Sciencemadness Discussion Board - dechlorinating 1,4-Dichlorobenzene

dechlorinating 1,4-Dichlorobenzene

Chemistry Alchemist - 29-10-2011 at 20:59

Question - How could you turn 1,4-Dichlorobenzene into benzene?

1,4-Dichlorobenzene is a chemical substitute for Naphthalene moth balls, so it could be easy to get for the home chemist, what would you have to do to remove the chlorine from it? what would be the byproducts?

[Edited on 30-10-2011 by Chemistry Alchemist]

BromicAcid - 30-10-2011 at 08:31

Organic Syntheses, Vol. 47, p. 103 (1967); Coll. Vol. 5, p.998 (1973).

You can view it at the orgsyn.org website since I have trouble with direct links due to their disclaimer and use of frames.

Chemistry Alchemist - 30-10-2011 at 08:55

I cant seem to find the section.

BromicAcid - 30-10-2011 at 09:03

Just enter the information on the main page and click 'go'. The procedure is for the reduction of chlorobenzene to benzene but this can be expanded to other aromatic halides.

Chemistry Alchemist - 30-10-2011 at 09:31

sorry if i sound like a noob but i still cant find it

querjek - 30-10-2011 at 09:33

This topic has been discussed a few times already. Search for "dichlorobenzene" or "paradichlorobenzene".

bbartlog - 30-10-2011 at 10:09

I'm going to guess that you're searching on 'dichlorobenzene', which will not bring up the relevant item. Try 'reduction of organic halides'. That will give you the article BromicAcid mentions as the only hit.

Chemistry Alchemist - 30-10-2011 at 19:36

Do u search up "Reduction of Organic Halides" on the search on this forum or on the site BromicAcid said?

Chemistry Alchemist - 30-10-2011 at 20:10

Would LiAlH4 work reducing the 1,4-Dichlorobenzene to benzene? i found a website and it says its used in alot of organic reactions as a reducing agent...

Chemistry Alchemist - 30-10-2011 at 22:55

How could i just make Chlorobenzene from 1,4-Dichlorobenzene?

Chemistry Alchemist - 1-11-2011 at 01:05

The process on the website BromicAcid said above is the reduction od organic halides, it only mentions chlorobenzene not 1,4-Dichlorobenzene... So what I thought instead of trying to make benzene from it, how could I brake it down to chlorobenzene? I can then make phenol from it.

497 - 3-11-2011 at 02:03

How about this? http://en.m.wikipedia.org/wiki/Poly(p-phenylene_sulfide)

Then hydrogenolysis with raney nickel should yield benzene. Easy as that...

[Edited on 3-11-2011 by 497]

Nicodem - 3-11-2011 at 10:18

Quote: Originally posted by Chemistry Alchemist

I can then make phenol from it.

How?

barley81 - 3-11-2011 at 11:51

Quote: Originally posted by Nicodem

Quote: Originally posted by Chemistry Alchemist

I can then make phenol from it.

How?

Base-catalyzed hydrolysis, but it was said previously somewhere in a thread that the hydrolysis needs impractical conditions.

Quote: (user not_important):
The Raschig phenol process is little used nowadays, having fallen out of favour in the 1970s. As it takes place in the vapour phase at temperatures in the low-to-mid 400 C range, and with incomplete conversion, it is not too convenient for amateur application; it really is an industrial scale process.

[Edited on 3-11-2011 by barley81]

Chemistry Alchemist - 3-11-2011 at 20:18

Phenol is made by reacting C6H5Cl + NaOH = C6H6O + NaCl

Sorry if the equation is unbalanced, just woke up

[Edited on 4-11-2011 by Chemistry Alchemist]

Nicodem - 4-11-2011 at 10:19

Quote: Originally posted by Chemistry Alchemist

Phenol is made by reacting C6H5Cl + NaOH = C6H6O + NaCl

Sorry if the equation is unbalanced, just woke up

I asked how can you make phenol from chlorobenzene. I did not ask you to write an equation. Do you seriously think I can not write equations myself? (Meanwhile your equation makes no sense chemistry-wise, even though it is balanced.)
The answer to my question should as a minimum contain at least one pertaining reference followed by the explanation on how are you going to replicate the synthesis. It is absurd that I have to explain on how to structure a reply to my very simple question.

