Posted by SLS on July 23, 2004, at 18:42:40
In reply to Re: whats the diff. between adderall and dexedrine » Shawn. T., posted by chemist on July 23, 2004, at 18:21:57
> hello there, chemist here...actually, a d- or l- designation tells us that there are two compounds that are chiral and interact with polarized light in different ways (rotation relative to laboratory axis): this does indicate that the compounds in question are not achiral and are, in fact, enantiomers, as you note.but we need not go directly to optics in order to answer the question: an enantiomer is a stereoisomer with the specific condition that the mirror images of the compounds are non-superposable. the d- and l- forms of amphetamine are, of course, chiral at the alpha carbon and cannot be superposed. hence, we can work with the simpler definition of enantiomer without getting into optics or the nomenclature of fischer or cahn et al., the former being troublesome and the latter, in my opinion, being of more utility. all the best, chemist
Will enantiomers differing at only one chiral center always rotate polarized light in opposite directions?When do scientists decide to use the d,l optical nomenclature as opposed to the r,s configuration designation, and why? Is it a matter of not knowing the molecular structure?
- Scott
poster:SLS
thread:369314
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