b) The structures are identical since rotation of the second structure around the horizontal axis indicated generates the first structure.
c) The structures are not identical The structures are isomers of one another (they have the same molecular formula) The structures are stereoisomers of one another (they have the same connectivity Cl-CH=CH-Cl) The structures are not enantiomers of one another (they are not mirror images of one another)
Therefore, since the structures are stereoisomers but are not enantiomers, they must be diastereomers.
d) The structures are not identical The structures are isomers of one another (they have the same molecular formula) The structures have different connectivities (both chlorine atoms are attached to the same carbon in the left hand structure, but they are attached to different carbon atoms in the right hand structure)
Therefore, the structures are constitutional isomers.
e) The structures are identical since rotation of the second structure around an axis perpendicular to the computer screen generates the first structure.
f) The structures are identical since rotation of the second structure around an axis perpendicular to the computer screen generates the first structure.
g) The structures are identical since rotation of the second structure around an axis perpendicular to the computer screen generates the first structure.
(If you thought the two structures were enatiomers, then you have fallen into the trap of thinking that any two structures which contain a stereocentre and are drawn differently are enantiomers.)
h) The structures are not identical The structures are isomers of one another (they have the same molecular formula) The structures are stereoisomers of one another (they have the same connectivity; a carbon atom attached to a hydrogen, chlorine, methyl, and methoxy group) The structures are mirror images of one another (see diagram below)
Therefore, the structures are enantiomers
back to CHAPTER 1 back to answers to problems back to STEREOCHEMISTRY home page