Search results
Results from the WOW.Com Content Network
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.
Acid catalyzed acetal formation from the corresponding hemiacetal. Acetals, as already pointed out, are stable tetrahedral intermediates so they can be used as protective groups in organic synthesis. Acetals are stable under basic conditions, so they can be used to protect ketones from a base. The acetal group is hydrolyzed under acidic conditions.
Used in a more general sense, the term X,Y-acetal also refers to any functional group that consists of a carbon bearing two heteroatoms X and Y. For example, N , O -acetal refers to compounds of type R 1 R 2 C(OR)(NR' 2 ) (R,R' ≠ H) also known as a hemiaminal ether or Aminal , a.k.a. aminoacetal.
Because of the greater stability of thioacetals, the equilibirum lies on the side of the acetal. In contradistinction to the O,O‑acetal case, it is not needed to remove water from the reaction mixture in order to shift the equilibrium. [65] S,O-Acetals are hydrolyzed a factor of 10,000 times faster than the corresponding S,S-acetals. Their ...
Cyclic acetals (8 C) H. Hemiacetals (1 C, 2 P) K. Ketals (1 C, 11 P) Pages in category "Acetals" The following 17 pages are in this category, out of 17 total.
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. D-ribose in itself is a hemiacetal and in equilibrium with the pyranose 3. In aqueous solution ribose is 75% pyranose and 25% furanose and a different acetal 4 is formed.
Main page; Contents; Current events; Random article; About Wikipedia; Contact us
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions.The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition.