Orgo - Q&A

[The Law]

So it's been ages since I've taken orgo, maybe a pro can help Law get his skill back! (He used to have it, I swear!). He also doesn't usually refer to himself in third person, but I digress...

 

So, I just tried an EK question and it asked "(-)- Nictoine is shown below. At which of the following carbons does the structure of +-nicotine differ from --nicotine?"

 

So I thought to myself, it has to be at the chiral carbons since that's what would be different for them to rotate light + or -.

 

The book claims 4 is the only chiral carbon, but I think both 4 and 5 are chiral... Obviously 4 is chiral, it's connected to a Nitrogen, Carbon, Hydrogen, and another ring.

 

Now, 5, it's attached to carbon 4 (another ring), a hydrogen, and 2 more carbons... however, can't those 2 carbons each be considered different from each other since they're not symmetrical? My orgo knowledge is failing, but I could have sworn that when you're in a ring you don't just look at the immediate atom, but the ring as a whole... or am I wrong?

 

 

Here's my attempt to draw it:

[ChexMix]

Nicotine has one chiral centre, this confused me at the beginning too.

The chiral carbon is the one that is labeled 4 in your diagram. Carbon 5 is not chiral because it is part of an aromatic ring. The ring has double bond character. Therefore, carbon 5 would be double bonded to one carbon in the ring, single bonded to the other carbon in the ring, and single bonded to carbon 4.

Here is the diagram from wiki

 

http://en.wikipedia.org/wiki/File:Nicotine-2D-skeletal.png

 

Hope that helps!

[The Law]

Ah, what dumb mistake! Yes, it has a double bond. Stupid circle threw me off!! Thanks for your help.

[The Law]

I've got a few more questions that I'll probably post when I get some time.

[AdamP]

 

oh man that deserves a billion lols.

[The Law]

oh man that deserves a billion lols.

 

lmao, as you can see, drawing is not my forte haha.