SN2 backside attack on a tertiary carbon?

[cmF]

So I was watching Chad's video on ethers/epoxides and he said that the following acid catalyzed epoxide will undergo backside attack:

I thought tertiary carbons can't undergo backside attack though?

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[Moka11]

For acid catalyzed the ring opens in a Sn1 manner with the carbocation forming on the more substituted carbon, which then is attacked by the nucleophile.

 

[xatlasb]

I think the main point was to indicate that there is inversion stereochemistry happening, like what you see in SN2 backside attack. However, the actual mechanism isn't SN2, a carbocation is what forms like mklein has said.

 

[roquer2]

Honestly, I don't think about SN2/SN1 etc. when it comes to epoxides. The main theme I'm seeing is that epoxides will open up.

Also, SN1/SN2 stuff usually involves a halide as a leaving group (note the 'usually involves' statement). Nothing leaves, and you're just opening up that sucker and performing a backside attack leading to the more substituted ether.

This is just my train of thinking. Hope this helps

 

[cmF]

Honestly, I don't think about SN2/SN1 etc. when it comes to epoxides. The main theme I'm seeing is that epoxides will open up.

Also, SN1/SN2 stuff usually involves a halide as a leaving group (note the 'usually involves' statement). Nothing leaves, and you're just opening up that sucker and performing a backside attack leading to the more substituted ether.

This is just my train of thinking. Hope this helps

Ah, this made the most sense. Thank you so much!