Why did coal tar become an important source of chemicals in the 1800s?

In the 1800s, coal tar transitioned from an industrial nuisance into a vital raw material for the burgeoning chemical industry because it served as a rich, accessible source of organic compounds.1

Initially, coal tar was merely a byproduct of coal gasification, a process used to produce gas for lighting and heating. By 1850, it had limited utility, used primarily as a wood preservative, road binder, or source of naphtha. However, chemists discovered that through distillation, coal tar could yield a variety of new organic compounds.231

This discovery proved transformative when the synthetic dye industry emerged following the 1856 invention of mauve. Researchers realized that coal tar compounds could be manipulated to create dyes, pharmaceuticals, and other products, such as aspirin and saccharin. By 1900, over 50 compounds had been isolated from coal tar, establishing it as the foundational feedstock for the synthetic chemical industry before it was eventually superseded by petroleum in the 1930s.1