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Benzyl Chloride Synthesis by madchemist
Benzyl chloride is made from a substituted toluene and chlorine gas. The rxn
is easy to perform and complete. The only major problem in this is the use of chlorine
gas. It can be very toxic, so please do not do this unless you are under a strong fume
hood, or outside. Benzyl chloride (whether made from toluene or a substituted toluene)
can be the starting point for both phenethylamines and amphetamines.
A substituted toluene is a toluene with susbstituents on the benzene ring. This
reaction is suitable for most, but there probably is going to be those ones with a substitution
pattern that is not compatible with this reaction. Experimentation is the answer to all that.
Chemicals:
toluene (or substituted toluene)
chlorine bleach (or any bleach that contains NaOCl)
Muriatic acid (SWIM gets 31.45% HCl)
Procedure:
1-Place about 300mL of toluene into a flask. Place this on a non-flame heat source.
2-Heat toluene to a rolling boil, why your waiting for it to boil, setup a gassing
apparatus and place into it 500mL bleach. For higher yeilds, reflux of the toluene
instead of just boiling it is better, so it isn't lost by evaporation.
3-Add about 300mL of your muriatic an quickly close the apparatus. This produces chlorine gas.
4-Make sure gas is exiting the gassing tube, then submerge it into the boiling toluene.
5-Ok, well, that was the hardest part. Now you just sit back and relax while the shit reacts.
Of course keep an eye on it. Make sure the tube stays submerged, and keep an eye on the chlorine
gas reaction.
6-When you start to notice the gas reactions to slow down and slack considerably, quickly open it
and add about 50-100mL more of muriatic. Quickly close. This will help produce a little more gas.
7-When it totally slacks off (be careful of suckback), remove the tube from the boiling toluene.
Open the gassing apparatus, and empty it out. Quickly add about 300mL more bleach, and about 150mL
more HCl to it. Quickly close it again, make sure gas is exiting, and gas the toluene once more.
8-When gassing slackens considerably, remove the tube from the boiling solution (which now contains
toluene, benzyl chloride, and HCl acid). While still hot, move to an already setup distillation
apparatus.
9-Distill off al fractions. Collect the fraction that boils around 175-180. This is benzyl chloride.
Notes:
I suppose if one were cheap and didn't have any distillation apparatus, one could just
slowly raise the heat until it reaches benzyl chlorides temp, which I beleive is the highest bp
fraction in the whole mix. But I would go with distillation.
Also like I said yeilds can be higher. This will generally yeild SWIM 90-110g. If a reflux
is used, the toluene won't be lost in evaporation, so more can be converted. Also, the procedure
above was really just slapping things together. I'm sure if one sat down and worked out exact st-
oichiometry to this particular rxn, then yeilds may be in the 90's.
1NaOCl + 1HCl------>1Cl2(g) + 1NaOH
Take the care to add extra HCl, as some gets used by the NaOH produced:
1NaOH + 1HCl------>1H2O + NaCl
1Cl2 + 1PhCH2----->1PhCHCl + 1HCl
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