# Difference between L&D and S&R in naming [duplicate]

What is the difference between L&D and S&R? Can we say S-alanine instead of L-alanine?

• Read stereochemistry in any standard textbook of organic chemistry. – Chakravarthy Kalyan Feb 17 '18 at 13:01

When you are distinguishing L-alanine from D-alanine, you only know that the $\ce{-NH2}$ group on the chiral carbon of alanine is on the left hand side, while in D it is on the right hand side relative in a Fischer projection. There you can't be specific about other functional groups (like $\ce{-COOH}$ or $\ce{-H}$) position.