in acetonitrile reflux;

n-butyric anhydride in further solvent(s) (N2); refluxed at ca 100°C, 150 Torr, 3 h;; concd., kept at -20°C overnight, ppt. filtered off, washed with cold pentane, dissolved in hot benzene, filtered, concd., cooled, ppt. washed with cold pentane, heated in vac. over NaOH overnight; elem. anal.;;

in neat (no solvent) Rh acetate was refluxed in soln. of butyric acid and butyric anhydride at 100°C (P=150 mmHg) for 3 h under N2; solvent was distilled off, cooled at -20°C overnight, filtered, rinsed with cold pentane, solid extd. with hot benzene, filtered, filtrate was concd., filtered, rinsed with cold pentane, dried in vac. for several h at 100°C; elem. anal.;

in ethanol saturated soln.;