Processes for preparing a C.sub.5 aldehyde and propene are disclosed, the processes comprising: (a) providing a feedstream, the feedstream comprising butane, 1-butene, 2-butene and 1,3-butadiene, the 1,3-butadiene present in the feedstream in an amount up to 1000 ppm; (b) contacting the feedstream with hydrogen and carbon monoxide in the presence of a hydroformylation catalyst to form a 2-butene-rich butane stream and a C.sub.5 aldehyde; (c) separating the 2-butene-rich butane stream and the C.sub.5 aldehyde; and (d) contacting the 2-butene-rich butane stream with ethene in the presence of a metathesis catalyst to form a propene-containing hydrocarbon stream.