Used as a protecting group reagent in organic synthesis, particularly for alcohols and diols. It reacts selectively with hydroxyl groups under mild acidic conditions to form cyclic acetals, which are stable to bases and nucleophiles. This protection allows multi-step synthesis to proceed without interference from reactive OH groups. The ethoxy substituent enhances solubility and influences the kinetics of acetal formation and deprotection. Deprotection is achieved under mild aqueous acidic conditions, regenerating the original alcohol without side reactions. Commonly employed in carbohydrate chemistry and natural product synthesis where selective protection is crucial.