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Revision as of 15:24, 28 December 2017 editMm9656 (talk | contribs)56 edits Added mechanisms to the mechanism section with sources← Previous edit Revision as of 15:26, 28 December 2017 edit undoMm9656 (talk | contribs)56 edits Created an applications section with examples of modern applications and links to the examples citedTag: Visual edit: SwitchedNext edit →
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==Applications== '''<u>Modern Synthetic Applications</u>'''
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Many artificial, man-made ], and many ] are condensation reactions.{{citation needed|date=March 2017}} In the latter case (reactions in nature), ] and ] reactions are generally all condensations, as are the key bond-forming reactions in all ] and ] syntheses, and much of ] and ] biosynthesis as well.{{citation needed|date=March 2017}} Examples of the large number of condensation reactions are used in synthetic ] include:{{1}}
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*]
*]
*]
*]
*] (glycidic ester condensation)
*]
*]
*]
*]
*]
*] or symmetrical aldol condensation
*]
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Condensation reactions are used throughout the field of synthetic and medicinal chemistry to synthesize target compounds. Their familiarity and predictable nature make them a widely used synthetic tool. In this section are several examples of some recent uses of condensation reactions in the fields of medicinal and synthetic chemistry.
The reactions that form ] from their constituent acids are also typically condensation reactions.{{citation needed|date=March 2017}}


A team of chemists led by Young Lok Choi and Jung-Nyoung Heo successfully synthesized dibenzoheptenones by combining a suzuki-miyaura coupling reaction with an aldol condensation reaction.<ref>{{Cite journal|last=Kim|first=Joa|last2=Kim|first2=Young|last3=Jung-Nyoung|first3=Heo|date=Winter 2017|title=Total Synthesis of Aristolactams via a One-Pot Suzuki−Miyaura Coupling/Aldol Condensation Cascade Reaction|url=http://pubs.acs.org/doi/abs/10.1021/ol801291k|journal=Journal of Organic Letters|volume=10|pages=3543-3546|via=}}</ref> These dibenzoheptenone form the skeleton for important medicinal drugs such as colchicine (anti-inflamatory used to treat gout).
==Condensation polymerization==
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Condensation polymerization produces many important ]s, for example: ], ], and other ]s and various ]. It is also the basis for the laboratory formation of ]s and ]s. In condensation ] or "]", multiple condensation reactions take place, joining ]s and ] into long chains called ]s. It occurs for example in the synthesis of ]s or ]s. It can be homopolymerization of a single monomer A-B with two different end groups that condense, or ]ization of two co-monomers A-A and B-B.


Condensation reactions have also recently been used to initiate tandem C-N bond formation to form heterocycles. In a paper published in 2017 by a team led by  Yan-Xiao Jiao and Gui-Fa Su* they managed to form quinoxilines which is a structure that is used throughout the pharmaceutical and technological industry.<ref>{{Cite journal|last=Jiao|first=Yan-Xiao|last2=Wu|first2=Ling-Ling|last3=Su|first3=Gui-FA|date=Winter 2017|title=Tandem C–N Bond Formation through Condensation and Metal-Free N-Arylation: Protocol for Synthesizing Diverse Functionalized Quinoxalines|url=http://pubs.acs.org/doi/abs/10.1021/acs.joc.7b00011|journal=Journal of Organic Chemistry|volume=82|pages=4407-4417|via=}}</ref>
Condensation polymerization releases multiple small molecules, in contrast to ] reactions, which do not. In general, ]s form more slowly than ]s, often requiring ]. They are generally lower in molecular weight. Monomers are consumed early in the reaction; the terminal ]s remain active throughout; and short chains combine to form longer chains. A high conversion rate is required to achieve high molecular weights, per ].

] monomers lead to linear chains, and therefore ] polymers, but, when the monomer ] exceeds two, the product is a ] that may be a ].


==See also== ==See also==

Revision as of 15:26, 28 December 2017

A condensation reaction is a class of an organic addition reaction that proceeds in a step-wise fashion to produce the addition product, usually in equilibrium, and a water molecule (hence the name condensation). The reaction may otherwise involve the formation of ammonia, ethanol, or acetic acid. It is a versatile class of reactions that can occur in acidic or basic conditions or in the presence of a catalyst. This class of reactions is a vital part of life as it is essential to the formation of peptide bonds between amino acids.

