Question: cis trans isomers are diastereomers?
Answer: Yes, cis and trans isomers are examples of diastereomers. ... But a diastereomer is any stereoisomer that is not an enantiomer. www.chemguide.co.uk. The cis and trans isomers of but-2-ene are isomers that are not mirror images of each other, so they are diastereomers.