uemura
(Hive Bee)
11-27-01 10:07
No 241293
      Properties of some epoxides
(Rated as: excellent)
 Bookmark   

Introduction

In the Hive there is currently going on some research on the preparation of 2-propanones synthesised from the propenylbenzenes via the epoxides. This small write-up gives some details on the physical properties of two epoxides, namely the anethol-epoxide and the asarone-epoxide. The preparation is based on an rxn proposed by Osmium, publish at Rhodiums site (see ../rhodium/chemistry /safrolepoxide.html. Uemura modified the precedure to allow re-use of the MeCN used in this synthesis. A more OTC method for the epoxide synthesis has been provided by Chromic.

Epoxide Synthesis (described for anethole) [N1]
0.13mol anethole (approx 20ml) are dissolved in 200ml of a MeCN/MeOH (1:1) mixture. 2g NaCO3 are added and the mixture is stirred under room temperature with slow stirring. [N2]
Within 10-15 minutes the molar amount of 30% H2O2 is added dropwise under stirring. [N3] Stirring is continued at room temp for 18-24Hrs. After the time has elapsed, the MeCN/MeOH solvent is destilled off on a waterbath. [N4] An oily water-epoxide suspension remains. The crude epoxide is extracted with ether or another non-polar solvent. The ether is washed with Brine and dried over NaSO4. [N5] After drying the ether is destilled off on a water bath and the last traces of the ether are removed in vaccuum leaving the crude epoxide in the flask.

Crude Anethole Epoxide: This is a clear yellow pleasant smelling oil. (Yield about 90%)
Crude Asarone Epoxide: This is a brown-gold clear oil with smell of asarone. Not too much pleasant. (Yield 80%) [N6] The following picture shows the crude asarone epxoide.


Purification of the epoxides
To purify the crude epoxides slow vaccuum destillation has been applied.

Anethole Epoxide Destillation:  The yellow crude epoxide was destilled at 13Torr and 15.4g (70%) of a water-clear, very pleasant smelling oil came over in the range between 118 to 126 DegC. Hring reports 132DegC at 11Torr.[N7] In the destillation flask a deeper yellow oil with a higher bp. remains. [N8]
Pictures of the purified anethole epoxide and the high-boiling residue.


Asarone Epoxide Destillation: The golden-brown oil (17g) are destilled under maximum vacuum (2-4 Torr). Within the range of 125-135Deg a clear light yellow oil destilles over. The yellow oil has the typical epoxide smell, very similar to the anthole one, but very different from the crude asarone epoxide. Yield 8.3g In the destillation flask a red thick oil remains (weight 4,3g) which after cooling solidifies but does not cristallize. [N9]
Pictures of the purified asarone epoxide and the high-boiling residue.


Discussion
As the 'law of difficulty conservation' predicted, the epoxidation of asarone is much more picky than the one of anethole. In case of anethole consistent results and clean products have been received. In case of asarone, the yield of the desired epoxide is low (8.3 gram out of 20ml asarone) and it seems to bee esential to purify already the crude epoxide before going ahead. [N10] A first thermal re-arrangment run on anethole epoxide went smoothly [N11], the similar attempt for the asarone epoxide should be worth a try as soon as sufficient clean epoxide is available.

Notes
[N1] Same procedure has been applied for asarone.
[N2] Not all of the NaCO3 will dissolve, but this has no effect on the performance of the rxn. It keeps the ph in the alkine area (p.h. about 8.5)
[N3] Do not use more than 1.1 molar amount of the H2O2. In one run Uemura 'overshoot' the H2O2 and some of the Acetonitrile has been oxidized to Acetamide, which cristallised during destillation and has been identified by its smell.
[N4] Uemura found the evap of the solvent mix must not be done under reduced pressure. The destilled aceotrop of the MeOH and the MeCN can be reused for further runs, which is more advantegous than Osmiums description. Uemura found the yield do not differ significantly. Remove the last traces of the solvent by applying vaccuum (may help to minimise the emulsion later on).
[N5] Emulsion forming may appear and the seperation becomes sometimes a bit a pain-in-the-neck. Be patient.
[N6] 'Low' yield of 80% was caused by problems separating the solvent mix.
[N7] (1) Hring, 'ber die Dibromide aromatischer Propenylverbindungen', Ber 38, 1905, pg. 3464
[N8] Yields of destilled epoxides have been between 70-75% percent in all three runs.
[N9] Like glas or molten plastic, may indicated some kind of polymerisation took place?
[N10] Uemura reported already earlier on the failure from asarone -> ketone in one step.
[N11] succesful to some extend, a write-up may follow later on.

