Sciencemadness Discussion Board

Research Project Idea Paradichlorobenzene

FloridaAlchemist - 8-6-2003 at 17:19

This is a research project idea for the home experimenter: Para Dichlorobenze mothball substitute can probably be used in a home lab for making other reagents if you 1st try to substitute one of the chlorines with Iodine...Very old and mostly overlooked method. then you can remove the iodine and get chlorobenzene.

Haggis - 8-6-2003 at 18:24

One could then use bromine to knock out the chlorine in chloro-benzene and aquire bromo-benzene. This chemical shall have lacrymating properties like bromo-acetone. On the subject of mothballs, anyone have any ideas on how to cleave the benzene rings apart in the old napthalene mothballs?

Nick F - 9-6-2003 at 07:57

Oxidation of napthalene (acidified permangante under reflux, I *think*) will yield phthalic acid, decarboxylation of this by distilling it from CaO should yield benzene via benzoic acid.

Organikum - 15-6-2003 at 07:09

When trying to distill benzene out from the benzoic acid/CaO one should add some CuSO4 and also then this is no fun at all.

stygian - 13-1-2005 at 09:57

Quote:
Originally posted by FloridaAlchemist
This is a research project idea for the home experimenter: Para Dichlorobenze mothball substitute can probably be used in a home lab for making other reagents if you 1st try to substitute one of the chlorines with Iodine...Very old and mostly overlooked method. then you can remove the iodine and get chlorobenzene.


How might one go about doing this? How do you substitute I for a Cl and then remove? methinks chlorobenzene would be nice to have :)

guy - 19-1-2007 at 21:37

Quote:
Originally posted by stygian
Quote:
Originally posted by FloridaAlchemist
This is a research project idea for the home experimenter: Para Dichlorobenze mothball substitute can probably be used in a home lab for making other reagents if you 1st try to substitute one of the chlorines with Iodine...Very old and mostly overlooked method. then you can remove the iodine and get chlorobenzene.


How might one go about doing this? How do you substitute I for a Cl and then remove? methinks chlorobenzene would be nice to have :)


yeah I want to know too

12AX7 - 19-1-2007 at 22:23

I take it the Cls stick pretty damn well? I mean, what's base do, fusing anhydrous if necessary? P-hydroxyphenol ought to have *some* acidity to allow this to go forward...

Tim

not_important - 19-1-2007 at 22:44

The chlorines stick really well. Refluxing with AlCl3 results mostly in the formation of ortho and meta isomers, with little transfers to give mono and tri chlorobenzenes (you can for it with a good column and very slow distillation) That is a decent way to get a mix of o- and m- dichlorobenzene, which is a useful solvent for some reactions, just chill the reaction mix to crystallize out most of the remaining para-DCB and recycle it.

I think that the alkali fusion route doesn't work well, lot of byproducts. Aqueous base under high pressure does go, similar to the commericial production of phenol from chlorobenzene.

Mononitration, which takes a bit of effort, followed by boiling alkali with the slow addition of H2O2 replaces the Cl ortho to the NO2 with OH. The H2O2 isn't functioning in a redox fashion, it's base form interacts with the NO2- and Cl-

Sauron - 19-1-2007 at 23:04

ortho-chlorophenyl derivatives ten to be very very nasty.

1,2-dichlorobenzene

2,-chlorophenol

2-chloronitrobenzene

All very unpleasant and toxic so be warned.

guy - 19-1-2007 at 23:08

Is the subsitution with hydroxide slow but favorable?

1st Add a Nitro Group

FloridaAlchemist - 20-1-2007 at 07:55

Fist put a nitro group on the ring to give 2-nitro para dichlorobenzene. It should now be possible to work on the chlorines;)

S.C. Wack - 20-1-2007 at 12:54

US3064059 claims that pDCB is hydrodechlorinated to chlorobenzene by their process in some yield that they refuse to give. Probably other exotic but different patents could be found.

There is something here and there on catalytic transfer of 1 chlorine from pDCB to benzene, and some reductions which maybe could be stopped at the chlorobenzene stage. But most reductions (Al/Ni/NaOH, Zn/Ni/NaOH, Ni/H, supported Pt or especially Pd, electroreduction with Pb cathode in divided cell with MeOH, hydrides, PPh3, etc.) that I've seen mentioned seem to go all the way to benzene. Don't have access to any of those articles and abstracts are abstracts so who knows.

[Edited on 20-1-2007 by S.C. Wack]