Chemistry Alchemist - 6-11-2011 at 07:57

Oh sorry, the method is via this route: This is a easy reason. All we need to do is react it with a strong base, the easiest base to get out hands on is sodium hydroxide so that's what we will use. Start by getting a round bottom flask and set up for heating, now place in 39.99 grams of Sodium Hydroxide and add to that 112.55 grams of Chlorobenzene. heat the 2 chemicals together, now we wont really know when the reaction is complete because there will be no indicator, but we could add a few drops of Phenolphthalein to the reaction vessel.. the solution will be deep purple as it will be really basic but will turn clear as the strong base is used up and reacted telling up its complete. Once complete, take it off heat and let it evaporate or continue boiling until dry. Now we have 2 products, Sodium Chloride and Phenol. the best way to separate the 2 will be acetone. this is a great way of separating because Phenol is easy soluble in the acetone while Sodium Chloride is practically insoluble (only 0.00042g/100ml of acetone). once fully mixed in filter off the Sodium chloride and then poor the acetone into a wide dish for faster drying, now you should have a reasonably pure Phenol...

I read up on dehalogenation of organic helides and it says reacting them with strong bases but it says it doesnt work with chlorobenzene... is this the same as 1,4 dichlorobenzene?

Nicodem - 6-11-2011 at 12:00

Quote: Originally posted by Chemistry Alchemist

Oh sorry, the method is via this route: This is a easy reason. All we need to do is react it with a strong base, the easiest base to get out hands on is sodium hydroxide so that's what we will use. Start by getting a round bottom flask and set up for heating, now place in 39.99 grams of Sodium Hydroxide and add to that 112.55 grams of Chlorobenzene. heat the 2 chemicals together, now we wont really know when the reaction is complete because there will be no indicator, but we could add a few drops of Phenolphthalein to the reaction vessel.. the solution will be deep purple as it will be really basic but will turn clear as the strong base is used up and reacted telling up its complete. Once complete, take it off heat and let it evaporate or continue boiling until dry. Now we have 2 products, Sodium Chloride and Phenol. the best way to separate the 2 will be acetone. this is a great way of separating because Phenol is easy soluble in the acetone while Sodium Chloride is practically insoluble (only 0.00042g/100ml of acetone). once fully mixed in filter off the Sodium chloride and then poor the acetone into a wide dish for faster drying, now you should have a reasonably pure Phenol...

I will heavily restrain myself, so I will only ask you to give us the references, please?

bbartlog - 6-11-2011 at 16:15

Quote: Originally posted by Chemistry Alchemist

Oh sorry, the method is via this route: [...]
I read up on dehalogenation of organic helides and it says reacting them with strong bases but it says it doesnt work with chlorobenzene... is this the same as 1,4 dichlorobenzene?

You are making stuff up. Nicodem is obviously aware that you have no reference for your flight of fancy. You don't even really seem to understand that there is a difference between reductive dehalogenation (which was what you initially asked for) and dehalogenation via basic hydrolysis, which replaces the halide with a hydroxyl group.

Anyway, if you actually care, here is a nice ACS overview from 1928: http://pubs.acs.org/doi/abs/10.1021/ie50218a006
Notice that in order to turn chlorobenzene into phenol via aqueous base you'll be wanting a pressure vessel, temps of 300C or thereabouts, and likely a copper catalyst to speed things along.

I also would like to point out that instead of trying to make any use of the answers that people have provided, you just keep changing the question. How about actually trying one of the many things you've proposed?

AndersHoveland - 7-11-2011 at 15:30

Samarium(II) Iodide probably would reduce it.
http://en.wikipedia.org/wiki/Reductions_with_samarium(II)_iodide

Chemistry Alchemist - 7-11-2011 at 16:09

Just my luck, I'm in the process of extracting samarium from a magnet

jon - 22-11-2011 at 11:55

ammonium formate/palladium on carbon, and methanol is a good way to dechlorinate aryl chlorides.
yeilds are quantitative, the reaction is done at room temp in 3 hours with stirring under inert atmosphere and, the reduction is chemoselective, it tolerates benzylic esters and alcohols, perfect for dechlorinating loperamide to something useful.
ratios are 5% molar palladium (loading 10% but 5 and 3% also work with a little heat input)
and 2 moles ammonium formate per mole chlorine.

[Edited on 22-11-2011 by jon]

[Edited on 22-11-2011 by jon]

Waffles SS - 24-11-2011 at 03:16

Quote: Originally posted by bbartlog

Anyway, if you actually care, here is a nice ACS overview from 1928: http://pubs.acs.org/doi/abs/10.1021/ie50218a006
Notice that in order to turn chlorobenzene into phenol via aqueous base you'll be wanting a pressure vessel, temps of 300C or thereabouts, and likely a copper catalyst to speed things along.

