[ChemBoy81]

Hi Everyone;

              I am writing a report on Ferrocene synthesis where the usual procedure is to add the Iron(II) chloride tetrahydrate slowly drop-wise over 30 minutes. I was hoping if you guys could explain to me why this addtion is done so Slowly (Please go into detail if you can...)

My second question was why the iron-cyclopendiene mixture then added to Cold HCl?

Thanks a MIllion !!

[AWK]

http://www.chem.ox.ac.uk/mom/ferrocene/synthesis.html
http://imr.chem.binghamton.edu/labs/ferrocene/ferrocene.html
http://spot.pcc.edu/~chandy/242/SynthesisofFerrocenesylvania.pdf
http://spot.pcc.edu/~gbackes/ORGANIC/CH%20242/Labs.CH242.W05/Synthesis.of.Ferrocene.htm
http://chemw.sc.mahidol.ac.th/scess/scch348/05_Ferrocene.pdf
http://curie.umd.umich.edu/srsmith/ferrocene%20lab.doc

[cst2]

i believe that in http://imr.chem.binghamton.edu/labs/ferrocene/ferrocene.html, it says that

Cyclopentadiene undergoes a 4+2 cycloaddition to form dicyclopentadiene

 perhaps this is the reason why? if you know about the diels-alders reaction then you'd know what they meant by the 4+2 cycloaddition part http://www.usm.maine.edu/~newton/Chy251_253/Lectures/Pericyclic/Pericyclic.html ...

[corey2]

cyclopentadiene is extremely reactive, even with itself, generating a dimer. Cyclopentadiene should be fractionally distilled and stored in a refrigerator before using.
 HCl is used to quench the residual sodium or potassium salt of cyclopentadiene.

[Dude]

The reason why many reagents are added dropwise involves heat.  Chemical reactions are generally exothermic and produce large amounts of heat.  The heat can present a safety hazard if not controlled properly and it can lead to undesirable side reactions (such as the DCPD formation from cyclopentadiene that was referenced).  I agree with corey2 as to why HCl would be used in the second step, to react with the excess or unreacted cyclopentadienyl anion.

[coldest]

             
My second question was why the iron-cyclopendiene mixture then added to Cold HCl?

but I think iron-cyclopendiene could react with HCl

[angie]

hi everyone,
does anyone know why is it necessary to exclude air when preparing ferrocene? if reactants are air stable, and also, why ferocene sublimes so readily while acetylferrocene doesnt?

[AWK]

Fe²⁺ salts are unstable on air