Sciencemadness Discussion Board

paradiclorobenzene - possible degradation of

Fluxor - 15-6-2010 at 10:03

While cleaning out my mother's attic, I found a large jar of 100% paradichlorobenzene as "moth killer". Apparently, it has never been opened. I was informed by her that it had been stored there about 35 years ago but was never used. The attic in which it was found lacks any kind of climate-control. I know for a fact that in the summers, there is an extraordinary heat build-up in this space.

My question is whether this material, because of the intense heat and over such a length of time, has undergone a level of degradation or decomposition that would likely make it not useful to keep around for future experiments. I don't have anything in mind at the moment, as I'm focusing on inorganic hobby chem for now. However, if in the estimation of the more experienced chemists here, it hasn't degraded, I may keep it.

Myself, I think it may have degraded, judging by its appearance inside the jar. The appearance would suggest that the paradichlorbenzene has partially sublimated owing to its (moderate) volatility. That would explain how the bottom of the jar is almost empty of the substance, and almost all what's remained is thrust toward the lid, as if it wanted to get out. Also, I think it's possible that some of it may have already decomposed into water and CO2.

These are just possibilities based on a google search of the basic properties of the substance. If you have a more accurate idea of what has occurred based on actual experience, I welcome your input and ideas.


rsz_1img_0966.jpg - 383kB rsz_1img_0967.jpg - 383kB

Nicodem - 15-6-2010 at 11:08

Don't worry, it is as clean is it was 35 years ago. If you don't trust me, then measure its melting point and see if it is depressed.

DJF90 - 15-6-2010 at 11:14

I agree with Nicodem, p-dichlorobenzene is pretty hardy stuff, and would take much more of a harsh environment than your attic could throw at it.

gutter_ca - 15-6-2010 at 11:15

IF it is even what it is labelled as. Asked a few people around the lab, doesn't really look like a benzene. After 35 years, not sure I would trust that the label matches the contents.

Lambda-Eyde - 15-6-2010 at 11:25

"Doesn't look like a benzene"? You can't generalize substituted benzenes to such a degree that they should all look the same. Ibuprofen doesn't look much like benzene either.

gutter_ca - 15-6-2010 at 11:34

Okay, that's fair.

Just adding my two cents. This is the important sentence:

"After 35 years, not sure I would trust that the label matches the contents."

measurement of melting point

Fluxor - 15-6-2010 at 11:45

Quote: Originally posted by Nicodem  
Don't worry, it is as clean is it was 35 years ago. If you don't trust me, then measure its melting point and see if it is depressed.


That's great to know. Thank you for your response. I will do some research and set out to try to measure the melting point. I think this could be an interesting experiment in its own right.

Quote: Originally posted by DJF90  
I agree with Nicodem, p-dichlorobenzene is pretty hardy stuff, and would take much more of a harsh environment than your attic could throw at it.


Interesting. What type of harshness would be required? I figured that the air outside the jar, over such a length of time, even with it never being opened, would have at some point begun to enter it and cause it to slowly sublimate.
I agree that it really isn't that harsh, though for a few months of the year the temps go above 37 C.

[Edited on 16-6-2010 by Fluxor]

Quote: Originally posted by gutter_ca  
Okay, that's fair.

Just adding my two cents. This is the important sentence:

"After 35 years, not sure I would trust that the label matches the contents."


Well, my mother claims that it was bought new on or about the time the house was purchased, some 35 years ago, and that it was never used. I tend to believe this is correct. It apparently was simply placed on the attic floor, along with a bunch of boxes in which old clothes were deposited and which piled up around the jar. Then it was just forgotten about. On the innumerable times I've entered the attic, I've never smelled the mothball smell.

[Edited on 16-6-2010 by Fluxor]

zed - 15-6-2010 at 12:58

Yup! Thats the stuff. I can smell it from here. Used to be cheap as dirt.






Nicodem - 15-6-2010 at 14:05

Quote: Originally posted by Fluxor  
Interesting. What type of harshness would be required? I figured that the air outside the jar, over such a length of time, even with it never being opened, would have at some point begun to enter it and cause it to slowly sublimate.
I agree that it really isn't that harsh, though for a few months of the year the temps go above 37 C.

p-Dichlorobenzene is thermaly stable up to a couple hundreds degrees, completely inert toward oxygen (air), water, nucleophiles, mild electrophiles, nonreactive toward most metals (with the exception of alkali metals), most bases and acids at room temperare, does not easily photodegradate, it can not biodegradate in its pure form...

Sublimation is just a solid-vapour-solid phase transition, that is a physical phenomenon. It does not cause chemical transformations or degradation! Utmost it alters the crystal structure (the sublimated compound often crystallizes into some different polymorph), but it does absolutely nothing to the molecular structure.

PS: Please start using the edit function (the "Edit" button on the top right of your post). I don't know what is the current forum record for multiple posting, but you sure appear like you are doing your best to beat it.

[Edited on 15/6/2010 by Nicodem]

Fluxor - 15-6-2010 at 17:53


p-Dichlorobenzene is thermaly stable up to a couple hundreds degrees, completely inert toward oxygen (air), water, nucleophiles, mild electrophiles, nonreactive toward most metals (with the exception of alkali metals), most bases and acids at room temperare, does not easily photodegradate, it can not biodegradate in its pure form...

