This Day in Chemistry: Sir Edward Frankland 

18th January 2018

Science

A portrait of Sir Edward Frankland, an important 19th century chemist

Born in Lancashire, England, Sir Edward Frankland is one of the most important British chemists in history. The father of organometallic chemistry, with a multitude of equally ground-breaking achievements under his belt, Frankland has helped to shape the world of chemistry we know today. So why isn’t he more well-known?

On 18th January 1825, Edward Frankland was born in Churchtown, Lancashire. As an illegitimate child, Frankland and his mother were labelled outcasts. Little did he know at fourteen-years-old, while working 70 hour weeks as a pharmacist’s apprentice, that he would one day be knighted for his contributions to chemistry and public health.

From discovering the first main-group organometallic compounds to devising new methods that tested the purity of water, we have a lot to thank this Victorian chemist for. It was in fact Frankland’s illegitimacy, which forced him to be secretive, that meant his scientific work was built upon and forgotten. Today, we take a look at the legacy left behind by Sir Edward Frankland.

An infographic that lists Sir Edward Frankland's achievements

Organometallic Chemistry

Organometallic chemistry is the study of compounds that contain a metal-carbon bond. This bond is highly covalent, meaning that the atoms share their electrons in order to complete their outer shell. Common organometallic compounds include ferrocene (Fe (C5H5)2) and nickel tetracarbonyl (Ni (CO)4). These compounds are widely used in homogenous catalysis, but have a variety of industrial applications.

In 1848, Edward Frankland combined zinc and ethyl iodide in an attempt to isolate the ethyl radical. While this reaction did not achieve the desired result, it did lead Frankland to a new accidental discovery. He was unaware that the reaction would produce the first main-group organometallic compounds: ethylzinc iodide and diethylzinc.

Diethylzinc is a pyrophoric organozinc compound where 2 ethyl groups sandwich a zinc atom. It is crucial in organic chemistry as a reagent, and is also available in hexane, heptane, and toluene solutions.

But Frankland’s discovery of organometallic chemistry didn’t stop there. In creating these compounds, he began investigating the nature of chemical bonding between atoms. This led Frankland to a crucial theory that has shaped structural chemistry today: valency.

Theory of Valence

In chemistry, valence refers to the combining power of electrons with atoms to form chemical compounds. It is used to explain chemical bonding and to measure the number of electrons needed to fill the outermost shell of an atom.

In 1852, Edward Frankland wrote a paper that proposed the theory of chemical valencies. It was Frankland’s work on organometallic compounds that lead him to the theory of combining power, and then valence. This is because he made the observation that elements possessed fixed combining powers.

Frankland’s proposed theory of valence was thus used to explain chemical bonding. This became the basis of modern structural chemistry, and posited Edward Frankland as one of the first investigators in this field.

Organometallic chemistry

Discovering Helium

In October 1868, Frankland co-discovered the element helium (He) with English astronomer, Joseph Norman Lockyer. This happened after they observed a yellow line in the solar spectrum, something which Lockyer named the D3 Fraunhofer line.

This spectral line emanating from the chromosphere of the Sun had been noticed a couple of months earlier by Jules Janssen, a French astronomer who noticed the line in India while observing a solar eclipse through a prism.

While Janssen erroneously stated that it was sodium, Frankland and Lockyer concluded that it was caused by an unknown element in the Sun. The duo decided to name the element Helios, the Greek work for Sun. This is how helium was first discovered.

Water Purification

While Frankland is known as the father of organometallic chemistry and valency, it was for his work in purifying Britain’s water supply that earned him his knighthood.

In the latter half of the nineteenth century, six cholera epidemics were circling around the world. In England alone, this outbreak was responsible for over 20,000 deaths. Cholera was the result of faecal contaminated drinking water, and its victims would die from dehydration and electrolyte imbalance. At the time, little was known about clean water and how to identify it. Cities were particularly vulnerable to cholera outbreaks because of urbanisation, and drinking reservoirs were often used as sewage dumps.

Frankland decided to take the public health into his own hands. Always a strong voice for clean water, Frankland became London’s water consultant in 1865 and, in 1868, joined the River’s Pollution Commission.

A chemist first and foremost, Frankland approached the issue of contaminated water with science. Assuming the then-radical position that sewage and microscopic bacteria were the culprits behind fatal waterborne diseases, he devised sensitive new techniques that would determine the amount of organic nitrogen and carbon in water samples. This method of analysing water was by combustion analysis of organic carbon and nitrogen in vacuo.

It wasn’t long before Frankland was the world’s leading authority on water purification. In 1897, he was knighted for this dedication.

Luminous Flame

Another equally important investigation dealt with by Frankland was the illuminating power of flames under different atmospheric pressures. Frankland’s goal was to figure out whether the rate of combustion was influenced by changes in atmospheric pressure.

In 1859, he even went to Mont Blanc and Chamounix to burn candles at the different pressures in order to determine their weight loss per hour.

While both locations yielded similar combustion rates, the illuminating power was significantly reduced in the location with lower pressure. After further experiments where atmospheric pressure could be controlled and varied at will, Frankland concluded that a flame’s luminosity increased proportionally to atmospheric pressure.

Photo of a luminous flame glowing in the dark

Sir Edward Frankland was an important chemist for many reasons beside these. Not only was he the founding father of organometallic chemistry and the theory of valency, he was also the first person to thoroughly analyse the gases produced by different types of coal and one of the first people to measure calories in food. He even popularised the notation we use in writing chemical formulas, and provided the basis on which modern structural chemistry rests.

Today, on the anniversary of his birth, we look back to Edward Frankland and tip our hats off to this remarkable Victorian chemist.

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