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Mendeleev
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Could benzyl chloride be effectively dried by mixing with calcium chloride and distilling? I am going to try this synthesis sometime next week and
will post my results.
[Edited on 2-7-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Mendeleev
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I tried the benzyl chloride synthesis today. I heated 500 mL toluene on a 95-98 degreee boiling water bath, then 210 grams of calcium hypochlorite, a
little less than half the mass of toluene. The loomis patent instructs one to use equal masses of bleaching powder, but it is only 35 % and super
pool shock from one of the links I posted earlier is 73%. My magnetic stirrer failed at this point because all the hypochlorite sunk to the bottom as
predicted, so I manually stirred it for several minutes. I then proceeded to relux the beaker by covering it with saran wrap and filling it the
indentation with ice, a la brainfever. The reaction proceeded for 4 hours and 40 minutes. I opened the apparatus halfway through to stir the
contents for several minutes.
Everything seems fine except for one thing, when I opened it, I did not notice any of the tear gas effects everyone has described. This means one of
4 things.
1. The temperature was too low and chlorobenzene was formed instead.
2. The high boiling point of benzyl chloride means there wasn't to much of it in the air.
3. The claim that leaving an open container of benzyl chloride for five minutes outside of a fume hood will cause one to cry for half an hour is
false.
4. I am somehow resistant to tear gas. Unlikely.
So, any input/tips? What is the minimum temperature which will prevent significant chlorination of the ring and the formation of chlorobenzene?
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Marvin
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Chemistry does not work on faith. Buy some glassware, do some fractional distilling, find out what youve made if anything.
You are using hypochlorite instead of bleaching powder, maybe this will cause the reaction to fail, after all it wont produce chlorine when acidified,
you need chloride as well to do that. Maybe what you have is hydrated, did the patent say anhydrous? Maybe that will cause the reaction to fail.
Altering a reaction and then doing it very badly could do anything, might do nothing, its not a question for chemists, try ringing a psychic hotline.
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Mendeleev
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Jeez man, I was just asking for some advice, you didn't have to be so mean  .
Just kidding. I didn't alter the reaction that much. I put it on a water bath instead of 105 C because I would rather have a failed reaction
than a lost limb. As far as bleaching powder vs. purer hypochlorite goes, the reaction calls for calcium hypochlorite, not bleaching powder, its just
that in the early 1900's, when the patent was written bleaching powder was the main form of calcium hypochlorite available, the other 65% are
inert calcium salts that have no effect on the reaction. Is a beaker not glassware? Furthermore, my method is based on previous attempts by other
people. There is a good thread in the hive called benzyl chloride from hypochlorite salts in which a glass coffe pot, pool chlorinator tablets, and
paint can toluene are used on a water bath for around four hours without drying any of the ingredients. The reaction time is lengthened to compensate
for the lower temeprature. This is not that different from the way I did it. The importan tquestion still stands, what is the minimum temperature
which will prevent significant ring chlorination? I searched google and could find nothing useful.
[Edited on 15-7-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Organikum
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1. Calcium hypochlorite so dry works better than bleaching powder. This is even mentioned in the patent.
2. In UV catalyzed chlorinations using Cl2 85°C is named as the lower limit for temperature. There is no defined borderline though. At 40°C you
have lots of ringchlorination.
You should have realized when the reaction kicked in, if you are not sure on this, it didnt happen. The Loomis procedure gets VERY exothermic and this
happens VERY sudden.
You had no reaction taking place. Not enough temperature to kickstart it.
I would say after what you told at least.
ORG
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Mendeleev
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I tried this on a smaller scale, one fourth of what I attempted and this time kept it on the hot plate directly, so temperature was 103 to 104.
However it was a pain in the ass, the toluene fumes made me dizzy, and constantly manipulating the hot plate knob was a pain in the ass. I did get
some benzyl chloride this time, my eyes were red and itchy and kept sneezing. So, I want to try photo chlorination, I already have a mercury vapor
lamp and a chlorine generator connected to a U-tube filled with calcium chloride. Basically, I was wondering before I try this, will the U-tube
sufficiently dry the chlorine, and what precautions would I have to go through with the touene. It is klean strip brand in a metal paint can labeled
"100% pure toluene". It still probably has to many metal contaminants and water, no? I am currently drying it with calcium chloride, and
distilling it through a calcium chloride tube. Will this give me toluene of sufficient purity? Furthermore I would probably be able to use it
straight from the paint-can using the hexamine method?  Thanks everyone for your
help, you especially Organikum.
Edit: Will CaCl2 screw up the photochlorination reaction?
[Edited on 18-7-2004 by Mendeleev]
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Organikum
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To dry toluene you can boil away 1/10 of the volume and done. Any whe water will be removed azeotropically then. Thats a common labaoratory method.
