06-28 – Emil Erlenmeyer's Birthday

Whether you know it as an Erlenmeyer flask, conical flask, or by some other name, it’s a piece of glassware most of us, chemists or not, have likely used at some point. The Erlenmeyer flask is the most stereotypical piece of chemistry glassware there is, and today marks its creator’s birthday. Emil Erlenmeyer was born on 28 June in 1825; here we take a look at his eponymous flask, as well as some of his other achievements.

Firstly, to give Erlenmeyer his full name: Richard August Carl Emil Erlenmeyer. Perhaps not surprising that he chose to shorten it! He was a German chemist who originally specialised in pharmacy, but eventually gravitated back toward chemistry. During his career, he synthesised or isolated numerous organic compounds for the first time, and also made some significant contributions to our understanding of the structure of organic molecules.

Despite this, the flask that bears his name is what Erlenmeyer is invariably remembered for, though in some countries it’s known by other names. In the UK, hearing it referred to as a conical flask is more common, whereas in Italy they sometimes call it a ‘beuta’. Erlenmeyer designed his flask in the late 1850s; he first described it in a paper published at the beginning of 1860, by which point he had already arranged its commercial production and sale.

The Erlenmeyer flask’s popularity lies in its utility. Its flat base means it isn’t easily toppled, unlike the round-bottomed flasks which can also be found in the laboratory. Its tapered, cone-like shape, coupled with its narrow neck, means that liquids inside it can be swirled without spilling easily. Additionally, the sides minimise loss of liquids from the flask when they are heated, as vapours condense on the sides. The narrow neck can also be plugged with a rubber or glass stopper.

It’s perhaps a little unfair on Erlenmeyer that he’s primarily remembered for his flask, because he was also an excellent chemist. He was the first to suggest that double and triple chemical bonds could form between two carbon atoms. Additionally, he was the first to synthesise or isolate a number of organic compounds, including glycolic acid from grapes. He also suggested the fused ring structure for naphthalene.

It’s little-known that Erlenmeyer’s flask isn’t the only thing in chemistry to bear his name: There’s also the Erlenmeyer rule. The Erlenmeyer rule relates to tautomerism of alcohols. Tautomerism is a type of isomerism; isomers are chemical compounds with the same chemical formula, but a different arrangement of atoms in the molecule. Tautomers are isomers of molecules which readily interchange by movement of an atom or group of atoms within the molecule.

Erlenmeyer’s rule concerns alcohols (organic compounds containing the OH group) where the OH group is directly bonded to a carbon which also has a double bond with another carbon. He discovered that these compounds instantly tautomerise to become aldehydes or ketones, which are different types of organic compound. They do this because these compounds are generally more stable than the alcohol-containing tautomer. This idea is now more commonly referred to as keto-enol tautomerism.

Though his rule, by name at least, may have passed into relative obscurity, Erlenmeyer is virtually assured scientific immortality due to his flask. Something to think about the next time you come across or use one!

Previous ‘Today in Chemistry History’ posts can be found here.

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