[confused0ne]

Hi guys,

Is the reaction below correct?

I don't know much about organic chemistry or Sn1 reactions, but I thought in this reaction benzene acts as a nucleophile and CH₃OH as the substrate. And then the OH group would become protonated to form a better leaving group (water) leaving behind CH₃⁺ as a carbocation which would then be attacked by benzene to form toluene or something. except of course i'm getting it all wrong

i would appreciate it if someone could help me explain the reaction taking place below and why it is taking place.

Thanks!

[Scatter]

I dont know a mechanism for the reaction you have there.  I know how to get methylbenzene out of that though.  As you said, a strong acid would protonate the methanol...like H3PO4 or something.  Then H2O would leave forming a carbocation.  This acts as an electrophile and undergoes electrophilic aromatic substitution forming methylbenzene.

I feel like a metal and heat would have to be involved to work like the way you are showing.

I don't understand how to get the carbocation to form on the methanol without kicking off the hydroxyl group...

This will be good knowledge for me too if someone else chimes in.

[Scatter]

What about this as a way to get a benzyl alcohol?  This involves an epoxide and highly acidic conditions for an electrophilic aromatic substitution rxn...

I know this doesn't involve methanol, but I'm curious as to how one gets a benzyl alcohol from cyclobenzene.  Somebody wanna check my work and tell me what I screwed up on?  heh...

[nj_bartel]

I think the most reasonable route to benzyl alcohol would be Friedel Crafts acylation with formyl fluoride then reducing, or brominating the benzene, forming the grignard, and sn2ing on formaldehyde (assuming you have to start with benzene for whatever reason).

As far as the first reaction, I'm not seeing how it would happen.

[Scatter]

How do you Brominate the Benzene?

Also, I just realized that I'd end up with too many carbons if I went the epoxide route.  Oops.

[Scatter]

So that would have been...

[confused0ne]

i'm really not good at this 

but i did have to somehow come up benzyl alcohol for my synthesis project... so what i did was get toluene (methylbenzene) the way i figured and Scatter mentioned earlier...

And then i reacted toluene with Cl2 to give benzylchloride...

which i finally hydrolyzed to benzyl alcohol.

All thanks to wikipedia!

http://en.wikipedia.org/wiki/Benzyl_chloride#Preparation

http://en.wikipedia.org/wiki/Benzyl_alcohol#Occurrence_and_preparation

long process but... i guess it works.

[Scatter]

Aha.  So by wiki:

"It can also be prepared via a Grignard reaction by reacting phenylmagnesium bromide (C6H5MgBr) with formaldehyde, followed by acidification."

That's a way I'd know how to do it.  So my initial suspicions of a metal being involved were correct, and nj_bartel was right on the money.  Cool.