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In organic chemistry, a hemiacetal is a functional group the general formula R 1 R 2 C(OH)OR, where R 1, R 2 is a hydrogen atom or an organic substituent. They generally result from the nucleophilic addition of an alcohol (a compound with at least one hydroxy group ) to an aldehyde ( R−CH=O ) or a ketone ( R 2 C=O ) under acidic conditions.
2-Hydroxytetrahydrothiophene is a rare example of a hemithioacetal that can be isolated. Hemithioacetals ordinarily readily dissociate into thiol and aldehyde, however, some have been isolated. In general, these isolable hemithioacetals are cyclic, which disfavors dissociation, and can often be further stabilized by the presence of acid. [ 2 ]
In coordination chemistry and catalysis hemilability (hemi - half, lability - a susceptibility to change) refers to a property of many polydentate ligands which contain at least two electronically different coordinating groups, such as hard and soft donors.
With acetone or 2,2-dimethoxypropane as the acetalisation reagent the reaction is under thermodynamic reaction control and results in the pentose 2. The latter reagent in itself is an acetal and therefore the reaction is actually a cross-acetalisation. Kinetic reaction control results from 2-methoxypropene as the reagent.
An oligosaccharide has both a reducing and a non-reducing end. The reducing end of an oligosaccharide is the monosaccharide residue with hemiacetal functionality, thereby capable of reducing the Tollens’ reagent, while the non-reducing end is the monosaccharide residue in acetal form, thus incapable of reducing the Tollens’ reagent. [2]
In organic chemistry, an acetyl group is a functional group denoted by the chemical formula −COCH 3 and the structure −C(=O)−CH 3.It is sometimes represented by the symbol Ac [5] [6] (not to be confused with the element actinium).
General structure of a monothioacetal General structure of a dithioacetal. In organosulfur chemistry, thioacetals are the sulfur analogues of acetals (R−CH(−OR) 2).There are two classes: the less-common monothioacetals, with the formula R−CH(−OR')−SR", and the dithioacetals, with the formula R−CH(−SR') 2 (symmetric dithioacetals) or R−CH(−SR')−SR" (asymmetric dithioacetals).
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. [2] Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.