Organic compound
Encyclopedia
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
eous, liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
, or solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
chemical compounds whose molecules contain carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
. For historical reasons discussed below, a few types of carbon-containing compounds such as carbide
Carbide
In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides...
s, carbonates, simple oxides of carbon, and cyanides, as well as the allotropes of carbon
Allotropes of carbon
This is a list of the allotropes of carbon.-Diamond:Diamond is one of the most well known allotropes of carbon. The hardness and high dispersion of light of diamond make it useful for both industrial applications and jewellery. Diamond is the hardest known natural mineral. This makes it an...
such as diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
and graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
, are considered inorganic
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
. The distinction between "organic
Organic
Organic may refer to:* Of or relating to an organism, a living entity* Of or relating to an organ- Chemistry :* Organic matter, matter that has come from a once-living organism, is capable of decay or the product of decay, or is composed of organic compound* Organic chemistry, chemistry involving...
" and "inorganic" carbon compounds, while "useful in organizing the vast subject of chemistry... is somewhat arbitrary".
Organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
is the science concerned with all aspects of organic compounds. Organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
is the methodology
Methodology
Methodology is generally a guideline for solving a problem, with specificcomponents such as phases, tasks, methods, techniques and tools . It can be defined also as follows:...
of their preparation.
Vitalism
The word "organic" is historical, dating back to the 1st century. For many centuries, Western alchemistsAlchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
believed in vitalism
Vitalism
Vitalism, as defined by the Merriam-Webster dictionary, is#a doctrine that the functions of a living organism are due to a vital principle distinct from biochemical reactions...
. This is the theory that certain compounds could be synthesized only from their classical element
Empedocles
Empedocles was a Greek pre-Socratic philosopher and a citizen of Agrigentum, a Greek city in Sicily. Empedocles' philosophy is best known for being the originator of the cosmogenic theory of the four Classical elements...
s — Earth, Water, Air, and Fire — by action of a "life-force" (vis vitalis) possessed only by organisms. Vitalism taught that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulation.
Vitalism survived for a while even after the rise of modern atomic theory and the replacement of the Aristotelian elements by those we know today. It first came under question in 1824, when Friedrich Wöhler
Friedrich Wöhler
Friedrich Wöhler was a German chemist, best known for his synthesis of urea, but also the first to isolate several chemical elements.-Biography:He was born in Eschersheim, which belonged to aau...
synthesized oxalic acid
Oxalic acid
Oxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...
, a compound known to occur only in living organisms, from cyanogen
Cyanogen
Cyanogen is the chemical compound with the formula 2. It is a colorless, toxic gas with a pungent odor.The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups — analogous to diatomic halogen molecules, such as Cl2, but far less oxidizing...
. A more decisive experiment was Wöhler's 1828 synthesis
Wöhler synthesis
rightThe Wöhler synthesis is the conversion of ammonium cyanate into urea. This chemical reaction was discovered in 1828 by Friedrich Wöhler in an attempt to synthesize ammonium cyanate. It is considered the starting point of modern organic chemistry. Although the Wöhler reaction concerns the...
of urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
from the inorganic salts potassium cyanate
Potassium cyanate
Potassium cyanate is an inorganic compound with the formula KOCN . It is a colourless solid. It is used to prepare many other compounds including useful herbicide. Worldwide production of the potassium and sodium salts was 20,000 tons in 2006.-Structure and bonding:Cyanate is isoelectronic with...
and ammonium sulfate
Ammonium sulfate
Ammonium sulfate , 2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions...
. Urea had long been considered to be an "organic" compound, as it was known to occur only in the urine of living organisms. Wöhler's experiments were followed by many others, where increasingly complex "organic" substances were produced from "inorganic" ones without the involvement of any living organism.
Modern classification
Even though vitalism has been discredited, the distinction between "organic" and "inorganic" compounds has been retained through the present. The modern meaning of "organic compound" is any one of them that contains a significant amount of carbon - even though many of the "organic compounds" known today have no connection whatsoever with any substance found in living organisms.There is no "official" definition of an organic compound. Some textbooks define an organic compound as one containing one or more C-H bonds; others include C-C bonds in the definition. Others state that if a molecule contains carbon―it is organic.
Even the broader definition of "carbon-containing molecules" requires the exclusion of carbon-containing alloys (including steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
), a relatively small number of carbon-containing compounds such as metal carbonates and carbonyls, simple oxides of carbon and cyanides, as well as the allotropes of carbon
Allotropes of carbon
This is a list of the allotropes of carbon.-Diamond:Diamond is one of the most well known allotropes of carbon. The hardness and high dispersion of light of diamond make it useful for both industrial applications and jewellery. Diamond is the hardest known natural mineral. This makes it an...
and simple carbon halides and sulfides, which are usually considered to be inorganic
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
.
The "C-H" definition excludes compounds that are historically and practically considered to be organic. Neither urea nor oxalic acid is organic by this definition, yet they were two key compounds in the vitalism debate. The IUPAC Blue Book
Nomenclature of Organic Chemistry
Nomenclature of Organic Chemistry, commonly referred to by chemists as the Blue Book is a collection of recommendations on organic chemical nomenclature published at irregular intervals by the International Union of Pure and Applied Chemistry...
on organic nomenclature specifically mentions urea and oxalic acid. Other compounds lacking C-H bonds that are also traditionally considered to be organic include benzenehexol
Benzenehexol
Benzenehexol, also called hexahydroxybenzene, is an organic compound with formula C6H6O6 or C66. It is a six-fold alcohol of benzene. The product is also erroneously called hexaphenol, but this name has been used also for other substances....
