Organic Chemistry › Stereochemistry
Which statement is not true regarding stereoisomers?
Corresponding stereoisomers have the same biological properties
Corresponding stereoisomers have the similar physical properties except for the rotation of light
Corresponding stereoisomers have the same molecular formulas
Diastereomers are easier to separate than enantiomers
Corresponding stereoisomers differ in biological properties. The inversion of just one stereocenter on a large, complex molecule can alter the biological properties of the entire molecule. All other statements are true.
How many configurational stereoisomers exist for this structure?
3
4
2
1
There are two tetrahedral asymmetrical stereocenters in this molecule (the carbon atoms attached to each of the chlorine atoms). Thus, the combinations of R and S include RR, RS, SR, and SS. Note the plane of symmetry in the molecule; RS and SR are the same molecule (meso compounds). Thus, there are three distinct configurational stereoisomers of this compound.
Which of these molecules is a meso compound?
III only
I only
II only
IV only
II and III
A molecule is meso if it contains at least two stereocenters, but is rendered optically inactive by internal structural symmetry. In other words, a meso compound may be split in half in some way such that portions on either side of an imaginary line are mirror images. Note: The absolute configurations of a meso compound with two stereocenters are opposite (R/S). The internal symmetry that makes molecule III a meso compound is best conveyed through a Haworth projection:
Which statement is not true regarding stereoisomers?
Corresponding stereoisomers have the same biological properties
Corresponding stereoisomers have the similar physical properties except for the rotation of light
Corresponding stereoisomers have the same molecular formulas
Diastereomers are easier to separate than enantiomers
Corresponding stereoisomers differ in biological properties. The inversion of just one stereocenter on a large, complex molecule can alter the biological properties of the entire molecule. All other statements are true.
How many configurational stereoisomers exist for this structure?
3
4
2
1
There are two tetrahedral asymmetrical stereocenters in this molecule (the carbon atoms attached to each of the chlorine atoms). Thus, the combinations of R and S include RR, RS, SR, and SS. Note the plane of symmetry in the molecule; RS and SR are the same molecule (meso compounds). Thus, there are three distinct configurational stereoisomers of this compound.
Which of these molecules is a meso compound?
III only
I only
II only
IV only
II and III
A molecule is meso if it contains at least two stereocenters, but is rendered optically inactive by internal structural symmetry. In other words, a meso compound may be split in half in some way such that portions on either side of an imaginary line are mirror images. Note: The absolute configurations of a meso compound with two stereocenters are opposite (R/S). The internal symmetry that makes molecule III a meso compound is best conveyed through a Haworth projection:
How many configurational stereoisomers exist for this structure?
3
4
2
1
There are two tetrahedral asymmetrical stereocenters in this molecule (the carbon atoms attached to each of the chlorine atoms). Thus, the combinations of R and S include RR, RS, SR, and SS. Note the plane of symmetry in the molecule; RS and SR are the same molecule (meso compounds). Thus, there are three distinct configurational stereoisomers of this compound.
Which of these molecules is a meso compound?
III only
I only
II only
IV only
II and III
A molecule is meso if it contains at least two stereocenters, but is rendered optically inactive by internal structural symmetry. In other words, a meso compound may be split in half in some way such that portions on either side of an imaginary line are mirror images. Note: The absolute configurations of a meso compound with two stereocenters are opposite (R/S). The internal symmetry that makes molecule III a meso compound is best conveyed through a Haworth projection:
Which statement is not true regarding stereoisomers?
Corresponding stereoisomers have the same biological properties
Corresponding stereoisomers have the similar physical properties except for the rotation of light
Corresponding stereoisomers have the same molecular formulas
Diastereomers are easier to separate than enantiomers
Corresponding stereoisomers differ in biological properties. The inversion of just one stereocenter on a large, complex molecule can alter the biological properties of the entire molecule. All other statements are true.
If a given molecule has 5 chiral centers, what is the maximum number of stereoisomers that exist for the molecule.
If a molecule has n sterocenters, it has up to possible steroisomers. Thus, the given molecule has
or
possible stereoisomers. Keep in mind the key word here is maximum, where the molecule may have less than 32 steroisomers, for instance when discussing meso compounds.