Tips for finding stereogenic centers? and determining Enantiomers?

Question

Im having trouble finding stereogenic centers in large molecules, does anyone have any tips or any good websites that might help?

I'm also having trouble determining if large molecules are Emantiomers, I can see what it looks like in my mind as a mirror image but I have no idea if it is superposable or not. Anyone have any tips or good websites with maybe some practice problems on it and answers?

Thanks!

Answer 1

When is comes to stereochemistry there are no short cuts. You have to look at every carbon in the molecule! Period.

If the carbon has four different groups attached then it is going to be optically active. The only way you are going to be able to tell if is an enantiomer and is superimposable on it's mirror image without a lot of experience and practice is to build models.

That is how EVERY organic chemist started - don't think that there is some trick to it - there isn't. It's a hands on discovery of "Oh yeah - I get it!"

After you get it, you will start to be able to solve them in your head without the models - you'll impress yourself!

Answer 2

Most people who have trouble visualising 3-D molecules resort to molecular model kits. I may be stating the obvious, but in an organic molecule at least, the first thing to do is look at all the carbon centres individually. All those with 4 different substituents are chiral. Quaternary nitrogen centres and phosphines are the only other common main-group elements capable of forming chiral centres within a molecule.

Answer 3

A carbon it somewhat is in a hoop could have a stereogenic midsection, which ability it has 4 diverse communities related it to it, if going around the hoop you meet a distinction. For chlorocyclopropane, the carbon interior the question, has a H and Cl related to it, and then related to 2 carbons of the hoop. Going around on the two section, you do no longer meet a distinction. for this reason chlorocyclopropane would not have a stereogenic midsection.