Organic chemistry is the branch of chemistry concerned with the study of carbon-containing molecules known as organic compounds (except carbon dioxide and monoxide). Although there is an overlap with biochemistry, the latter is the specific study of the molecules made by living organisms.

Some of the classes of substances studied in organic chemistry include: aliphatic compounds which are chains of carbon which may be modified by functional groups; aromatic hydrocarbons which are compounds having a benzene ring or similar group; heterocyclic compounds, compounds which include non-carbon atoms as part of a ring structure; physiologically active compounds which have an effect on the human body; and polymers, which are long chains of repeating groups.

Organic chemistry as a science is generally held to have started with Friedrich Woehler's 1828 synthesis of urea from inorganic compounds.

Aliphatic compounds

Hydrocarbons - Alkanea - Alkenes - Dienes or Alkadienes - Alkynes - Halogenoalkanes - Alcohols - Ethers - Aldehydes - Ketones - Carboxylic acids - Esters - Carbohydrates - Alicyclic compounds - Lipids

Aromatic compounds

benzene-toluene

Heterocyclic compounds

Polymers

Concepts

Organic nomenclature - Chemical formula - Structural formula - Skeletal formula - Organic reaction

Characteristics of organic substances

The reason that there are so many carbon compounds is that carbon has the ability to form many carbon chains of different lengths, and rings of different sizes (catenation). A lot of carbon compounds are extremely sensitive to heat, and generally decompose below 300'C. They tend not to be so soluble in water compared to many inorganic salts. In contrast to such salts, they tend to be much more soluble in organic solvents such as ether or alcohol. Organic compounds are covalently bonded.

• Organic chemistry textbook at Wikibooks.