ResCC

How to apply electronegativity and resonance to understand reactivity

How to apply electronegativity and resonance to understand reactivity

January 17, 2012

One thing has been missing from the discussion of resonance. What’s the point? Who cares if we can write out resonance structures? What does it matter if we can figure out the two or three most stable resonance …

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Common Mistakes: How not to draw resonance curved arrows

Common Mistakes: How not to draw resonance curved arrows

January 10, 2012

No discussion of resonance structures would be complete without mention of how to royally screw them up. This isn’t something to feel bad about, by the way: there isn’t a chemist alive who hasn’t ma…

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In Summary: Resonance

In Summary: Resonance

December 22, 2011

After all these posts about resonance, I thought it would be good to have a post summarizing what’s been discussed so far. One of the key skills in analyzing the reactivity of a molecule is to be able to figure …

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Exploring Resonance: Pi-acceptors

Exploring Resonance: Pi-acceptors

December 19, 2011

Last time I talked about π donation and π donors, which are atoms capable of forming a new π bond with an adjoining C-C π bond.  The upshot of π donation is that these molecules will have an important resonanc…

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Exploring Resonance:  Pi-Donation

Exploring Resonance: Pi-Donation

December 15, 2011

You’d think after five or six posts on resonance, that would be enough. But NO, friends, it just keeps going. I promise that today’s post is actually useful, although to be honest it’s probably most …

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Evaluating Resonance Forms (4): Positive Charges

Evaluating Resonance Forms (4): Positive Charges

December 14, 2011

As I mentioned before, the resonance form(s) of lowest energy are those where the charges are minimized. However, sometimes you can’t get around it: you have to put a charge somewhere. Last time I talked about t…

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Evaluating Resonance Forms (3): Where to put the negative charge?

Evaluating Resonance Forms (3): Where to put the negative charge?

December 13, 2011

So far in discussing resonance forms I’ve mentioned two important principles: 1. Minimize charges: the resonance form with the fewest charges will be the most stable. 2. How to break π bonds. If you absolutely …

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Evaluating Resonance Forms (2): Applying Electronegativity

Evaluating Resonance Forms (2): Applying Electronegativity

December 12, 2011

The last time I talked about evaluating resonance structures the molecules were, to be honest – pretty simple. Evaluating the resonance structures of ethene, the allyl carbocation, and the allyl carbanion are a …

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Evaluating Resonance Forms (1) – The Rule of Least Charges

Evaluating Resonance Forms (1) – The Rule of Least Charges

December 8, 2011

So far I’ve talked about resonance, and introduced the curved arrow formalism to show the movement of electrons. Importantly, we’ve talked about how the “true” picture of a molecule is a hybrid…

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Introduction to Resonance (2) : Curved Arrows!!

Introduction to Resonance (2) : Curved Arrows!!

November 30, 2011

So last time I talked about resonance forms as being two (or more) different ways to draw the same molecule, which differ only in their distribution of electrons. Let’s look a little more closely at these reson…

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