Sciencemadness Discussion Board - 'newbie' Chlorination Of Toluene via Calcium Hypochlorite

'newbie' Chlorination Of Toluene via Calcium Hypochlorite

drfro2 - 2-7-2009 at 15:58

Hey everyone,

Im new to this forum and wouldn't mind some help from people with a greater chemistry understanding than myself,

I would like to make Benzyl Chloride via Toluene and Calcium Hypochlorite,

What i would like to know is,

What light is best used in this reaction?
What are the risks involved? such as explosions and or gas
What is the recommended equipment/apparatus for this synthesis?
How long does the reaction take?
How will i know i have Benzyl Chloride when im done?
And at what temperature will the reaction safely take place?

Also if someone could explain the steps for this procedure for it would be much appreciated

entropy51 - 2-7-2009 at 16:09

Welcome Dr Fro. Abandon hope all ye who enter here.

It's generally considered bad form to post without searching first. Practically everything imaginable has been discussed here in the past.

Click "Search" at the top of the page, enter benzyl chloride in the search box, select "subject only" and "all forums" and you will be truly amazed by how many threads are returned for your viewing pleasure.

Feel free to visit the forum library, accessible from the home page. There are many textbooks and lab manuals available for FREE download that will answer many of your questions. Enjoy!

Once you have some of the basics down, you could then ask specific questions that are less "newbie".

I hope this information is helpful to you!

drfro2 - 2-7-2009 at 16:31

I was surprised to get such a fast reply lol,

I am aware that when entering a new forum people like newbies to read through already existing material, hence excluding the need for constant re-discussion of topics,

I have read mostly all the threads floating around this topic but there are so many conflicting opinions,

What im looking for is a synthesis thats tried and tested by someone on here, I could not find this because everyone seems to have a different opinion, I could not find a post where someone discussed their materials, equipment, steps and yield,
this is why i started this post,

However if i just missed this and there is a post like that, please link me to it

I am aware there are easier ways to do this such as with benzyl alcohol and hydrochloric acid,

But seeing as toluene is is $10 a litre here and Ca(ClO)2 is around $15 per kg i tought i would give this reaction a go,

After reading for a few weeks im confident i can complete this reaction, i just need more of the specifics.

Any information and discussion would be much appreciated, not looking to start arguments

entropy51 - 2-7-2009 at 16:55

Dr Fro! You said "After reading for a few weeks im confident i can complete this reaction". But you also said
"What is the recommended equipment/apparatus for this synthesis?
How long does the reaction take?
How will i know i have Benzyl Chloride when im done?
And at what temperature will the reaction safely take place?"

Seems like your confidence may have gotten ahead of your knowledge!

Have you read Gatterman and Vogel in the Forum Library? Most of the questions you asked are answered in Gatterman!

You are right about BnOH + HCl being the best route! Chlorination of tolune is not to be attempted lightly.

For starters, did you look at this https://www.sciencemadness.org/whisper/viewthread.php?tid=10...

[Edited on 3-7-2009 by entropy51]

drfro2 - 2-7-2009 at 17:26

entropy51,

I asked those questions to be sure what i have been reading is fact, i dont intend to be taking this reaction lightly and am aware that chemisty involves risks, some of which are far greater than others.

All i am asking for are specifics, so i can carry out the reaction in the safest way possible, with a decent factual understanding of the task at hand,

If my confidence was ahead of my knowledge i would have already attempted this without the proper understandings and quite possibly had a disaster,

I posted the thread asking for help for this reason, in no way do i think i know all there is to know, this is why in my first post i wrote ''wouldn't mind some help from people with a greater chemistry understanding than myself''.

So obviously i need help, and am asking for specific steps from anyone who has successfully performed this reaction and has the proper understanding of the ideal conditions this reaction is to take place,

Also i tried that link and for some reason i wont allow me to access the page,

So yes i am confident i could carry out this reaction IF i was properly equipped for the task, had an understanding of tried and tested reaction conditions and also full understanding of the risks and hazards involved,

This is why im here, FOR HELP

I dont intend to be trying anything without a proper understanding, and when i do finally attempt this reaction it will be on a small scale so if anything does go wrong the risk is lowered.

not_important - 2-7-2009 at 17:40

The thread entropy51 is Len's excellent write-up on chlorinating toluene and hydrolysis of those chlorides. Until you've read that, I suspect few here will be interested in further helping you.

