Copper-catalyzed acetoxylation (hydroacetoxylation) of butadiene: A comparison with the hydrocyanation reaction

Copper bromide catalyzes the monoaddition of acetic acid to butadiene (and less effectively to substituted conjugated dienes) yielding mixtures of acetoxybutenes. The presence of LiBr as additive is necessary for efficient catalytic activity. The efficiency of the catalyst can be further improved by adding halogenated additives and strong carboxylic acids. In contrast, complexing ligands (e.g., PPh3 polyethers) inhibit the catalyst activity. When compared with the copper-catalyzed hydrocyanation of butadiene, the regioselectivity of the acetoxylation is low, easy interconversion of the linear and branched isomeric products being achieved under the reaction conditions, the 1,4-isomer corresponding to the thermodynamically controlled one. © 1986.