(R,R)-butane-2,3-diol + NAD(+) = (R)-acetoin + H(+) + NADH Binds 1 Zn(2+) per subunit. Homotetramer (Ref.5). Interacts with BrxC (PubMed:33722570). Cells lacking this gene have no acetoin reductase/2,3-butanediol dehydrogenase activity. Belongs to the zinc-containing alcohol dehydrogenase family.