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The conversion of ethanol to ethylene is a fundamental example: [3] [4] CH 3 CH 2 OH → H 2 C=CH 2 + H 2 O. The reaction is accelerated by acid catalysts such as sulfuric acid and certain zeolites. These reactions often proceed via carbocation intermediates as shown for the dehydration of cyclohexanol. [5] Some alcohols are prone to dehydration.
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. [1] If water is lost, the reaction is also known as a dehydration synthesis.
The carbon snake is a demonstration of the dehydration reaction of sugar by concentrated sulfuric acid. With concentrated sulfuric acid, granulated table sugar ( sucrose ) performs a degradation reaction which changes its form to a black solid-liquid mixture . [ 1 ]
Because of the removal of the water molecule from the product, the term of convenience for such a process is "dehydration reaction" (also "condensation reaction" or "dehydration synthesis"). For example, milk sugar (lactose) is a disaccharide made by condensation of one molecule of each of the monosaccharides glucose and galactose, whereas the ...
After which it may undergo dehydration to give a unsaturated carbonyl compound, the aldol condensation product. The scheme shows a simple mechanism for the base-catalyzed aldol reaction of an aldehyde with itself. Base-catalyzed aldol reaction. Simple mechanism for base-catalyzed aldol reaction of an aldehyde with itself. Base-catalyzed dehydration
Shiina macrolactonization (or Shiina lactonization) is an organic chemical reaction that synthesizes cyclic compounds by using aromatic carboxylic acid anhydrides as dehydration condensation agents. In 1994, Prof. Isamu Shiina ( Tokyo University of Science , Japan) reported an acidic cyclization method using Lewis acid catalyst , [ 1 ] [ 2 ...
Another useful example is the one pot two-step synthesis of halfordinol, a parent compound for Rutaceae alkaloids. The initial steps follow the Fischer oxazole synthesis, although the acid-catalyzed cyclization occurs in two steps rather than one, which ensures the formation of the di-chloro intermediate , preventing formation of the regioisomer .
The Weiss–Cook reaction consists in the synthesis of cis-bicyclo[3.3.0]octane-3,7-dione employing an acetonedicarboxylic acid ester and a diacyl (1,2 ketone). The mechanism operates in the same way as the Knoevenagel condensation: [ 10 ]