- #1
Harrisonized
- 208
- 0
I don't understand why it's chiral. It's not like any of the phenyl rings are stuck in a single resonance structure.
I don't understand why it's chiral. It's not like any of the phenyl
- Thread starter Harrisonized
- Start date
-
- Tags
- Chiral
In summary, hexaphenylbenzene is a molecule that is chiral due to the arrangement of its phenyl groups in a propeller shape. This can be seen in its crystal structure where the phenyl groups are all angled the same way, making the two structures non-superimposable. However, in the gas phase, hexaphenylbenzene is not chiral due to the ability of the phenyl groups to freely oscillate between left- and right-handed conformations. The reason for the molecule's preference for one chiral conformation over the other is still unknown, but it is suggested that crystallization may play a role in selecting one conformation over the other. This is a classical case of
- #2
aroc91
- 183
- 5
http://en.wikipedia.org/wiki/Hexaphenylbenzene
Take a look at the crystal structure. The phenyl groups are all angled the same way. If you turned them all the other way, the two structures would not be superimposable. The same concept is seen in left- and right-handed propellers (see picture).
Attachments
- #3
Borek
Mentor
- 28,951
- 4,245
aroc91 said:
I think you have missed the point - phenyls can oscillate freely in some range of angles, so they are not chiral in a stable way, they can easily switch between right- and left- handed propeller shape. Questions is - what makes them "select" one of the chiral conformations.
According to the information on the wiki page hexaphenylbenzene is not chiral in the gas phase. My bet is that the propeller shaped molecule has lower volume and better contact surface and crystallizes easier - and once it starts to crystallize it just attracts other molecules in exactly the same conformation. But that's just a guess.
- #4
DrDu
Science Advisor
- 6,357
- 974
Classical case of spontaneous symmetry breaking. Crystallization of SiO2 melts leads also either to D or L quartz.
- #5
LudusRex
- 1,433
- 0
Chirality refers to the property of a molecule that cannot be superimposed on its mirror image. It is determined by the arrangement of atoms and bonds in a molecule, rather than the presence of specific functional groups such as phenyl rings. While phenyl rings can contribute to the overall chirality of a molecule, they are not the sole determining factor.
In order for a molecule to be chiral, it must have at least one chiral center, which is a carbon atom bonded to four different groups. This means that the molecule has two different versions, or enantiomers, that cannot be superimposed on each other. This is similar to how your left and right hands are mirror images of each other, but cannot be perfectly overlapped.
Therefore, it is possible for a molecule to be chiral even if it does not contain phenyl rings. The specific arrangement of atoms and bonds in the molecule will determine its chirality. It is important to consider all aspects of a molecule's structure when determining its chirality, rather than focusing solely on the presence of certain functional groups.
1. Why is chirality important in science?
Chirality is important in science because it affects the properties and interactions of molecules. It can determine how a molecule reacts with other molecules and how it interacts with biological systems. In pharmaceuticals, for example, chirality can determine the effectiveness and safety of a drug.
2. What makes a molecule chiral?
A molecule is chiral if it has a non-superimposable mirror image. This means that the molecule cannot be rotated or flipped in a way that it exactly matches its mirror image. Chirality is based on the arrangement of atoms in a molecule and can be determined by its symmetry or lack thereof.
3. How can I determine if a molecule is chiral?
One way to determine if a molecule is chiral is by looking at its three-dimensional structure. If it has a chiral center, or a carbon atom with four different groups attached, it is chiral. Another method is using a polarimeter, which measures the rotation of polarized light by a chiral molecule.
4. What are the implications of chirality in everyday life?
Chirality has a significant impact on our daily lives. Many natural and synthetic products, such as sugars, amino acids, and drugs, are chiral and have different properties and effects depending on their chirality. Chirality is also important in the food industry, as it can affect taste and smell.
5. Can molecules with the same chemical formula be chiral?
Yes, molecules with the same chemical formula can be chiral. This is because chirality is determined by the spatial arrangement of atoms, not just the number and type of atoms. This is why two molecules with the same chemical formula but different arrangements, such as L-alanine and D-alanine, can have different properties and effects.
Similar threads
-
Biology and Chemistry Homework Help
-
Chemistry
-
High Energy, Nuclear, Particle Physics
-
Biology and Chemistry Homework Help
-
Quantum Physics