Ethers.. how to cleave 'em

[SuperSaiyan3]

I studied in organic chem that you can cleave ethers by reacting them in acids (HI or HBr).

But I did a Kaplan passage where they say that ether is stable in both base AND acid, so not susceptible to cleavage.

If so, then what am I left with?

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[loveoforganic]

You cleave with strong, concentrated acid.

 

[wanderer]

You cleave with strong, concentrated acid.

OP: This is one of the things that can be reasoned out. Protonating the oxygen of an ether forms a good leaving group, and then the halide can substitute the oxygen via sn1 or sn2 depending on the structure in question.

Using this reasoning it can be expected that H2SO4 can cleave certain ethers but not all of them.

 

[RogueUnicorn]

to add to this epoxides are special in that they are cleaved in mild conditions, both acidic and basic.. the only ethers to cleave in basic rxn conditions

 

[SuperSaiyan3]

OP: This is one of the things that can be reasoned out. Protonating the oxygen of an ether forms a good leaving group, and then the halide can substitute the oxygen via sn1 or sn2 depending on the structure in question.

Using this reasoning it can be expected that H2SO4 can cleave certain ethers but not all of them.

yes I understand that, but why did Kaplan say that ethers are stable in both acid and base? If it's stable in it, would it not be ineffective to throw in acid into the ether solution?

I think Kaplan was confused...

 

[wanderer]

~

 

[RogueUnicorn]

I think Kaplan was confused...

it's not. the cleavage happens in STRONG acids

 

[wanderer]

it's not. the cleavage happens in STRONG acids

This works too.

 

[SuperSaiyan3]

gotcha. thanks that makes sense now...