Sublimation is just a solid-vapour-solid phase transition, that is a physical phenomenon. It does not cause chemical transformations or degradation! Utmost it alters the crystal structure (the sublimated compound often crystallizes into some different polymorph), but it does absolutely nothing to the molecular structure.

PS: Please start using the edit function (the "Edit" button on the top right of your post). I don't know what is the current forum record for multiple posting, but you sure appear like you are doing your best to beat it.

[Edited on 15/6/2010 by Nicodem][/rquote]

According to one study it does react with air, with nitrogen to form hydroxl radicals:

Quote:

Reactions with hydroxyl radicals occur in the atmosphere to breakdown p-DCB to produce nitrochlorobenzene, chlorophenol, and aliphatic dicarbonyl product that are further degraded by photolysis (INCHEM, 2004).


source: Environmental Fate of Paradichlorobenzene

not_important - 15-6-2010 at 19:16

I think you failed to read that correctly : Reactions with hydroxyl radicals to produce the products, not "react with air, with nitrogen to form hydroxl radicals". Hydroxyl radicals are extremely reactive, and produced by high energy reactions generally involving peroxides or short wave UV; they are noted for their ability to chew on aromatic rings. This is taking place in the range of 15 to 60 km up, where there's plenty of shortwave UV; I seriously doubt there as much of that around your jar given it was "on the attic floor, along with a bunch of boxes in which old clothes were deposited and which piled up around the jar."

Figure 2 of that PDF shows this, pDCB + ·OH => intermediate radical, which reacts with O2 or NO2 (not N2) to form those other compounds.

When I was quite young and innocent, I tried "doing things" to pDCB as it was an easily accessible organic compound. Dissolving sodium metal in anhydrous alcohol, then adding pDCB and distilling off the excess alcohol, then refluxing for hours did nothing. It turned out to be more difficult to nitrate or sulfonate than nitrobenzene, and unlike nitrobenzene it had no easy-to-reduce attributes.


Fluxor - 15-6-2010 at 19:51

Quote: Originally posted by not_important  
I think you failed to read that correctly : Reactions with hydroxyl radicals to produce the products, not "react with air, with nitrogen to form hydroxl radicals". Hydroxyl radicals are extremely reactive, and produced by high energy reactions generally involving peroxides or short wave UV; they are noted for their ability to chew on aromatic rings. This is taking place in the range of 15 to 60 km up, where there's plenty of shortwave UV; I seriously doubt there as much of that around your jar given it was "on the attic floor, along with a bunch of boxes in which old clothes were deposited and which piled up around the jar."

Figure 2 of that PDF shows this, pDCB + ·OH => intermediate radical, which reacts with O2 or NO2 (not N2) to form those other compounds.

When I was quite young and innocent, I tried "doing things" to pDCB as it was an easily accessible organic compound. Dissolving sodium metal in anhydrous alcohol, then adding pDCB and distilling off the excess alcohol, then refluxing for hours did nothing. It turned out to be more difficult to nitrate or sulfonate than nitrobenzene, and unlike nitrobenzene it had no easy-to-reduce attributes.



not_important - Thanks for clarifying. I'd be the first to admit I read wrong. You, Nicodem and the others are a beacon of light in the sea of my ignorance.

I was going to keep it based on the posts by Nicodem, DJF90, but it sounds like you're saying its not a very interesting chem to keep around, owing to its lack of reactivity. What experiments for the beginner (if any) would you suggest can be done with it?

woelen - 15-6-2010 at 22:55

Don't throw it away. It is an interesting chemical which can be used for quite a few physics experiments. E.g. melt some in a test tube and let it cool down again. You can get beautiful glass-like structures in the material. It also can supercool and suddenly freeze. Sublimation and crystallization experiments are others which can be done with it. Its melting point is low and it can be lowered by adding other chemicals. E.g. melting point depression experiments can be done with it.

It only is slightly toxic and has a strong smell (good warning properties). This makes it a safe chemical to do these physics experiments.

From a chemical point of view it indeed is not the most interesting chemical. It might be possible to have it reacting with concentrated HNO3/H2SO4 at higher temperatures. I don't know if this gives interesting results.

Nicodem - 16-6-2010 at 00:01

The mononitration and dinitration of p-dichlorobenzene has been discussed a few times on the forum and I remember that I posted some references about it in some thread in the Energetic materials section. UTFSE and you will surely find a lot, though most posts are from those who still can not see the difference between an alkyl chloride and an aryl chloride (or SN2 and NAS substitutions) and consequently think they can easily do nucleophilic substitutions on p-dichlorobenzene.
It is hard to design a synthesis experiment with this substrate which would strictly use only readily available reagents. The only one I can think of is the synthesis of hexachlorobenzene, but this is not for some beginner as it requires hazardous conditions: heating of p-dichlorobenzene in concentrated sulfuric acid with trichloroisocyanuric acid. Besides the product is toxic and a possible carcinogen (it was used as a fungicide but not anymore). It is not dangerous for an experienced chemist with proper equipment and a fume hood, but certainly not appropriate for a beginner's experiment where things often go wrong when they can go wrong.
It does react with strong nucleophiles under forcing conditions by the addition/elimination mechanism (NAS substitution), but relatively easily with S-nucleophiles. Only one Cl gets substituted with O- and N-nucleophiles, while with S-nucleophiles it is possible to substitute both Cl. It is a good substrate for transition metal catalysed couplings (particularly for Suzuki-Miyaura and Kumada couplings, but Heck and few other couplings are also described). It also works relatively well for Ullmann condensations but again in most literature examples only one Cl gets substituted. In the Buchwald-Hartwig amination both chlorines get substituted. It is also possible to prepare p-chlorophenylmagnesium chloride from it. You can also hydrogenate it to benzene. Under rather extreme conditions it can even be acylated via the Friedel-Crafts reaction (for example with phthaloyl chloride and AlCl3 at 120°C, or acylation with MeCOCl at 150°C!). Sulfonation is also possible. At least one patent also claims that Friedel-Crafts alkylation is possible.

For now, you just add it to your inventory of chemicals - you will find some interesting experiments to do with it later on.

THANK YOU

Fluxor - 16-6-2010 at 03:58

E.g. melt some in a test tube and let it cool down again. You can get beautiful glass-like structures in the material. It also can supercool and suddenly freeze. Sublimation and crystallization experiments are others which can be done with it. Its melting point is low and it can be lowered by adding other chemicals. E.g. melting point depression experiments can be done with it.

It only is slightly toxic and has a strong smell (good warning properties). This makes it a safe chemical to do these physics experiments.

From a chemical point of view it indeed is not the most interesting chemical. It might be possible to have it reacting with concentrated HNO3/H2SO4 at higher temperatures. I don't know if this gives interesting results.[/rquote]


Thanks woelen!:D



Quote: Originally posted by Nicodem  
The mononitration and dinitration of p-dichlorobenzene has been discussed a few times on the forum and I remember that I posted some references about it in some thread in the Energetic materials section. UTFSE and you will surely find a lot, though most posts are from those who still can not see the difference between an alkyl chloride and an aryl chloride (or SN2 and NAS substitutions) and consequently think they can easily do nucleophilic substitutions on p-dichlorobenzene.
It is hard to design a synthesis experiment with this substrate which would strictly use only readily available reagents. The only one I can think of is the synthesis of hexachlorobenzene, but this is not for some beginner as it requires hazardous conditions: heating of p-dichlorobenzene in concentrated sulfuric acid with trichloroisocyanuric acid. Besides the product is toxic and a possible carcinogen (it was used as a fungicide but not anymore). It is not dangerous for an experienced chemist with proper equipment and a fume hood, but certainly not appropriate for a beginner's experiment where things often go wrong when they can go wrong.
It does react with strong nucleophiles under forcing conditions by the addition/elimination mechanism (NAS substitution), but relatively easily with S-nucleophiles. Only one Cl gets substituted with O- and N-nucleophiles, while with S-nucleophiles it is possible to substitute both Cl. It is a good substrate for transition metal catalysed couplings (particularly for Suzuki-Miyaura and Kumada couplings, but Heck and few other couplings are also described). It also works relatively well for Ullmann condensations but again in most literature examples only one Cl gets substituted. In the Buchwald-Hartwig amination both chlorines get substituted. It is also possible to prepare p-chlorophenylmagnesium chloride from it. You can also hydrogenate it to benzene. Under rather extreme conditions it can even be acylated via the Friedel-Crafts reaction (for example with phthaloyl chloride and AlCl3 at 120°C, or acylation with MeCOCl at 150°C!). Sulfonation is also possible. At least one patent also claims that Friedel-Crafts alkylation is possible.

For now, you just add it to your inventory of chemicals - you will find some interesting experiments to do with it later on.


and Thanks Nicodem!?! :o

not_important - 16-6-2010 at 06:46

-
A silly trick is to put roughly equal amounts of solid pDCB and camphor (natural or synthetic) in a test tube together, they soon form a liquid - in effect dissolving in each other. If you crush each finely beforehand, as well as a little naphthalene, and layer pDCB, a thin layer of naphthalene, and then camphor, in a test tube, they will remain solids for awhile - to a casual view the tube appearing to contain a white powder as the 3 layers are not greatly different in appearance. Shake the tube, the camphor and pDCB mix and liquefy, and dissolve the small amount of naphthalene, giving a single transparent liquid in the test tube.

Liquid pDCB is a solvent for polystyrene, and for sulfur at temperatures from around 100 C to around the melting point of sulfur; the camphor-pDCB liquid also dissolves polystyrene. On cooling back to room temperature some of the dissolved material comes out of solution, giving a somewhat milky to fractured glass appearance to the solid. If left to sit exposed to the air for some time, the pDCB sublimes away, leaving the polystyrene or sulfur as a network of fine threads and thin plates forming a sparse, fragile sponge.


