Organic and Inorganic Chemistry Lesson of the Day – DO NOT USE THE PREFIXES (d-) and (l-) TO CLASSIFY ENANTIOMERS
September 9, 2014 Leave a comment
Some people use d- and l- instead of (+) and (-), respectively. I strongly discourage this, because there is an old system of classifying stereogenic centres that uses the prefixes D- and L-, and the obvious similarity between the prefixes of the 2 systems causes much confusion.
This old system classifies stereogenic centres based on the similarities of their configurations to the 2 enantiomers of glyceraldehyde. It is confusing, non-intuitive, and outdated, so I will not discuss its rationale or details on my blog. (If you are interested, here is a good explanation from the University of Maine’s chemistry department.)
Also, note that D- and L- classify stereogenic centres, whereas d- and l- classify enantiomers – this just adds more confusion.
- DO NOT use d- and l- to classify enantiomers; use (+) and (-) instead.
- DO NOT use D- and L- to classify stereogenic centres; use the Cahn-Ingold-Prelog priority rules (R/S) instead.