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]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.{{cn|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 ]. 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 ].


] ]
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 ]s in the ], as is characteristic of all ]s. Examples of intermolecular condensations often lead to ], and include the synthesis of ]s via the same bond forming process as just described, as well as ]s, in which the two ] groups within a diester molecule react with release of an ] molecule to form a β-] product. 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 ]s in the ], as is characteristic of all ]s. Examples of intermolecular condensations often lead to ], and include the synthesis of ]s via the same bond forming process as just described, as well as ]s, in which the two ] groups within a diester molecule react with release of an ] molecule to form a β-] product.


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. 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== ==Mechanisms==
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{{expand section|an encyclopedic description of the mechanisms by condensation reactions occur (e.g., as in Carey & Sundberg or March) | small = no|date=March 2017}} {{expand section|an encyclopedic description of the mechanisms by condensation reactions occur (e.g., as in Carey & Sundberg or March) | small = no|date=March 2017}}
Condensation reactions can follow a variety of different ]s, depending on the groups reacting and the conditions employed to perform the reaction (solvent, temperature, reaction additives, etc.).{{cn|date=March 2017}} Condensation reactions can follow a variety of different ]s, depending on the groups reacting and the conditions employed to perform the reaction (solvent, temperature, reaction additives, etc.).{{citation needed|date=March 2017}}


==Applications== ==Applications==
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{{Cleanup-list|section|date=March 2017}} {{Cleanup list|section|date=March 2017}}
Many artificial, man-made ], and many ] are condensation reactions.{{cn|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.{{cn|date=March 2017}} Examples of the large number of condensation reactions are used in synthetic ] include:{{cn|date=March 2017}} 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:{{citation needed|date=March 2017}}
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The reactions that form ] from their constituent acids are also typically condensation reactions.{{cn|date=March 2017}} The reactions that form ] from their constituent acids are also typically condensation reactions.{{citation needed|date=March 2017}}


==Condensation polymerization== ==Condensation polymerization==
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{{cleanup|reason = 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 |date=March 2017}} {{cleanup|reason = 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 |date=March 2017}}
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 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 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 ]. 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 ].

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The condensation of two amino acids to form a peptide bond (red) with expulsion of water (blue)

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.

Dieckmann condensation reaction

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 intermolecular 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.

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

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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

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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:

The reactions that form acid anhydrides from their constituent acids are also typically condensation reactions.

Condensation polymerization

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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

References

  1. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (1994) "Condensation Reaction". doi:10.1351/goldbook.C01238
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