The link he gave was via https access, and as sciencemadness signs its own security certificate your browser probably didn't like that; a decent browser should have given you a message to that effect and allowed you the open to accept the certificate.

the plan old http link is http://www.sciencemadness.org/talk/viewthread.php?tid=10256

[Edited on 3-7-2009 by not_important]

drfro2 - 2-7-2009 at 17:45

not_important,

Thankyou for the reply,

The link works thankyou

Reading now!

entropy51 - 2-7-2009 at 17:57

OK, that link opens up for me. It's the Benzyl Cl thread by Len1 in Prepublications in the Special Topics Forum. It shows some of the glassware setups you would need. What type of glassware do you have? You really need glass with ground joints for this prep; corks don't take it well. You also need a fume hood! Chlorine is dangerous and BnCl is a very efficient tear gas.

Basically you heat toluene (flammable!) to reflux in a flask with a reflux condenser and a gas inlet tube passing into the toluene. With exposure to sunlight or sunlamp you pass in Cl2 gas for several hours. The top of the relux condenser is connected to a trap containing aqeous NaOH to absorb the fumes. Finally you distill off the product under vacuum, there is a forerun of unreacted toluene; Gatterman has details.

Taking everything apart and cleaning the glassware is a bear. It must be done inside a hood.

If you plan to generate the Cl2 using Ca hypochlorite, you should consult the ten page long chlorine thread here. The problem with using hypochlorite is that O2 is also generated, and that may very well screw up your reaction.

I'm really not trying to be argumentative, but you are likely to find more help here if you show some initiative to find out things on your own, using for example the forum library.

Thanks not_important, for pointing out the problem with https.

[Edited on 3-7-2009 by entropy51]

drfro2 - 2-7-2009 at 18:22

Thankyou for the information,

The glassware i currently have is varied somewhat, i have 2 x liebig condensers 1 x allihn condenser and 1 x graham condenser, 2 x 1 litre vacuum flasks, 2 x 1 litre rbf, 2 x 500ml rbf, 2 x 2 litre rbf, also a few different adapters like 3 way clasien and vacuum, 2 separatory funnels and just other general glass, Most have ground glass joints,

Glass isn't a problem for me to obtain so getting correct tools for the job isn't too hard,

The thread is very detailed and well written, definately alot more specific than another synthesis which i have read,

This is why i asked for help becuase i had read elsewhere that clacium hypochlorite and toluene could be added to a flask, with the presence of blue light, heated to 105C and refluxed,

It sounded far too simple to be true, does that method even work?

entropy51 - 2-7-2009 at 18:46

Adding Ca hypochlorite directly to toluene? I was afraid you were thinking of that and I should have warned you. The hypochlorite is a class I oxidizer and I certainly wouldn't want to try that. I think it might do something unpleasant or dangerous, but I doubt it will give benzyl Cl. Someone who knows better can correct me if I'm wrong.

I thought you would like Len1's writeup. There is a tremendous wealth of knowledge archived on this forum (also some that's less than accurate) so spend some time digging around and finding the good stuff. Again, welcome!

And heed Len1's warnings about the chlorinated toluenes. My advice is to get some experience with more friendly sytheses before trying this one.

drfro2 - 2-7-2009 at 18:52

Advice taken!

Thanks guys

Sedit - 2-7-2009 at 18:56

" I think it might do something unpleasant or dangerous, "

You get a nasty runaway.

drfro2 - 2-7-2009 at 19:07

Also,

For this reaction instead of a 3 neck rbf can i use a 4 inch neck reaction flask with 3 mouth adapter?

Sauron - 2-7-2009 at 20:01

Do you have a fume hood, goggles, respirator, etc?

Benzyl chloride is Not Nice. Toxic and lachrymatory.

Where I live it is a restricted dhemical by the MOD.

The best light is UV so sunlight, sun lamps, bright unfiltered quartz-iodide floodlights with heat glass plate removed skk work. BUT what is good for rxn is bad for your eyes and epidermis. Do not expose yourself to US even reflected or indirect.