Fluxor - 16-6-2010 at 10:29

Quote: Originally posted by not_important  
-
A silly trick is to put roughly equal amounts of solid pDCB and camphor (natural or synthetic) in a test tube together, they soon form a liquid - in effect dissolving in each other. If you crush each finely beforehand, as well as a little naphthalene, and layer pDCB, a thin layer of naphthalene, and then camphor, in a test tube, they will remain solids for awhile - to a casual view the tube appearing to contain a white powder as the 3 layers are not greatly different in appearance. Shake the tube, the camphor and pDCB mix and liquefy, and dissolve the small amount of naphthalene, giving a single transparent liquid in the test tube.

Liquid pDCB is a solvent for polystyrene, and for sulfur at temperatures from around 100 C to around the melting point of sulfur; the camphor-pDCB liquid also dissolves polystyrene. On cooling back to room temperature some of the dissolved material comes out of solution, giving a somewhat milky to fractured glass appearance to the solid. If left to sit exposed to the air for some time, the pDCB sublimes away, leaving the polystyrene or sulfur as a network of fine threads and thin plates forming a sparse, fragile sponge.



Thank you friend!:) ....And to think I was about to get rid of it...(actually, take it to a hazardous waste facility). Glad I had second thoughts and posted here.


Sandmeyer - 17-6-2010 at 17:05

Quote: Originally posted by Nicodem  
The only one I can think of is the synthesis of hexachlorobenzene, but this is not for some beginner as it requires hazardous conditions: heating of p-dichlorobenzene in concentrated sulfuric acid with trichloroisocyanuric acid. Besides the product is toxic and a possible carcinogen (it was used as a fungicide but not anymore). It is not dangerous for an experienced chemist with proper equipment and a fume hood, but certainly not appropriate for a beginner's experiment where things often go wrong when they can go wrong.
It does react with strong nucleophiles under forcing conditions by the addition/elimination mechanism (NAS substitution), but relatively easily with S-nucleophiles. Only one Cl gets substituted with O- and N-nucleophiles


:o I wouldn't try to substitute -Cl for -OH on hexachlorobenzene! My guess is that under the basic conditions the pentachlorophenol condenz to give octachlorodibenzodioxin. I do not know the dangers associated with this compound, but I know that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is nothing I would like to produce in my lab since it is extremely potent mutagen (remember the chlor-acne face of that former Ukraine prezident). Even if the condensation to the heterocycle is a minor side reaction it might make enough compound to ruin your life (and your coming children) if you are not cautious. TCDD is nasty since the organisms have trouble metabolizing it and I can't see where metabolizm would attack octachlorodibenzodioxin either, although it might not be as toxic, but Fluxor, I would advise you not to mess around mixing hexachlorobenzene with NaOH/KOH to make the pentachlorophenol...

woelen - 18-6-2010 at 09:32

Don't make Fluxor afraid. You are talking about hexachlorobenzene, he has p-dichlorobenzene. Fluxor will need to go along a difficult route before he has hexachlorobenzene. With p-dichlorobenzene you can do some funny physics experiments and from a chemical point of view it indeed is best for Fluxor to wait some time before he has more experience/knowledge.

Nicodem - 19-6-2010 at 07:01

Quote: Originally posted by Sandmeyer  
Quote: Originally posted by Nicodem  
The only one I can think of is the synthesis of hexachlorobenzene, but this is not for some beginner as it requires hazardous conditions: heating of p-dichlorobenzene in concentrated sulfuric acid with trichloroisocyanuric acid. Besides the product is toxic and a possible carcinogen (it was used as a fungicide but not anymore). It is not dangerous for an experienced chemist with proper equipment and a fume hood, but certainly not appropriate for a beginner's experiment where things often go wrong when they can go wrong.
It does react with strong nucleophiles under forcing conditions by the addition/elimination mechanism (NAS substitution), but relatively easily with S-nucleophiles. Only one Cl gets substituted with O- and N-nucleophiles


:o I wouldn't try to substitute -Cl for -OH on hexachlorobenzene! My guess is that under the basic conditions the pentachlorophenol condenz to give octachlorodibenzodioxin. I do not know the dangers associated with this compound, but I know that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is nothing I would like to produce in my lab since it is extremely potent mutagen (remember the chlor-acne face of that former Ukraine prezident). Even if the condensation to the heterocycle is a minor side reaction it might make enough compound to ruin your life (and your coming children) if you are not cautious. TCDD is nasty since the organisms have trouble metabolizing it and I can't see where metabolizm would attack octachlorodibenzodioxin either, although it might not be as toxic, but Fluxor, I would advise you not to mess around mixing hexachlorobenzene with NaOH/KOH to make the pentachlorophenol...

Hm, I guess my review of the p-dicholorobenzene reactivity had an ambigous start. The reactions listed are in regard to p-dichlorobenzene and NOT hexachlorobenzene. Hexachlorobenzene is not that scary. We have half a kilo of it at my job, but nobody yet figured out what to do with it. Still I do agree and like I already said before, it is not an appropriate target for a beginner. But some other reactions on p-dichlorobenzene can be interesting for amateur chemists. Some that can be run under relatively mild conditions should be fine for beginners as well (for examples, bisarylating it by a Suzuki coupling is a nice introduction to the Pd- or Ni-catalysed coupling reactions).

woelen - 28-6-2010 at 02:46

I did a funny little experiment with p-dichlorobenzene. I took approximately 2 grams of the solid and put this in a test tube. I heated this material, such that it became a colorless mobile liquid (I didn't measure the temperature, but it was not really hot, at most 75 C or so). To this liquid I added a tiny speck of solid iodine. This dissolves with a beautiful purple color. Next, I let the liquid cool down slowly. At a certain point in time, it solidifies, but when this happens a peculiar effect can be observed. The liquid first solidifies at the glass walls (which is expected, heat is lost through the glass walls of the test tube), but the solidified material is colorless! Slowly the solidification goes more inwards and the colorless layer reaches a thickness of well over 3 mm. Finally, when all of the material has solidified, a dark core is in the middle of the sample and a colorless/transparent layer is around the core.

