Acetal and ketal

The primary and secondary alcohol functionahties have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undergoes most of the typical alcohol reactions, such as reaction with a free acid, acyl hahde, or acid anhydride to form an ester reaction with alkaU metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial appHcation of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. [Pg.366]

Cyclic carbonates and cyclic boronates have also found considerable use as protective groups. In contrast to most acetals and ketals the carbonates are cleaved with strong base and sterically unencumbered boronates are readily cleaved by water. [Pg.119]

CYCLIC ACETALS AND KETALS 123 7. Acetonide (Isopropylidene Ketal) (Chart 3)... [Pg.123]

Formylbenzenesulfonate, 170 PROTECTION FOR CATECHOLS CYCLIC ACETALS AND KETALS... [Pg.144]

Catechols can be protected as diethers or diesters by methods that have been described to protect phenols. However, formation of cyclic acetals and ketals (e.g., methylenedioxy, acetonide, cyclohexylidenedioxy, diphenylmethylenedioxy derivatives) or cyclic esters (e.g., borates or carbonates) selectively protects the two adjacent hydroxyl groups in the presence of isolated phenol groups. [Pg.170]

Methyl-5-2-(methylthio)ethyl, 209 Cyclic Monothio Acetals and Ketals... [Pg.176]

Methods similar to those used to form and cleave dimethyl acetal and ketal derivatives can be used for other dialkyl acetals and ketals. [Pg.178]

Bis(2,2,2-trichloroethyl) Acetals and Ketals R2C(OCH2CCl3)2 (Chart 5) Formation ... [Pg.183]

Dibenzyl Acetals and Ketals R2C(OCH2Ph)2 Fonnation/Cleayage ... [Pg.184]