Carpe Diem
 
 
 
 
    Rhodium
(Chief Bee)
11-27-01 10:51
No 241300
      Re: Properties of some epoxides  Bookmark   

Wonderful! This goes right onto my page.
 
 
 
 
    Osmium
(Stoni's sexual toy)
11-27-01 10:54
No 241302
      Re: Properties of some epoxides  Bookmark   

laugh

Very good results!
 
 
 
 
    uemura
(Hive Bee)
11-27-01 11:27
No 241305
      Re: Properties of some epoxides  Bookmark   

Thanks a lot, bees! Your are very quick, Uemura hadn't even the time to massage and clean up a bit the write-up. Some red modifications done. Rhod, please check for further typos or more faulty thingies.

Carpe Diem
 
 
 
 
    Chromic
(Hive Addict)
11-27-01 15:53
No 241384
      Re: Properties of some epoxides  Bookmark   

Excellent work! I can't wait to see your work on rearranging asarone epoxide!
 
 
 
 
    uemura
(Hive Bee)
11-28-01 13:17
No 241734
      Asarone Epoxide Rearrangment  Bookmark   

Bees, fasten your seat belts....smile Uemura couldn't wait and did the following:

In a thick-walled test tube 1ml of the destilled asarone epoxide was added and the test tube mounted above a hot-air-pistol. A thermometer 0-300DegC was placed inside the test tube and some anti-bumping stones added.
The hot-air-pistol was switched on and the temperature climbed quickly up to 260DegC. Tiny air bubbles were released from the anti-bumping stones. 270DegC, still nothing.

Then, when the temperature was up at 280DegC, the asarone epoxide started to boil. The colour turned to orange but the destillate which climbed up the test tube at 285-290DegC was water clear, no sign of any decomposition. The boiling was continued for two minutes, then the heating was switched off.

After cooling a orange clear oil remained. The smell was different from the expoxide, it had the typical ketone flavour. The content of the test tube was poured into a petri dish waiting for cristallisation over night (hopefully).

The rest of the oil in the tube was diluted with a bit of EtOH, then bisulfit was added. Heavy shaking. Oily precipitate only. Heavy shaking continued. Some white cristals appeared. Oily precipitate seems to solidify.  Anyway:

ASARONE EPOXIDE THERMAL REARRANGMENT IS POSSIBLE.
KETONE BOILS AT 285-290Degc AT ROOM TEMPERATUR
SMELL IS KETONE LIKE; BISULFITE TEST INDICATES POSITIVE RESULT.
EXTRAPOLATION OF LITERATURE BP TO ATMOSPHERIC PRESSURE FITS PERFECTLY SEE Post 241739 (uemura: "Asarone ketone bp data", Chemistry Discourse)


Have a good night
 
 
 
 
    sunlight
(Pioneer Researcher)
11-28-01 16:19
No 241818
      Re: Asarone Epoxide Rearrangment  Bookmark   

Wow Uemura, I'm impressed with your research, good work.
 
 
 
 
    Chromic
(Hive Addict)
11-28-01 19:21
No 241892
      Re: Asarone Epoxide Rearrangment  Bookmark   

<Hugs!>

Thanx! You're sure to make a dream come true. cool
 
 
 
 
    uemura
(Hive Bee)
11-29-01 00:18
No 241981
      Re: Asarone Epoxide Rearrangment  Bookmark   

Postscript: In the morning the oil was still a oil. But this is not surprising since the mp of the pure ketone is only 45DegC. Impurities prevent cristallisation. The test tube with the bisulfite however shows a resonable amount of white precipitate, minor oil drops on top of the deep yellow bisulfite solution. (Either non reacted expoxide and/or sideproducts).
Next step ould bee proper rearrangement followed by destillation. Perhaps Uemura builds a small-scale dest apparatus.
Carpe Diem
 
 
 
 
    uemura
(Hive Bee)
11-30-01 06:44
No 242503
      Re: Asarone Epoxide Rearrangment  Bookmark   

Postscript2: In the oil on the petri dish first white critalls appear smile
 
 
 
 
    Antibody2
(Commodore "Mole Bouncer")
11-30-01 11:15
No 242601
      Re: Asarone Epoxide Rearrangment  Bookmark   

My goodness, are you ever meticulous Uemura. Nice Work!

