[ecnerwalc3321]

Hello,

Most Friedel-Crafts reactions described in textbooks use an aromatic (ring) reagent that is in the liquid state.  If you want to do Friedel-Crafts on polystyrene (PS), what kind of solvent would you use to dissolve PS and also remain inert?  Common solvents for polystyrene such as toluene and benzene all participate in FC reactions themselves.  I've read somewhere that chlorobenzene and dicholoromethane are good solvents.  However, although chlorobenzene wouldn't add to PS wouldn't the acid chloride or methylchloride add to the chlorobenzene (para director)? 

Also I've read that chloroform is able to undergo FC reactions three times due to three Cl's; wouldn't dichloromethane also not be a good solvent for this reason?  Thanks.

[discodermolide]

One good solvent for FC reactions is carbon disulphide. A bit smelly, but that can be contained. But I don't know if it dissolves PS.
Another approach is to do it as a melt. Mix everything and melt it, stand well back and watch 100% yield come out of the flask.

[ecnerwalc3321]

Thanks for the suggestion.  Is my reasoning regarding dichloromethane and chlorobenzene correct (that they can't be used)?

[discodermolide]

Chlorobenzene can be used. May be better with dichlorobenzene as they are deactivated aromatic systems. I would not use chloroform.

[NotExactly]

I would not use chloroform.

I concur.  I don't have much experience doing FC reactions but I'd imagine acetonitrile may also work okay. 

[orgopete]

Just as noted, chloro, dichloro, and trichloromethane cannot be used. Chlorobenzene can be used because the aromatic ring deactivates the chlorines ability to coordinate with a Lewis acid and aromatic rings resist forming carbocations.

The electrons of acetonitrile are too available to be used as a solvent though it can be used as an electrophile if protonated or coordinated.