Braille chem books are hard to come by.

not_important - 2-7-2009 at 20:02

Adding to the comments on direct mixing and heating of calcium hypochlorite and toluene, consider the following...

While hypochlorites themselves are oxidisers, in https://www.sciencemadness.org/whisper/viewthread.php?tid=10... the production of calcium chlorate from calcium hypochlorite. Heating chlorates and organic compounds together seems like a bad idea.

As Len noted in his write-up, chlorination of the aromatic ring is much more likely to occur in the liquid phase than in the vapour phase. Given that pool grade calcium hypochlorite isn't exactly reagent quality, there's a good chance it contains small amounts of one or more transition metals that catalyse hologenation of the ring. This means that your product will likely contain chlorinated toluenes (2; 4; 2,4; and 2,6 at least) and toluene derivatives chlorinated both on the ring and the methyl group.

And commenting on light sources, as Len notes you want light in the range of around 350 to 490 nm. Clear globe mercury vapour lamps put out a goodly segment of their light in this range, while generating far less waste heat than quartz-halogens.

[Edited on 3-7-2009 by not_important]

drfro2 - 2-7-2009 at 20:38

Sauron,

No i do not yet have my saftey equipment or fume cupboard, i am still in the process of buying all of my equipment,

I have begun reading len1's thread on the chlorination which is very interesting but still looks out of my league at the moment,

As for the toluene and calcium hypochlorite, has anybody actually completed this? or is it just a case of dont believe what you read on the internet?

Sauron - 2-7-2009 at 21:26

Another way to get to PhCH2Cl is by chlorination of benzul alcohol. A qide variety of reagents will work.

A third method is chloromethylation.

But NO method is a good idea unless/until you have the appropriate protective equipment.

Where on or off the Net does it say toluene can be alpha-chlorinated with calcium hypochlorite? I am not saying it is impossible. But it probably is not the best choice even for OTC. I would put TCCA ahead of it, just as an example.

drfro2 - 2-7-2009 at 22:18

http://www.designer-drug.com/pte/12.162.180.114/dcd/chemistr...

Is where I initially read it, but after reading len1's post i can also see its from my huge misunderstanding of how the reaction works aswell,

I just typed in benzyl chloride synthesis into google and thats how i found it.

[Edited on 3-7-2009 by drfro2]

Sauron - 2-7-2009 at 22:35

I wish that site wouls shrivel up and die. And if you are their habitue, that explains why you are so intent on benzyl chloride, next step phemylacetonitrile, after that phenylacetic acid, and then P2P.

Son't expect any assistamce from me.

drfro2 - 2-7-2009 at 22:50

Actually when i typed benzyl chloride synthesis into google,

That is one of the sites that came up,

I was actually looking for a synthesis to do with OTC chemicals when i saw a post someone had made on another science forum that toluene could be used to produce benzyl chloride,

Toluene can be bought at every hardware store here so i began to search the synthesis, the more i read i found it interesting and it looked challenging so i set out to find more information hence coming here,

Also if you are implying what i think you are, I would be on a drug forum not here!

I came to this forum looking to learn and for help from people who know about real chemistry! not to be a cook and land myself in jail for a good 25 years!

[Edited on 3-7-2009 by drfro2]

Nicodem - 2-7-2009 at 23:11

Drfro2, the literature is full of examples of toluene alpha-chlorination with Cl2 and several other reagents, yet you opened a thread without providing a single reference (this you are only allowed to do in the Beginnings section where I'm moving the thread) and asking questions that were already answered innumerable times, even on this forum. Keep in mind that you will unlikely get any useful reply without showing your effort and maturity. Considering this reaction simple when it is quite likely to give you a serious injury is a bit irresponsible in the context of your lack of doing a literature search.

entropy51 - 3-7-2009 at 07:56

Quote: Originally posted by Sedit

" I think it might do something unpleasant or dangerous, "

You get a nasty runaway.

Yeah, that's the second time this week someone has suggested adding a strong oxidizer to neat toluene. The other was chromyl chloride.

Must be time for nominations for the Darwin Award

Sedit - 3-7-2009 at 08:12

LOL what are you suggesting entropy

Im still alive and kicking so can I get to be runner up?

It was all very small scale though because it seemed like a bad idea to me also.

[Edited on 3-7-2009 by Sedit]

entropy51 - 3-7-2009 at 10:58

No No, Sedit. You were right on with your warning!

I couldn't even convince myself to try Ca(OCl)2 + toluene in a test tube on a 1/2 gm scale. I'm not good at predicting reactions, but this one doesn't pass the smell test.

But I knew better about the CrO2Cl2 because it's in the literature that a couple of chemists were blinded doing that back in the 19th century. And they used solvents too...just the wrong ones.

As Sauron says, there are old chemists, and bold chemists, but no old, bold chemists. I'm pretty old myself, and proud of it.

I sometimes wonder if the mods shouldn't be deleteing the dangerous stuff, instead of the name calling.

P.S. Woelen, to clarify I meant the plain stupid dangerous stuff you refer to, not the reactions that just require extra caution. And I agree with you that the forum members are generally very good at pointing out the hazards.

[Edited on 3-7-2009 by entropy51]

woelen - 3-7-2009 at 11:06

Quote:

I sometimes wonder if the mods shouldn't be deleteing the dangerous stuff, instead of the name calling.

No it would not be good at all if the moderators delete dangerous stuff. What is dangerous and what is not? Who decides for us? But when something plain stupid dangerous is posted without any warning, then it is much better if any of us (non-moderator) members tells and warns about that and then the moderators can decide what they want to do with the member or even move the thread to detritus (which is not the same as deleting it completely!).

I also sometimes do dangerous things (such as making chlorine azide

) but when I do so, I know that I am doing and I take measures to reduce the risk (most of the time the measure is simply using very small amounts of chemicals). In this particular thread there are warnings about the dangerous nature of Ca(ClO)2/toluene mixes and that is a good thing. I personally believe that the sciencemadness community is very good at regulating the spreading of all kinds of stupid/dangerous information and giving good and realistic warnings when stupid/dangerous things are posted.

entropy51 - 3-7-2009 at 16:33

Quote: Originally posted by Sauron

I wish that site wouls shrivel up and die. And if you are their habitue, that explains why you are so intent on benzyl chloride, next step phemylacetonitrile, after that phenylacetic acid, and then P2P.

Son't expect any assistamce from me.

I respectfully approach the Dark Lord with a question:

You seem to be vehemently against thinly-disguised drug threads as am I. In this thread you have said you will not offer assistance in the synthesis of BnCl, which is several steps removed from a precursor to a controlled substance.

But in the Phenyl-2-bromopropane thread, which is currently active, you have offered considerable advice, although this compound is a DIRECT precursor to a controlled substance.

Do you find these two positions to be somewhat inconsistent, as I do?

I make no accusations, but am just asking about the apparent inconsistency. I'm wondering if established forum members are being granted a "pass" that is not extended to newbies. If so, I think we should be a little more circumspect about the double standard.

[Edited on 4-7-2009 by entropy51]

DJF90 - 3-7-2009 at 16:57

I believe sauron is deciding to offer help where he feels it will not be wrongly used. I also do the same.

Paddywhacker - 5-7-2009 at 14:29

May I try and redeem this thread by suggesting a more chemical turn of conversation?

Compared with Xylene, Toluene is boring. Xylene has two methyl groups, and is a mixture of isomers as wall.

Has anyone anything to tell about subjecting Xylene to these oxidation and chlorination reactions?

drfro2 - 5-7-2009 at 14:37

Xylene is still OTC here and readily available,

What reactions can be done with this that are relatively easy?

Sedit - 5-7-2009 at 14:52

"Has anyone anything to tell about subjecting Xylene to these oxidation and chlorination reactions? "

I tryed this very reaction on Xylene to get my feet wet and it makes the run away experianced with toluene seem tame because it takes off very quickly. Toluene runs away but it does so in a way that you know its comming IE you start to see the Toluene reach a rolling boil and then take off where as Xylene goes from a few faint bubbles to a hell storm of boiling hot xylene spewing Cl fumes everyware. The hypochlorite route should just not be used as TCCA is to avalible in a purer form.

Notes say:

Quote:

47.6% Ca(OCl)2 pool shock and Xylene was Heated till temperature reached 105-110 degrees F at which point a runaway takes over and temperature soars to about 220 degrees F then cools to about 170 degrees in a matter of minutes. leaving with a yellow solution.

