Johann Wolfgang Doebereiner

Translated from German by Alexandra Igna (2019)

 

Johann Wolfgang Döbereiner (born December 13, 1780 in Hof, died March 24, 1849 in Jena) was a German chemist who is considered a pioneer in the elaboration of the periodic table and who paved the way for catalysis in the study of platinum.

Life

As the son of a coach, Johann Wolfgang Döbereiner grew up in poor conditions on the estate of a knight near Weißdorf and only received moderate education. He began his apprenticeship as a pharmacist in Munich in 1794. He worked in pharmacies in Dillenburg, Karlsruhe and Strasbourg and also acquired self-taught knowledge in chemistry, botany and mineralogy. He returned to his hometown in 1802, but was unable to work independently as a pharmacist. Döbereiner drew attention to himself by examining complex and practical chemical problems. In 1810 he has received a job in the chemistry, pharmacy and technology department at the University of Jena from Duke Carl August of Saxony-Weimar through Johann Wolfgang von Goethe. As he did not have an academic degree, he was awarded the title of Dr. Phil. because his previous publications “already unmistakably bore the stamp of genius and perfection.

Döbereiner's selection was a stroke of luck for the institution, as he combined his genius as a researcher, a very strong interest in technical processes and excellent teaching abilities. His lectures were modelled very practically through numerous experiments on inorganic and organic chemistry. In addition, he organized many trips to chemical plants in the Jena area to show his students chemical technology and pneumatic chemistry in practice. One of his most successful students was Rudolf Christian Böttger, inventor of safety matches and additional board developer. As a chemical consultant to Duke Carl August, he worked on improving manufacturing processes. He was involved in the construction of a sulfuric acid factory and developed advanced processes for extracting and recycling indigo instead of paint fabric. Moreover, a factory for the production of starch sugar was built at the time of continental closure with the participation of Döbereiner in Tiefurt, and the production of acetic acid by the rapid vinegar process by oxidation of alcohol is mentioned. There are also distilleries and beer. Around 1818, at the suggestion of Goethe and the Grand Duke, he attempted to produce gas for lighting purposes, finding that “when coal and water interact at high temperatures, they produce the cheapest and purest fire gas. "

In 1828 he performed melting tests for the production of celestial barite glass and also examined fermentation processes. He made the most important and well-known discoveries in the area of ​​the catalytic effect of platinum metals and in determining the similarities in the properties of the elements known at that time. Döbereiner is less well known as a pioneer of chemical internships in teaching at German universities. Even before Justus von Liebig in Gießen, Döbereiner held a college of practical chemistry at Jena in 1820, which was extremely popular with students. Goethe claimed this by buying a house in Jena and procuring laboratory equipment. In gratitude, despite financial problems, Döbereiner remained loyal to Jena University, although he received honorable appointments to other universities. He died on March 24, 1849 in Jena and was buried in the Johannisfriedhof on the Philosophenweg. The inscription on his tombstone is written: Goethe's advisor, creator of the triad theory, discoverer of platinum catalysis.

Discoveries

The Triad Rule

Döbereiner is considered a pioneer in the structure of the periodic table of elements. In 1816 he discovered a connection between the elements calcium, strontium and barium. They had very similar properties, and the atomic mass of the middle element was the average of the atomic masses of the other two elements. This finding was published in 1829 and it was part of his attempt to group elemental substances by analogy. Döbereiner arranged 30 of the 53 known elements in groups of three, called the "triads." The rule of the triad made it possible to make predictions about elements that were still unknown. Döbereiner predicted the atomic weight of bromine. His triad rule made it possible for the periodic table of elements to be developed around the 1870s.

Much of his research was related to the investigation of the catalytic effects of platinum metals. In 1816, with the help of the platinum mill, he successfully oxidized alcohol to acetic acid. A few years later, he ignited a detonating gas mixture under the influence of the platinum sponge and made one of the most important discoveries in early catalytic chemistry. This led to the invention of the Döbereiner lighter, which became a coveted commercial object. With the observation that oxyhydrogen gas could also explode using an iridium-osmium mixture, in 1824, Döbereiner formulated the principle of mixed catalysts later used in the chemical industry. The function of the Döbereiner lighter is, as follows: diluted sulfuric acid is contained in a glass vessel and a piece of zinc is immersed in a glass bell. At the top, the bell jar is closed by a valve; if you open it by operating a lever, the gas in the glass bell flows through a nozzle, the acid rises and reacts with zinc, producing hydrogen gas H 2, which then flows through the nozzle on a "platinum sponge" (finely divided platinum). It then catalyzes the reaction of hydrogen with oxygen 2H 2 + O 2 -> 2H 2 O (gas detonation reaction); the gas mixture is ignited by the heat released in the process (exothermic reaction). When the lever is released, the valve is closed again and the hydrogen gas can no longer escape upwards, pressing the acid from the glass bell back into the storage container.

 

Source:

*chemie.de