So, two remarkable effects can be observed:
1) The freezing process removes the impurity of the iodine to quite a large extent.
2) The color of the dissolved iodine changes from purple to brown when the liquid solidifies.

This is a cute and safe experiment, which may be interesting for Fluxor as well. Iodine can be made from KI, some acid and dilute H2O2. You just need a few specks.

Cleanup after this experiment can be done by heating the material again, such that it becomes liquid again. Then the liquid can be poured out on a paper tissue (do this outside) and the paper tissue can be put in the household waste. The test tube then can be rinsed with 1 to 2 ml of acetone or petroleum ether. The liquid can be evaporated outside on a paper tissue and when most of the liquid has evaporated the tissue can be put in the household waste. Two or even three rinses may be necessary to make the test tube really clean.

[Edited on 28-6-10 by woelen]

Fluxor - 28-6-2010 at 07:20

Thanks for that, woelen. This sounds like something I'd like to do. I may try the experiment today, in fact!

I don't have KI in stock in my home lab right now, but I do have tincture of iodine, H2O2 (3%), HCL (10.3M) from which I can make I crystals by mixing the three chemicals, filtering, and then evaporating the precipitate to dryness.

I know this is an inefficient way to obtain elemental iodine but I'm planning to place a large order in about a month to round out my lab stock, so I will soon have KI. I checked the Readily Available Chems website but an OTC source for KI is not mentioned.

Greatly appreciate your ideas for experimentation. Thank you once again.

Ozone - 28-6-2010 at 10:16

I wouldn't be surprised if the purity of your sublimed product exceeds that of the original contents.

p-DCB can also be obtained from urinal cakes.

It looks like p-DCB can be reacted with sodium sulfide (Na2S) to give poly(p-phenylene sulfide), which might be interesting:

http://en.wikipedia.org/wiki/Poly(p-phenylene_sulfide)

I attached a paper detailing the preparation (and mechanism) of this polymer.

Cheers,

O3

[Edited on 28-6-2010 by Ozone]

Attachment: Poly(p-phenylene sulfide)_Fahey et al, 1997.pdf (341kB)
This file has been downloaded 1309 times


woelen - 28-6-2010 at 12:02

Ozone, your reaction must be done using N-methylpyrrolidinone as a solvent. This does not sound like something most home chemists have on their shelves. In aqueous solution this polymerization reaction cannot work, because p-dichlorophenol does not dissolve in water.

Ozone - 28-6-2010 at 19:03

I thought N-methylpyrrolidinone could be had from "green" paint strippers:

http://www.popularwoodworking.com/features/finish7.html

A fairly "innocent" product that is NMP, 99%:

http://talasonline.com/photos/msds/MSDS_NMP.pdf

I suspect that other polar aprotic solvents might work as well, e.g. N,N'-DMF. See:

http://www.freepatentsonline.com/4038263.html

Specifically, "The organic amides for use in the process of this invention should be substantially liquid at the reaction temperatures and pressures employed. The amides can be cyclic or acyclic and can have 1 to about 10 carbon atoms per molecule. Examples of some suitable amides include formamide, acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-ethylpropionamide, N,N-dipropylbutyramide, 2-pyrrolidone, N-methyl-2pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, N,N'-ethylenedi-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, and the like, and mixtures thereof."

I attached the supplimentary material from this patent.

Cheers,

O3



Attachment: US4038263-phenylenesulfide.pdf (230kB)
This file has been downloaded 316 times


Nicodem - 12-8-2013 at 07:06

Quote: Originally posted by Nicodem  
Under rather extreme conditions it can even be acylated via the Friedel-Crafts reaction (for example with phthaloyl chloride and AlCl3 at 120°C, or acylation with MeCOCl at 150°C!).

An example of the Friedel-Crafts benzoylation of 1,4-dichlorobenzene can be found at Synthetic Pages: 2,5-Dichlorobenzophenone (DOI: 10.1039/SP584).

Synthesis of substituted aromatics from paradichlorobenzene

Elemental Phosphorus - 20-10-2017 at 15:23

Recently, while going through some old boxes, I found a bunch of old bottles of pesticides. I also found some moth killing crystals that claim to be pure paradichlorobenzene. They seemed just too good not to use for some chemistry, the crystals are clear and appear to be pure, so I thought I'd have a go at synthesizing some double substituted aromatics. (I don't know anything beyond very basic organic chemistry). Anyhow, perhaps someone here can help. I am now unsure what to make (no guaiacol), but can I convert the paradichlorobenzene to a bromo or iodo compound?

