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/sci/ - Science & Math

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6075668 No.6075668 [Reply] [Original]

Hey guise....
Just was wondering if you can help me out quick.
What if any are the resonance structures for the molecule (pic related)?

I am not seeing any as there are only two sp2 orbitals that could possible accept electrons but wont work due to there then being to many electrons....

Thanks guise.

Not asking for homework help, i am just doing some practice problems from the internet and this one came up....Organic Chemistry.

>> No.6075682
File: 77 KB, 780x585, 1379781033727.jpg [View same] [iqdb] [saucenao] [google]
6075682

no, no resonant structures

>> No.6075684

>>6075668

There's no resonance structures for that molecule. If you cut any of the sigma bonds, you'll just be breaking the molecule apart. If you move any of the pi bonds around, you'll be messing with the octet rule.

>> No.6075701

push some electrons from the oxygen atom to make a double bond with C-1. Push the electrons from the current double bond onto C-2. Negative charge on C-2. Positive charge on oxygen.

There's your one alternative resonance structure.

>> No.6075704
File: 676 KB, 2920x1616, blade_runner___rachel_by_maxhitman-d39c7r5.jpg [View same] [iqdb] [saucenao] [google]
6075704

>If you cut any of the sigma bonds, you'll just be breaking the molecule apart

Not the OP but I'm curious why you would mention cutting sigma bonds when talking about resonance

>> No.6075708

Thanks guise. Appreciate it

>> No.6075710
File: 15 KB, 306x295, 1272781844634.jpg [View same] [iqdb] [saucenao] [google]
6075710

>>6075701
except that such a resonant structure is very unstable and doesn't actually happen

>> No.6075711

>>6075704

Resonance is about moving electrons around. The molecule is rather basic, so instead of just saying 'no', I thought I'd just go into a little bit more explanation... Even if not moving sigma bonds is pretty basic.

>>6075701

Making a double bond with O and C-1 would give C 5 bonds. When dealing with resonance structures like this, you don't want to give Carbon more than 4 bonds...

>> No.6075728

>>6075710
>it's not stable

Doesn't matter if it's stable, it's a resonance structure.

>it doesn't happen

It very much happens and is a very important, and very basic reaction intermediate for carbon-carbon bond formation.

>>6075711
>5 bonds to carbon

That's why you take two of the electrons in that little double bond right there, and stick them on C-2.

4 bonds to carbon.

>> No.6075729
File: 20 KB, 1152x648, 1381208886077.png [View same] [iqdb] [saucenao] [google]
6075729

>>6075711
Pretty sure he meant c3 instead of c1, as in my picture, but like I said it's unstable and won't contribute

>> No.6075731

>>6075729
>it's unstable and won't contribute
You mean in this specific case? Because methoxy groups are very well known electron donors.

>> No.6075734

>>6075729
That's C-1. Longest change, only one that's substituted.

IUPAC, people. You would have already covered this.

>> No.6075744

>>6075734
I blame my educational system. I do Ochem and learn tons of important shit but then I'm forced to trudge through years of unrelated academic content, allowing for what I've learned to decay from lack of reinforcement.

When I graduate I will have forgotten it all completely and it enrages me. I could have done something with the knowledge but the educational system is forcing me to squander it.

>>6075731
Are you suggesting that such a resonant structure contributes to the molecule's stability?

As long as the answer is no then I think we're in agreement.

>> No.6075751

>>6075744
The resonance structure contributes both to the molecule's stability, and it's reactivity.

It is an essential resonance structure. If this is a question on an exam, and you fail to include that resonance structure, you will get it wrong.

>> No.6075766
File: 135 KB, 250x250, ren.png [View same] [iqdb] [saucenao] [google]
6075766

>>6075751
Ok, I'm wrong.

But I still think you're an ass hole for not at least acknowledging that that resonance structure is much less stable than the original structure. The O-C BO may be higher than 1, but not by much.

>> No.6075768

>>6075766
it doesn't fucking matter if it's less stable. When you're asked to draw all the different resonance structures of a molecule, you don't just draw the most stable one. It's a resonance structure, and if you knew anything about organic chemistry beyond sophmore undergraduate basic shit, you'd know it's a damn important resonance structure.

Call me an asshole all you want. I think you're an asshole for being both wrong and stupid.

>> No.6075812

>>6075768
>sophmore undergraduate basic shit
Don't flatter yourself. Resonant structures are covered in detail in ochem.

I'm suspect that you're oversimplifying what you're saying. Again you've avoided talking about the fact that not all resonant structures are created equal, and these difference do impact how much a form can contribute to the structure of a molecule and, by extension, a reaction that depends on it. This is also *important*.

I think if there was a reaction that relied on that particular resonant form, you would want to set up the reaction to stabilize the less stable structure and destabilize the most stable structure (with a particular solvent, for example). Or something to that effect.