Organic chemistry

Organic chemistry is a major branch of chemistry. It is the scientific study of organic compounds and organic materials. These materials are defined as matter that contains carbon atoms.

This field is vital because organic compounds form the basis of all life on Earth. They also make up the majority of all known chemicals. Scientists in this field study the structure of these materials. They determine structural formulas to see how atoms are arranged. They also analyze physical and chemical properties to understand how substances behave. By evaluating chemical reactivity, they can predict how compounds will change during reactions.

The unique behavior of organic chemistry comes from the carbon atom itself. Carbon has a valence of four. This means it can form four chemical bonds with other atoms. It can create single, double, or triple bonds. Carbon can also form structures with delocalized electrons. These bonding patterns allow carbon atoms to link together into a large lattice. This ability makes organic compounds incredibly diverse in their shapes and structures.

Because of this diversity, organic chemistry overlaps with many other fields. It connects to organometallic chemistry, which studies carbon-metal bonds. It also links to biochemistry, medicinal chemistry, polymer chemistry, and materials science.

Scientists use several methods to build and study these molecules. One primary method is chemical synthesis. This is the process of making new substances through chemical reactions. Scientists use synthesis to create natural products, new drugs, and polymers. Polymers are long chains of molecules.

Researchers study these molecules in physical laboratories or through theoretical in silico studies using computers. They can also perform total synthesis. This is the multi-step process used to build very complex organic molecules from scratch. Scientists have successfully used total synthesis to create molecules like glucose, terpineol, and vitamin B12.

Before the 19th century, people believed in a theory called vitalism. This theory suggested that organic matter possessed a unique "vital force." People thought this force distinguished living things from non-living things. This belief changed through several key discoveries. In 1816, Michel Chevreul studied soaps made from fats and alkalis. He showed that he could change fats into new compounds without a "vital force." In 1828, Friedrich Wöhler achieved a major breakthrough. He synthesized urea, a component of urine, from inorganic salts.

This event is widely accepted as the moment vitalism was disproved.

As the field grew, new discoveries drove even more interest. In 1856, William Henry Perkin accidentally created a purple dye called Perkin's mauve. This discovery was a financial success and increased interest in the science. In 1858, Friedrich August Kekulé and Archibald Scott Couper independently developed the concept of chemical structure. They proposed that carbon atoms link to form a lattice. By the late 1890s, the company Bayer began manufacturing acetylsalicylic acid, known as aspirin.

In the early 20th century, Adolf von Baeyer developed synthetic methods for indigo. This changed the industry significantly. In 1897, 19,000 tons of indigo came from plants. By 1914, that number dropped to 1,000 tons. By 2002, 17,000 tons of synthetic indigo were produced from petrochemicals.

To understand these complex mixtures, scientists use advanced characterization techniques. Many organic compounds are analyzed using chromatography to check for purity. This includes methods like HPLC and gas chromatography. Traditional "wet methods" used chemical tests, but these are now often replaced by computer-intensive methods. One of the most common tools is Nuclear Magnetic Resonance (NMR) spectroscopy. It allows scientists to map how atoms are connected.

Mass spectrometry is another essential tool. It tells researchers the molecular weight and structure of a compound. Crystallography is also used to determine molecular geometry if a single crystal is available. These tools allow for the precise study of everything from simple hydrocarbons to complex antibiotics like cefalotin.

Organic compounds have specific physical properties that scientists measure. Many organic compounds melt or boil, which helps identify their purity. These points often relate to the weight and polarity of the molecules. Some substances, like the mothball component para-dichlorobenzene, can sublime. Most organic compounds are not stable above 300 °C. Solubility is another important factor. Most neutral organic compounds are hydrophobic, meaning they do not dissolve well in water. Instead, they tend to dissolve in organic solvents. This characteristic is important for everything from industrial lubricants to the medicines used in chemotherapy.