menchaca - 13-3-2003 at 15:46
can somebody help me to find a way to obtain phenol from 1,4 dichlorobenzene?
i thought in dissolve it in alchol and heat in with NaOH to ontain chlorophenol and NaCl,
taking the chlorophenol and heating it with aluminium or zinc and and hidrochloric acid to obtain phenol and zinc or aluminium chloride
1,4 C6H4Cl2+NaOH-->C6H5CL(OH)+NaCl
C6H5Cl(OH)+2Zn+3HCl-->C6H5OH+ZnCl2
Is this posible? is there a way to obtain picric acid or a similar explosive directly from dichlorobencene or chlorophenol?
vulture - 14-3-2003 at 11:59
I don't think reacting it with NaOH will work, as the chlorine works strongly deactivitating.
It is however possible to exchange chlorine for OH when there are strongly electrondrawing groups, such as NO2, attached to the ring.
But ofcourse nitrating will be slow and difficult to because of the chlorine....
BASF - 14-3-2003 at 13:15
Oh, ít does work, but for example, substitution of 1-chlorbenzene violent reaction conditions are needed: 350°C, 15MPa......
At least we have the second chlorine that desactivates the ring maybe at least to an extent that the substitution of one chlorine would be possible at
atmospheric pressure...
(that´s what i can get out of my "Vollhardt" about nucleophilic aromatic substitution.
BTW, menchaca, how do you know you can reduce a chlorine-substituent with nascent hydrogen on an aromatic ring?
[Edited on 14-3-2003 by BASF]
BASF - 14-3-2003 at 13:23
Ah, now i know why menchaca is fixed on 1,4-dichlorbenzene....
This is identical with p-dichlorbenzene, which is a main ingredient in some moth balls...
I still put a curse on the day they replaced naphthaline in moth balls......so no opportunity to play with TeNN in the near future....
Polverone - 14-3-2003 at 13:49
In the U.S., many moth balls use paradichlorobenzene but you can still find some that use naphthalene. Perhaps you just haven't examined
different brands closely enough?
Mumbles - 23-3-2003 at 19:30
I can still get Naphthalene mothballs here. I had to look a bit but finally found them. They are called "Old Fashion Mothballs."
It's made by Enoz. They are a blue cardboad box, and says 99% naphthalene right on the front.
Nick F - 24-3-2003 at 10:11
I have to search quite hard to find p-DCB mothballs; I only know of one shop that sells them! All the rest are napthalene round here, 100g for £0.80.
But I'm sure there is something that can be done with p-DCB...
The trouble is those chlorines make everything quite hard! In theory they could be removed by forming a Grignard, then reacting it with water to form
chlorobenzene and/or benzene, but I don't think Grignard formation is easy on aromatics.
You may have to nitrate it first, under harsh conditions. The Cl's are conflicting in their orientation, so you might get a mixture of isomers IF
you manage to get more than one -NO2 onto the ring. Assuming you only get one -NO2, you will clearly have 1,4-dichloro-2-nitrobenzene. Now that the
electron-withdrawing -NO2 is there, other reactions (Grignard, substitution) will proceed more easily since it will weaken the Ph-Cl bond. Then if you
manage to form a Grignard you can get to nitrobenzene.
That's all the help I can give!
You might be better off looking for napthalene!
tantalizing information
Polverone - 27-3-2003 at 13:08
The dye chemistry book I'm scanning right now has some interesting diagrams/tables in the back, showing derivations of different chemicals and
their relationships to one another. It shows 1,4 dichlorobenzene being converted to 1,4 diaminobenzene by the action of NH3 + Cu. Unfortunately, this
particular procedure is not elaborated elsewhere in the book, so no reaction conditions or proportions are given. The book makes heavy use of
autoclaves; the required reaction conditions may be pretty extreme.
But those amino groups, once added, are going to be extremely reactive: much easier to affect than chlorine. Of course this doesn't get much
closer to pure benzene.