pungent and irritating odor. It is stable at around 150 °C, but when condensed to a liquid, it polymerizes.

• 1,3,5-Trioxane, having the formula (CH2O)3. It comes as a white solid that dissolves in organic solvents without degrading and is a trimer of molecular formaldehyde.

• Methanediol, having the formula CH2(OH)2. Also, this compound exists in equilibrium with different oligomers (or the short polymers) based on temperature and concentration. “100% formalin” is a saturated water solution containing about 37 percent formaldehyde by mass or 40 percent formaldehyde by volume.

Occurrence

Around 90% of the overall formaldehyde in the world comes from processes in the upper atmosphere. It is an intermediate in the oxidation (or the combustion) of methane and of other carbon compounds as well. For example, automobile exhaust, forest fires, and tobacco smoke. When it is produced in the atmosphere by the action of oxygen and sunlight on atmospheric methane and the other hydrocarbons, it becomes part of smog. The formaldehyde compound has also been detected in outer space.

Interstellar Formaldehyde

Formaldehyde appears to be a useful probe in astrochemistry because of the prominence of the transitions of 110←111 and 211←212 K-doublet. It was given as the first polyatomic organic molecule that is detected in the interstellar medium. In 1969, since its initial detection, it had been noticed in several regions of the galaxy. Because of the widespread interest in interstellar formaldehyde, it has been extensively researched, resulting in new extragalactic sources.

Synthesis

Laboratory Synthesis

Formaldehyde was the compound, which is first reported in 1859 by the Russian chemist named Aleksandr Butlerov (1828–86). In his paper, Butlerov has referred to formaldehyde as “di-oxymethylene” (which is called methylene dioxide) because his empirical formula for it was not correct (C4H4O4). Conclusively, it was identified by August Wilhelm von Hofmann, who is the one, first announced the formaldehyde production by passing methanol vapor in the air over the hot platinum wire. Hoffmann’s system has been modified, but it still serves as the foundation for today’s industrial path.

Formaldehyde Solution Uses

Industrial Applications

Formaldehyde is given as a common precursor to many complex materials and compounds. Melamine resin, urea-formaldehyde resin, polyoxymethylene plastics, phenol-formaldehyde resin, 1,4-butanediol, and methylene diphenyl diisocyanate are among the formaldehyde-derived products, in roughly decreasing order of use.

The formaldehyde resins can be used as the finishers in the textile industry to make fabrics crease-resistant. Materials of formaldehyde-based are a key in automobile manufacturing and can be used to make components for the electrical system, transmission, door panels, engine block, brake shoes, and axles.

The sales value of formaldehyde and the derivative products was up to $145 billion in 2003, nearly 1.2% of GDP (Gross Domestic Product) of the US and Canada. In the United States and Canada, the formaldehyde industry employs nearly 4 million employees, including indirect staff, in nearly 11,900 plants.

Niche Uses

Disinfectant and Biocide

Formaldehyde’s aqueous solution is useful as a disinfectant because it kills most fungi (including their spores) and bacteria. Also, it is used as an additive in the manufacturing of vaccines to inactivate pathogens and toxins. The releasers of formaldehyde are used as biocides in several personal care products such as cosmetics. Although at present, the levels are not generally considered harmful, they are well-known to cause allergic contact dermatitis in certain sensitized individuals.