STANISLAO CANNIZZARO: BIOGRAPHY AND OUTSTANDING CONTRIBUTIONS - CHEMISTRY - 2025

Stanislao Cannizzaro (1826-1910) was a prominent European scientist of Italian origin whose studies in medicine, physiology, and chemistry earned him great recognition throughout his professional life.

His main contributions to science are the Cannizzaro reaction, the explanation of Avogadro's hypothesis, the essay Sunto di un corso di philosophia chimica and having established in a forceful way the difference between atoms and molecules.

Several discoveries are also attributed to him, including cyanamide, benzyl alcohol, and benzoic acid. Due to the anatomical reform, many cataloged him as the father of the Law of Atoms.

This Italian was co-founder of the scientific journal Gazzetta Chimica Italiana. Not satisfied with his medical, academic and scientific activities, Cannizzaro intervened in the January Revolution of 1848: he was appointed officer of the Sicilian artillery and was part of the House of Commons as a deputy in Francavilla.

Biography

Stanislao Cannizzaro was born in Palermo on July 13, 1826. He grew up in a wealthy Italian family with ten siblings. His father Mariano Cannizzaro was a magistrate and general director of the Sicilian Police, and his mother was named Anna Di Benedetto.

Studies

The first years of study were attended in private schools and in the normal school of Palermo. In 1836 he was admitted to the royal Carolino Calasanzio. The following year, much of Italy suffered from the cholera epidemic and two of his brothers died from it.

Stanislao was infected with cholera, but after a long recovery he came out of the situation with the intention of studying philosophy, literature and mathematics.

At just 15 years of age, in 1841 the young Cannizzaro entered to study Medicine at the University of Palermo. After having spent three years in the chair of physiology, he began a friendship with his professor Michele Fodera.

Under the supervision of Fodera Cannizzaro he carried out several experiments that made him fall in love with chemistry. Motivated by the lack of laboratory infrastructure at the university, Stalisnao Cannizzaro promoted the creation of modern university classrooms for the proper practice of students.

In 1845 Cannizzaro participated in a scientific congress held in Naples. It was there that he was invited to work for the chemistry laboratory at the University of Pisa. In this laboratory he lasted two years and, together with several of his colleagues, he consolidated his foundations in the area of ​​chemistry.

Revolution of 1848

During his school holidays in 1847, while in Sicily, he participated in the Revolution of January 1848. He accused the government of the day of mismanagement and treason against Sicily.

Stanislao Cannizzaro was appointed officer of the Artillery in the new army of Sicily; this had its own regulations and Constitution. After a few months he was elected as a member of the House of Commons and deputy for Francavilla. From there he asked for the absolute reform of the Constitution of 1812.

After winning the confidence of the Sicilian revolutionary government, Stanislao Cannizzaro remained in Taormina. On this occasion he did so as commissioner of the aforementioned regime where he had participated against the resistance of the Bourbon troops.

Fall of the Sicilian revolution and flight

When the truce ended in 1849, he fled together with the revolutionary troops to Palermo. In April of that same year the Sicilian revolution fell and he was sentenced to death.

This led him to flee to the Island of Marseille. Later he went to Lyon, France, where he studied industries. Then he went to Paris, where he was offered a job in a prestigious laboratory called Michel-Euguéne Chevreul; It was there that he obtained cyanamide in 1851.

Together with his colleague Edmond Fremy, he carried out a series of experiments in the Gay Lussac laboratory. Then he received calorimetry classes at the College de France. He also achieved the Chair of Physics and Chemistry at the National College of Alexandria.

With the arrival of the autumn of the year 1855, Stanislao Cannizzaro established a small laboratory to continue his experiments. That's where what is called the Cannizzaro reaction was born, an alcoholic solution of potassium hydroxide.

That same year he was called by the Minister of Education to take charge of the Chair of Chemistry at the University of Genoa.

Teaching and research work

For bureaucratic reasons, their investigative processes were delayed. At the end of the year 1857, a fundamental study of a course in Chemical Philosophy was reviewed in a scientific journal called Nuovo Cimento.

The young Italian scientist wrote such concepts with the idea of ​​structuring and ordering a large part of his discoveries, mainly to help his students and colleagues.

Success continued for this great scientist, since in 1860 he was the guest of honor at the Karlsruhe Congress. There he had the opportunity to explain all the advances and discoveries made. This made him part of the Academy of Sciences, in 1865.

Another notable achievement of Cannizzaro was that he taught classes in Pisa and Naples. There he dictated the chair of Organic and Inorganic Chemistry at the University of Palermo.

