Merdan
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I have question abt drawing the optical isomer/mirror images. In the case of E/Z isomerism to classify which one it is the priority is given to the atom or group of atoms with the highest atomic no. I have read from a book which says that when drawing optical isomer mirror images should use the same rule but this time from highest atomic no to lowest cloakwise and the mirror image should be opposite. But on some drawings in the book I saw that hydrogen with lowest atomic no was in between the second highest (NH2) and the highest (COOH) I have been drawing them in random positions so far. Would that get me marked down in an exam? I was told by one of friends its fine as long as its drawn as tetrahedral shape?
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gingerbreadman85
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Firstly, optical isomers are different to E/Z (geometric isomers).

Naming E/Z runs off the Cahn-Ingold-Prelog (CIP) rules, which very generally assign higher priority to heavier substituents. E is when the heavier groups either side of the C=C are on the opposite side as each other, Z is when they are on the same side.

Naming optical isomers it depends on whether you use R/S, which runs off the Cahn-Ingold-Prelog (CIP) rules again, or D/L, which is used for some biological systems, particularly amino acids and uses the "CORN" rule.
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Merdan
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(Original post by gingerbreadman85)
Firstly, optical isomers are different to E/Z (geometric isomers).

Naming E/Z runs off the Cahn-Ingold-Prelog (CIP) rules, which very generally assign higher priority to heavier substituents. E is when the heavier groups either side of the C=C are on the opposite side as each other, Z is when they are on the same side.

Naming optical isomers it depends on whether you use R/S, which runs off the Cahn-Ingold-Prelog (CIP) rules again, or D/L, which is used for some biological systems, particularly amino acids and uses the "CORN" rule.
Ok I get it now thanks. I have one more question through. Is 1,3-difluorocyclopentane a chiral compound? It has exactly 2 chiral carbon atoms. However its mirror image is superimposable. So a chiral compound means a compound that contains chiral carbon centre or both with chiral carbon and the compound that has non superimposable mirror image?
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gingerbreadman85
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1,3-difluorocyclopentane has geometric isomers (cis/trans) but I don't think it is chiral.
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Merdan
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Yes probably, I thought that carbon atom adjacent to fluorine atoms have 4 different group of atoms attached to it but I guess it has to have a proper mirror image to say that it exhibits optical isomerism..
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