steric strain vs. torsional strain

[1800RAW]

I was under the impression that torsional strain referred to repulsion of electrons in bonds as a result of an eclipsed conformation and steric strain referred to the difficulty in bringing 2 substituents close together due to their size. ie. torsional strain = electron repulsion and steric strain = strain due to bulkiness of subs. But, thinking about this, I have no idea where I came up with these distinctions or if theyre correct. anyone wanna chime in?

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[Cool Beans]

You've got them both right on!

 

[Kahr]

http://www.chem.ucla.edu/harding/IGOC/S/steric_strain.html
(with molecular examples)

Also has links to angle and ring strain.

 

[1800RAW]

gotcha, thanks guys

 

[Lane138]

Also, there is a 0.1 percent chance they'll ask you this on the orgo section. The orgo section was almost all reactions, with one or two procedural questions thrown in there (filtration, IR/NMR Spectrophotometry) but it's really rare that they will ask you a concept question like that. Focus on reactions and catalysts!

 

[Kahr]

Also, there is a 0.1 percent chance they'll ask you this on the orgo section. The orgo section was almost all reactions, with one or two procedural questions thrown in there (filtration, IR/NMR Spectrophotometry) but it's really rare that they will ask you a concept question like that. Focus on reactions and catalysts!

Ahh so this is why everyone gives so much acclaim to the Destroyer road maps.

Because of the ridiculous scoring method they use though, I'm trying to cover everything, seems you can't afford to miss anything if you want a score higher than 21. 🙁

 

[invictusx]

Ahh so this is why everyone gives so much acclaim to the Destroyer road maps.

Because of the ridiculous scoring method they use though, I'm trying to cover everything, seems you can't afford to miss anything if you want a score higher than 21. 🙁

Nah!!!! Not true! If you can fully understand WHY the reactions occur, then you're golden. There's no such thing as memorizing reactions. Memorizing and regurgitating what you remember is the hard part.

If you can understand the concepts and the arrow formalisms (or mechanisms if you would like), then you're SET for at LEAST a 21.

 

[invictusx]

Also, there is a 0.1 percent chance they'll ask you this on the orgo section. The orgo section was almost all reactions, with one or two procedural questions thrown in there (filtration, IR/NMR Spectrophotometry) but it's really rare that they will ask you a concept question like that. Focus on reactions and catalysts!

I agree! CATALYSTS! Know the REAGENTS! KMnO4... wolf-kishner, wittig, and the usual substitution and elimination reactions.

Also, KNOW o/p/m and WHY they direct. What increases acidity? What decreases acidity? Why? Know it!

I didn't get any procedural questions, though you should look over sugars because it may be on it. Know mutarotation (H2O hydrolysis), epimerization, and know how to determine reducing/nonreducing sugars.

 

[1800RAW]

yeah it probably wont come up but I just wanna cover my bases. Like Kahr said, your score is really sensitive in the 25+ range so I wanna try and get as much exposure as I can to everything