[Karakth]

How would you go from benzene to diphenyl?

I've played around with a few ideas like a chlorobenzene with AlCl₃, but I've got a feeling that that won't work (with the Cl being bonded to strongly to the ruing). I've thought about going through the diazonium salt, since it's a platform to take you anywhere usually in aromatics. Still, I'm stumped. Any ideas?

[Jellybaby]

Didn't reply to me sms did ya?   I dunno my wild guess may be reacting 1,2-dichlorobenzene with benzene (presence of AlCl3 anhydrous). Do pray tell me what you think.

Not too sure about the diazonium salt although theres another possibilty...but then you'd need the benzene to behave as a nucleophile in two positions?? Dunno. Any idea if a di(diazonium) salt exists?

[movies]

How about converting benzene to bromobenzene and then dimerizing through an Ullman reaction?

[HP]

Dehydrogenation of benzene at 800C is one possible synth of biphenil.
Another possible route is Wurz-Fitig synthesis from 2brombenzene and Na.
Grignard reaction of ArMgBr with brombenzene is good route. Also Suzuki coupling of organoboranes is fine and works at mild conditions but some expensive If try synthesis with aryldiazonium salt it could be coupled to biphenyl in the presence of H3PO3 as reductive agent...

[Arsenic]

here are some more .
you can find a review of ULLMANN SYNTHESIS OF BIARYLS  at (chem.rev 1964,64,613)

[HP]

Gomberg-Bachmann-Hey Reaction as reaction for arylation aromatic ring is very nice too:
Ar-N2+ Cl:- NaOH ---> ArN2OH heat---> Ar. + Benzene--> biphenyl
What about benzidine rearangement?

[Slyos]

And what about a simple Scholl reaction?

[HP]

With benzophenone it doesenr seems to work for biphenil synthesis.

[movies]

Benzophenone has one too many carbons....

[Mitch]

Just do an Ullmann reaction with a halobenzene derivative.