gdflp
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Anhydrous Zinc Chloride Attempted Synthesis
Today I attempted the synthesis of anhydrous zinc(II) chloride. First 3.5g of 300 mesh zinc powder was placed into a 125ml Erlenmeyer flask and 100ml
of acetone was added. Next I made a hydrogen chloride generator using sodium bisulfate, sodium chloride and a filter flask with enough reactants to
make twice the HCl needed. This generator was heated to 400°C(my hotplates maximum) and let to run for about 15min. Every few minutes I would swirl
the flask containing the zinc to keep it in solution. About 10 minutes into the synthesis the liquid became a chlorine color when the zinc had
settled. I continued for five more minutes, then cut the synthesis and transferred the liquid, now orange and translucent, to a clean flask leaving
behind the left over zinc and heated this liquid on the hot plate. The acetone boiled off quickly as expected, but instead of being left with a white
powder I was left with a blood red liquid which was not boiling at 200°C. At this point I cut the heating and now I am waiting to see if this will
solidify. Any ideas to what happened?
EDIT : The liquid has now cooled and it is a foul smelling liquid with a similar viscosity to water and looks black unless it is swirled to show the
red color on the side of the beaker.
EDIT : Maybe they are polymers since the acetone used was tech grade?
[Edited on 23-8-2014 by gdflp]
[Edited on 23-8-2014 by gdflp]
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plante1999
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Acetone does indeed do enol type polymerization. Methylene chloride, Chloroform or even toluene would be a lot better.
[Edited on 23-8-2014 by plante1999]
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unionised
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I suspect that you have demonstrated the acid catalysed condensation of acetone and the polymerisation/ dehydration of the products.
You probably also managed this
http://en.wikipedia.org/wiki/Clemmensen_reduction
Did you think the HCl wouldn't react with acetone?
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gdflp
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I wasn't sure, it was on a reasonably small scale so I thought it couldn't hurt to try it. I'm still not great at organic chemistry, taking a college
class in the fall, so that might explain my lack of knowledge. Thanks for the link BTW unionised, I did a quick search for a reaction of acetone and
hydrochloric acid which didn't turn up anything. What alkane would be formed from acetone, propane it would seem from that link? So what I am now
guessing happened is some alkane was formed along with acetone polymers. Would the Clemmensen reduction produce chlorine, because there was the
distinct smell of chlorine at one point? Also, what do acetone polymers smell like?
[Edited on 23-8-2014 by gdflp]
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Fantasma4500
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i surely recall HCl to react over time with a solution of HCl, forming some weird oily stuff, in which then had H2O2 added to it to form an alledgedly
superior form of AP -- in which has caused severe rage on this very site 
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blogfast25
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I'm not convinced that dry HCl (and it has to be bone dry!) will react with zinc at room temperature in an inert solvent. If it does that reaction
should be fairly exothermic, so beware.
Any water in your HCl will cause HCl solution droplets to react with zinc to produce hydrated zinc chloride.
Try leading dry HCl over zinc powder with the possibility to heat the powder externally, e.g. in at test tube, combustion tube or such like.
[Edited on 24-8-2014 by blogfast25]
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AJKOER
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Per Atomistry.com on ZnCl2 (link: http://zinc.atomistry.com/zinc_chloride.html ):
"The pure anhydrous salt of Zinc Chloride, ZnCl2, has been prepared by heating 3NH4Cl.ZnCl2 in a current of dry hydrogen chloride. The anhydrous salt
has also been prepared by distilling anhydrous zinc sulphate with sodium or calcium chloride, by the action of heated zinc vapour and hydrogen on
barium chloride, by distilling zinc with mercuric chloride, and by the action of chlorine on zinc oxide. Hydrous zinc chloride partially decomposes on
heating, but the anhydrous salt may be obtained from it by treatment with concentrated hydrochloric acid and evaporation in an atmosphere of hydrogen
chloride. It may also be prepared by adding zinc to molten lead chloride, passing dry chlorine into fused zinc, or by fusing zinc bromide in an
atmosphere of chlorine.
Commercially, the salt is obtained anhydrous by distilling a mixture of zinc sulphate and sodium chloride, and in solution by dissolving zinc scraps,
zinc blende, or zinc oxide in hydrochloric acid. "
Also, to quote:
"The trihydrate, ZnCl2.3H2O, separates in large crystals, when a solution containing 70.5 per cent. ZnCl2 is cooled for twenty-four hours at 0° C.
The crystals are hygroscopic rhombic tablets that begin to melt at 4° or 5° C., and form a homogeneous liquid at 9° C. "
I may have time to carefully heat Zinc ammonium chloride packed into a tube as the simplest path to the anhydrous ZnCl2 as the HCl formed per the
thermal decomposition of NH4Cl at the bottom of the tube may obviate the need for a stream of dry hydrogen chloride gas.
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gdflp
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I was on vacation for a week so I couldn't continue experimenting. The reason I wanted the anhydrous zinc chloride in the first place was the
preparation of solid fluorescein using the procedure found in Vogel. I have lots of concentrated sulfuric acid however, and have used that to make a
solution of fluorescein before. Would their be many differences in replacing the zinc chloride with sulfuric acid in the procedure found in Vogel,
specifically during the workup. About how much sulfuric acid would be needed to replace the zinc chloride?
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DraconicAcid
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Sorry for ressurrecting this thread, but I'm looking at a synthesis that requires a small amount of anhydrous zinc chloride. I'm thinking I could
probably react zinc metal with chlorine or hydrogen chloride using glacial acetic acid as a solvent. It occurred to me that zinc might react with
chloroacetic acid to give a mixture of zinc acetate and zinc chloride. Anyone have any experience with this?
Did find a patent for the use of dry HCl :https://patents.google.com/patent/CN106277036A/en
[Edited on 21-3-2019 by DraconicAcid]
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Sulaiman
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Unfamiliar with the method of HCl production I turned to Wikipedia, https://en.wikipedia.org/wiki/Sodium_bisulfate
where it states that sodium bisulfate decomposes at 280oC to sodium pyrosulfate and H2O.
CAUTION : Hobby Chemist, not Professional or even Amateur
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DraconicAcid
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That's only in the absence of chloride ion.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Sulaiman
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The NaCl will not melt at hotplate temperatures,
so why would at least some of the H2O not leave the reaction vessel,
or combine with the produced HCl gas ?
i.e. is this a valid method of directly generating dry HCl gas ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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Ubya
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https://youtu.be/YGjd7xxTuZw
dry media reaction, if not in the molten state have always low yeld or are slow, only the outher part of particles would react.
nurdrage added a bit of water, and in draconicacid case a washing bottle could be used. if sulphuric acid is not avaliable calcium chloride should be
compatible with HCl gas
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feel free to correct my grammar, or any mistakes i make
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DraconicAcid
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Quote: Originally posted by Sulaiman  | The NaCl will not melt at hotplate temperatures,
so why would at least some of the H2O not leave the reaction vessel,
or combine with the produced HCl gas ?
i.e. is this a valid method of directly generating dry HCl gas ? |
NaCl + NaHSO4 -> Na2SO4 + HCl
is more favourable than
2 NaHSO4 -> Na2S2O7 + H2O
If the sodium chloride is there, you will form HCl without decomposing the NaHSO4.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Tsjerk
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I think you could even do this in dry ethanol or another dry alcohol, like methanol or isopropanol.
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DraconicAcid
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I've made the iodide in dry methanol- it seems to work well. Solid I2 is far easier to measure out than dry HCl.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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clearly_not_atara
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| Quote: | | Sorry for ressurrecting this thread, but I'm looking at a synthesis that requires a small amount of anhydrous zinc chloride. I'm thinking I could
probably react zinc metal with chlorine or hydrogen chloride using glacial acetic acid as a solvent. It occurred to me that zinc might react with
chloroacetic acid to give a mixture of zinc acetate and zinc chloride. Anyone have any experience with this? |
The similar reaction of zinc with organic vicinal halides, e.g. zinc + 1,2-dichloroethane >> ZnCl2 + ethylene, is well-known. This version
produces no byproducts, and ZnCl2 should be nearly insoluble in the rxn mixture.
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Metacelsus
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Here's an interesting method that uses decomposition of the ammine complex.
In the past, I've also made (mostly) anhydrous ZnCl2 by heating the hydrate under HCl atmosphere. It's not completely anhydrous but it works for most
purposes (such as alkyl halide preparation from alcohols).
Attachment: cdc_10599_DS1.pdf (343kB)
This file has been downloaded 688 times
[Edited on 2019-3-23 by Metacelsus]
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