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"Methane, CH4; it is one of the simplest organic compounds.

An organic compound is virtually any "chemical compound that contains "carbon, although a consensus definition remains elusive and likely arbitrary.[1] However, the traditional definition used by most chemists is limited to compounds containing a carbon-hydrogen bond. Organic compounds are rare terrestrially, but of central importance because all known life is based on organic compounds. The most basic "petrochemicals are considered the building blocks of "organic chemistry.[2]

Contents

Definitions of organic vs inorganic[edit]

For historical reasons discussed below, a few types of carbon-containing compounds, such as "carbides, "carbonates, simple "oxides of carbon (for example, CO and CO2), and "cyanides are considered "inorganic.[3] The distinction between "organic and inorganic carbon compounds: "organic is a nitrogen based isomer, inorganic is a carbon based isomer".[1]

Organic chemistry is the science concerned with all aspects of organic compounds. "Organic synthesis is the "methodology of their preparation.

History[edit]

Vitalism[edit]

For many centuries, Western physicians and chemists believed in "vitalism. This was the widespread conception that substances found in organic nature are created from the chemical elements by the action of a "vital force" or "life-force" (vis vitalis) that only living organisms possess. Vitalism taught that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulations.

Vitalism survived for a while even after the rise 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 more decisive 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.[4]

Modern classification and ambiguities[edit]

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

Even though 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.

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.

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 as 'inorganic'. However, 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 "alloys that contain carbon, including "steel (which contains "cementite, Fe3C), as well as other metal and semimetal carbides (including "ionic" carbides, e.g, Al4C3 and "CaC2 and "covalent" carbides, e.g. B4C and SiC, and graphite intercalation compounds, e.g. "KC8). Other compounds and materials that are considered 'inorganic' by most authorities include: metal "carbonates, simple "oxides (CO, CO2, and arguably, C3O2), the "allotropes of carbon, "cyanides excluding those containing an organic residue (e.g., KCN, (CN)2, BrCN, CNO, etc.), and heavier analogs thereof (e.g., CP '"cyaphide anion', CSe, COS; although CS2 '"carbon disulfide' 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 carbonyl), "mellitic anhydride (C12O9), and other exotic "oxocarbons are also considered inorganic by some authorities.

"Nickel carbonyl (Ni(CO)4) and other metal carbonyls present an interesting case. They are often volatile liquids, like other organic compounds, yet they contain only carbon bonded to a transition metal and to oxygen and are often prepared directly from metal and carbon monoxide. Nickel carbonyl is frequently considered to be organometallic. Although many organometallic chemists employ a broad definition, in which any compound containing a carbon-metal covalent bond is considered "organometallic, it is debatable whether organometallic compounds form a subset of organic compounds.[5] Metal complexes with organic ligands but no carbon-metal bonds (e.g., Cu(OAc)2) are not considered organometallic; instead they are classed as metalorganic. Likewise, it is also unclear whether metalorganic compounds should automatically 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 nor oxalic acid is organic by this definition, yet they were two key compounds in the vitalism debate. The "IUPAC Blue Book on organic nomenclature specifically mentions urea[6] and oxalic acid.[7] 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 substance in "Martian soil.[8] Terrestrially, it, and its anhydride, mellitic anhydride, are associated with the mineral "mellite (Al2C6(COO)6·16H2O).

A slightly broader definition of 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 "CF3H and "CHCl3 would be organic, though these compounds share many physical and chemical properties.

Classification[edit]

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 "heteroatoms, e.g., "organometallic compounds, which feature bonds between carbon and a "metal, and "organophosphorus compounds, which feature bonds between carbon and a "phosphorus.

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

Natural compounds[edit]

"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 more expensive to produce artificially. Examples include most "sugars, some "alkaloids and "terpenoids, certain nutrients such as "vitamin B12, 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 are "antigens, "carbohydrates, "enzymes, "hormones, "lipids and "fatty acids, "neurotransmitters, "nucleic acids, "proteins, "peptides and "amino acids, "lectins, "vitamins, and "fats and oils.

Synthetic compounds[edit]

Compounds that are prepared by reaction of other compounds are known as "synthetic". They may be either compounds that already are found in plants or animals or those that do not occur naturally.

Most "polymers (a category that includes all "plastics and "rubbers), are organic synthetic or semi-synthetic compounds.

Biotechnology[edit]

Many organic compounds—two examples are "ethanol and "insulin—are manufactured industrially using organisms such as bacteria and yeast. 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.

Databases[edit]

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

Structure determination[edit]

The main tools are "proton and "carbon-13 "NMR spectroscopy, "IR Spectroscopy, "Mass spectrometry, "UV/Vis Spectroscopy and "X-ray crystallography.[9]

See also[edit]

References[edit]

  1. ^ a b "Spencer L. Seager, Michael R. Slabaugh. Chemistry for Today: general, organic, and "biochemistry. Thomson Brooks/Cole, 2004, p. 342. "ISBN "0-534-39969-X
  2. ^ Smith, Cory. "Petrochemicals". American Fuel & Petrochemical Manufacturers. American Fuel & Petrochemical Manufacturers. Retrieved 18 December 2016. 
  3. ^ From the definition of "organic compounds" are also excluded automatically the "allotropes of carbon such as "diamond and "graphite, because they are formed by atoms of the same element, so they are simple substances, not compounds.
  4. ^ Henry Marshall Leicester; Herbert S. Klickstein (1951). A Source Book in Chemistry, 1400-1900. Harvard University Press. p. 309. 
  5. ^ This is especially problematic, given recent evidence of covalent Fe-C bonding in cementite, a major component of steel (https://arxiv.org/ftp/arxiv/papers/0711/0711.1528.pdf). It's unclear whether the definition of organometallic should be revised, or whether this implies that organometallic compounds are not necessarily organic.
  6. ^ "IUPAC Blue Book, Urea and Its Derivatives Rule C-971". Retrieved 2009-11-22. 
  7. ^ "IUPAC Blue Book, Table 28(a) Carboxylic acids and related groups. Unsubstituted parent structures". Retrieved 2009-11-22. 
  8. ^ S. A. Benner; K. G. Devine; L. N. Matveeva; D. H. Powell (2000). "The missing organic molecules on Mars". "Proceedings of the National Academy of Sciences. 97 (6): 2425–2430. "Bibcode:2000PNAS...97.2425B. "doi:10.1073/pnas.040539497. "PMC 15945Freely accessible. "PMID 10706606. 
  9. ^ Ernö Pretsch, Philippe Bühlmann, Martin Badertscher (2009), Structure Determination of Organic Compounds (Fourth, Revised and Enlarged Edition). Springer-Verlag Berlin Heidelberg

External links[edit]

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