For all this you need a powerful condensor and an exhaust line ending over lye. Look in the Vogel´s 3rd (best version available is to find on our
ftp, its the OCR-pdf made by mephisto - recommended) and you may also take a look in the old "Gattermann" from 1909 available here from the
sciencemadness library (www.sciencemadness.org then go to "library" .
Read at least the Vogel´s 3rd on this, its written in fairly a understandable language and a "must read" here.
After my experience it is possible to substitute/improvise parts of the setup recommended in the book, but it is not possible to omit anyone. Say, you
can improvise washbottles/security-anti-suckback bottles/condensor/exhaust-gas-scrubber, but dont leave one away.
The reaction spits huge amounts of HCl (and some Cl2 escapes). The lye-scrubber is ESSENTIAL. This CANNOT be done open pot, no way.
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Mendeleev
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Don't use platic bottles out of the recycling as sulfuric acid wash bottles for chlorine, for chlorinating toluene. I had a bad experience with
that today. It made me realize I like fresh air. I moving back to the easier if more dangerous hypochlorite method, meanwhile I ordered some benzoyl
peroxide for the TTT method, which is neithre explosive nor toxic, but it is not clear yet whether it will work without carbon tetrachloride. I
believe it will, but the important thing is to have benzoyl peroxide as the promoter.
[Edited on 16-9-2004 by Mendeleev]
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Mendeleev
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Queer things happened with this reaction as of late. I performed the calcium hypochlorite toluene reaction using 275 g of toluene to 275 g of pool
Ca(OCl)2. The toluene was redistilled from the paint can and boiled to anhydrousness. The glassware was clean and oven dried. The toluene was
heated to 95 C before the hypochlorite was added and the reaction was refluxed for 5-6 h at 100-110 C. Protection from moisture was afforded by
sodium hydroxide.
The problem is that when I got a whiff of the contents of the flask, no tear gas effects, but there was an organic odor, very different from toluene
or calcium hypochlorite, sort of smelled like industrial cleaning agents. The odor is very persistent too. After the hypochlorite was wrapped in 15
sets of platic bags, it's presence in the trashcan for 1 day caused the trash can to smell for weeks afterward.
I am guessing I have either benzal chloride or benzotrichloride from using too much hypochlorite or benzaldehyde because I didn't dry the
hypochlorite, the water may have caused the benzyl chloride to decompose into benzaldehyde.
Has anyone ever smelled benzal chloride or benzaldehyde, who could verify what I have? I have not fractioned the mix yet because my vacuum pump has a
leak which I am currently fixing. Thanks.
[Edited on 27-10-2004 by Mendeleev]
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Esplosivo
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Benzaldehyde (phenylmethanal) smells of almonds, a smell similar to, but stronger than, phenylmethanol. But I have heard many friends describing the
smell differently, therefore the smell is subjective.
Theory guides, experiment decides.
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Mendeleev
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I believe that what I have as a result of my last attempt to make benzyl chloride is actually benzaldehyde because after almost a month now, the
solution has turned yellow, and I have read benzaldehyde is clear to yellow.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Organikum
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Benzaldehyde has an distinctive smell. The color says nuthing here.
How does it smell?
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Mendeleev
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I can't really describe it, but it does smell, sort of like some cleaning agent or something, but no chlorine like odor and no burning/tears. I
guess its not too bad, since I've also been working on various syntheses for benzaldehyde.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Mephisto
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Can really everybody smell Benzaldehyde? It's the same smell like HCN and a certain part of people can't smell HCN. Maybe they can't
smell Benzaldehyde too, because of the missing receptor, which is generally responsible for this certain smell?
Sure a far theory. Anyway, those, who mistrust their own olfactoric abilities could at least count on chemistry. The presence of Benzaldeyhde (as
it's the only aldehyde in the described product) can be checked with the Schiff reagent (fuchsine and a sulfit-source).
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Organikum
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The problem with HCN can be overcome by smoking a cigarette, its the traditional method to avoid HCN poisoning in the lab. Cigarette + HCN gives a
certain bad taste, and then its time to leave.
Everybody else may ask himself if he knows the smell of bitter-almonds.
But for sure benzaldehyde has no "sharp" smell. Tinkering with unidentified reaction products is a waste of time IMHO, its always easier to
discard the stuff and to run a new reaction. After the third or forth time one starts to get product, after some more runs good yields. At least thats
how it works for me
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Mendeleev
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If chlorinating toluene to benzal chloride, with the purpose of hydrolyzing to benzaldehyde, would you be able to avoid using sulfuric acid wash
bottles, since you are going to hydrolyze your product, what difference would it make if it is hydrolyzed as it is formed by wet Cl2?
[Edited on 20-11-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Organikum
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The hydrolysis being the second, independent step, this is no argument that wet chlorine can be used.
All literature speaks of dry chlorine to be used. H2SO4 is probably best, but I would say that two not to small drying stages with CaCl2 will suffice.
It is important to use not too strong a base for the hydrolysis, calcium carbonate for example.