"All those memories lost like rain..."
 
 
 
 
    Vibrating_Lights
(Hive Bee)
11-30-01 11:38
No 242615
      Re: Asarone Epoxide Rearrangment  Bookmark   

Beautiful.  Any one know what the typical yeilds are for a hydroxlamine condensation followed by an al/Hg with the asarone ketone or does Umera posses the first asarone ketone. Again swim says beautiful.  TEE HEEsmile
 
 
 
 
    Chromic
(Hive Addict)
11-30-01 17:53
No 242796
      Re: Properties of some epoxides  Bookmark   

The more I read of peracetic acid in dcm (sodium acetate to buffer the H2SO4), the more inclined I am to believe that they can be used to produce asarone epoxide as well... it appears that only strong acids will cleave the epoxides, and not weaker acids like acetic acid. I'm ready to try this reaction soon, I hope it works because MeCN isn't as easy for me to find.
 
 
 
 
    Rhodium
(Chief Bee)
11-30-01 18:22
No 242825
      Re: Properties of some epoxides  Bookmark   

The peracetic should work, if you use more buffering carbonate than usual (1 eqv).
 
 
 
 
    Antibody2
(Commodore "Mole Bouncer")
11-30-01 23:47
No 242914
      Careful with GAA!!!!  Bookmark   

procced with caution guys on that one guys. here is why Post 36661 (Antibody2: "pseudonitrosites via Toennies method", Novel Discourse), you will see that after ca 24 hours in glacialacetic acid i had a purple mess, back then no one bothered to point out that the pseudonitrosite of asarone was not purple, (aside from Rhods faq)but we had been dealing at that time also with red and black pseudonitrosite yeilds, so no-one knew for sure what to look for from different reactions.

in retrospect i now realize that the reason that batch failed hydrogenation is because it was no pseudonitrosite, just a pretty batch of decomposed asarone. decomposed by the acetic acid.

Mind you, that was in galcial acetic acid, no dcm, no water from the H202 either and no buffer. The peracetic might work, but i wouldn't be placing any bets just yet. Goiterjoe attempted it a while ago, as far as i know it was not a sucess, he never reported back on amination yeilds from the red syrup, the rxn yeilded.

for what they are worth, my two cents

"All those memories lost like rain..."
 
 
 
 
    uemura
(Hive Bee)
12-01-01 00:34
No 242930
      Re: Properties of some epoxides  Bookmark   

Bees, say a nice 'Thank you' to sunlight. He provided Uemura with the following reference:

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0126

This is close to the rxn Uemura is using but has a very big advantage: It only uses the MeCN in molar equivalents, not in a 1:1 mixture with the MeOH.

Based on Osmiums write-up is was obvious to Uemura that the MeCN forms with H2O2 the oxidant agent acting on the olefine. So a 1:1 mix with MeOH looked to him as an overkill but he wasn't sure. Since the MeCN is 1) expensive, 2) not easy to aquire he redestilled the azeotrope off for futher use.

The reference allows 'waste' of it since the MeCN is used in molar equivalents only and it simplyfies the workup a bit (more important, evap of solvents can be done at low temp). Further Uemura thinks that -at least for asarone- the evap of solvents at boiling temp (i.e. 60DegC) may not do that good. He will test this on the current batch in his lab.

Carpe Diem
 
 
 
 
    uemura
(Hive Bee)
12-01-01 00:48
No 242935
      What to do with it?  Bookmark   

Bees,

I think it was ab2 smile who said 'what do you want to do with the ketone?'

Uemura thinks that is exactly where the previous experiments boil down to! The only written reference Uemura has seen is the Leuckart conversion on Rhod's site provided by R. Carter?

To avoid to get much off-topic, Uemura opened a new thread.

Carpe Diem
 
 
 
 
    Rhodium
(Chief Bee)
12-01-01 17:16
No 243134
      Re: What to do with it?  Bookmark   

Uemura: I edited your document somewhat and put it here: ../rhodium/chemistry /epoxide.html - Is that okay?
 
 
 
 
    Ritter
(Master Whacker)
12-01-01 18:43
No 243147
      Re: What to do with it?  Bookmark   

Uemura and gang:

I have a theory based on a ref I saw many moons ago on a similar CH3CN/base/H2O2 catalyzed epoxidation reaction.  The ref used 50-55% H2O2 in CH3CN/NaOH to epoxidize cyclohexene in very high yield.

