Common Blind Spot: Intramolecular Reactions

by James

in Drawing Reaction Mechanisms, Understanding Electron Flow

So I bought a belt today (pleather, 75 cents at the Goodwill).  and decided to show it off. This is me putting it together.

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This is what it looks like now:

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At this point you’re probably saying WTF: that’s not what a belt is supposed to look like when you put it together. That’s because I linked it together with my other belt.

I say: broaden your horizons of how nucleophiles and electrophiles can meet.

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Here’s a typical reaction you meet early on in Org 2. Formation of an ether through the addition of an oxygen nucleophile to an alkyl halide. This is the Williamson ether synthesis.

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Makes some sense, right? Nucleophile, electrophile: give the product.

Here’s the same reaction. Exactly the same. But a lot of students I talk to will look twice at it the first time they see it,  not quite sure what to do.

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Different example: the Friedel Crafts acylation between aromatic rings and acyl halides.

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Then, here’s the exact same reaction. Common result: hesitation. What happens?

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Last example: formation of esters from alcohols and carboxylic acids. The Fischer esterification. Once people see this, they usually find it straightforward.

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But then hand them this reaction, and it’s a stumper.

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What do all of these reactions have in common?

When the nucleophile and electrophile are on the same molecule, they form RINGS.

6-intraBecause you’re probably used to seeing linear molecules – not chains – it looks weird.  But if you think about it, you’re already familiar with an example of this:

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{ 3 comments… read them below or add one }

ntakirutimana emmanuel

very interesting to get this web,i am a science teacher at blind school,some times it is very difficult to me to teach my students .big up!!

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Oskar Henriksson

Maybe you should mention something about why these reactions usually are favoured kinetically?

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Anurag

U r best. Thanks lord for creating humans like u. It explanations and creativeness are just WOW!!

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