Hermann Kolbe (1818-1884): The Brilliant and Combative Chemist of Leipzig

Introduction

Adolph Wilhelm Hermann Kolbe was a German chemist who made important discoveries in synthetic organic chemistry: the synthesis of acetic acid from its elements, Kolbe electrolysis and the Kolbe-Schmitt process for salicylic acid. He was also known for strong and sometimes unfair attacks on new theories. His legacy in one line: a great experimenter whose reactions are still used, and whose quarrels are a warning to every scientist.

Early Life and Family

Kolbe was born on 27 September 1818 in Elliehausen, a village near Gottingen, in the kingdom of Hanover. His father was a Protestant pastor, and he grew up in a religious and hardworking home. He went to the gymnasium in Gottingen, and he was drawn to chemistry in school, a subject he was determined to pursue even though his family had hoped for a career in the church or in medicine.

Education and Mentors

In 1838 Kolbe entered the University of Gottingen, where he studied under Friedrich Wohler, the first to make urea from an inorganic salt. He worked as Wohler's assistant. In 1842 he moved to Marburg as an assistant to Robert Bunsen, and he took his doctorate there in 1843. In 1845 he went to London, where he worked at the Museum of Practical Geology with Lyon Playfair, and there he met Edward Frankland, with whom he did some early work on nitriles. He then worked in Braunschweig as editor for Liebig's Handworterbuch der Chemie, helping with the great dictionary of the time.

Career Timeline

Major Scientific Contributions

• Synthesis of acetic acid (1845): A step from inorganic compounds to an organic acid, supporting the end of vitalism.
• Kolbe electrolysis (1849): Electrolysis of carboxylate salts to alkanes.
• Kolbe-Schmitt process (1860): Carboxylation of phenoxide, giving salicylic acid for antiseptics and aspirin.
• Prediction of new alcohols: Around 1860 he predicted that secondary and tertiary alcohols should exist, a prediction soon confirmed by Friedel and by Butlerov, who prepared tertiary butyl alcohol.
• Theory of carbonic acid derivatives: He saw many organic acids as derivatives of carbonic acid, which was a step toward structure ideas.
• Salicylic acid as antiseptic: He studied its antiseptic properties and promoted its use.

2 CH3COO(-) -> C2H6 + 2 CO2 + 2 e(-)       (Kolbe electrolysis)
C6H5ONa + CO2 -> o-HOC6H4COONa             (Kolbe-Schmitt)

Awards, Honours and Nobel Prize

Kolbe was a member of several academies in Germany, and he was a foreign member of learned societies. He lived before the Nobel Prize (1901), so he could not receive one.

Personality, Struggles and Lesser-Known Facts

• He was a strong and independent thinker who wrote with harsh words. In his journal he attacked those who put forward ideas he disliked, including Kekule's benzene structure and the three-dimensional carbon of van 't Hoff and Le Bel.
• In 1881 he attacked van 't Hoff's "La chimie dans l'espace" in strong language, calling the ideas fanciful speculations that were not based on facts. Chemists today use this as a classic example of how a great scientist can be wrong when he refuses new ideas.
• He was an experimentalist who disliked theories that went beyond direct evidence, yet his own suggestion about alcohols showed good theoretical insight.
• He opposed the popular views of Kekule and others on aromatic structure, and he opposed the idea of the benzene ring.
• As a teacher at Leipzig he built a large institute that trained many chemists, including Ernst von Meyer, Rudolf Schmitt, and Friedrich von Heyden.

Legacy and Influence on Modern Chemistry

The Kolbe-Schmitt process remains the industrial route to salicylic acid and so to aspirin. Kolbe electrolysis is now being used again in the electrochemical conversion of biomass-derived acids. His synthesis of acetic acid is a milestone in the story of organic synthesis. His prediction about alcohols helped the growth of structural thinking, though he did not accept the structure theory that others developed from it. His successor at Leipzig, Wislicenus, who supported structural ideas, later changed the character of the institute.

Lessons for Students

• Experiments matter. Kolbe's reactions still work after 150 years.
• Be open to new ideas. His refusal of stereochemistry shows the cost of dismissing theories without testing them.
• Criticise ideas, not people. His personal attacks did harm to his own reputation.
• Train students well. Schmitt and von Heyden carried his work into the factory.

FAQ

What is Kolbe famous for?

For Kolbe electrolysis, the Kolbe-Schmitt reaction and the synthesis of acetic acid from its elements.

Why did Kolbe criticise van 't Hoff?

He thought that atoms arranged in space was speculation without proof, and he disliked theory not based directly on experiment.

Who was Rudolf Schmitt?

He was Kolbe's student who improved the carboxylation of phenoxide by using pressure in 1885.

Did Kolbe win a Nobel Prize?

No. He died in 1884, years before the prizes were created.

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