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A pseudoacid in 
The position of equilibrium in oxocarboxylic acids, toward the open form or the cyclic (pseuodacid) form, is influenced by a number of factors. In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...
is a cyclic oxocarboxylic acid. Most commonly, these form from aldehyde
In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...
and keto carboxylic acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...
s, and the cyclic forms are furanoid (5-membered ring with oxygen) or pyranoid (6-membered ring with oxygen). The original pseudoacid to be described as such (using the German ) was levulinic acid (4-oxopentanoic acid).Bredt, J., 1886. Über Acetyllävulinsäure und die Constitution der γ-Ketonsäuren. Annalen der chemie 236, 225–240.
Unlike the parent (open-form) oxocarboxylic acid, the pseudoacid has a chiral center.
The position of equilibrium in oxocarboxylic acids, toward the open form or the cyclic (pseuodacid) form, is influenced by a number of factors. In aliphatic
In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated (in which all ...
4- and 5-oxocarboxylic acids, intervening substituents assists in ring closure. Alkenes
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins.
The Internationa ...
with the interacting groups substituted ''cis'' to each other also assists in ring closure. Aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...
systems with the interacting groups substituted ''ortho'' to each other assists in ring closure. Other factors such as the gem-dialkyl effect ( Thorpe–Ingold effect), electronic influences, and steric compression can also influence the open-cyclic equilibrium.
Like carboxylic acids, pseudoacids have "pseudoacyl" derivatives. These include pseudoacyl halides, pseudoesters, endocyclic and exocyclic-N pseudoamides, and pseudoanhydrides. Like aldehyde
In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...
s and ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...
s, pseudoacids have "pseudocarbonyl" derivatives also.
References
{{reflist Organic acids Functional groups