This oxidation is an example of a condensation reaction involved in the linking of peptides.

There are also copious variations of condensation reactions carried out in the lab, common examples include the Aldol Condensation, the Claisen Condensation, the Knoevenagel Reaction and the Dieckman Condensation (intramolecular Claisen Condensation).

Condensation reaction between two symmetrical aldehydes. The final product is formed irreversibly due to stability from the conjugation of the double bonds.
  1. "Condensation Reaction". IUPAC Copendium of Chemical Terminology (Gold Book). IUPAC. Retrieved 7 December 2017.
  2. Voet, Donald; Voet, Judith; Pratt, Chriss (2008). Fundamentals of Biochemistry. Hoboken, NJ: John Wiley & Sons, Inc. p. 88. ISBN 978-0470-12930-2.
  3. Bruckner, Reinhard (2002). Advanced Organic Chemistry (First ed.). San Diego, California: Harcourt Academic Press. pp. 414–427. ISBN 0-12-138110-2. {{cite book}}: |access-date= requires |url= (help)

The condensation reaction-speed can be catalyzed, by simply adding a concentrated acid to the reaction. It effects it by acidifying the environment whereas the reaction takes place the acid thereby binds with the water molecules and speed up the process. Also, an example of the condensation reaction is the dehydration synthesis.

Mechanisms

The numerous amount of condensation reactions correspond to numerous mechanisms but they all tend to follow a similar pathway.

Knoevenagel Reaction Mechanism

This reaction takes between a carbonyl compound and a activated methylene compound or with a nitromethane group, in mildly basic conditions. The final product of the reaction is an alkene with two geminal acceptor groups or one nitro group

Mechanism for the reaction of active-methylene compounds with carbonyls to form alkenes.
Mechanism for the reaction of active-methylene compounds with carbonyls to form alkenes.

Crossed Claisen Condensation Reaction Mechanism

The crossed claisen reaction results in the acylation of an ester enolate with another ester. These reactions are only possible when one ester has no alpha hydrogens. The reaction conditions call for a highly basic solution and a rapid acidic workup to achieve the final compound.

Formation of diethyl phenylmalonte by a crossed claisen condensation reaction.
Formation of diethyl phenylmalonte by a crossed claisen condensation reaction.

Modern Synthetic Applications

Condensation reactions are used throughout the field of synthetic and medicinal chemistry to synthesize target compounds. Their familiarity and predictable nature make them a widely used synthetic tool. In this section are several examples of some recent uses of condensation reactions in the fields of medicinal and synthetic chemistry.

A team of chemists led by Young Lok Choi and Jung-Nyoung Heo successfully synthesized dibenzoheptenones by combining a suzuki-miyaura coupling reaction with an aldol condensation reaction. These dibenzoheptenone form the skeleton for important medicinal drugs such as colchicine (anti-inflamatory used to treat gout).

Condensation reactions have also recently been used to initiate tandem C-N bond formation to form heterocycles. In a paper published in 2017 by a team led by  Yan-Xiao Jiao and Gui-Fa Su* they managed to form quinoxilines which is a structure that is used throughout the pharmaceutical and technological industry.

See also

References

  1. Cite error: The named reference :0 was invoked but never defined (see the help page).
  2. Bruckner, Reinhard (2002). Advanced Organic Chemistry. San Diego, California: Harcourt Academic Press. p. 418. ISBN 0-12-138110-2.
  3. Kim, Joa; Kim, Young; Jung-Nyoung, Heo (Winter 2017). "Total Synthesis of Aristolactams via a One-Pot Suzuki−Miyaura Coupling/Aldol Condensation Cascade Reaction". Journal of Organic Letters. 10: 3543–3546.
  4. Jiao, Yan-Xiao; Wu, Ling-Ling; Su, Gui-FA (Winter 2017). "Tandem C–N Bond Formation through Condensation and Metal-Free N-Arylation: Protocol for Synthesizing Diverse Functionalized Quinoxalines". Journal of Organic Chemistry. 82: 4407–4417.
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