It certainly seems like you are getting great yields with the anethole epoxide, however I feel that the poor yields obtained from asarone can be increased dramatically by using a more highly concentrated H2O2 solution.  I'm willing to bet that if you were to use a 50-60% concentrated peroxide solution, yields would skyrocket.  Now here's the good news:  Our standard 35% H2O2 solutions can easily be concentrated to over 50% and if you have the courage up to 65% by simple distillation.  A standard fractional vacuum distillation is capable of concentrating the peroxide to a level of about 65% before it starts azeotroping and getting concentrated to the point it could explode.  If you decide to do this, please use appropriate blast shields and the cleanest glassware you can possibly get your hands on to avoid the chance of trace contaminants catalyzing decomposition(explosive) of the highly concentrated peroxide.  For more info on concentrating peroxide mixtures, do a google search for hydrogen peroxide and model rocketry.  Concentrated peroxide is used as an excellent monopropellant by model rocket enthusiasts and there is a plethora of info on the web on how to make and work with super concentrated peroxide solutions.  As a matter of fact, I recall one web page where some guys simply boiled down 35% solution on a hotplate in an open beaker with magnetic stirring until evapareted to roughly half its initial volume.  The resulting solution was at least 60%, so this can be done without too much trouble it seems. 
 
 
 
 
    Rhodium
(Chief Bee)
12-01-01 18:54
No 243148
      Re: What to do with it?  Bookmark   

Does anyone have a detailed description for titrimetric determination of hydrogen peroxide concentration determination? Or is a density measurement enough for the purpose?
 
 
 
 
    uemura
(Hive Bee)
12-02-01 01:15
No 243219
      Re: What to do with it?  Bookmark   

Rhod

Uemura: I edited your document somewhat ...  Is that okay?



Sure! Uemura however beliefs the rxn can still be optimised futher. Running it at lower temp and evap solvents under reduced pressure seems to give less deeply colored crude epoxides. Also, the Ritter proposal taking higher conc. H2O2 may improve yields as well. The guideline should nevertheless be the one described so far.

Ritter!

thanks for this direction. Uemura tried improving yields by other means (see above) but woudn't have come to the idea of user higer conc. H2O2. Would it be possible instead of the risky destillation under normal pressure to do either:
1) frac vaccum dest to concentrate the h2o2?
2) freeze out the water?


Carpe Diem
 
 
 
 
    Ritter
(Master Whacker)
12-02-01 08:52
No 243290
      Re: What to do with it?  Bookmark   

Uemura,

One more tip on improving epoxide yields:
If you check this link carefully http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0126

you will see it mentions POTASSIUM carbonate is a superior base to sodium carbonate.  Perhaps if you switch bases, yields will go even higher!
 
 
 
 
    uemura
(Hive Bee)
12-02-01 08:57
No 243293
      Re: What to do with it?  Bookmark   

Thank you Ritter,
this is the references sunlight also pm-ed me. Do you think you can just use K2CO3 instead of KHCO3? Uemura never gets the fine details when you have to take the carbonate resp. the di-carbonate. Could you perhaps give Uemura a hint when either one is appropiate. Is it the ph range which is different?
Carpe Diem
 
 
 
 
    sunlight
(Pioneer Researcher)
12-02-01 11:37
No 243317
      Re: What to do with it?  Bookmark   

Here you are the short text of the original CA reference Osmium gave us:
CA 107: 39790k Isosafrol epoxide:
Isosafrol epoxide, useful as a intemediate for drugs and perfumes was prepd by epoxidizing isosafrol in mixt. of aq. H2O2 and MeCN or PhCN at 15-45 C and pH 8-10.5. Thus, isosafrol was stirred with a mixture of MeCN and aq. H2O2 in MeOH contg. Na2CO3 at 30 C and pH 10 for 20 h. to give 93.8 % of isosafrol epoxide.

As you see they used Na2CO3 instead of KHCO3.
I've made a test of direct epoxidation of safrol based in orgsyn procedure, but using Na2CO3 ph 9, and at 40 hours a TLC showed two spots, one of safrol and the other supposedly of the epoxide, but it's a small spot and it seems the conversion has been too low to make it interesting.
If we get a 80-90 % of epoxide from iso, and a thermal rearragement with 70-80 % yield it would be a preferable alternative to the performic, due the simplicity of rxn and work-up.
Nice dreams.
 