Or use the Sommelet as describe above.
Or use acidid hydrolysis with HCl and ZnCl, but I would have to look the details up.
It is important though to have a security bottle before the reaction flask as the reaction can get quite violent and is prone to drive toluene
backwards, not filling the reaction flask to more than 1/2 is recommended.
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ballzofsteel
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Cold , Wet Sidechain chlorination
This is the simplest route to benzyl chloride Ive found so-far.
PATENT NO.GB134250
Abstract:
4,250. Levinstein, Ltd., Levinstein, H., and Bader, W. July 27, 1918. Chlorhydrocarbons. - Benzyl chloride, benzal chloride, and similar side-chain
chlor-substituted aromatic hydrocarbons are prepared by treating toluene or its homologues at a low temperature with aqueous hypochlorous acid
(hypochlorite and acid). The process can also be applied to the treatment of the chlor-derivatives of these hvdro- carbons containing one or two
chlorine atoms in the nucleus or one chlorine atom in the side chain, e.g. monochlortoluenes, 2 : 4-dichlorto- luene, or benzyl chloride. Examples are
given of the preparation of benzyl chloride from toluene and benzal chloride from benzyl chloride; m- xylene gives m-tolyl chloride and m-tolal
chloride
Obviously Benzyl/benzal;chloride mixtures can be obtained by increasing the amount of hypochlorite.
Calcium hypochlorite works.
HCL works fine.
Strong mixing seems to help somewhat.
Slow addition of acid.
Can I link this patent directly?sorry.
Hope this helps.
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antibond
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alcohol chlorination
Don't believe this has been discussed.
A very simple way of making benzyl chloride :
1 mol benzyl alcohol
1-3 moles aqueous HCl
add stirbar, and stir for sufficient time (follow on TLC if you want), add heat to speed up the reaction (not necessary though). Fractionally distill
the benzyl choride. Yields are high.
Raffike from the Hive used to swear by this method and has been confirmed.
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solo
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Ref: Synthesis of benzylchloride
I have always thought that the Lucas test , i.e. clorination of alcohols the tertiary>secondary> primary were chlorianted in that order. While
it's true that tertiary alcohols can be chlorinated with just HCl , the secondary , benzyl alcohols included, would need the ZnCl in order to get
chlorinated, but ZnCl is cheap and that 's easy to get ......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Organikum
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Thanks Ballz!
I guess this will be my new method of choice so it works with TCCA.
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Organikum
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preliminary results - better than sliced bread
The method of the patent as posted by Ballzofsteel was tried with TCCA and seems not to work when done as described.
A yellow compound is produced which is probably something highly ringchlorinated.
But......
.....when one omitts the addition of HCl completely it works.
Say: Grinded TCCA tablets + water + excess toluene (in the cold, time, shaking) = Benzylchloride
As told, these are PRELIMINARY, unchecked results, but I thought this so goil that I couldnt resist to post it ASAP.
I am not going to fuck around with the lachrymatoric BzCl, I will run a Sommelet and post the final amount of Benzaldehyde yielded, as this is what I
want.
The explanaition is easy:
toluene + HOCl (cold) = BzCl
TCCA + H2O = HOCl + isocyanuric acid
(this is an equilibrium! No Cl2, no HCl in the cold!)
/ORG
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ballzofsteel
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Great work
Use Ice instead of water,in an insulated container
This seemed to help yeilds a little,I reason due to the localised formation of HOCL,and thus a lesser chance of polychlorination.
This also avoids the need for external cooling to some degree.
That is if you are aiming for plain benzyl chloride,otherwise it dont matter.
Tip,form an Ice stirrer by freezing some water around a paint stirrer.
still,this may be of no advantage whatsoever when using tcca.
ORG.Thanks for trying this.
Roughly what ratios did you use?
Did you aim for benzyl chloride,or a mix of benyl/benzal/benzo?
[Edited on 21-12-2004 by ballzofsteel]
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Organikum
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You can use a metal-stirrer when adding 0,1% to 1% w/w hexamine to the toluene. This binds the metal ions and prevents them from catalyzing
ring-chlorination.
I thought about using ice and did in involuntarily by letting the broth ouside over nicht without stirring.
I would say the ice just provides a higher concentration of HOCl - using less water might do the same trick.
I didnt try it up to now with bleaching powder.
/ORG
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ballzofsteel
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Yellow
Tried today with Tcca.
Added a couple of kilo ice to 1l toluene
and roughly 500gm TCCA.
Stirred only occasionally.
Maybe overshot with to much chlorine,because I ended up with the deep yellow product you described when hcl was added.
For some reason I didnt have this trouble when roughly the same amount of Hypochlorite was used(chlorine content wise)
In both cases I was aiming to favour the formation of benzalchloride.
After christmas I will try again with tcca using ratios closer to those proposed in the patent.
Merry Christmas you mad scientists.
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