, mesoxalic acid
Mesoxalic acid
Mesoxalic acid, also called oxomalonic acid or ketomalonic acid, is an organic compound with formula C3H2O5 or HO-3-OH.Mesoxalic acid is both a dicarboxylic acid and a ketonic acid. It readily loses two protons to yield the divalent anion C3O52−, called mesoxalate, oxomalonate, or ...
, and carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
. Mellitic acid
Mellitic acid
Mellitic acid, also called graphitic acid or benzenehexacarboxylic acid, is an acid first discovered in 1799 by M. H. Klaproth in the mineral mellite , which is the aluminium salt of the acid.- Preparation :...
, which contains no C-H bonds, is considered to be a possible organic substance in Martian
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
soil. All do, however, contain C-C bonds.
The "C-H bond-only" rule also leads to somewhat arbitrary divisions in sets of carbon-fluorine compounds, as, for example, Teflon is considered by this rule "inorganic" but Tefzel organic. Likewise, many Halons are considered inorganic, whereas the rest are considered organic. For these and other reasons, most sources consider C-H compounds to be only a subset of "organic" compounds.
In summary, most carbon-containing compounds are organic, and most compounds with a C-H bond are organic. Not all organic compounds necessarily contain C-H bonds (e.g., urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
).
Classification
Organic compounds may be classified in a variety of ways. One major distinction is between natural and synthetic compounds. Organic compounds can also be classified or subdivided by the presence of heteroatomHeteroatom
In organic chemistry, a heteroatom is any atom that is not carbon or hydrogen. Usually, the term is used to indicate that non-carbon atoms have replaced carbon in the backbone of the molecular structure...
s, e.g., organometallic compounds, which feature bonds between carbon and a metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
, and organophosphorus compounds, which feature bonds between carbon and a phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
.
Another distinction, based upon the size of organic compounds, distinguishes between small molecule
Small molecule
In the fields of pharmacology and biochemistry, a small molecule is a low molecular weight organic compound which is by definition not a polymer...
s and polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s.
Natural compounds
Natural compounds refer to those that are produced by plants or animals. Many of these are still extracted from natural sources because they would be far too expensive to be produced artificially. Examples include most sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s, some alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s and terpenoid
Terpenoid
The terpenoids , sometimes called isoprenoids, are a large and diverse class of naturally occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways. Most are multicyclic structures that differ from one another not only in...
s, certain nutrients such as vitamin B12
Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
, and, in general, those natural products with large or stereoisometrically complicated molecules present in reasonable concentrations in living organisms.
Further compounds of prime importance in biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
are antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
s, carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
s, enzymes, hormones, lipids and fatty acids, neurotransmitters, nucleic acids, protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
s and amino acids, lectin
Lectin
Lectins are sugar-binding proteins that are highly specific for their sugar moieties. They play a role in biological recognition phenomena involving cells and proteins. For example, some viruses use lectins to attach themselves to the cells of the host organism during infection...
s, vitamins, and fats and oils.
Synthetic compounds
Compounds that are prepared by reaction of other compounds are referred to as "synthetic". They may be either compounds that already are found in plants or animals or those that do not occur naturally.
Most polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s (a category that includes all plastics and rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
s), are organic synthetic or semi-synthetic compounds.
Nomenclature
The IUPAC nomenclature of organic compoundsIUPAC nomenclature of organic chemistry
The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry . Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be drawn. ...
slightly differs from the CAS
Chemical Abstracts Service
Chemical Abstracts is a periodical index that provides summaries and indexes of disclosures in recently published scientific documents. Approximately 8,000 journals, technical reports, dissertations, conference proceedings, and new books, in any of 50 languages, are monitored yearly, as are patent...
nomenclature.
Databases
- The CASChemical Abstracts ServiceChemical Abstracts is a periodical index that provides summaries and indexes of disclosures in recently published scientific documents. Approximately 8,000 journals, technical reports, dissertations, conference proceedings, and new books, in any of 50 languages, are monitored yearly, as are patent...
database is the most comprehensive repository for data on organic compounds. The search tool SciFinder is offered.
- The Beilstein databaseBeilstein databaseThe Beilstein database is the largest database in the field of organic chemistry, in which compounds are uniquely identified by their Beilstein Registry Number. The database covers the scientific literature from 1771 to the present and contains experimentally validated information on millions of...
contains information on 9.8 million substances, covers the scientific literature from 1771 to the present, and is today accessible via ReaxysReaxysReaxys is a web-based tool for the retrieval of chemistry information and data from published literature including journals and patents. The information includes chemical compounds, chemical reactions, chemical properties, related bibliographic data, substance data with synthesis planning...
. Structures and a large diversity of physical and chemical properties is available for each substance, with reference to original literature.
- PubChemPubChemPubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information , a component of the National Library of Medicine, which is part of the United States National Institutes of Health . PubChem can...
contains 18.4 million entries on compounds and especially covers the field of medicinal chemistryMedicinal chemistryMedicinal chemistry and pharmaceutical chemistry are disciplines at the intersection of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties, where it is involved with design, chemical synthesis and development for market of pharmaceutical...
.
There is a great number of more specialized databases for diverse branches of organic chemistry.
Structure determination
- See Structure determination
Today, the main tools are proton
Proton NMR
Proton NMR is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of a substance, in order to determine the structure of its molecules. In samples where natural hydrogen is used, practically all of the hydrogen consists of the...
and carbon-13
Carbon-13 NMR
Carbon-13 NMR is the application of nuclear magnetic resonance spectroscopy to carbon. It is analogous to proton NMR and allows the identification of carbon atoms in an organic molecule just as proton NMR identifies hydrogen atoms...
NMR spectroscopy
NMR spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained...
and X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
.
See also
- Organometallic compounds
- List of organic compounds | List of chemical compounds
- Inorganic compoundInorganic compoundInorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
s