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Magpie
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cyclopentanone
I tried to make cyclopentanone today but I don't think it worked out too well. After laboriously collecting about 12.5 g of adipic acid I ground it
together with 1.6g Ba(OH)2*8H2O. Then I charged it to a small RBF for dry distillation. The mix readily melted and I held it at 285-295C while it
boiled for quite some time. When I finally quit I only had about 2mL of a liquid that floated on a water layer, collected as condensate. The
decarboxylation is supposed to happen like this:
(CH2)4-(COOH)2 --> CO2 + H2O + (CH2)4-C=O
with the Ba(OH)2 serving as catalyst.
I tried to get a boiling point on it but the best I could get was about 121C vs the literature value of 131C. It was quite flammable, however.
I felt fortunate that my 50mL RBF escaped any lesions during the high temperature melting with Ba(OH)2.
Has anyone else tried this? If so, hopefully you had better results.
The single most important condition for a successful synthesis is good mixing - Nicodem
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garage chemist
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I have done the third and until now best batch of cyclopentanone today.
I have modified the Vogel procedure in some seemingly small details, but it works much better with those modifications:
1. I used Barium carbonate instead of barium hydroxide. This has the advantage that the raw product contains less water because BaCO3 does not contain
crystal water. For 40g adipic acid (my batch of today), I used 1,25g BaCO3 instead of the 2g Ba(OH)2*8H2O that is recommended in Vogel.
The BaCO3 slowly dissolves under fizzing after the adipic acid has fully melted.
2. After all adipic acid has been decomposed (as indicated by cessation of CO2 evolution seen on the washing bottle I connected to the vacuum adapter
of the distillation setup as a gas flow indicator), the biphasic raw product is distilled to get rid of adipic acid that has codistilled during the
reaction. This is very important! Do NOT rely on the K2CO3 to remove the adipic acid, because there is quite a lot of it and the resulting potassium
adipate will clog up your product and make phase separation very difficult.
3. The distillate from the second distillation again separates into two phases. The upper ketone layer is withdrawn and the aqueous layer extracted
once with a little DCM. This reduces losses due to the appreciable solubility of cyclopentanone in water.
I have discovered in the redistillation of the raw distillate that cyclopentanone and water form an azeotrope that boils at 93°C (temperature stays
there for quite a while). This is remarkable, since both pure cyclopentanone and pure water boil higher than that.
This azeotrope seperates into two layers in the receiver.
After the azeotrope has come over, the temperature rises to 130°C and pure cyclopentanone distills. This indicates that the reaction does not produce
enough water to make all of the cyclopentanone come over as the azeotrope!
I will do a detailed report of the synthesis with pictures soon.
[Edited on 6-1-2007 by garage chemist]
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guy
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Can you use calcium adipiate?
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garage chemist
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Do you mean as a catalyst? That would have to be found out experimentally. I don't have Ullmann here at the moment, but I remember that under the
chemical properties of adipic acid some of the decomposition catalysts for cyclopentanone formation were listed. I think calcium was among them, but
barium is the most effective.
Or do you want to use pure calcium adipate as the reagent? I don't think that would work. Please be more specific! What's with calcium adipate? Have
you seen it for sale anywhwere? If yes, you should convert it to adipic acid first and then use BaCO3 as catalyst.
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Rosco Bodine
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I'll take a wild guess here that the 93C steady state
distillation of the mixture with water is a steam distillation effect and not an azeotrope . You could calculate the predicted approximate steam
distillation temperature by subtracting the vapor pressure of
cyclopentanone at 100C from 760mm and then comparing
the remainder figure to a boiling point reduction for pure
water ......and if the temperature closely agrees with 93C then it will be a fair bet it is simply steam distilling .
I think I remember this right .....but to be sure , somebody maybe should look it up  IIRC , *all* steam distillations come across a lower BP than that of water ,
it being the relative vapor pressures combined to form 760mm for the atmospheric pressure distillation molar *proportion* or molar percentage of the
higher BP material mixed with water which comes over as vapor .
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garage chemist
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I obtained 17,6g Cyclopentanone (actually 15,9g, but I redistilled the DCM fraction and got a little extra product) from 40g adipic acid. Vogel says
that 40g adipic acid should give 18,4g cyclopentanone in practice. The theoretical yield would be 23g.
Therefore I have obtained 77% yield, while Vogel says that 80% yield is possible when working with 200g adipic acid. My yield is therefore very
acceptable, especially when considering the multiple distillations I have done. Good to have a very small distillation setup with NS 14/23 and 200mm
liebig condenser for such tasks!
However, the extraction of the aqueous phase with DCM was actually a bad idea because the DCM is not seperated efficiently enough from the product by
simple distillation. If one distills until the steam temperature reaches the 128°C at which the pure cyclopentanone fraction begins, about 1,7g
cyclopentanone go over with the DCM. The DCM in the receiver therefore has to be redistilled to avoid this loss.
So better use no DCM in the preparation. I will mention this in the coming synthesis report.
(Edited the miscalculation, the yield is 77% and not 72%!)
[Edited on 7-1-2007 by garage chemist]
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Sauron
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Just a suggestion as I have not looked it up yet but, I have found that Vogel copied many of his procedures out of Org.Syn. early volumes. Typically
he scaled them down in size significantly. That is because Vogel's book was intended as a practical lab instructional manual for a university course;
while early Org.Syn. was intended as preparative procedures for American chemists cut off from German suppliers.
You may well find that if there is an Org.Syn. procedure for cyclopentanone, (1) it is probably same, and (2) it is on larger scale and will be much
more thoroughly commented and annotated and referenced than Vogel. If the procedure is subject to mechanical losses on smaller scale you may get a
better yield at the original scale.
Finally, are you fractionating the cyclopentanone/DCM or just doing a simple distillation?
Interposing a column and slowly distilling after adequate time for column equilibration ought to do the trick. Slowly slowly catchee monkee.
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Sauron
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Sure enough, cyclopentanone from adipic acid and barium hydroxide is in annual Volume 5 of Org.Syn. Here's the prep.
(see below)
This is on a 200g adipic acid scale.
In the commentary, various other catalysts are discussed with references and a particularly high yield reported with barium carbonate (94%).
Old Vogel did nothing wrong by cribbing preps from elsewhere but I do rather wish he had acknowledged the debt by referencing his sources. He rarely
if ever did so.
[Edited on 6-1-2007 by Sauron]
[Edited on 6-1-2007 by Sauron]
[Edited on 6-1-2007 by Sauron]
Attachment: cyclopentanone.pdf (111kB)
This file has been downloaded 1060 times
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garage chemist
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Thanks for the paper. This is on the same scale as the Vogel preparation. But it is indeed better described.
It also says that calcium adipate gives cyclopentanone when heated. So this question is answered.
Interesting is the high yield reported with barium carbonate. I came up with barium carbonate as a better catalyst than the hydroxide by myself, and
now I see that it is the best catalyst that one can use!
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Sauron
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Yes, you can be justly proud.
Note that adipic acid is prepared from cyclohexanol
Also note that while Vogel said 80% yield, Org.Syn. said 75-80% and so given the technique-sensitive workup garage_chemist's 72% yield from a reduced
scale run was not at all to be sneered at. After all, the submitters and checkers at Org.Syn. were and are the best of the best (Roger Adams was a
checker on this cyclopentanone procedure) and ran these preps over and over many times to smooth out all the wrinkles.
Org.Syn. is usually my first resort, followed by Vogel, and then a peak at Merck Index, then a look to see if Aldrich and/or Acros have any
interesting references listed. Merck used to give references sometimes on their online tech data sheets but no longer provide those - only MSDS. Sic
transit gloria mundi.
[Edited on 6-1-2007 by Sauron]
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Sauron
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I had a thirty day free trial of DiscoveryGate (MDL-Elsevier) which provides access to Beilstein Crossfire and lots of other databases. Frankly I
thought it was rather kludgy, and when I found out that their most limited, narrow subscription would be something like $20,000 per annum I lost all
interest
Beilstein in print is unbeatable; the bulk makes it rather a daunting project for digitizing. Too bad.
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guy
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| Quote: | Originally posted by garage chemist
Do you mean as a catalyst? That would have to be found out experimentally. I don't have Ullmann here at the moment, but I remember that under the
chemical properties of adipic acid some of the decomposition catalysts for cyclopentanone formation were listed. I think calcium was among them, but
barium is the most effective.
Or do you want to use pure calcium adipate as the reagent? I don't think that would work. Please be more specific! What's with calcium adipate? Have
you seen it for sale anywhwere? If yes, you should convert it to adipic acid first and then use BaCO3 as catalyst. |
What's the difference between using the solid adipiate salt and reacting a base with adipic acid, just wondering?
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Sauron
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In the case of the barium hydroxide or carbonate only a small amount is required. Not a stoichiometric amount.
On his 40 g scale, adipic acid basis, less than 2 g barium salt was used. As Ba is rather heavy, clearly the molar ratio is up there.
If you used calcium adipate you'd end up with a lot of calcium oxide in the pot and not all that much cyclopentanone in the receiver, in terms of the
mass of starting material. So unless calcium adipate were a whole lot easier and cheaper to obtain than adipic acid, using the acid would be the way
to go.
Using the Org.Syn. or Vogel method, very little solid material is left in the pot. That's be barium oxide.
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Maya
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Beilstein in print is unbeatable; the bulk makes it rather a daunting project for digitizing. Too bad
Thats how I got good in german , by having to translate all the refs.
Beilstein is the best, next best I've found is the Combined chemical dictionary and that is digitized 
[Edited on 7-1-2007 by Maya]
\"Prefiero ser yo extranjero en otras patrias, a serlo en la mia\"
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garage chemist
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Here is a lot of azeotrope data, including cyclopentanone/water:
http://www.chemeng.ed.ac.uk/people/jack/azeotrope/
You can see that I measured the boiling point of the azeotrope correct to within half a degree centigrade without even knowing before the synthesis
that an azeotrope like that existed.
I have made a synthesis documentation on versuchschemie:
http://www.versuchschemie.de/topic,8199,-Synthese+von+Cyclop...
One thing I want to mention is that at a certain point the barium adipate precipitates from the reaction mix and the mixture suddenly looks like
boiling tar:
Do not let yourself be irritated by this, a lot of adipic acid is still present in the mix!
The heating must be continued like before until the residue in the flask is nearly dry, the distillate starts to turn yellow and adipic acid sublimate
starts to deposit in the condenser. Do not stop the heating earlier. If in doubt, continue the heating.
Also, a thermometer inside the melt itself is not necessary. The thermometer can be in the gas phase like in a normal distillation setup, I have done
this. The heating is adjusted so that the thermometer displays between 130 and 140°C during the reaction. This makes for an acceptable speed of the
distillation and reduces adipic acid carryover to a minimum.
It is also very advantageous to connect a washing bottle filled with water to the vacuum connection of the distillation setup to serve as a bubble
counter to monitor CO2 evolution and therefore the reaction itself. With my 40g batch, about 3-4 bubbles per second were produced. This is the best
method to see when the reaction has finished.
[Edited on 11-1-2007 by garage chemist]
[Edited on 11-1-2007 by garage chemist]
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Magpie
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Very interesting GC. My old school procedure (Brewster, 1962) which calls for Ba(OH)2, does not mention a black tar as you show. It also says to
place the thermometer within 4mm of the bottom of the RBF. Then it says to heat to 285-295C until no more distillate is produced. Quite a difference
from your procedure.
As a side note I looked at the azeotropic data site you posted and find it puzzling that it says acetic acid forms an azeotrope with water. Now I
generally respect NIST, but I find this a direct contradiction with Gmehling's 2 volume tome Azeotropic Data which says there is no
azeotrope and backs this up with numerous citations. This also is very interesting. 
The single most important condition for a successful synthesis is good mixing - Nicodem
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Rosco Bodine
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Immiscible binary systems where one component
is water are " heteroazeotropes " which follow the steam distillation rule for molar proportional composition of the distillate that agrees
with the sum of the respective vapor pressures being 760mm at the
depressed bp where the mixture boils . Anything
that is immiscible with water and has any even trivial
vapor pressure near the bp of water at STP will be
"volatile with steam" and will "azeotrope over with water" ( steam distill )
at <100C at STP .
The immiscible organic / H2O binaries all do this whether they are charted or not , and you can calculate the expected temperature for the azeotrope
as well as its composition . It is a physical chemistry basic that
is governed by Daltons Law of partial pressures .
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Sauron
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Draw the curves and you will probably find that you can break the heteroazeotrope by distilling with a fairly high vacuum.
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Rosco Bodine
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Most of the time you don't want to break the azeotrope ,
but use the steam distillation as a substitute for vacuum distillation to remove your desired product from a complex reaction mixture .
Then you use a volatile solvent to extract the organic
phase from the steam distillate if it didn't form a clean separation , and then you use the vacuum to flash away any residual solvent to
obtain the higher boiling material as a residue .....then lastly distill under vacuum .
[Edited on 11-1-2007 by Rosco Bodine]
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garage chemist
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Cyclopentanone and water are anything but immiscible.
I have observed that the biphasic mixture in the distilling flask becomes homogenous upon heating, making this practically a homogenous azeotrope (but
one that partially seperates into its components on condensing). The water layer in the receiver also still contains some of the product, making for
my initial suggestion to extract this with DCM.
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Aubrey
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I attempted the cyclopentanone synthesis using as the catalyst Calcium Hydroxide. Everything went as described beside the redistillation, i had a
temperature of 92.3 on my digital thermometer at the distillation head, this remained static until such point as it dropped down to around 55 degrees
with another transparent fraction appearing, which settled in mall globules at the bottom of my previous layer.. I was expecting 130 degrees, i
swapped out my thermometer but this wasn't the problem. Any idea what might have happened?
ho hum
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Globey
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Any time you do such a reaction or a destructive distillation, you might want to consider using a home-made crude distillation apparatus (maybe a
pipe, with threaded nipple/ferrel, attached to copper coil to condense.) which would yield your crude cyclopentanone. This way, you can really heat
the krap out of your reactor, and not have to worry about destroying your glass. Save the more delicate glassware to re-distill the impure ketone. It
is really the best way.
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Ebao-lu
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Aubrey, are you sure your adipic acid was pure? If you used a descaling agent, it could contain a mixture of organic acids, and as a result you got
substance boiling at 55. Because it can not be cyclopentanone. When you say the second fraction was heavier then water (that was you first fraction
probably), i can assume you used a chlorinated lime, not a caustic one. And that was a chloroform-water azeotrope, boiling at 55. I wonder, how you
avoided an explosion or a vigourous reaction with heating chloride of lime with organic substances. Sorry, if i'm mistaken, but i dont see any other
explaintations of the heavy layer boiling at 55C formation. Or, i did not understand you correctly
[Edited on 22-2-2009 by Ebao-lu]
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benzylchloride1
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This method can also be used to produce dibenzyl ketone which is useful for producing tetraphenylcyclopentadienone which is an interesting molecule
that can be used in the synthesis of hexaphenyl benzene and other highly arylated aromatic hydrocarbons. Phenyl acetic acid is heated with barium
hydroxide and the crude dibenzyl ketone distilled off. I have not tried this procedure, but I recently used iron powder to form dibenzyl ketone from
phenyl acetic acid. The product is very impure due to the color, but works great in the aldol reaction with benzil to produce tetracyclopentadienone.
I am currently steam distilling the remainder of the ketone, it soldifies in the condenser. I have collected several liters of distillate and have
still not distilled all of the 6 grams of crude ketone due to its boiling point of around 340 celsius. Next time I plan to use the barium salt method
for producing dibenzyl ketone that is found in Vogels. A method for producing acetophenone from calcium benzoate and calcium acetate exists, it could
possibly be improved by using a barium salt instead.
Amateur NMR spectroscopist
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Klute
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Benzylchloride, I love the work you do. ALot of intereting reactions. Would have time to make longer reports, possibly including pictures? It would be
delightfull!
Keep up the good stuff
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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