Use of Acetic Acid as an Acetylating Agent of Alcohols and PhenolsCatalyzed by Recyclable Solid Acids

LUIS R. PIZZIO; GUSTAVO P. ROMANELLI; MIRTA N. BLANCO

Acetic Acids: Chemical Properties, Production and Applications

Nova Science Publishers, Inc

Lugar: Nueva York; Año: 2013; p. 99 - 133

Acetic acid is one of the simplest carboxylic acid, and an important chemical andindustrial chemical for different uses. It is employed, for example, in the production ofcellulose and, in the food, diluted acetic acid acts as an acidity and as a condiment. Theglobal demand of acetic acid is very important, around 6.5 million tonnes per year.The acetylation reaction of organic compounds is one of the most frequently usedtransformations in organic synthesis. Among the various protected groups used for thehydroxyl function, the acetyl group is the most convenient in view of its easyintroduction, being stable to the acidic reaction condition and also easily removable bymild alkaline hydrolysis. The most common and inexpensive reagent used to perform theacetylation is the acetic anhydride however, from an environmental point of view, a muchconvenient method for performing the acetylation is the use of acetic acid as acetylatingagent, because only water is produced as by product, and it is a relative cheaper route forindustrial purposes when compared to anhydrides or acid chlorides.In this chapter we reviewed the performance of different recyclable solid acidssynthesized in our laboratory as catalysts for the use of acetic acid as acetylating agent: 1)alcohols and phenols acetylation using borated zirconia; 2) alcohols and phenolsacetylation using borated zirconia modified with ammonium metatungstate; 3) isoamylalcohol acetylation using tungstophosphoric acid supported on zirconia; and 4) isoamylalcohol acetylation using partially substituted Cs and K salts of tungstophosphoric acid.The alcohols and phenols acetylation with the borated zirconia-based catalysts gavevery good yields to the desired products with very high selectivity, though the alcoholand phenol structure is a key in the yield to the acetylation product. The zirconiasupportedtungstophosphoric acid prepared by the incipient wetness impregnation led toobtain isoamyl acetate with high activity and selectivity, and similar results wereobtained using the Cs and K tungstophosphates, observing a correlation with the acidicproperties of the catalysts.