Reacting anisole with concentrated H2SO4

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Discussion Overview

The discussion revolves around the reaction of anisole with concentrated sulfuric acid (H2SO4), exploring the mechanisms involved in this chemical process. Participants inquire about the specific reaction pathway and the role of H2SO4 in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the specific mechanism of the reaction between anisole and concentrated H2SO4.
  • One participant suggests that H2SO4 does not decompose when acting as a normal acid and discusses its deprotonation behavior, noting that it does not hydrate aromatic rings like it does with alkenes.
  • Another participant proposes that the reaction might involve aromatic sulfonation, indicating that sulfur trioxide can be considered as the electrophile in this context.
  • There is mention of the cleavage of ethers with strong acids, but it is noted that halogen acids are typically required for generating halogenated products from anisole.

Areas of Agreement / Disagreement

Participants express differing views on the mechanism of the reaction, with no consensus reached regarding the specifics of how anisole reacts with concentrated H2SO4.

Contextual Notes

The discussion includes assumptions about the reactivity of H2SO4 and its role in aromatic reactions, but these assumptions are not fully explored or resolved.

tellmesomething
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Homework Statement
Can someone explain to me how this mechanism works, and why wouldn't h+ be generated and attack the ortho para electron rich sites in anisole? It seems it breaks as OH- and So3H+ but mostly reactions we had done before had H+ breaking, how do I decide how the acid breaks? ( I thought since H is attached to O its very acidic and would always give us a supply of hydronium ions)
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What mechanism?
 
mjc123 said:
What mechanism?
I have stated in the title. Reacting anisole with conc. H2so4..
 
Not sure what you mean. H2SO4 doesnt decompose when acting as a normal acid; it deprotonates completely into one equivalent and partially into a second equivalent.

The cleavage of ethers with strong acids is known, but usually a halogen acid (HCl, HBr, HI) most be used to generate a halogenated product (halomethane in the case of anisole). H2SO4 wont hydrate aromatic rings like it does alkenes since aromaticity changes the reactivity and nature of the double bonds.

Your question is a bit unclear so I hope this answers it.
 
I assume you're doing an aromatic sulfonation? If you google "aromatic sulfonation mechanism" you'll get various diagrams. There's different ways of depicting it; I think the most clear to me is just to consider sulfur trioxide as your electrophile (sulfuric acid, especially when concentrated, can for some purposes be thought of as a solution of sulfur trioxide)
 

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