acetyl chloride synthesis ?
thirdeye
acetal chloride ?
thanks
Simon
thir...@eisa.net.au
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Uncle Al
>
> Could any one please refer me to documentation or cite me a synthesis for
> acetal chloride ?
Acetyl chloride? You gotta be kidding. Here: Helv. Chim. Acta 36
2021 (1953)
Acetal chloride? Compt. Rend. 231 234 (1950)
And why can't you visit a library to look in Beilstein?
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juster
produced by several methods. The Merck Index is a good resource for this.
CaCl2 and Ac2O will work. Possibly thionyl Chloride and acetic acid will
work also. Look in hte Merck for refrences and other methods. Hope this
helps
juster
>Could any one please refer me to documentation or cite me a synthesis for
>acetal chloride ?
>
>thanks
>Simon
>thir...@eisa.net.au
Dave
>Could any one please refer me to documentation or cite me a synthesis for
>acetal chloride ?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Acetyl Chloride
Connect a dry 250 ml three neck flask with a distillation adaptor,
condenser and addition funnel. Use a 250 ml rb flask for the receiver
connected to the condenser with a vacuum adaptor. Use the vacuum
adaptor
to make a gas trap with rubber tubing to an anhydrous CaCl2 drying tube
exiting to an inverted funnel suspended over a beaker of water. This
important stage is to protect the distillate from water while absorbing
HCl evolved in the reaction.
Place 54 g. (52 ml.) of glacial acetic acid in the three neck flask,
close with a stopper and add slowly through the addition funnel 46 g.
(29 ml.) of phosphorus trichloride. Cool the flask by immersion in a
water bath. Mix the reactants thoroughly and, after allowing the mixture
to stand for ten minutes, heat the water bath to 40-50º and maintain it
at this temperature for thirty minutes, with occasional swirling of the
flask. During the heating the liquid usually separates into two layers.
Acetyl chloride forms the upper layer.
Distil the acetyl chloride by heating the water bath to boiling and
maintaining it at that temperature as long as any liquid passes over.
Cool the receiver in an ice bath during the distillation. The syrupy
residue in the distilling flask is phosphorous acid, which is discarded.
--> CAUTION: The reaction mixture must not be overheated since this will
lead to formation of phosphine, which is spontaneously flammable in
contact with air.
To the distillate add two drops of glacial acetic acid, to destroy mixed
phosphorous-acetic anhydrides that would cause turbidity to develop on
standing. Redistil the acetyl chloride from a distillation apparatus
arranged as before except without the addition funnel and with a
thermometer. Collect separately in a dry receiver the portion boiling at
50-56º and transfer it to a dry weighed glass-stoppered bottle. Acetyl
chloride attacks corks and rubber stoppers. The yield is 44-56 g.
Acetic Anhydride
The apparatus for this process is similar to that used for the
preparation of acetyl chloride. The same precautions for exclusion of
moisture must be observed but it is unnecessary to provide the inverted
funnel arrangement, since hydrogen chloride is not evolved.
In a 250ml. rb flask fitted as for making acetyl chloride, place 60 g.
of
finely pulverised anhydrous sodium acetate.* Arrange in place the
condenser, dry receiving flask and drying tube; the receiver need not be
cooled. Check to insure that all connections are tight.
Cool the reaction flask in a bath of cold water and add dropwise,
through
the addition funnel, 40 g. (36 ml.) of acetyl chloride.
After the addition has been completed, remove the water bath and shake
the
flask to obtain good mixing of the reactants. Recheck the connections
for
tightness.
Dry the outside of the flask with a towel and heat it with a mantle or
oil bath.
Continue the heating until no more distillate comes over but do not
overheat the solid residue.
To the distillate add 4-6 g. of finely powdered anhydrous sodium
acetate,
to react with a small amount of acetyl chloride that may be present.
Add
a boiling chip and redistil the crude acetic anhydride. Collect the
product distilling at 132-138º in a dry flask. The yield is 30-40 g.
* NB: Commercial anhydrous sodium acetate usually contains some
moisture. To remove moisture fuse 70-80 g. in a casserole and stir until
no more water is evolved. Do not overheat! Cool and quickly pulverise.
Store in a tightly sealed container before use.