regioisomers

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i don't believe they are equivalent terms. constitutional isomers have the same molecular formula but different connectivity (they have a different "constitution"). in contrast, configurational isomers have the same connectivity but the atoms are arranged differently in space (configurational is a sub-class of stereoisomers that is not easily interconverted)

hope that helps
 
ah...i misread your question. in that case, i'm pretty sure that the two terms fall under regioisomers. does anyone else know for sure?
 
i think i have it posted correctly. on the other hand, conformation isomers are compounds that have the same molecular formula and connectivity but differ by rotation around a single bond--that's where conformational and configurational differ.

the way i remember conformational is thinking back to the newman projections and seeing gauche/staggered/anti. conformational isomers are the exact same molecule (just rotated around sigma bond differently) where configurational can't be superimposable
 
i think i have it posted correctly. on the other hand, conformation isomers are compounds that have the same molecular formula and connectivity but differ by rotation around a single bond--that's where conformational and configurational differ.

the way i remember conformational is thinking back to the newman projections and seeing gauche/staggered/anti. conformational isomers are the exact same molecule (just rotated around sigma bond differently) where configurational can't be superimposable

alright, thats cool. so, are you saying then that constitutional and configurational are two distinct terms fall under the umbrella regioisomers? I'm actually thinking that configurational is different than regio. I know that regioselective reactions prefer products with substituents on certain carbons--constitutional isomers. stereoselective prefers a specific orientation of substituents on the same carbon--configurational.
 
yeah, i think what you're saying is correct. here's a definition i looked up for regioisomers: a type of structural isomer that result from a reaction where two possible orientations of the starting material give two different structural isomers as products

according to that definition, i think you're right in saying that configurational is different from regio. i've also heard that configurational is essentially the same thing as stereoisomers because isomers that differ by configuration at a chiral center are stereoisomers

it seems like these terms are splitting hairs sometimes
 
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