 
 
 
    terbium
(Old P2P Cook)
12-02-01 12:04
No 243324
      Re: What to do with it?  Bookmark   

I want to know if the nitrile solvent is essential or if perhaps something more OTC like dimethylsulfoxide would work.

Edit:
Nevermind! Sorry, should have reread the whole thread before posting. I see that the nitrile is presumed to take part in the reaction and thus is essential.
 
 
 
 
    lugh
(Hive Bee)
12-02-01 17:54
No 243407
      Hydrogen Peroxide Concentrations/Density  Bookmark   

%      d184
  01      1.0022
  02      1.0058
  04      1.0131
  06      1.0204
  08      1.0277
  10      1.0351
  12      1.0425
  14      1.0499
  16      1.0574
  18      1.0649
  20      1.0725
  22      1.0802
  24      1.0880
  26      1.0959
  28      1.1040
  30      1.1122
  35      1.1327
  40      1.1536
  45      1.1749
  50      1.1966
  55      1.2188
  60      1.2416
  70      1.2897
  80      1.3406
  90      1.3931
100      1.4465

 
 
 
 
    Rhodium
(Chief Bee)
12-07-01 02:04
No 245249
      Asarone glycol distillation  Bookmark   

It seems like the distillation of asarone glycol (and possibly also the distillaion of the epoxide, if water is present) forms a crystalline by-product, which is a glycol dimer, and not solely 2,4,5-trimethoxyphenyl-2-propanone.

Asarone 1,2-glycol

Distillation of asarone 1,2-glycol (an oil) at 170-230C/4 mmHg gives a red oil, which solidifies on standing. Through crushing the crystals under ether, a solid was left undissolved, which after recrystallization from alcohol melted at at 204-205C, and had the molecular formula C24H32O8 [Could possibly be the 2,5-dimethyl-3,6-(2,4,5-trimethoxyphenyl)-1,4-dioxane cyclic ether]. Evaporation of the ether from which the dimer was separated gave an oil which partly crystallized, and after purification through its semicarbazone (mp 157-158C), 2,4,5-trimethoxyphenyl-2-propanone (mp 47-48C) was obtained. On heating asarone 1,2-glycol with acetic anhydride, the dimeric compound is formed in quantitative yield.

Asarone dibromide

To 5g beta-asarone in 20ml dry ether cooled to -20C, there was added 4g Br2 in 6ml CS2 [Use another solvent, like ether or DCM]. Removal of the solvent gave 0.4 g of a crystalline dibromide (mp 82-83C), while the main product remained as an oil. The same procedure on alpha-(trans)-asarone gave 7g of a solid dibromide (mp 82-83C).

Reference: J. Chem. Soc. 1338 (1937)
 
 
 
 
    uemura
(Hive Bee)
12-07-01 04:05
No 245271
      Re: Asarone glycol distillation  Bookmark   

Things getting clearer!

The 1st run of the epoxidation of asarone gave indeed this red oil which solidified upon standing and is likely to be this glycol dimer.  Two things to add:

1) Uemura got in his 2nd run which has been performed under ice/water cooling at 4DegC warming up to rt after 16hrs (+ evap of solvents under reduced pressure) no red oil, but obviously unreacted? asarone! Only minor yellow color of crude epoxide, almost water clear destilled epoxide.

2) The yield (40%) was however not better than with run 1!. Uemura now thinks the idea of Ritter using highly conc. h2o2 would help a lot. Water seems to limit the yield and high temperature favours the dimer formation!

Now, a question on the dibromide. When the ref says Removal of the solvent gave 0.4 g of a crystalline dibromide (mp 82-83C), while the main product remained as an oil. does this mean the oil is NOT the dibromide or is it just not crystallising?
Carpe Diem
 
 
 
 
    Rhodium
(Chief Bee)
12-07-01 04:25
No 245274
      Re: Asarone glycol distillation  Bookmark   

The article are talking about dibromides formed from cis- and trans-asarone, respectively. The bromides formed have different stereocofiguration, one is solid and one is an oil. Both are 2,4,5-trimethoxyphenyl-1,2-dibromopropane, "asarone dibromide".
 
