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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.
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 ]
The Evelyn effect is defined as the phenomena in which the product ratios in a chemical reaction change as the reaction proceeds. This phenomenon contradicts the fundamental principle in organic chemistry by reactions always go by the lowest energy pathway. The favored product should remain so throughout a reaction run at constant conditions.
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.
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 Robinson–Gabriel synthesis is an organic reaction in which a 2-acylamino-ketone reacts intramolecularly followed by a dehydration to give an oxazole.A cyclodehydrating agent is needed to catalyze the reaction [1] [2] [3] It is named after Sir Robert Robinson and Siegmund Gabriel who described the reaction in 1909 and 1910, respectively.
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone. The overall reaction equation is as follows (where the Rs can be H)
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 ]