| Revision as of 02:48, 30 June 2017 editJockey Raj 786 (talk | contribs)19 editsmNo edit summaryTags: Visual edit Mobile edit Mobile web edit← Previous edit | Revision as of 09:43, 2 July 2017 edit undoMean as custard (talk | contribs)Extended confirmed users, New page reviewers, Pending changes reviewers, Rollbackers190,541 editsm Reverted edits by Jockey Raj 786 (talk) to last version by 39.45.249.57Next edit → | ||
| Line 1: | Line 1: | ||
| {{refimprove|date=April 2017}} | {{refimprove|date=April 2017}} | ||
| ]s to form a ] (red) with expulsion of water (blue)]] | ]s to form a ] (red) with expulsion of water (blue)]] | ||
| A '''condensation reaction''' is a ] in which two ]s or ], often ]s, combine to form a larger molecule, together with the loss of a small molecule.<ref name=goldbook>{{GoldBookRef|title=Condensation Reaction|file=C01238|year=1994}}</ref> Possible small molecules that are lost include ], ], ], or ], but most commonly in biological reactions it is water.{{citation needed|date=March 2017}} | A '''condensation reaction''' is a ] in which two ]s or ], often ]s, combine to form a larger molecule, together with the loss of a small molecule.<ref name=goldbook>{{GoldBookRef|title=Condensation Reaction|file=C01238|year=1994}}</ref> Possible small molecules that are lost include ], ], ], or ], but most commonly in biological reactions it is water.{{citation needed|date=March 2017}} Condensations producing water as a byproduct are the opposite reaction of transformations involving ], which split a reactant into two new species through addition of a ]. | ||
| ] | ] | ||
Revision as of 09:43, 2 July 2017
 | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Condensation reaction" – news · newspapers · books · scholar · JSTOR (April 2017) (Learn how and when to remove this message) |
A condensation reaction is a chemical reaction in which two molecules or moieties, often functional groups, combine to form a larger molecule, together with the loss of a small molecule. Possible small molecules that are lost include water, acetic acid, hydrogen chloride, or methanol, but most commonly in biological reactions it is water. Condensations producing water as a byproduct are the opposite reaction of transformations involving hydrolysis, which split a reactant into two new species through addition of a water molecule.
Condensation can be intermolecular (between two different molecules) or intramolecular (involving different groups within the same molecule). A simple example of an intermolecular condensation is the joining of two amino acids in the peptide bond, as is characteristic of all proteins. Examples of intramolecular condensations often lead to ring formation, and include the synthesis of cyclic peptides via the same bond forming process as just described, as well as Dieckmann condensations, in which the two ester groups within a diester molecule react with release of an alcohol molecule to form a β-ketoester product.Actually in this process two water molecules are released. As given below (n+n=2n)
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.
Mechanisms
 | This section needs expansion with: an encyclopedic description of the mechanisms by condensation reactions occur (e.g., as in Carey & Sundberg or March). You can help by adding to it. (March 2017) |
Condensation reactions can follow a variety of different reaction mechanisms, depending on the groups reacting and the conditions employed to perform the reaction (solvent, temperature, reaction additives, etc.).
Applications
| This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (March 2017) (Learn how and when to remove this message) |
 | This section may contain unverified or indiscriminate information in embedded lists. Please help clean up the lists by removing items or incorporating them into the text of the article. (March 2017) |
Many artificial, man-made chemical reactions, and many biological transformations are condensation reactions. In the latter case (reactions in nature), phosphorylation and glycosylation reactions are generally all condensations, as are the key bond-forming reactions in all polypeptide and polynucleotide syntheses, and much of polyketide and terpene biosynthesis as well. Examples of the large number of condensation reactions are used in synthetic organic chemistry include:
- Acyloin condensation
- Aldol condensation
- Claisen condensation
- Claisen–Schmidt condensation
- Darzens reaction (glycidic ester condensation)
- Dieckmann condensation
- Guareschi–Thorpe condensation
- Knoevenagel condensation
- Pechmann condensation
- Rap–Stoermer condensation
- Self-condensation or symmetrical aldol condensation
- Thorpe–Ziegler reaction
The reactions that form acid anhydrides from their constituent acids are also typically condensation reactions.
Condensation polymerization
| This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (March 2017) (Learn how and when to remove this message) |
| This article may require cleanup to meet Misplaced Pages's quality standards. The specific problem is: the current array of sentences fails as encyclopedic, lacking the scope, structure, details, examples, and sources of even a stub section compliant with WP:VERIFY. Please help improve this article if you can. (March 2017) (Learn how and when to remove this message) |
Condensation polymerization produces many important polymers, for example: nylon, polyester, and other condensation polymers and various epoxies. It is also the basis for the laboratory formation of silicates and polyphosphates. In condensation polymerization or "step-growth polymerization", multiple condensation reactions take place, joining monomers and monomer chains into long chains called polymers. It occurs for example in the synthesis of polyesters or nylons. It can be homopolymerization of a single monomer A-B with two different end groups that condense, or copolymerization of two co-monomers A-A and B-B.
Condensation polymerization releases multiple small molecules, in contrast to polyaddition reactions, which do not. In general, condensation polymers form more slowly than addition polymers, often requiring heat. They are generally lower in molecular weight. Monomers are consumed early in the reaction; the terminal functional groups remain active throughout; and short chains combine to form longer chains. A high conversion rate is required to achieve high molecular weights, per Carothers' equation.
Bifunctional monomers lead to linear chains, and therefore thermoplastic polymers, but, when the monomer functionality exceeds two, the product is a branched chain that may be a thermosetting polymer.
See also
- Anabolism
- Hydrolysis, the opposite of a condensation reaction
- Condensed tannins
References
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (1994) "Condensation Reaction". doi:10.1351/goldbook.C01238