At the beginning of the 19th century the emperor Napoleon Bonaparte appointed the chemist as Interior Minister Jean Antoine Chaptalwhich commissioned the also chemist Louis Jacques Thenard (1777-1857) to find a new blue pigment, with which to replace the scarce and expensive lapis lazuli.
To solve the assignment, Thénard started with cobalt arsenate, the chemical compound used to color Sevres porcelain blue. After multiple experiments, in 1804 he obtained an intensely blue pigment, very stable and much cheaper than the lapis lazuli. The French chemist obtained it by heating a mixture of arsenate and cobalt phosphate with alumina red hot.
In a very short time the new cobalt blue became the favorite of artists. It was, for example, the color you used vincent van gogh in 1890 in his famous composition ‘He Dr. Paul Gachet‘, which is currently in the Musée d’Orsay, in Paris.
colorless and very unstable
Barely fourteen years after his fabulous discovery -in 1818- Thénard discovered the hydrogen peroxidealso known as hydrogen peroxide, did so by attacking the barium peroxide –a highly reactive substance-. This finding would be of enormous importance in the health field for almost two centuries.
Hydrogen peroxide is a colorless liquid –although in large quantities it can turn blue- and with a density greater than that of water. Each molecule is made up, as its name suggests, of two hydrogen atoms and two oxygen atoms.
Hydrogen peroxide is a highly reactive compound that has been used as a disinfectant and whose concentration is expressed in volumes, which indicate the amount of oxygen released during its decomposition.
Another of the singularities of hydrogen peroxide is its instability, and it is that it spontaneously decomposes into oxygen and water. It is true that this process occurs very slowly if there is no exposure to light, which explains why the containers that contain it are opaque, but in the presence of a catalyst the process becomes very fast. In the list of accelerators are metals, some salts and some enzymes, such as catalase.
Toxic and inefficient
It is precisely the presence of this enzyme in animal tissues that allows hydrogen peroxide to be used as a wound disinfectant. And it is that catalase is an enzyme belonging to the group of oxidorreductasas that catalyzes the decomposition of hydrogen peroxide to oxygen – the one responsible for the bubbling that appears when hydrogen peroxide is applied to a wound – and water.
The oxygen resulting from the decomposition creates a toxic and lethal environment for many pathogenic bacteria present on the skin, since they are anaerobic in nature. In other words, catalase allows an anaerobic environment to become aerobic.
In recent decades the use of hydrogen peroxide as a disinfectant has decreased enormously, this has been due to two reasons, on the one hand, the presence of bacterial enzymes capable of destroying it; and on the other, hydrogen peroxide is capable of damaging healthy cells in the body.
It is precisely this harmful effect that makes it inadvisable to use hydrogen peroxide as a tooth or skin whitener, home remedies that were widely used for decades.