Definition of Organic Compounds
In general, organic compounds contain carbon (C), and carbon atoms provide the key structural framework that generates the vast diversity of organic compounds.
All things on the Earth (and most likely elsewhere in the universe) that can be described as the living have a crucial dependence on organic compounds.
Foodstuffs—namely, fats, proteins, and carbohydrates—are organic compounds, as are such vital substances as hemoglobin, chlorophyll, enzymes, hormones, and vitamins.
Other materials that add to the comfort, health, or convenience of humans are composed of organic compounds, including clothing made of cotton, wool, silk, and synthetic fibers; common fuels, such as wood, coal, petroleum, and natural gas; components of protective coatings, such as varnishes, paints, lacquers, and enamels; antibiotics and synthetic drugs; natural and synthetic rubber; dyes; plastics; and pesticides.
Other Definitions of Organic Compounds
There are more definitions of the organic compounds
Definition 1 –
The first significant synthesis of an organic compound from inorganic materials was an accidental discovery of Friedrich Wohler, a German chemist. Working in Berlin in 1828, Wohler mixed two salts (silver cyanate and ammonium chloride) to make the inorganic substance ammonium cyanate. To his complete surprise, he obtained a product with the same molecular formula as ammonium cyanate but was instead the well-known organic compound urea.
From this advantageous result, Wohler correctly concluded that atoms could arrange themselves into molecules in different ways, and the properties of the resulting molecules were critically dependent on the molecular architecture.
The inorganic compound ammonium cyanate is now known to be an isomer of urea; both contain the same type and number of atoms but in different structural arrangements.) Encouraged by Wohler’s discovery, others made simple organic compounds from inorganic ones, and by roughly 1860.
It was generally recognized that a vital force was unnecessary for the synthesis and interconversion of organic compounds.
Definition 2 –
Although many organic compounds have since been synthesized. The structural complexity of certain compounds continues to pose major problems for the laboratory synthesis of complicated molecules.
But modern spectroscopic techniques allow chemists to determine the specific architecture of complex organic molecules. And molecular properties can be correlated with carbon bonding patterns and characteristic structural features known as functional groups.
Definition 3 –
Organic compounds also contain carbon, along with other elements essential for the reproduction of living organisms.
Carbon is the main factor as it has four electrons that can accommodate eight electrons in an outer shell. As a result, several bonds can be formed with other carbon atoms and elements such as hydrogen, oxygen, and nitrogen.
Hydrocarbons and proteins are strong examples of organic molecules capable of producing long chains and complex structures.
Definition 4 –
The modern, commonly accepted definition of organic compound essentially amounts to any carbon-containing compound, excluding several substances traditionally considered 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 has cementite, Fe3C). As well as other metal and semimetal carbides (including “ionic” carbides, e.g., Al4C4 and CaC4 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, cyanide derivatives not containing an organic residue (e.g., KCN, (CN)2, BrCN, CNO–, etc.), and heavier analogs there of (e.g., CP− ‘cyaphide anion,’ Cse2, COS; although CS2 ‘carbon disulfide’ is often classed as an organic compound.
Halides of carbon without hydrogen (e.g., CF4 and CClF3), phosgene (COCl2), carborne, metal carbonyls (e.g., nickel carbonyl), mellitic anhydride (C12O9), and other exotic oxo carbons are also considered inorganic by some authorities.
Definition 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.
Definition 6 –
The relatively narrow definition of organic compounds as those containing C-H bonds excludes (historically and practically) compounds 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 and oxalic acid. Other compounds lacking C-H bonds but traditionally considered organic include benzenehexol, me oxalic acid, and carbon tetrachloride.
Mellitic acid, which contains no C-H bonds, is considered a possible organic substance in Martian soil. Terrestrially, it, and its anhydride, mellitic anhydride, are associated with the mineral mellite (Al2C6(COO)6·16H2O).
Definition 7 –
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 CF3H and C2Cl6 would be organic, though these compounds share many physical and chemical properties.
History of Organic Compounds
Vitalism – Vitalism was a widespread conception that substances found in organic nature are created from the chemical elements by the action of a “vital force” or “lifeforce” (vis vitalis) that only living organisms possess.
The Vitalism taught that these “organic” compounds were fundamentally different from the “inorganic” compounds obtained from the elements by chemical manipulations. Vitalism survived for a while, even after the rise of modern ideas about atomic theory and chemical elements.
It first came under question in 1824. When Friedrich Wohler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A further experiment was Wohler’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. Wohler’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.
Although vitalism has been discredited, scientific nomenclature retains the distinction between organic and inorganic compounds.
The modern meaning of the 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, and covalent bonds from carbon to oxygen and nitrogen.
Types of Organic Compounds
The organic compounds made up of these molecules form the basis for chemical reactions in plant and animal cells – reactions that provide the energy required to find food, to replicate, and for all other life-related processes.
Followings are the types of Organic Compounds
Acyclic or Open Chain Compounds
These compounds are also known as aliphatic compounds, they have branched or straight chains.
Alicyclic or Closed Chain or Ring Compounds
These are cyclic compounds which contain carbon atoms connected to each other in a ring (homocyclic). When atoms other than carbon are also present then it is called as heterocyclic.
They are a special type of compounds which contain benzene and other ring related compounds. Similar to alicyclic, they can also have heteroatoms in the ring. Such compounds are called heterocyclic aromatic compounds. Some examples are as follows
- Benzenoid aromatic compounds.
Classifications of Organic Compounds
Organic compound 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 phosphorus. Another distinction, based on the size of organic compounds, distinguishes between small molecules and polymers.
Natural Organic Compounds
Natural compounds refer to those that plants or animals produce. 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 stereo isometrically complicated molecules present in reasonable concentrations in living organisms. Further compounds of prime importance in bio chemistry are antigens, carbohydrates, enzymes, hormones, lipids, and fatty acids, neurotransmitters, nucleic acids, proteins, peptides, amino acids, lectins, vitamins, and fats and oil.
Synthetic Organic Compounds
Compounds that are prepared by the reaction of other compounds are known as “synthetic”. They may be either compounds already 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.
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.
Organic compounds can also be classified on the basis of functional groups into families or homologous series.
The functional group can be defined as an atom or a group of atoms that are joined together in a specific manner which is responsible for the characteristic chemical properties of organic compounds.
Examples, in this case, are the hydroxyl group -OH, aldehyde group -CHO and carboxylic acid group -COOH.
A group or a series of organic compounds in which each member contains the same characteristic functional group and differs from each other by a fixed unit form a homologous series, and therefore its members are known as homologous.
A general formula can represent the members of the homologous series, and the successive members differ from each other in the molecular formula by a CH4 unit. There are a number of homologous series in organic chemistry, such as alkanes, alkenes, alkynes, haloalkanes, alkanols, amines, etc.
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