CRK
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Benzyl Iodide/Benzyl Cyanide Synthesis
One of the most common ways to synthesize benzyl cyanide is to start from benzyl chloride. Is it possible to substitute benzyl chloride for benzyl
iodide? If so, how would one approach this? I would imagine it would work if you bubble I2(g) through Toluene at ~100 degress Celsius, the
same process you would use if you were making benzyl chloride with chlorine. Would that work, or how could you synthesize benzyl iodide? Iodine is a
lot safer to handle compared to chlorine.
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Chemosynthesis
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Unfortunately, the most common production method I have seen for alkyl iodides is a halide swapping reaction from the chloride, known as the
Finkelstein reaction. Iodides also tend to be difficult to store.
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UnintentionalChaos
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Iodine cannot substitute for Br2 or Cl2 in this reaction as far as I know. Other complications are the significant instability of benzyl iodide and
it's extremely lachrymatory nature. According to a PhD student I know, the iodide is far worse than the chloride and bromide despite lower volatility.
Additionally, as as alkylating agent, the iodide is the most potent of the three and is thus the most dangerous benzyl halide to handle.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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CRK
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Okay, well since I will be abandoning that idea. Would ClO2 react with Toluene? I'm planning on mixing NaClO and HCl to produce Chlorine
gas, but ClO2 is a side product, will this interfere with the reaction?
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forgottenpassword
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It would be simpler to react benzyl alcohol with hydrochloric acid. Using chlorine gas and toluene will likely give you a mixture of products and a
separation problem.
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CuReUS
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| Quote: | CRK -why dont you try making benzyl iodide from benzene diazonium chloride(aniline +NaNO2 +excess HCl) with methyl iodine
i have seen a similar reaction with benzene diazonium chloride with nitromethane to form nitromethyl benzene(N-phenyl nitro methane) but that may be
due to the electron withdrawing effect on the nitro group so you may have to use a catalyst. |
thinking of it now,maybe you could just react benzene diazonium chloride with acetonitrile to get benzyl cyanide instead of an aralkyl halide
route
[Edited on 1-10-2014 by CuReUS]
[Edited on 1-10-2014 by CuReUS]
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Metacelsus
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Benzyl bromide is the easiest to prepare, given that bromine is a liquid. I've done the reaction before myself. The bromide should work fine for
making benzyl cyanide.
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Mercedesbenzene
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I have made benzyl chloride from toluene and chlorine using TCCA and hydrochloric acid. The reaction worked quite well and the mixture of the mono/di
chlorinated derivatives were easy to separate by distillation. The bromide should be even easier to make because as previously mentioned bromine is a
liquid which simplifies handling.
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Oxirane
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This reaction is actually described in Versuchschemie, but there are many variations to it. Easiest would be to mix benzyl alcohol and hydrochloric
acid. Most difficult, though used in industry, is to react chlorine gas with toluene under strong UVB light source. Benzyl cyanide synthesis is
described in couple of sites and it should be quite easy.
Does anyone have any data on benzyl cyanide toxicity, by the way? I generally classify all common cyanides in the highest safety class, but somebody
mentioned once that benzyl cyanide toxicity is substantially lower than common salts.
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CRK
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I attempted to synthesize benzyl chloride. 100mls of Toluene was place in a 500ml two neck round bottom flask fitted with a reflux condenser and a
vacuum receiver with tubing leading into the Toluene (Not the best way it could've been performed, but it sufficed). NaClO and HCl were mixed to
produce chlorine with ClO2 as a side product. The chlorine was bubbled through the Toluene as it was gently boiling and a 60 Watt lamp was
my light source. The rfinal product I ended up with was a clear/yellow solution, normally I'd be ecstatic since benzyl chloride has a slightly yellow
tint, but I'm thinking some ClO2 dissolved in it to give it the yellow colour. Do you think the reaction was successful or unsuccessful?
The next time I attempt this I'm going to use KMnO4 and HCl to avoid the chlorine dioxide by product. Also, I haven't had time to check the
boiling point of the solution.
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Nicodem
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Thread Moved
1-10-2014 at 22:25 |
forgottenpassword
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Quote: Originally posted by CRK  | | Do you think the reaction was successful or unsuccessful? The next time I attempt this... |
Why not complete this reaction first, rather than planning your next attempt? It is a waste of time attempting any reaction if you will then only look
at the colour and think "no good, try again". Separate your products by distillation and record the boiling points. Then you can tell us if it was
successful, and what quantity of each product you synthesised.
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Metacelsus
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Did your eyes burn? That's a good (though maybe not so safe) way to detect formation of benzyl halides.
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Steam
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I have worked with benzyl chloride before and let me tell you from experience, it is a nasty chemical. It seams to penetrate clothes and for some
reason once you smell it it lingers in the back of the nose for hours.
It also tends to polymerize in storage to a thick yellow gunk...
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