Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Darkstar on September 18, 2004, 06:10:42 AM

Title: Cyclohexene
Post by: Darkstar on September 18, 2004, 06:10:42 AM
Cyclohexene from cyclohexane. Sounds simple, but it’s harder than it looks. How would you actually do it in the laboratory?
Title: Re:Cyclohexene
Post by: Demotivator on September 18, 2004, 12:26:06 PM
Chlorinate the cyclohexane, distill the monosubstituted -  Then dehydrohalogenate wiyh KOH.
According to an article,
Chlorination can be achieved with CCl4 catalyzed with PdBr2(PPh3)2  with acetonitrile (to enhance catalyst solubility) and potassium carbonate.
www.kcn.ru/tat_ru/universitet/persons/annot/7411/2.pdf
Title: Re:Cyclohexene
Post by: Darkstar on September 19, 2004, 01:37:59 PM
Thanks. I just wonder if more simple radical agents like (PhCOO)2 would work just as well... This one seems far too complex for a college test.
Title: Re:Cyclohexene
Post by: Demotivator on September 19, 2004, 06:19:31 PM
The benzoyl peroxide initiator would work with Cl2 gas or
Sulfuryl Chloride: SO2Cl2  (safer to handle).  
www.chemistry.mtu.edu/~kmsmith/ Organic/Manuals/2411/FreeRad/FreeRad04.pdf -

Also, Bromination with Br2 might be an alternative.
Title: Re:Cyclohexene
Post by: Darkstar on September 20, 2004, 08:01:30 AM
Thanks for your detailed answer. I wonder why a monosubstitution takes place here. I'd figure most radical processes would lead to a mixture of substituted compunds.
Title: Re:Cyclohexene
Post by: Darkstar on September 20, 2004, 08:05:16 AM
Oh, I think I'll answer this myself. Probably because we use cyclohexane in excess.