Organic chemistry

Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of chemical compounds that are based on carbon. Organic compounds are primarily composed of carbon and hydrogen, and may contain any number of other elements, the most common of which are nitrogen and oxygen. Carbon, with its pattern of forming four covalent bonds can connect with other carbon atoms in an large number of ways to give the enormous variety of organic compounds found. Each molecule is often described as having a "skeleton" of carbon atoms. The essential indication for existence and relationship inherent in four-based structures is appropriate for carbon, as it is the basis of life itself.

History

Organic chemistry as a science is generally agreed to have started in 1828 with Friedrich Woehler's synthesis of the organic, biologically significant compound urea by accidentally evaporating an aqueous solution of ammonium cyanate NH₄OCN. The name organic chemistry comes from the idea that carbon chains were only produced by living things or organisms. This has been proven false, but remains the reason why organic chemistry is close in name to the word organism.

Characteristics of organic substances

Organic compounds are covalently bonded and thus, its bonds are directional. This allows for unique structures such as long carbon chains and rings. The reason carbon is excellent at forming unique structures and that there are so many carbon compounds is that carbon atoms form very stable covalent bonds with one another (catenation). In contrast to inorganic materials, organic compounds typically melt, sublime, or decompose below 300°C. Neutral organic compounds tend to be less soluble in water compared to many inorganic salts, with the exception of certain compounds such as ionic organic compounds and low molecular weight alcohols and carboxylic acids where there is hydrogen bonding present. Organic compounds tend to be much more soluble in organic solvents such as ether or alcohol, but the solubility in each solute is dependent on the functional groups present and of the general structure.

Organic nomenclature

Organic nomenclature is the system established for naming and grouping organic compounds.

Aliphatic compounds

Aliphatic compounds are organic molecules that do not contain aromatic systems. Typically, they contain hydrocarbon chains.

Hydrocarbons - Alkanes - Alkenes - Dienes or Alkadienes - Alkynes - Haloalkanes

Aromatic compounds

Aromatic compounds are organic molecules that contain one or more aromatic ring system. This usually means, but is not limited to, those compounds that contain a benzene ring.

Benzene - Toluene - Styrene - Xylene - Aniline - Phenol - Acetophenone - Benzonitrile - Haloarenes - Naphthalene - Anthracene - Phenanthrene - Benzopyrene - Coronene - Azulene - Biphenyl

Heterocyclic compounds

Heterocyclic compounds are cyclic organic molecules whose ring(s) contain at least one heteroatom. These heteroatoms can include oxygen, nitrogen, phosphorus, and sulfur.

Imidazole - Indole - Pyridine - Pyrrole - Thiophene - Furan - Purines

Functional groups

These are parts of an organic molecule characterized by specific composition and connected strucure of the constituent atoms. Each functional group has a specfic pattern of properties and reactions that characterize the compound. Some common functional groups are: Alcohols, Aldehydes, Amides, Amines, Carboxylic acids, Esters, Ethers, Ketones, Nitriles.

Polymers

Polymers are a special kind of molecule. Generally considered "large" molecules, polymers get their reputation regarding size because they are molecules that consist of multiple smaller segments. The segments could be chemically identical, which would make such a molecule a homopolymer. Or the segments could vary in chemical structure, which would make that molecule a heteropolymer. Polymers are a subset of "macromolecules" which is just a classification for all molecules that are considered large.

Polymers can be organic or inorganic. Commonly-encountered polymers are usually organic (e.g., polyethylene, polypropylene, Plexiglass, etc.). But inorganic polymers (e.g., silicone) are also familiar to everyday items.

Important biological molecules such as proteins, nucleic acids and polysaccharides are also polymers (biopolymers).

Determining the molecular structure of an organic compound

Currently, there exist several methods for characterizing an organic compound. In general usage are (in alphabetical order):

Crystallography: This is the most precise method; however, it is very difficult to grow crystals of sufficient size and high quality to get a clear picture, so it remains a secondary form of analysis.
Elemental Analysis: A destructive method used to determine the elemental composition of a molecule.
Infrared spectroscopy: Chiefly used to determine the presence (or absence) of certain functional groups.
Mass spectrometry: Used to determine the molecular weight of a compound and the fragmentation pattern.
Nuclear magnetic resonance (NMR) spectrometry
UV/VIS spectroscopy: Used to determine degree of conjugation in the system

See Analytical chemistry for additional methods.

Organic reactions

Due to the huge number of possible organic compounds an important part of organic chemistry is understanding the synthesis and reactions of organic compounds. There are distinct patterns based on functional group and carbon structure that can be applied to classes of compounds, see Organic reaction. Many types of reaction bear the name of the person who discovered it, such as Grignard reactions, or the Williamson synthesis of ethers. Modern organic chemistry also tries to understand the mechanism, or process at the molecular level, for each type of reaction.

External links

General subfields within the Natural sciences
Astronomy \| Biology \| Chemistry \| Earth science \| Ecology \| Physics

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

Organic chemistry ^history

The history of this article since it was imported to New World Encyclopedia:

History of "Organic chemistry"

Note: Some restrictions may apply to use of individual images which are separately licensed.