He investigated aromatic compounds and amines. He also passed through the University of Rome and was a professor of Chemistry; this prompted his nomination as a senator. In this public administration, he made innumerable efforts to modernize and raise the level of Italian scientific education.

This scientist developed his facet as a writer by being co-founder of the scientific journal Gazzetta Chimica Italiana. Stanislao Cannizzaro died in Rome on May 10, 1910.

Main contributions

Cannizzaro reaction

Cannizzaro's studies focused on organic compounds and reactions in aromatic compounds.

In 1853, he discovered that when a benzaldehyde reacts with a concentrated base, two substances are produced: benzoic acid and benzyl alcohol. This phenomenon is known as the Cannizzaro reaction.

This is a disproportionate reaction, meaning that one molecule is reduced (the alcohol molecule), while the other is oxidized (the acid molecule). Cannizzaro's reaction occurs in three phases:

1 - In the first phase, a hydroxide ion attaches to the carbonyl.

2 - In the second phase, the transfer of the hydride occurs.

3 - Finally, in the third phase, the acid and the base are balanced.

"Sunto di un corso di philosophia chimica"

In 1858, Cannizzaro published his essay Sunto di un corso di philosophia chimica ("Summary of a course in chemical philosophy"), in the newspaper Nuovo Cimento.

This text was of great contribution to chemistry, since it responded to a series of diatribes on contemporary chemistry, such as the differentiation between atomic weight and molecular weight; likewise, in this essay, Avogadro's hypothesis was explained.

Explanation of Avogadro's hypothesis

In 1811, Amadeo Avogadro had developed a hypothesis that stated that equal volumes of different gaseous bodies, subjected to the same temperature and the same pressure, contained the same number of molecules.

From this it follows that, under equal conditions of temperature and pressure, the relative molecular weights of two gaseous bodies are equal to the density of these two bodies.

When Avogadro raised his hypothesis, he put it in much more complex and abstract terms that made it difficult to understand.

It was Cannizzaro who clarified certain aspects of this law. In addition, he demonstrated how Avogadro's ideas could be applied to the branch of organic chemistry.

Differentiation between molecular weight and atomic weight

Sunto di un corso di philosophy chimica by Cannizzaro

In his text Sunto di un corso di philosophia chimica, Cannizzaro established the delimitation between molecular weight and atomic weight.

This scientist demonstrated that the atomic weights of the elements found in volatile substances could be deduced from the molecular weight of these substances.

He also discovered that the density of the vapor and the atomic weights of these elements could be determined if one had knowledge of the temperatures of these. For these discoveries, he was awarded the Copley Medal of the Royal Society of London in 1891.

Cannizzaro and the periodic table

When Cannizzaro studied Avogadro's hypothesis, he stated that this scientist's theories were the key to the standardization of atomic weights. His observation was initially unappreciated, but later it paid off.

In 1860, the first international congress of chemists was held in Karlsruhe, Germany. The purpose of this congress was to solve certain problems in contemporary chemistry, such as the definition of molecule and atom, chemical nomenclature, atomic weight, among others. Sunto di un corso di philosophie chimica made it possible to resolve some of these questions.

In fact, Cannizzaro's observations inspired Dmitri Mendeleev during the creation of the periodic table (as stated by the scientist), which includes the atomic weight of the elements and Avogadro's number.

Cannizzaro courses

Throughout his life, Cannizzaro taught at different universities. His chemistry courses were a space for historical reflection on this science.

He dedicated his lessons not only to explaining the works of famous and renowned scientists, but also to figures of little renown such as the Frenchman Marc Antoine August Guadin (1804-1880) and his compatriot Amadeo Avogadro.

In this sense, his classes were the basis for the creation of his book Sunto di un corso di philosophia chimica.

The second revolution in chemistry

The second revolution in chemistry took place between 1855 and 1875. One of the scientists whose contributions allowed the development of this revolution was Stanislao Cannizzaro, along with Frankland, Wurtz, Keluké and Williamson, to name a few.

Cannizzaro's most significant contribution to this revolution was the introduction of the atomic weight.

References

1. Great Scientists of Humanity, (1998) Volume 2, Editorial Espasa-Calpe.
2. Biography of Stanislao Cannizzaro. Search Biographies (1999). Recovered in: Buscabiografias.com
3. Stanislao Cannizzaro - EcuRed. (2018). Recovered in: ecured.cu
4. Biography of Stanislao Cannizzaro. Biographies and Lives. The Online Biographical Encyclopedia. (2004-2018). Recovered in: biografiasyvidas.com
5. (S / D) Stanislao Cannizzaro. MCNBiografias.com The Web of Biographies. Recovered in: mcnbiografias.com