@Dear bbatlog,
Accoding to this patent you think using Copper Catalyst has same effect in hydrolysis of P-Chlorotoluene to cresol(Para and meta)?

Quote:

Treatment of para-chlorotoluene with sodium hydroxide solution at temperatures above 350 ºC gave an equimolar mixture of meta- and para-cresols (hydroxytoluenes)
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/benz...

[Edited on 24-11-2011 by Waffles SS]

bbartlog - 24-11-2011 at 14:12

That's not a patent, and it makes no claims about what I think. And I don't know the answer to the question that I *think* you asked, which is whether copper would be a viable catalyst for the reaction that is described. It would definitely be worth trying, though, since NaOH at 350C is no joke and copper would at least give you a chance at conducting the reaction at a somewhat lower temperature.

Chemistry Alchemist - 24-11-2011 at 19:30

I'm sorry if we have already discussed this and sorry if it's wrong..l I'm just guessing.... Blame the caffeine if I'm wrong

would NaOH have any effect to 1-4 Dichlorobenzene? Would it produce chlorobenzene or not? Just a random thought...

Nicodem - 25-11-2011 at 07:24

Quote: Originally posted by Chemistry Alchemist

I'm sorry if we have already discussed this and sorry if it's wrong..l I'm just guessing.... Blame the caffeine if I'm wrong

would NaOH have any effect to 1-4 Dichlorobenzene? Would it produce chlorobenzene or not? Just a random thought...

How about reading the whole thread and the reference bbartlog so kindly provided you?
Instead of cluttering the forum with random thoughts, start reading literature.

naf - 13-12-2011 at 10:26

though it wouldn't be the highest yeild and you'd likely get some wierd byproducts, refluxing 1,4-dichlorobenzine in NaOH would produce Hydroquinone, or 1,4-hydroxylbenzine as its major product and NaCl. Extract the NaCl, then refluxing Hydroquinone with an excess of a strong acid like H2SO4 in an aqueous soln should produce benzine.

ScienceSquirrel - 13-12-2011 at 10:32

Quote: Originally posted by naf

though it wouldn't be the highest yeild and you'd likely get some wierd byproducts, refluxing 1,4-dichlorobenzine in NaOH would produce Hydroquinone, or 1,4-hydroxylbenzine as its major product and NaCl. Extract the NaCl, then refluxing Hydroquinone with an excess of a strong acid like H2SO4 in an aqueous soln should produce benzine.

Not a chance.
1,4-Dichlorobenzene is not going to react with aqueous alkali at all.
Hydroquinone will not form benzene on refluxing in acid either.

SteveJones - 22-12-2011 at 15:25

First off, using 1-4, dichlorobenzene to make benzene is not especially practical nor I imagine, especially cost effective. You should consider the dry distillation of sodium benzoate with hydroxide methods on this forum. Yields are generally pretty good and it can be done on a relatively large scale. Reducing dichlorobenzene simply isn't practical. If you really must then you might consider forming the double-Grignard product by addition of magnesium, then quench with water or ammonium chloride solution.

Ephoton - 23-12-2011 at 18:48

what about a samarium iodide reduction with HMPA ?
it works through an organometal intermediate.

Samarium can be obtained from rare earth magnets
but probably better pure and reacted with iodine in THF
or some other ether to form the iodide.

both are available on ebay

.

damb AndersHoveland beat me too it.

http://www.ebay.com.au/itm/Samarium-Vacuum-Packed-Dendritic-...

[Edited on 24-12-2011 by Ephoton]

CuReUS - 2-1-2015 at 01:22

Quote: Originally posted by Chemistry Alchemist

Phenol is made by reacting C6H5Cl + NaOH = C6H6O + NaCl

Quote: Originally posted by Chemistry Alchemist

This is a easy reason. All we need to do is react it with a strong base... sodium hydroxide so that's what we will use....

..Start by getting a round bottom flask and set up for heating, now place in 39.99 grams of Sodium Hydroxide and add to that 112.55 grams of Chlorobenzene. heat the 2 chemicals together... Once complete, take it off heat and let it evaporate or continue boiling until dry. Now we have 2 products, Sodium Chloride and Phenol... now you should have a reasonably pure Phenol...

Its not that easy,read the last paragraph of this wiki article about dow's process
http://en.wikipedia.org/wiki/Dow_process

but you can make benzene from 1,4 dichlorobenzene using raney nickel in alkaline medium
http://www.sciencemadness.org/talk/viewthread.php?tid=14054&...

[Edited on 3-1-2015 by CuReUS]