Edit: removed mentions of guaiacol synthesis, for obvious (but apparently not obvious enough to me) reasons.

The can ;):


IMG_0086.JPG - 1.2MB IMG_0087.JPG - 1MB

[Edited on 21-10-2017 by Elemental Phosphorus]

Elemental Phosphorus - 20-10-2017 at 16:17

Right, I'm a complete idiot. I'll have to settle for something para-substituted then. How could I have made such a lapse as to suggest the synthesis of an ortho-substituted compound. But perhaps it could be converted to the iodide by treatment with sodium iodide (of any other alkali iodide) in acetone solution. Anyway I'd honestly have this thread deleted at this point.

Edit: The route with sodium iodide I described will not work. The reaction only works when the organic iodide is insoluble in the reaction solvent, but the chloride is. Also, it should not work on compounds where the chlorine is on the benzene ring directly and not a side chain.

[Edited on 21-10-2017 by Elemental Phosphorus]

clearly_not_atara - 20-10-2017 at 17:42

:p I think you could substitute the chlorines with something, but because they're chlorines, you'd need a copper catalyst and ligands. If this sounds like your cup of tea, keep at it, but if making pyridine or 2,2'-bipyridine or 1,10-phenanthroline or maybe ethyl nicotinate all sounds like too much trouble, then you may not find success.

The first hydrolysis should be pretty fast, so maybe you could make p-chlorophenol or p-chloroanisole?

http://www.orgsyn.org/demo.aspx?prep=cv5p0102

I wonder if Urushibara nickel can be used?

EDIT: No Finkelstein on aryl halides, sorry.

EDIT2: The diol used here:

http://pubs.acs.org/doi/abs/10.1021/jo900438e?journalCode=jo...

can be prepared by the rxn of maleic anhydride with anthracene and reduction with LAH

Someone did it with palladium and sodium methoxide under PTC:

http://onlinelibrary.wiley.com/doi/10.1002/anie.201000576/fu...

I've looked high and low for substitutions of aryl chlorides and the only practical methods go by the intermediacy of organometallic reagents.

EDIT3: Let's follow up on the organometallic for a minute. Anhydrous chromium (II) salts and nickel halide catalyst make aryl Nozaki reagents:

http://en.wikipedia.org/wiki/Nozaki_reaction

These condense with aldehydes or maybe some other moieties of interest...

[Edited on 21-10-2017 by clearly_not_atara]

AvBaeyer - 20-10-2017 at 19:14

Chemically, p-dichlorobenzene is not useful for very much because of its lack of reactivity. That being said, however, it can be mononitrated which then renders the chlorine ortho to the nitro group readily displaceable. For example, the chlorine can be displaced by amines, sulfur (eg, mercaptans) and oxygen (eg alcohols). If you are interested, I can dig up a reference to the nitration which is in an undergrad lab manual that I have stashed somewhere. You could also do a google search on the nitration of p-dichlorobenzene and find the procedure.

Another use if your sample is pure enough is for molecular weight determination by melting point lowering. This was a pretty standard procedure and a description of it can be found in older organic qualitative analysis textbooks. Its not used anymore since mass spec is so easily available.

AvB

Elemental Phosphorus - 21-10-2017 at 06:22

Actually, I searched for mononitration of paradichlorobenzene, and I didn't find much, so the reference would be appreciated.

Edit: I found a procedure. I am not sure if it is similar to yours, but I can't imagine it is much different, so here it is (from PubChem):

Nitration of 1,4-dichlorobenzene with mixed acid at 35-65 deg C results in a 98% yield of essentially pure 1,4-dichloro-2-nitrobenzene.
Booth G; Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2012). New York, NY: John Wiley & Sons; Nitro Compounds, Aromatic. Online Posting Date: June 15, 2000

[Edited on 21-10-2017 by Elemental Phosphorus]

[Edited on 21-10-2017 by Elemental Phosphorus]

AvBaeyer - 21-10-2017 at 21:02

For the nitration procedure of p-dichlorobenzene and some reactions of the nitro compound search on Google:

"Fundamental Processes of Dye Chemistry" for a free download.

Examine pages 108ff for the pertinent information. Actually, the entire book is quite interesting and useful.

AvB

Nicodem - 22-10-2017 at 00:09

Quote: Originally posted by Elemental Phosphorus  
Actually, I searched for mononitration of paradichlorobenzene, and I didn't find much, so the reference would be appreciated.

You must have misspelled something. It took me 1 minute to find the articles for mono- and dinitration using the forum search engine:

mononitration of p-dichlorobenzene
dinitration of p-dichlorobenzene

Elemental Phosphorus - 23-10-2017 at 12:00

Alright, so I nitrated 5 grams of paradichlorobenzene in mixed acid at about 50-100 degrees Celsius (I accidentally went a little overboard on the heating) for about an hour. I got a yellow, water insoluble product. I'll have to weigh it and do some tests on it soon. Anyway, here are some photos of the reaction.

The starting paradichlorobenzene:


The reaction itself:


The final product:

IMG_0088.JPG - 1.2MBIMG_0100.JPG - 1.4MBIMG_0106.JPG - 1.1MB

SWIM - 23-10-2017 at 15:49

Intergalactic_Captain made some of this back in 2005 and reported it to be very irritating to eyes mouth and nose.
He got a little on his hands and it was transferred to his face later inadvertently.

So be careful to wash up and you might want to consider gloves.

I just saw this one report, so it could be erroneous.

It's in the
paradichlorobenzene -> chlorobenzene?
thread



[Edited on 23-10-2017 by SWIM]

Boffis - 25-10-2017 at 07:11

Once you have nitrated it (p-DCB) the chlorine in the ortho position to the nitro group should be activated towards substitution as is the case with 2,4 dinitrochlorobenzene, though I suspect its not quite as active but enough to replace the ortho Cl with OH, SH or NH2 groups. The chloro group in the para position can then be removed by hydrogenation (see US 4207261 Preparation of o-phenylenediamine from p-dichlorobenzene).

It may also be possible to reduce the nitro group to give 2,5-dichloroaniline and then nitrate this further, though the result may be a mixture of isomers and mono and dinitro substituted compounds. Someone with reaxsys may want to have a look and see if they can find a reference to such a nitration.

I have done a bit more digging and found a Chinese patent that claims that 2,5-dichloroaniline can be nitrated as its acetylated derivative to give the 4-nitro aniline that is then reduced to 2,5-dichloro-p-phenylenediamine.

I also found a University of Iowa dissertation on the uses of p-dichlorobenzene from 1919. So most of the reactions are reasonably repeatable for a well equipped amateur apart from the ones that require oleum but you may be able to get away with alkali nitrate and excess conc sulphuric acid at higher temperatures.

Elsewhere on this forum I saw a reference to an Org Synth reaction for dechlorinating chlorobenzene to benzene. Has anyone ever tried this with pDCB?

Attachment: Manufacture of 2,5-dichloro-p-phenylenediamine Chinese Patent CN 1974540 B.docx (20kB)
This file has been downloaded 172 times

[Edited on 25-10-2017 by Boffis]

Attachment: A study of paradichlorobenzene IowaUni Dissertation J H Crowell 1919.pdf (4.8MB)
This file has been downloaded 126 times


Elemental Phosphorus - 25-10-2017 at 10:04

Yes, I would like to substitute the ortho chlorine with an alcohol. Perhaps someone knows of a procedure? Also in response to SWIM, I do use gloves when conducting most reactions, so I did not experience any irritation. Unfortunately, I am not set up to hydrogenate, so that's not an option.

Elemental Phosphorus - 1-3-2018 at 14:41

Late update, but I found my nitrated paradichlorobenzene product to be soluble in acetone and anhydrous isopropyl alcohol. All of the product was dissolved in about 30mL of 50/50 isopropyl alcohol-acetone mixture. 5 grams of sodium hydroxide was added, a large excess, and heated with strong stirring.

The solution's color changed from yellow (like the starting nitrated paradichlorobenzene) to a dark crimson red that was relatively opaque. After about 15 minutes, the solution was almost boiling. 20mL of water was added, and the solution was brought to a boil. Then, all of the remaining water and solids were transferred to a large beaker, more water was added, and everything water-soluble was discarded. The remaining solids were broken up, washed again, and then recrystallized by dissolving them in hot acetone and boiling it off.

This yielded a brown (dark crimson red in solution) solid that did not form large crystals. It was not hard and relatively easy to remove from the flat bottomed flask in which it was dissolved in acetone and recrystallized. It had a smell like paradichlorobenzene, but mustier.

This was all in an attempt to replace the chlorine next to the nitro group with a hydroxyl group.

I can post pictures of the product, weigh it, test its solubility, etc. if necessary. Was this sufficient to replace the chlorine with an OH group?
Thanks to Nicodem, AvBaeyer, Boffis, clearly_not_atara and SWIM for the suggestions.


[Edited on 1-3-2018 by Elemental Phosphorus]

Boffis - 2-3-2018 at 10:23

Well, the first problem I see is the presence of acetone as a solvent in the presence of sodium hydroxide which is likely to cause the acetone to turn into resinous crap if the reaction mention in my second point below does react with it first.

When some nitrohalobenzenes are heated with alcoholic hydroxide solutions they yield the appropriate halophenyl ether. Unfortunately many are reduced to azo or azoxybenzene compounds. There is a paper posted on SM that details these compounds and I believe it reducing agent too under these forcing conditions. As you can see from these comments there is a lot of scope for side reactions. The desired product 4-chloro-2-nitrophenol should be colourless when pure.

I would suggest trying this reaction with a strong potassium hydroxide solution. Although the nitrohalo compound isn't soluble in KOH the reaction product is. I am sure I have a reference to the preparation of 2-nitro-4-chloroaniline by fusing the nitrohalo compound with urea.

I'll see if I can find these references.

Elemental Phosphorus - 12-3-2018 at 14:52

Yes, there were a lot of problems with my process. Right now I only have fuming nitric acid, and while I could obviously dilute it, will it create a di-nitro product if I use it directly in mixed acid nitration?

Anders Hoveland posted a graph:

Here is a graph which shows that the paradichlorobenzene is mostly consumed after 15 minutes using 12M (molar concentration) HNO3, at only 10 °C.
http://www.chem.uiuc.edu/weborganic/arenes/Nitration/diClben...

Is it possible that at higher temperatures and using concentrated sulfuric acid as well that some of the di-nitro derivative may have been produced?
I will try again using the method you outline, but would you suggest using KOH in water, or alcohol (which alcohol, I have anhydrous methanol and isopropanol, but not ethanol) and if so, under reflux, or at room temp, etc. Naturally I would tend to think that reflux would be best, but I don't know.
(Polverone or woelen, can I have access to references?)




Boffis - 14-3-2018 at 05:39

Hi Elemental Phosphorus; I prepared a large amount of the mononitro compound using standard 68% nitric acid some years ago and now have rather a lot of it. I looked into dinitration and if you have fuming nitric acid this is possible, however, the the process yields a difficult to separate mixture of of 2,3; 2,5 and 2,6 dinitro compounds. There is a good deal of literature available on this nitration and the subsequent separation. If you are interested I can dig out and bundle up the papers but some have already been linked to above (Nicodem).

These papers also contain a fair amount of information about preparing the diamino derivatives too.

clearly_not_atara - 4-8-2018 at 12:37

Sulfonation of p-dichlorobenzene occurs in 10% oleum:

https://books.google.com/books?id=eopPAQAAMAAJ&pg=PA152&...

The resulting 2,5-dichlorobenzenesulfonic acid is very strong, comparable to perchloric acid, but much more stable.

wg48temp9 - 30-5-2019 at 15:16

Any progress on getting the chlorines to react without having to nitrate it first and preferable not involving an autoclave?

Boffis - 8-6-2019 at 12:49

@ wg48temp9; I think the simple answer to your question is "no".

What are you interested in or what is your aim? Why not through the nitration route? Mononitration is easy with sodium nitrate and sulphuric acid, there is no other easy "amateur friendly" route from this compound to anything even sulphonation requires oleum.

I have never found any reference to chlorosulphonation of p-dichlorobenzene with chlorosulphonic acid but this should work too; again not really amateur friendly.

[Edited on 8-6-2019 by Boffis]

[Edited on 8-6-2019 by Boffis]

wg48temp9 - 8-6-2019 at 14:16

Quote: Originally posted by Boffis  
@ wg48temp9; I think the simple answer to your question is "no".

What are you interested in or what is your aim? Why not through the nitration route? Mononitration is easy with sodium nitrate and sulphuric acid, there is no other easy "amateur friendly" route from this compound to anything even sulphonation requires oleum.

I have never found any reference to chlorosulphonation of p-dichlorobenzene with chlorosulphonic acid but this should work too; again not really amateur friendly.

[Edited on 8-6-2019 by Boffis]

[Edited on 8-6-2019 by Boffis]


My aim was to use a OTC compound that may provide access to interesting reactions and synthesises (or is it synthei). I thought PDB was now not OTC but I recently found it is still available though it is expensive at £10/100g.
There was also one seller that claimed their old fashioned mothballs was PDB, well perhaps it was old stock.

XeonTheMGPony - 9-6-2019 at 06:23

Nope I have brand new moth balls, in Canada and they where the good ol stuff

clearly_not_atara - 10-6-2019 at 14:55

So I have found on Orgsyn a method where o-nitrophenyl chloride is converted to the bis-aryl disulfide by treatment with sodium sulfide and sulfur in ethanol with Na2S2 forming in situ:

http://www.orgsyn.org/demo.aspx?prep=cv1p0220

In a 3-l. round-bottomed flask fitted with a reflux condenser are placed 360 g. (1.5 moles) of crystalline sodium sulfide (Note 1) and 1.5 l. of 95 per cent alcohol. The flask is heated on a steam bath until the sulfide dissolves. Then 48 g. (1.5 atoms) of finely ground sulfur is added, and the heating is continued until the sulfur has dissolved, forming a brownish-red solution of sodium disulfide (Note 2).

This reaction is effective in refluxing ethanol without an autoclave. In our case the reaction should be even faster since the 4-chloro provides additional activation towards SNAr.

Oxidation of the disulfide with chlorine in aqua regia gives the sulfonyl chloride:

http://www.orgsyn.org/demo.aspx?prep=CV2P0471

This is a fierce choice of rxn conditions of course; I think that this may be done to avoid any reduction of the nitro group by the intermediate sulfenic and sulfinic acids which would lead to the formation of polymeric side products.

I think that perhaps the use of ozone could be attempted in this case. Of course, it is more dangerous than chlorine... but much easier to generate at low flow rates.

PirateDocBrown - 11-6-2019 at 02:38

I'm thinking it would be possible to cajole PDCB to react with sodium alkoxides, provided you have polar, aprotic solvent.

Chlorines will deactivate the pi electrons, sure, but catalytic amounts of silver oxide can push things forward.

From there, you would have an ether, and further substitution would be much easier.

My local Wal-Mart had some PDCB mothballs, maybe I'll play with it some when I have some time.

I'm thinking translithiation might also be possible, allowing a route for reaction with alkyl halides.


[Edited on 6/11/19 by PirateDocBrown]