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{{short description|Chemical reaction in which two molecules are combined and a small molecule, usually water, is lost}}
⚫ 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<ref>{{cite web|url=https://goldbook.iupac.org/html/C/C01238.html|title=Condensation Reaction|website=IUPAC Copendium of Chemical Terminology (Gold Book)|publisher=IUPAC|accessdate=7 December 2017}}</ref>. 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<ref>{{Cite book|title=Fundamentals of Biochemistry|last=Voet|first=Donald|last2=Voet|first2=Judith|last3=Pratt|first3=Chriss|publisher=John Wiley & Sons, Inc.|year=2008|isbn=978-0470-12930-2|location=Hoboken, NJ|pages=88}}</ref>.
]
⚫ 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)<ref name=":0">{{cite book|title=Advanced Organic Chemistry|last1=Bruckner|first1=Reinhard|date=2002|publisher=Harcourt Academic Press|isbn=0-12-138110-2|edition=First|location=San Diego, California|pages=414-427|accessdate=8 December 2017}}</ref>.
]
<references />


In ], a '''condensation reaction''' is a type of ] in which two ]s are ] to form a single molecule, usually with the loss of a small molecule such as ].<ref>{{cite book |title=Book: Introductory Chemistry (CK-12) |date=12 August 2020 |publisher=Chemistry Libre Texts |url=https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_Introductory_Chemistry_(CK-12)/25%3A_Organic_Chemistry/25.18%3A_Condensation_Reactions |access-date=9 January 2021 |chapter=25.18 Condensation Reactions}}</ref> If water is lost, the reaction is also known as a ]. However other molecules can also be lost, such as ], ], ] and ].<ref>{{cite journal|url=https://goldbook.iupac.org/html/C/C01238.html|title=Condensation Reaction|website=IUPAC Compendium of Chemical Terminology (Gold Book)|year=2014|publisher=IUPAC|doi=10.1351/goldbook.C01238|access-date=7 December 2017|doi-access=free}}</ref>
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.


⚫ The addition of the two molecules typically proceeds in a step-wise fashion to the addition product, usually in ], and with loss of a water molecule (hence the name ]).<ref>{{Cite journal|last=Fakirov|first=S.|date=2019-02-01|title=Condensation Polymers: Their Chemical Peculiarities Offer Great Opportunities|journal=Progress in Polymer Science|volume=89|pages=1–18|doi=10.1016/j.progpolymsci.2018.09.003|s2cid=105101288|issn=0079-6700}}</ref> The reaction may otherwise involve the ]s of the molecule, and is a versatile class of reactions that can occur in ]ic or ] conditions or in the presence of a ]. This class of reactions is a vital part of life as it is essential to the formation of ]s between ]s and to the ].<ref>{{Cite book|title=Fundamentals of Biochemistry|url=https://archive.org/details/fundamentalsbioc00voet|url-access=limited|last1=Voet|first1=Donald|last2=Voet|first2=Judith|last3=Pratt|first3=Chriss|publisher=John Wiley & Sons, Inc.|year=2008|isbn=978-0470-12930-2|location=Hoboken, NJ|pages=}}</ref>
==Mechanisms==
The numerous amount of condensation reactions correspond to numerous mechanisms but they all tend to follow a similar pathway.


].]]
<u>Knoevenagel Reaction Mechanism</u>


⚫ Many variations of condensation reactions exist. Common examples include the ] and the ], which both form water as a by-product, as well as the ] and the ] (intramolecular Claisen condensation), which form alcohols as by-products.<ref name=":0">{{cite book|title=Advanced Organic Chemistry|url=https://archive.org/details/advancedorganicc00bruc|url-access=limited|last1=Bruckner|first1=Reinhard|date=2002|publisher=Harcourt Academic Press|isbn=0-12-138110-2|edition=First|location=San Diego, California|pages=–427}}</ref>
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<ref name=":0" />
]
<u>Crossed Claisen Condensation Reaction Mechanism</u>


]
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.
]


== Synthesis of prebiotic molecules ==
==Applications==
{{main|Abiogenesis}}
{{unreferenced section|date=March 2017}}
Condensation reactions likely played major roles in the synthesis of the first biotic molecules including early ]s and ]s. In fact, condensation reactions would be required at multiple steps in ] oligomerization: the condensation of ]s and ]s, ] ], and ] polymerization.<ref name=":02">{{Cite book |last=Fiore |first=Michele |title=Prebiotic Chemistry and Life's Origin |publisher=Royal Society of Chemistry |year=2022 |isbn=9781839164804 |location=United Kingdom |pages=124–144}}</ref>
{{Cleanup list|section|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:{{1}}
{{colbegin|3}}
*]
*]
*]
*]
*] (glycidic ester condensation)
*]
*]
*]
*]
*]
*] or symmetrical aldol condensation
*]
{{colend}}

The reactions that form ] from their constituent acids are also typically condensation reactions.{{citation needed|date=March 2017}}

==Condensation polymerization==
{{unreferenced section|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 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==
*] * ]
*], the opposite of a condensation reaction * ], the opposite of a condensation reaction
*]s * ]s


==References== ==References==
{{Reflist}} {{Reflist}}


{{Authority control}}
⚫ ]

⚫ ]

Latest revision as of 17:03, 23 December 2024

Chemical reaction in which two molecules are combined and a small molecule, usually water, is lost

In organic chemistry, a condensation reaction is a type of chemical reaction in which two molecules are combined to form a single molecule, usually with the loss of a small molecule such as water. If water is lost, the reaction is also known as a dehydration synthesis. However other molecules can also be lost, such as ammonia, ethanol, acetic acid and hydrogen sulfide.

The addition of the two molecules typically proceeds in a step-wise fashion to the addition product, usually in equilibrium, and with loss of a water molecule (hence the name condensation). The reaction may otherwise involve the functional groups of the molecule, and 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 and to the biosynthesis of fatty acids.

Idealized scheme showing condensation of two amino acids to give a peptide bond.

Many variations of condensation reactions exist. Common examples include the aldol condensation and the Knoevenagel condensation, which both form water as a by-product, as well as the Claisen condensation and the Dieckman condensation (intramolecular Claisen condensation), which form alcohols as by-products.

Aldol condensation overview

Synthesis of prebiotic molecules

Main article: Abiogenesis

Condensation reactions likely played major roles in the synthesis of the first biotic molecules including early peptides and nucleic acids. In fact, condensation reactions would be required at multiple steps in RNA oligomerization: the condensation of nucleobases and sugars, nucleoside phosphorylation, and nucleotide polymerization.

See also

References

  1. "25.18 Condensation Reactions". Book: Introductory Chemistry (CK-12). Chemistry Libre Texts. 12 August 2020. Retrieved 9 January 2021.
  2. "Condensation Reaction". IUPAC Compendium of Chemical Terminology (Gold Book). IUPAC. 2014. doi:10.1351/goldbook.C01238. Retrieved 7 December 2017.
  3. Fakirov, S. (2019-02-01). "Condensation Polymers: Their Chemical Peculiarities Offer Great Opportunities". Progress in Polymer Science. 89: 1–18. doi:10.1016/j.progpolymsci.2018.09.003. ISSN 0079-6700. S2CID 105101288.
  4. Voet, Donald; Voet, Judith; Pratt, Chriss (2008). Fundamentals of Biochemistry. Hoboken, NJ: John Wiley & Sons, Inc. pp. 88. ISBN 978-0470-12930-2.
  5. Bruckner, Reinhard (2002). Advanced Organic Chemistry (First ed.). San Diego, California: Harcourt Academic Press. pp. 414–427. ISBN 0-12-138110-2.
  6. Fiore, Michele (2022). Prebiotic Chemistry and Life's Origin. United Kingdom: Royal Society of Chemistry. pp. 124–144. ISBN 9781839164804.
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