Portal:Organic chemistry

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The Organic chemistry Portal

The structure of methane by pictorial representation of a Lewis diagram showing the sharing of electronpairs between atomic nuclei in a covalent  bond.  Please do not form the impression from the diagram that the real picture is two-dimensional, because this is not the case.

Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting primarily of carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, halogens as well as phosphorus, silicon and sulfur.

Molecular models of caffeine

The original definition of "organic" chemistry came from the misconception that organic compounds were always related to life processes. Not all organic compounds support life on Earth, but life as we know it also depends heavily on inorganic chemistry; for example, many enzymes rely on transition metals such as iron and copper; and materials such as shells, teeth and bones are part organic, part inorganic in composition. Apart from elemental carbon, inorganic chemistry deals only with simple carbon compounds, with molecular structures which do not contain carbon to carbon connections (its oxides, acids, carbonates, carbides, and minerals). This does not mean that single-carbon organic compounds do not exist (viz. methane and its simple derivatives). Biochemistry mainly deals with the chemistry of proteins (and other large biomolecules).

Maitotoxin, a complex organic biological toxin.

Because of their unique properties, multi-carbon compounds exhibit extremely large variety and the range of application of organic compounds is enormous. They form the basis of, or are important constituents of many products (paints, plastics, food, explosives, drugs, petrochemicals, to name but a few) and (apart from a very few exceptions) they form the basis of all earthly life processes.

The different shapes and chemical reactivities of organic molecules provide an astonishing variety of functions, like those of enzyme catalysts in biochemical reactions of live systems. The autopropagating nature of these organic chemicals is what life is all about.

Trends in organic chemistry include chiral synthesis, green chemistry, microwave chemistry, fullerenes and microwave spectroscopy.

Selected article

The aldol reaction is an important carbon-carbon bond formation reaction in organic chemistry. In its usual form, it involves the nucleophilic addition of a ketone enolate to an aldehyde to form a β-hydroxy ketone, or "aldol" (aldehyde + alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals.

Typicalaldol2.gif

Sometimes, the aldol addition product loses a molecule of water during the reaction to form an α,β-unsaturated ketone. This is called an aldol condensation. The aldol reaction was discovered independently by Charles-Adolphe Wurtz and by Alexander Porfyrevich Borodin in 1872. Borodin observed the aldol dimerization of 3-hydroxybutanal from acetaldehyde under acidic conditions. The aldol reaction is used widely in the large scale production of commodity chemicals such as pentaerythritol and in the pharmaceutical industry for the synthesis of optically pure drugs. For example, Pfizer's initial route to the heart disease drug Lipitor (INN: atorvastatin), approved in 1996, employed two aldol reactions, allowing access to multigram-scale quantities of the drug.

The aldol structural motif is especially common in polyketides, a class of natural products from which many pharmaceuticals are derived, including the potent immunosuppressant FK506, the tetracycline antibiotics, and the antifungal agent amphotericin B. Extensive research on the aldol reaction has produced highly efficient methods which enable the otherwise challenging synthesis of many polyketides in the laboratory.

Selected Picture

TaxolTotalSynthesisColor.png

Paclitaxel is an important drug used for the treatment of cancer. Its complex structure provided a challenging target for its total synthesis by the Nicolaou group. The colors indicate the approach they used.

Selected reaction

The Wittig reaction is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide (often called a Wittig reagent) to give an alkene and triphenylphosphine oxide.

Wittig Reaction

The Wittig reaction was discovered in 1954 by Georg Wittig, for which he was awarded the Nobel Prize in Chemistry in 1979. It is widely used in organic synthesis for the preparation of alkenes. It should not be confused with the Wittig rearrangement.

Wittig reactions are most commonly used to couple aldehydes and ketones to singly substituted phosphine ylides. With simple ylides this results in almost exclusively the Z-alkene product. In order to obtain the E-alkene, the Schlosser modification of the Wittig reaction can be performed.

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Selected Biography

Elias James Corey (born July 12, 1928) is a renowned American organic chemist. In 1990 he won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis", specifically retrosynthetic analysis.[1][2] Regarded by many as one of the greatest living chemists, he has developed numerous synthetic reagents, methodologies, and has advanced the science of organic synthesis considerably. He was awarded the Japan Prize in 1989.

He was born "William" to Christian Lebanese immigrants in Methuen, Massachusetts, 30 miles north of Boston. His mother changed his name to "Elias" to honor his father who died eighteen months after the birth of his son. His widowed mother, brother, two sisters and an aunt and uncle all lived together in a spacious house- struggling through the depression. He attended Catholic elementary school and Lawrence public High School.[1]

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Organic chemistry Resources

organic nomenclature
Organic reactions

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Organic chemistry Topics

Functional Groups

Organic Reactions

According to the Reaction's Mechanism

  1. electrophilic addition or EA
  2. nucleophilic addition or NA
  3. radical addition or RA
  1. nucleophilic aliphatic substitution with SN1, SN2 and SNi reaction mechanisms
  2. nucleophilic aromatic substitution or NAS
  3. nucleophilic acyl substitution
  4. electrophilic substitution or ES
  5. electrophilic aromatic substitution or EAS
  6. radical substitution or RS
  1. 1,2-rearrangements
  2. pericyclic reactions
  3. metathesis
In Condensation reactions a small molecule, usually water, is split off when two reactants combine in a chemical reaction. The opposite reaction, when water is consumed in a reaction, is called hydrolysis. Many Polymerization reactions are derived from organic reactions. They are divided into addition polymerizations and step-growth polymerizations.

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References

  1. ^ E. J. Corey, X-M. Cheng, The Logic of Chemical Synthesis, Wiley, New York, 1995, ISBN 0-471-11594-0.
  2. ^ "The Logic of Chemical Synthesis: Multistep Synthesis of Complex Carbogenic Molecules (Nobel Lecture)" E.J. Corey, Angew. Chem. Int. Ed. Engl. 1991, 30, 455.