Never tryed to isolate anything because I was just running some test and pretty much playing around at the same time. The bulk of 47% pool shock prohibited using this in any real sence because 1/4 of the amount thats needed will completely engulf the amount of Xylene or Toluene used.

DJF90 - 5-7-2009 at 16:00

Did you try portionwise addition over a reasonable period of time?

drfro2 - 5-7-2009 at 16:37

DJF90,

You mention adding portionwise over a period of time,

So if i was to add small portions of Ca(ClO)2 to toluene in the presence of light, spacing additions of the portions by allowing each portion to react with the toluene, could this lower the chance of a runaway reaction?

Also would having the toluene on an ice bath while adding portions make a difference to this?

entropy51 - 5-7-2009 at 16:53

Perhaps you two should read Sedit's advice again, because he has actually performed an experiment:

"The hypochlorite route should just not be used as TCCA is to avalible in a purer form."

Many a big fancy theory has been demolished by one dirty little experiment.

Sedit, thanks for posting your results. I for one am paying attention to your words of wisdom.

Sedit - 5-7-2009 at 17:11

Quote: Originally posted by DJF90

Did you try portionwise addition over a reasonable period of time?

No, more then likely should have though. It was all small test tube scale anyway gearing myself up for the chlorination of toluene. The volume of 47% Ca(OCl)2 is just to much to perform this synthesis correctly though.

Quote:

Also would having the toluene on an ice bath while adding portions make a difference to this?

Sure would. Reaction can't runaway if its not taking place at all right.

Ill quote from the paper you got your procedure from

Quote:

Toluene and dry Calcium Hypochlorite (bleaching powder) are heated together to 105°C in the abscence of other reagents. This avoids by-product formation. If equal amtounts are used, volume-wise, there is a high conversion. If more bleaching powder is used, the conversion is more robust, but contaminants such as benzal chloride and benzotrichloride are formed [...]

Now understand that when this chlorinates HCl is a by product and Ca(OCl)2 + HCl generates more chlorine.... I have tryed a few of the dirty little experiments as entropy rightly so called them and it was deemed that this reaction just sucks.

It was completely abandoned and the Ca(OCl)2 was used with H2SO4 to generate Cl2 and chlorinated that way instead of this insitu crap. I later found MnO2 + HCl and heat to be more reliable slow generator as I could speed up or slow down Cl2 generation with a little heat or lack there of.

Here is something I have recently been musing about for the chlorination of toluene. It is known that higher wavelengths work fast but they do not penetrate the toluene as well so we compromise by using a frequency somewhere around 400nm(sorry cant recall off the top of my head). Has anyone seen if higher frequency UV feed into the toluene using a bundle of fiber optics as to give larger surface area could speed up the reaction.

[Edited on 6-7-2009 by Sedit]

UnintentionalChaos - 5-7-2009 at 18:18

Quote: Originally posted by Sedit

Here is something I have recently been musing about for the chlorination of toluene. It is known that higher wavelengths work fast but they do not penetrate the toluene as well so we compromise by using a frequency somewhere around 400nm(sorry cant recall off the top of my head). Has anyone seen if higher frequency UV feed into the toluene using a bundle of fiber optics as to give larger surface area could speed up the reaction.

Well, allow me to propose this instead: having a quartz tube made like a cold finger with a ground joint without the top portion so that the UV source can be lowered down into the reaction vessel with minimal absorption by the glass. I've been wondering how much this would cost to have made, since it is rather custom, but not very complex.

a small air pump may be necessary to help cool the UV source in this case if it's a standard bulb.

However, 1W UV LEDs are available in the range of $10/ea. and put out UV mainly in the upper 300s. I wonder how these compare to typical UV sources.

[Edited on 7-6-09 by UnintentionalChaos]

entropy51 - 6-7-2009 at 14:25

The source of this prep is apparently US Patent 1280612. It calls for the toluene to be heated to about 90 C and the Ca(OCl)2 slowly added and the whole mess held at 100 to 105 for an hour with a reflux condenser.

I do not believe that the patent mentions UV irradiation.

I suppose hot toluene might react immediately rather than allowing a buildup of Ca(OCl)2 during an induction period following which it refluxes from the ceiling.

Danger Will Robinson!

