The simplest type in the aldehyde group of chemicals, formaldehyde is a pungent-smelling substance with the formula CH2O. It exists naturally in a range of sources, including lightning and forest fires, but can also be produced industrially for a range of uses. In this article, we’ll explore the various aspects of formaldehyde, from its sources and chemistry to why it’s toxic to the body.
Where does formaldehyde come from?
- Natural sources
While formaldehyde can be synthetically mass-produced for industrial use, it’s actually a naturally-occurring organic chemical. About 90% of naturally-occurring formaldehyde is produced in the upper atmosphere when oxygen reacts with methane, with the help of ultraviolet rays from the sun. This is known as the oxidation of methane, and it’s the main source of formaldehyde in the atmosphere.
Formaldehyde is also naturally produced:
- As a by-product of pollutants like automobile exhaust and tobacco smoke
- During forest fires, specifically when carbon compounds in trees and other plants combust
- In organisms as a waste product of metabolic processes, particularly the metabolism of endogenous amino acids
- Formaldehyde can also be detected in our blood, but only at a very small concentration of around 0.1 millimolar
Despite its ubiquitous presence in organisms and the environment, formaldehyde doesn’t significantly accumulate. In the atmosphere, for example, the same sunlight that helps produce it also breaks it down after a matter of hours. Meanwhile, formaldehyde in water and soil is broken down by bacteria, and in the human body, any excess formaldehyde is quickly metabolised into formic acid just a few minutes after it has formed.
- Synthetic sources
On an industrial level, formaldehyde is produced through the catalytic oxidation of methanol. Silver is commonly used as a catalyst in this process, but other chemicals can also be used, like a mixture of iron and molybdenum or vanadium oxides.
The industrial catalytic production of formaldehyde is known as the formox process, and involves subjecting methanol and oxygen to high temperatures ranging between 250–400°C. This is done in the presence of catalysts. The balanced chemical equation for this is:
2 CH3OH + O2 → 2 CH2O + 2 H2O
Higher temperatures of about 650°C are needed when using the silver-based catalyst. Two types of reactions occur at the same time here, both producing formaldehyde; the one shown above, and the dehydrogenation reaction illustrated by the balanced equation below:
CH3OH → CH2O + H2
- Demand and production
Formaldehyde has many industrial and household uses. It’s also used in aviation, pharmaceutical production, and automotive products because of its reactivity and versatility. Industrially, it’s a key precursor in manufacturing many materials and chemical compounds. However, formaldehyde is primarily used in manufacturing industrial resins that are then used in the production of other materials, like particle boards.
Transparency Market Research (TMR) estimates that the global demand for formaldehyde will moderately increase over the years, with the annual production expected to reach 36.6 million tonnes by 2026. According to a study by Acumen Research and Consulting, the global revenue for this chemical will reach $34.8 billion by 2026.
- Interstellar presence
Interestingly, formaldehyde can also be found among interstellar gases, and was in fact the first polyatomic organic molecule to be identified in interstellar space. Originally detected in 1969, formaldehyde has since been observed all over the galaxy and studied all over the world.
At the moment, the most widely accepted theory of how formaldehyde is formed in space is through the hydrogenation of CO ice:
H + CO → HCO
HCO + H → CH2O
Who Discovered Formaldehyde?
In 1859, Russian chemist Aleksandr Mikhailovich Butlerov was the first to identify formaldehyde as a colourless gas with a pungent, irritating odour. This was actually an accidental discovery by Butlerov, who was originally attempting to synthesise methylene glycol.
It was almost a decade before formaldehyde was conclusively identified by August Wilhelm von Hofmann, a chemistry professor and laboratory director at the University of Berlin. Von Hofmann was able to synthesise formaldehyde by using platinum as a catalyst in oxidising methanol. He also identified the structure and composition of formaldehyde, and his method of synthesis became the foundation for industrial production of this chemical.
What Is The Chemical Formula For Formaldehyde?
Formaldehyde is the simplest aldehyde, with the chemical formula CH2O and a trigonal planar shape. Despite the simplicity of its chemical formula, formaldehyde actually has several forms. For example, trioxane is a cyclic trimer form of the chemical. Paraformaldehyde, on the other hand, is the common form of the chemical and has many industrial applications.
When formaldehyde is dissolved in water, it’s known as formalin, which is commonly used as an embalming fluid. Its other uses, particularly in industry, are less well-known to the public. As a precursor or as a direct ingredient, some of the most common products derived from formaldehyde are:
- Urea formaldehyde resin
- Melamine resin
- Phenol formaldehyde resin
- Polyoxymethylene plastics
- Methylene diphenyl diisocyanate
In turn, these products are essential in manufacturing other products such as plywood, foam insulations, and cast resin products. The textile industry also makes use of formaldehyde-based resins to prevent fabrics from forming creases when they’re folded. Other derived products are essential in manufacturing automobiles and their components, including the engine block, door panels, and brake shoes.
CH2O also has other niches, or specialised uses, such as in drug testing; and, when combined with an 18 molar sulphuric acid, Marquis reagent is created. This is a reagent that can detect alkaloids and other compounds commonly found in many types of illicit drugs.
Is Formaldehyde Toxic?
Formaldehyde is a highly toxic substance to humans, especially when inhaled in its gaseous form. It can cause systemic poisoning as the cells of the lungs absorb it, allowing it to dissolve into the bloodstream and distribute to the other parts of the body, like the brain. Formaldehyde can cause dizziness or suffocation, as well as severe irritation of the respiratory tract, eyes, and skin.
Formaldehyde is also classified as a carcinogen, because repeated exposures over time may lead to the development of cancer. In fact, studies show that those who are commonly exposed to this chemical, like embalmers, pathologists, and industrial workers, have higher risks of developing various types of cancer later in life. Some of the correlated cancers are the following:
- Multiple myeloma
- Non-Hodgkin’s lymphoma
- Ocular melanoma
- Brain cancer
- Connective tissue cancer
- Pancreatic cancer
Where Can I Buy Formaldehyde?
Formaldehyde is commercially available as an aqueous solution, otherwise known as formalin (you can buy it from ReAgent right here). It’s available in various concentrations or grades, but the most common is 37% concentration. You can buy it from chemical stores or manufacturers in various pack sizes.
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