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Ethylene glycol protects a ketone (as an acetal) during an ester reduction, vs. unprotected reduction to a diol. A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction.
Generic structure of acetals. In organic chemistry, an acetal is a functional group with the connectivity R 2 C(OR') 2. Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments not hydrogen. The two R' groups can be equivalent to each ...
In aqueous solution ribose is 75% pyranose and 25% furanose and a different acetal 4 is formed. Selective acetalization of carbohydrate and formation of acetals possessing atypical properties is achieved by using arylsulfonyl acetals. An example of arylsulfonyl acetals as carbohydrate-protective groups are phenylsulfonylethylidene acetals.
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.
In organic chemistry, an acetonide is the functional group composed of the cyclic ketal of a diol with acetone. The more systematic name for this structure is an isopropylidene ketal. Acetonide is a common protecting group for 1,2- and 1,3-diols. [1] The protecting group can be removed by hydrolysis of the ketal using dilute aqueous acid.
Structure of the benzylidene acetal of glucose. In organic chemistry, a benzylidene acetal is the functional group with the structural formula C 6 H 5 CH(OR) 2 (R = alkyl, aryl). Benzylidene acetals are used as protecting groups in glycochemistry.
Dioxolane is a heterocyclic acetal with the chemical formula (CH 2) 2 O 2 CH 2. It is related to tetrahydrofuran (THF) by replacement of the methylene group (CH 2) at the 2-position with an oxygen atom. The corresponding saturated 6-membered C 4 O 2 rings are called dioxanes.
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).