[Edited on 6-7-2009 by entropy51]

[Edited on 7-7-2009 by entropy51]

Sedit - 6-7-2009 at 15:23

Addition in portions below the runaway temperature is interesting seeing as it did not APPEAR to react until the runaway occurs at which point the Toluene turns yellow indicating free Chlorine as opposed to the BnCl. As many know in organic chemistry just because it does not appear to happen does not mean that its not. Perhaps another small scale adding small spatulas of Ca(OCl)2 is in order to see if it still takes off when the temperature is raised.

Toluene + Cl2 ==hv==> BnCl + HCl

Ca(ClO)2 + 4 HCl → CaCl2 + 2 H2O + 2 Cl2 <== This is where I feel the runaway is taking place. Its not so much as a runaway chlorination but a runaway decomposition of the hypochlorite generating heat and speeding itself along at an ever increasing rate.

If the HCl dissolves in H2O is will allow it to react faster then opposed to if it was allowed to slowly boil out at first decreasing the HCl concentration. At 100 C give or take the H2O formed will start to boil and that could be the cause of alot of problems in the way of a more mobil reaction. I have not read the patent yet but will do so before attempting any form of test. I would sure like to hear Lens input on this as they have more knowlage of these reactions then myself.

Also Ca(OCl)2 decomposes under direct sunlight as per,

Quote:

A diluted aqueous solution of HOCl will decompose very slowly in the dark,
but more rapidly in the presence of light, particularly rapidly in full sun light, by producing hydrogen chloride and
oxygen. Some chlorine and chloric acid (HClO3) may also develop. The physico-chemical properties indicate that
chlorine released into the environment as HClO or Cl2 is distributed into water and air. Consequently, the effects
that may manifest in the natural environment are considered common to those assessed for the other source of
hypochlorite.
In the natural water, in the presence of organic or inorganic compounds, the free available chlorine immediately
reacts forming various chlorinated and/or oxidized by-products e.g. chloramines or chloromethanes.

Reference:http://www.inchem.org/documents/sids/sids/7778543.pdf

Makes me think that there is a possibility of placing a bottle of Toluene/Ca(OCl)2 out in the sun for a while(days maybe longer) may also achieve the same product under much more milder conditions. Orrrrrr you could have a massive out gassing of Chlorine and piss off your neighbors and kill all of your flowers.

not_important - 6-7-2009 at 20:20

Shorter wavelength isn't going to enhance the reaction rate. You need to disassociate Cl2, which means light wavelengths below 488 nm; shorter wavelengths will leave the Cl radicals with extra energy but only so much is needed to abstract the hydrogen. Past a point shorter wavelengths result in some of the energy of each photon just being wasted, not an increase in reaction rate. To make the reaction go faster you need more photos in the target wavelength range.

Look at the reaction rate peaks vs wavelength

from http://www.sciencemadness.org/talk/viewthread.php?tid=10256

Glass is transparent enough in the wavelength range needed, quartz/silica is just a waste of money.

UV LEDs are also overkill. Ordinary mercury lighting bulbs put out at least 10 times the useful energy per unit cost, as applicable to this reaction, as UV or even blue LEDs.

Lambda-Eyde - 7-7-2009 at 04:08

I've been thinking of something like that too, UC. Cooling was the first problem that came to my mind, however, a cool stream of air would probably be adequate.

A standard taper quartz joint isn't that costy, and considering that this apparatus is essentially nothing more than a short, closed tube with a male joint on the end I don't think it would cost much more than 15-20$ more than the joint itself.

Edit: Typo

[Edited on 7-7-2009 by Lambda-Eyde]

Sedit - 7-7-2009 at 05:58

As I understand it the glass is not what stops the higher wavelenghts but the Toluene itself will not let the UV pass more then a few mm. That web page that the black chart above is from explains the theory behind the chlorination nicely yet I can't seem to find it again. If anyone knows the address could you please post it.

drfro2 - 7-7-2009 at 17:07

I think the site you are talking about is one of these two links,

http://www.faizkaskar.8k.com/light.html

http://www.faizkaskar.8k.com/light1.html

Sedit - 7-7-2009 at 21:17

That looks like a partial clone of the site I was speaking of but it does appear to have some of the information there. Perhaps my memory just is not that great.