Several scientists can be credited with the discovery and development of stereochemistry. They include Louis Pasteur, Jacobus H. van ‘t Hoff, and Joseph Le Bel.
Stereochemistry is a branch of chemistry that focuses on the relative spatial arrangement of atoms in molecules and their manipulation.
Continue reading to learn more about the origins of stereochemistry and its impact on modern chemistry.
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The origins of stereochemistry
Stereochemistry looks at stereoisomers and their geometric structure and functional groups in three-dimensional space. It can be traced back long before the theory of molecular structure was developed.
In fact, the foundations for stereochemistry were actually laid in 1815, when Jean-Baptiste Biot discovered that certain crystallised substances were capable of rotating the plane of polarised light. He believed this property had something to do with the fundamental structures of substances.
Despite Biot’s early observations, Louis Pasteur is widely credited as being the first stereo chemist. In 1842, he discovered that salts of tartaric acid collected from wine production vessels could rotate the plane of polarised light. This was not observed in salts from other sources.
Further advancements in stereochemistry came in 1874, when the theory of organic structure in three dimensions was independently proposed by both Jacobus H. van ’t Hoff and Joseph-Achille Le Bel.
Key figures in the discovery of stereochemistry
The clues to stereochemistry predate the development of various theories of molecular structures like the valence bond theory, molecular orbital theory, and ligand field theory.
Chemists didn’t understand the fundamental structures of molecules, so its discovery was mainly based on theoretical speculations and indirect empirical observations.
As we mentioned earlier, two of the key figures in the discovery and development of stereochemistry are Jacobus Henricus van ‘t Hoff and Joseph Le Bel.
Jacobus Henricus van ‘t Hoff
Van ‘t Hoff was a Dutch physical chemist and the first person to propose the idea that atoms can form specific and predictable structures as molecules.
In a pamphlet published in 1874, he formulated the hypothesis that carbon atoms can form tetrahedral structures. He also correctly predicted the geometric structures of certain hydrocarbons (namely allenes and cumulenes) and identified the chirality of these compounds. Because of this achievement, Van ‘t Hoff is now considered to be one of the pioneers and founders of physical chemistry.
Joseph Le Bel
Le Bel was a French chemist best known for his work in stereochemistry. In the same year that Van ‘t Hoff published his pamphlet on carbon-based structures, Le Bel announced his theory on how the molecular structure of a substance is related to its optical activity, particularly with polarised light. His theory became a foundation for the science of stereochemistry.
The work of both of these pioneering chemists led to what is now known as the Le Bel–van ‘t Hoff rule. The rule states that:
The number of stereoisomers of an organic compound containing no internal planes of symmetry is 2n, where n represents the number of asymmetric carbon atoms.
The impact of stereochemistry on chemistry
Stereochemistry has had a huge impact on chemistry. Firstly, understanding the three-dimensional structures of molecules has made it possible for chemists to accurately predict the complicated reactions of organic molecules.
It’s also paved the way for synthesising organic chemicals and biomolecules. As you might expect, this has led to significant advances in fields such as chemical manufacturing, medicine, and materials science.
The thalidomide scandal demonstrates why it’s so important to consider stereochemistry, particularly when it comes to medicines. Thalidomide was given as a sedative to pregnant mothers in the 1950s and early 1960s. However, the drug’s isomer had detrimental effects on developing foetuses, resulting in thousands of babies being born with serious birth defects.
The molecules (S)-thalidomide and (R)-thalidomide are readily interchangeable. Although the R-isomer functions as a sedative, research later revealed that S-isomer is actually a teratogen.
A teratogen is a chemical that interferes with genetic expressions during a baby’s development in the womb, which then leads to physical deformities such as non-formation or stunted limbs.
Stereochemistry in modern chemistry
Stereochemistry is widely used in modern chemistry – in fact, many industries may not even exist without our knowledge of stereochemistry. It’s particularly crucial in the synthesis and efficacy of pharmaceutical drugs.
Take the medicine clonidine, for example, which is used to treat hypertension and ADHD. For it to work, the drug has to bind with the α2-adrenoceptors in the brain and peripheral nerves. It blocks certain signals of the brain, which then helps to relax the blood vessels.
Current applications and research
Current applications and research on stereochemistry are primarily focused in the field of materials science.
These include nanotechnology like nanographene. Thanks to stereochemistry, in the not-too-distant future it may even be possible to construct nanorobots that can be programmed to repair cells and attack viral infections.
Conclusion
The discovery and development of stereochemistry was pioneered by van ‘t Hoff and Le Bel, and led to advancements in medicine, organic chemistry, and materials science. Knowing the geometrical structures of molecules allows scientists to synthesise a wide range of organic molecules and design precise nano-objects.
