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Okay, here's my understanding of chirality now. Correct me if I'm wrong:
(+) = dextrorotatory = d (small d, not capital d) = rotates light CW (right)
(-) = levorotatory = l = rotates light CCW (left)
R = rectus = when assigned priorities, arrow drawn fr 1 to 3 is CW (right)
S = sinister = when assigned priorities, arrow drawn fr 1 to 3 is CCW (left)
So +/- (or d,l) designate RELATIVE configuration, because they distinguish between the different ways chiral compounds rotate light. But since a compound could be R and (+) or R and (-), knowing which way a compound rotates light doesn't tell us anything about its actual structure.
On the other hand, ABSOLUTE configuration gives us info about a molecule's actual structure.
Is that understanding correct? I'm confused about whether D/L (capital) give info on absolute configuration or relative configuration ?
My guess is that it gives relative configuration, since D-series sugars could be either (+) or (-). The one exception is glyceraldehyde, for which we know (+)-glyceraldehyde is D glyceraldehyde, so there's a correspondence there.
But then, what is R/S? Is that relative configuration or absolute configuration ? What gives info on absolute configuration? Also, I've seen problems where a reaction involves an inversion of configuration going from reactant to product, BUT, the reactant and product have the same designation (e.g. "R"). So... doesn't that mean R/S give relative configuration ?
I'm confused.
(+) = dextrorotatory = d (small d, not capital d) = rotates light CW (right)
(-) = levorotatory = l = rotates light CCW (left)
R = rectus = when assigned priorities, arrow drawn fr 1 to 3 is CW (right)
S = sinister = when assigned priorities, arrow drawn fr 1 to 3 is CCW (left)
So +/- (or d,l) designate RELATIVE configuration, because they distinguish between the different ways chiral compounds rotate light. But since a compound could be R and (+) or R and (-), knowing which way a compound rotates light doesn't tell us anything about its actual structure.
On the other hand, ABSOLUTE configuration gives us info about a molecule's actual structure.
Is that understanding correct? I'm confused about whether D/L (capital) give info on absolute configuration or relative configuration ?
My guess is that it gives relative configuration, since D-series sugars could be either (+) or (-). The one exception is glyceraldehyde, for which we know (+)-glyceraldehyde is D glyceraldehyde, so there's a correspondence there.
But then, what is R/S? Is that relative configuration or absolute configuration ? What gives info on absolute configuration? Also, I've seen problems where a reaction involves an inversion of configuration going from reactant to product, BUT, the reactant and product have the same designation (e.g. "R"). So... doesn't that mean R/S give relative configuration ?
I'm confused.