 
 
 
    uemura
(Hive Bee)
12-07-01 06:05
No 245288
      Water Reduction  Bookmark   

An idea poped up in Uemuras head: He doesn't like the idea of concentrating the 30% H2O2 solution by means of destillation. Now, say you have 250ml organic, waterfree MeCN/MeOH solvent and you add 12ml H2O2 which is 4g H2O2 and 8g water. This means you have 3% water in your organic mix. Would it be possible to get rid off or to reduce this percentage by adding either
a) a neutral drying agent (MgSO4, Na2SO4) or
b) silica gel?
Would a) or b) interfere with the epoxidation? Or would you need too much? .... Some ideas?
Carpe Diem
 
 
 
 
    Rhodium
(Chief Bee)
12-07-01 06:31
No 245295
      Re: Water Reduction  Bookmark   

Metal ions and possibly silica gel (definitely the indicating variety) may catalyze the breakdown of H2O2. Do you have molecular sieves, they should work.
 
 
 
 
    uemura
(Hive Bee)
12-20-01 14:41
No 249364
      DC Results  Bookmark   

Bees,

x-mas is close ..... and here we have something interesting:

To allow to contemplate on a TLC picture Uemura presents some plates with results on his olefine epoxidation. The interpretation make sense, it shows the following evidence:

1) Asarone epoxidation shows that only a certain amount of asarone is epoxidised, the rest seems not to be  affected - second run under cold conditions-solvent evap in vac, see Post 245271 (uemura: "Re: Asarone glycol distillation", Novel Discourse)! (plate III, IV).
2) Crude anethole-epoxide destillation gives the epoxide together with some none affected anethole + obviously some glycols as mentioned in the reference provided by Rhod (plate V).

Green: pure anethole, Red: destilled indian asarone.

Perhaps the Hive moderators take some pre-x-mas time to have a look on the provided picture and to comment. BTW: the colours are Uemuras interpretation, the spots have been identified as indicated.

'Thermal Residue'='What has been left after destillation of the CRUDE epoxide in vacuum' Thermal has nothing to do with the 'thermal' re-arragement od the epoxide!. Sorry if this could lead to confusion
Again, it's late, uemura confused his write-up with results on plate I and II showing the anethole-ketone

Carpe Diem
 
 
 
 
    sunlight
(Pioneer Researcher)
12-20-01 14:49
No 249366
      Re: DC Results  Bookmark   

Very nice uemura, congratulations, you are making the Hive more serious.
 
 
 
 
    uemura
(Hive Bee)
12-20-01 15:23
No 249379
      Re: DC Results  Bookmark   

Thanks a lot for the 'late night' congratulation, Sunlight smile
 
Uemura has nevertheless to apologize (he's now veryyy tired....) He mixed up some wording in the post with his lab-book write-up concerning plate I and II. The above post only shows:

1) original substance (asarone, anethole)
2) destilled epoxide (asarone, anethole)
3) left over of epoxide-destillation in flask (asarone, anethole)


This was his first TLC attempt and on plate I and II he put down a anethole-ketone drop (from thermal rearragements) NOT SHOWN above! The plates just arrived yesterday.

Thanks again to Osmium and Rhodium to encourage Uemura to apply TLC. It's indeed easy and very helpful and leads to the Hive's scientific future!!!!!

Unobtainium, did Fritz disappear - how more pics are needed !!! smile
 
 
 
 
    Osmium
(Stoni's sexual toy)
12-20-01 15:36
No 249382
      Re: DC Results  Bookmark   

How much of the substances to be tested did you apply onto the plates? How did you apply it? Capillary? Diluted or undiluted? How did you detect the spots? And what solvent system was used?
 
 
 
 
    uemura
(Hive Bee)
12-20-01 16:16
No 249391
      Re: DC Results  Bookmark   

Osmium,

you prevent me from going to bed. O.K. here we go:
  
1) Plates (25x80mm) are COTS [*]. 0.2mm Silical gel on PE foils with UV indicator. Chromatography paper sucks! Forget it for this purpose!

2) Drops have been set via small Pasteur-pipette resulting in (undiluted) starting material with diameter < 1mm [**]

3) Development in a saturated(=lid down long enough) glas pot with a 50:50 mix of drugstore pet-ether and ethylacetate (home made -- but not kitchen-style like, i.e. waterfree and not too much EtOh or GAA)

4) Spot detection was surprisingly easy. Against a plant lamp the spots could be easily detected after drying the plates. Uemura found that the spots are even easier to see when looking at the back of the plate againt the lamp. No iodine or real UV lamp seemed required.

5) Since the results made sense and the eperiments just started, no further verification have been done so far.

Please advise how to confirm the above approach (without a genuine UV light).
  • COTS=Commercial Of The Shelf
[**] