Organic compound

Source: Wikipedia, the free encyclopedia.
Methane (CH4) is among the simplest organic compounds.

Some chemical authorities define an organic compound as a

carbon-carbon bonds (e.g. carbon tetrachloride CCl4), and certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion CN−, hydrogen cyanide HCN, chloroformic acid ClCO2H, carbon dioxide CO2, and carbonate ion CO2−3).[citation needed
]

Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even hydrogen cyanide despite the fact it contains a carbon-hydrogen bond), are generally considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive.[1]

Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living things incorporate inorganic carbon compounds into organic compounds through a network of processes (the carbon cycle) that begins with the conversion of carbon dioxide and a hydrogen source like water into simple sugars and other organic molecules by autotrophic organisms using light (photosynthesis) or other sources of energy. Most synthetically-produced organic compounds are ultimately derived from petrochemicals consisting mainly of hydrocarbons, which are themselves formed from the high pressure and temperature degradation of organic matter underground over geological timescales.[2] This ultimate derivation notwithstanding, organic compounds are no longer defined as compounds originating in living things, as they were historically.

In chemical nomenclature, an organyl group, frequently represented by the letter R, refers to any monovalent substituent whose open valence is on a carbon atom.[3]

Definition

For historical reasons discussed below, a few types of carbon-containing compounds, such as

allotropes) of pure carbon, such as diamond, graphite, fullerenes and carbon nanotubes[4] are also excluded because they are simple substances composed of a single element and so not generally considered chemical compounds
.

The word "organic" in this context does not mean "natural".[5]

History

Vitalism

Main article: Vitalism

Vitalism was a widespread conception that substances found in organic nature are formed from the chemical elements by the action of a "vital force"[6] or "life-force" (vis vitalis) that only living organisms possess.[7]

In the 1810s,

inorganic compounds).[8] Vitalism taught that formation of these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulations in laboratories.[9][10]

Vitalism survived for a short period after the formulation of modern ideas about the

atomic theory and chemical elements. It first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A further experiment was Wöhler's 1828 synthesis of urea from the inorganic salts potassium cyanate and ammonium sulfate. Urea had long been considered an "organic" compound, as it was known to occur only in the urine of living organisms. Wöhler's experiments were followed by many others, in which increasingly complex "organic" substances were produced from "inorganic" ones without the involvement of any living organism, thus disproving vitalism.[11]

Modern classification and ambiguities

The L-isoleucine molecule, C6H13NO2, showing features typical of organic compounds. Carbon atoms are in black, hydrogens gray, oxygens red, and nitrogen blue.

Although vitalism has been discredited, scientific nomenclature retains the distinction between organic and inorganic compounds. The modern meaning of organic compound is any compound that contains a significant amount of carbon—even though many of the organic compounds known today have no connection to any substance found in living organisms. The term carbogenic has been proposed by

E. J. Corey as a modern alternative to organic, but this neologism remains relatively obscure.[citation needed
]

The organic compound L-isoleucine molecule presents some features typical of organic compounds: carbon–carbon bonds, carbon–hydrogen bonds, as well as covalent bonds from carbon to oxygen and to nitrogen.[citation needed]

As described in detail below, any definition of organic compound that uses simple, broadly-applicable criteria turns out to be unsatisfactory, to varying degrees. The modern, commonly accepted definition of organic compound essentially amounts to any carbon-containing compound, excluding several classes of substances traditionally considered "inorganic". The list of substances so excluded varies from author to author. Still, it is generally agreed upon that there are (at least) a few carbon-containing compounds that should not be considered organic. For instance, almost all authorities would require the exclusion of

cyanide derivatives not containing an organic residue (e.g., KCN, (CN)2, BrCN, cyanate anion OCN−, etc.), and heavier analogs thereof (e.g., cyaphide anion CP−, CSe2, COS; although carbon disulfide CS2 is often classed as an organic solvent). Halides of carbon without hydrogen (e.g., CF4 and CClF3), phosgene (COCl2), carboranes, metal carbonyls (e.g., nickel tetracarbonyl), mellitic anhydride (C12O9), and other exotic oxocarbons are also considered inorganic by some authorities.[citation needed
]

organometallic compound as it satisfies the broad definition that organometallic chemistry covers all compounds that contain at least one carbon to metal covalent bond; it is unknown whether organometallic compounds form a subset of organic compounds. For example, the evidence of covalent Fe-C bonding in cementite,[12] a major component of steel, places it within this broad definition of organometallic, yet steel and other carbon-containing alloys are seldom regarded as organic compounds. Thus, it is unclear whether the definition of organometallic should be narrowed, whether these considerations imply that organometallic compounds are not necessarily organic, or both.[citation needed
]

Metal complexes with organic ligands but no carbon-metal bonds (e.g., (CH3CO2)2Cu) are not considered organometallic; instead, they are called metal-organic compounds (and might be considered organic).

The relatively narrow definition of organic compounds as those containing C-H bonds excludes compounds that are (historically and practically) considered organic. Neither urea CO(NH2)2 nor oxalic acid (COOH)2 are organic by this definition, yet they were two key compounds in the vitalism debate. However, the IUPAC Blue Book on organic nomenclature specifically mentions urea[13] and oxalic acid[14] as organic compounds. Other compounds lacking C-H bonds but traditionally considered organic include benzenehexol, mesoxalic acid, and carbon tetrachloride. Mellitic acid, which contains no C-H bonds, is considered a possible organic compound in Martian soil.[15] Terrestrially, it, and its anhydride, mellitic anhydride, are associated with the mineral mellite (Al2C6(COO)6·16H2O).

A slightly broader definition of the organic compound includes all compounds bearing C-H or C-C bonds. This would still exclude urea. Moreover, this definition still leads to somewhat arbitrary divisions in sets of carbon-halogen compounds. For example,

CF4 and CCl4 would be considered by this rule to be "inorganic", whereas CHF3, CHCl3, and C2Cl6 would be organic, though these compounds share many physical and chemical properties.[citation needed
]

Classification

Main article: Organic chemistry §  compounds

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

organophosphorus compounds, which feature bonds between carbon and a phosphorus.[citation needed
]

Another distinction, based on the size of organic compounds, distinguishes between small molecules and polymers.

Natural compounds

stereoisometrically
complicated molecules present in reasonable concentrations in living organisms.

Further compounds of prime importance in

fats and oils
.

Synthetic compounds

Compounds that are prepared by reaction of other compounds are known as "

occur naturally.[citation needed
]

Most

rubbers
) are organic synthetic or semi-synthetic compounds.

Biotechnology

Many organic compounds—two examples are ethanol and insulin—are manufactured industrially using organisms such as bacteria and yeast.[16] Typically, the DNA of an organism is altered to express compounds not ordinarily produced by the organism. Many such biotechnology-engineered compounds did not previously exist in nature.[17]

Databases

  • The CAS database is the most comprehensive repository for data on organic compounds. The search tool SciFinder is offered.
  • The Beilstein database contains information on 9.8 million substances, covers the scientific literature from 1771 to the present, and is today accessible via Reaxys. Structures and a large diversity of physical and chemical properties are available for each substance, with reference to original literature.
  • PubChem contains 18.4 million entries on compounds and especially covers the field of medicinal chemistry.

A great number of more specialized databases exist for diverse branches of organic chemistry.[18]

Structure determination

Main article:
Structure determination

The main tools are

NMR spectroscopy, IR Spectroscopy, Mass spectrometry, UV/Vis Spectroscopy and X-ray crystallography.[19]

See also

References

  1. OCLC 155910842
    .
  2. ^ Smith, Cory. "Petrochemicals". American Fuel & Petrochemical Manufacturers. Archived from the original on 11 September 2021. Retrieved 18 December 2016.
  3. doi:10.1351/goldbook.O04329
  4. ^ Fullerene derivatives are more frequently considered organic, and fullerene chemistry is usually considered a branch of organic chemistry. The methods of organic synthesis have been applied to the rational synthesis of fullerenes and carbon nanotubes.
  5. ^ "Organic Chemistry". Archived from the original on 2022-09-16. Retrieved 2022-08-25.
  6. ^ "Life Force, Naturalism & Holism". Encyclopedia Britannica. July 20, 1998. Retrieved March 10, 2024.
  7. doi:10.1007/s00016-023-00297-z
    . Retrieved 2024-03-10.
  8. PMC 6208063
    .
  9. PMID 32549817
    . Retrieved 2024-03-10.
  10. ^ "Vitalism: Physiological Chemistry". Routledge Encyclopedia of Philosophy. March 10, 2024. Retrieved March 10, 2024.
  11. ^ Henry Marshall Leicester; Herbert S. Klickstein (1951). A Source Book in Chemistry, 1400-1900. Harvard University Press. p. 309.
  12. S2CID 94576016
    .
  13. ^ "IUPAC Blue Book, Urea and Its Derivatives Rule C-971". Archived from the original on 2021-05-06. Retrieved 2009-11-22.
  14. ^ "IUPAC Blue Book, Table 28(a) Carboxylic acids and related groups. Unsubstituted parent structures". Archived from the original on 2021-06-28. Retrieved 2009-11-22.
  15. PMID 10706606
    .
  16. S2CID 98688955. Archived
    from the original on 2023-01-04. Retrieved 2023-01-04.
  17. PMID 32809354, archived
    from the original on 2023-07-09, retrieved 2023-01-04
  18. PMID 28182744
    .
  19. ^ Ernö Pretsch, Philippe Bühlmann, Martin Badertscher (2009), Structure Determination of Organic Compounds (Fourth, Revised and Enlarged Edition). Springer-Verlag Berlin Heidelberg

External links

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