Chemistry · Ch 8 — Organic Chemistry – Some Basic Principles and Techniques
General Introduction
General Introduction
The Birth of Organic Chemistry
Organic chemistry is the study of carbon compounds. But this was not always the definition. For centuries, chemists believed that the compounds found in living things — plants and animals — were fundamentally different from those found in rocks and minerals. They thought a special "vital force" was needed to make them. This idea, called vitalism, was the first major concept in the history of organic chemistry.
The story begins around 1780, when chemists started to clearly separate substances into two groups: those from living sources (organic) and those from non-living, mineral sources (inorganic). The Swedish chemist Jöns Jacob Berzelius championed the vital force theory. He argued that organic compounds could only be produced inside living organisms because they possessed this mysterious force. Inorganic compounds, by contrast, could be made in a laboratory.
This view held for nearly fifty years. Then, in 1828, a German chemist named Friedrich Wöhler made a discovery that shattered the vital force theory. He was trying to make ammonium cyanate, an inorganic salt, by heating it. Instead, he obtained a white, crystalline solid that was identical to urea — a waste product found in the urine of mammals. Urea was undeniably an organic compound. Wöhler had made it from an inorganic starting material, with no help from any living organism.
The reaction is simple:
Here, ammonium cyanate (), an inorganic salt, rearranges on heating to form urea (), an organic compound. This was the first synthesis of an organic compound from an inorganic source in a laboratory.
Wöhler's synthesis of urea in 1828 is the single most important event in the history of organic chemistry. It disproved the vital force theory and showed that organic compounds obey the same chemical laws as inorganic ones.
The death blow to vitalism was followed by more triumphs. In 1845, the German chemist Hermann Kolbe synthesised acetic acid (vinegar's main component) from carbon disulphide and chlorine — entirely inorganic starting materials. In 1856, the French chemist Marcellin Berthelot synthesised methane from carbon and hydrogen. These successes proved conclusively that organic compounds could be made in a laboratory from inorganic sources. There was no special force; the same principles of chemistry applied everywhere.
The Modern Foundation: Electronic Theory of Covalent Bonding
The final piece that shaped organic chemistry into its modern form was the development of the electronic theory of covalent bonding. This theory, built on the work of Lewis, Langmuir, and others in the early 20th century, explained how atoms share electrons to form molecules. For organic chemistry, this was revolutionary. It provided a way to understand the structure of carbon compounds, the nature of their bonds, and the mechanisms of their reactions — all based on the behaviour of electrons.
With this foundation, organic chemistry moved from a descriptive science (what compounds exist) to a predictive and explanatory one (how and why reactions happen). This is the framework you will use throughout your study of the subject.