Condensation Reaction


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condensation reaction

[‚kän·dən′sā·shən rē′ak·shən]
(chemistry)
One of a class of chemical reactions involving a combination between molecules or between parts of the same molecule.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Condensation Reaction

 

the historically established name in organic chemistry for a large group of reactions that form complex compounds from two or more (several) simple compounds. condensation reactions, differentiated according to the nature of the reagents and the nature of the chemical trans-formations, include many intramolecular and intermolecular processes of formation of new carbon-carbon (C—C) bonds. Most such reactions are accompanied by the separation of some simple inorganic or organic X—Y molecule (for example, water, hydrogen, alcohol, hydrogen halide, halogen):

Examples of this type of condensation reaction are crotonic condensation, the Wurtz reaction, the Claisen condensation, the Knoevenagel reaction, the Perkin reaction, and the Friedel-Crafts reaction.

Unlike the aforementioned reactions, condensation reactions such as benzoin condensation, aldol condensation, and diene synthesis take place without separation of any simple molecule. Furthermore, all reactions that produce heterocyclic compounds are referred to in organic chemistry as condensation reactions; new bonds may emerge during these processes, for example, carbon-carbon, carbon-heteroatom, and heteroatom-heteroatom. Esterification, ester interchange, alkylation, and alkylation over oxygen or nitrogen are generally not included among the condensation reactions. The reactions of the formation of polymers according to these schemes, however, are known as polycondensation reactions.

REFERENCES

Kratkaia khimicheskaia entsiklopediia, vol. 2. Moscow, 1963. Page 678.
Die Methoden der Organischen Chemie, 3rd ed., vol. 2. Edited by J. Houben. Leipzig, 1925. Page 716.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The hydrolysis and condensation reactions can be accelerated by acids, bases, and organometallics.
The reaction of benzaldehyde with malononitrile in water at room temperature without the use of a catalyst raises the following questions: can we apply this technique to other condensation reactions of aldehydes and ketones with active methylene compounds?
On the other hand, the temperature selected must not be so high that a premature reaction occurs between the silane and the rubber (pre-scorch), the viscosity of the compound falls to such an extent that the dispersion is impaired and an intermolecular condensation reaction of the silane (polysiloxane formation) leads to a deterioration of the hydrophobization.
However, there is no characteristic band of nitrogen-containing groups in FT-IR spectra, illustrating that the L-arginine does not join the carbon forming reaction, but it changes the solution property and promotes starch hydrolysis and polymerization and condensation reaction. The surface functional groups are markedly decreased when the CMs are carbonized at 500 AdegC, which is shown in the FT-IR spectra in Fig 4 (b).
The condensation reaction between Si-OH or between Si-OH and Si-(O[C.sub.2][H.sub.5]), cf.
L has also been prepared from the condensation reaction of 1,4-di-(4- fluoro-2aminophenoxy)butane (DFAB) and Salicylaldehyde in ethanol and characterized by IR, 1H-NMR and 13C-NMR spectroscopy and mass spectrometry.
Polymerization is an equilibrium condensation reaction leading to side products such as water, making reaching a very high molecular weight very difficult.
The [alpha], [beta]-unsaturated carbonyl compounds 48a-c were prepared by a condensation reaction of 4-acetyl-2-phenyl-1,2,3-triazole 46 with substituted aldehydes 47a-c.
Moreover, in the conditions under pH 7, the rate of the condensation reaction rapidly decreases, but the rate of hydrolysis sharply increases [22].
The transformation involves the condensation reaction of benzaldehyde dimedone and phthalhydrazide in aqueous media at 80[degrees]C temperature (Scheme 1).
Carboxyl groups of the alkyd can react with melamine but act as more of a catalyst for the melamine-melamine condensation reaction and a large amount of the alkyd remains unreacted, acting as a plasticizer.