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I wonder why the number of chiral centres in sorrbital is 4? Why isn't it 2? Is it because the H-C-OH bond cannot be rotated? Otherwise isn't the two chiral centres above identical to the 2 at the bottom?
Uhhm, I don't understand what you are saying.Are you saying that the whole chain has to rotate and not just a part of it?Continuity said:If the atoms on the carbons at the end are switched around, the carbon will be able to rotate to bring back the orignial configuration. If the other carbons have the atoms they are attached to switched around, they will not be able to rotate any which way to find the original configuration. Does that sound about right?
If so, shouldn't there be only two chiral centres? Why 4? Since if they can rotate aren't the top 2 same as the bottom 2?Continuity said:each of the carbon atoms can rotate individually. If you rotate the carbon at either end you will see that all the different configurations are equivalent. That is, if you switch the OH with one of the H's, it will look different but it will be the same molecule because the carbon atom can just rotate back. Don't forget that the bonds can always rotate and they are constantly rotating when there is any energy present at all.
Ok thanks. The third and fourth carbon from the top are also chiral centres right? Even if you rotate them, their numberings just change, that's all.Continuity said:Ok I think I understand your question. I think you're forgetting about the tetrahedral configuration of each of the carbons. The third carbon from the top can rotate but that does not mean it becomes equivalent to the ones around it. Remember that in this representation of the molecule the atoms that come out to the sides are actually intended to be coming out of the paper towards you. If it rotates around it will be going into the paper away from you. Get out a plastic model kit or visualize the tetrahedral structures in your head.
Ok, thanks.Continuity said:yeah I'm pretty sure there's no symmetry between the third and fourth carbon. Even though they have the same groups attached to them, they are attached in a different configuration.
A chiral centre is a carbon atom that is bonded to four different groups. This results in the molecule having non-superimposable mirror images, known as enantiomers.
Sorbitol has six chiral centres, as it is a six-carbon molecule with each carbon bonded to four different groups.
The presence of chiral centres in sorbitol makes it a chiral molecule, meaning it can exist in two different enantiomeric forms. This can have implications in terms of its biological activity and interactions with other molecules.
Chiral centres in sorbitol can be determined by looking at the arrangement of the atoms around each carbon atom and identifying if they are bonded to four different groups. This can also be confirmed through experimental techniques such as X-ray crystallography or NMR spectroscopy.
No, sorbitol can only have six chiral centres because it is a six-carbon molecule. The number of chiral centres in a molecule is equal to the number of carbon atoms, as each carbon can only have four bonds and therefore only four different groups attached to it.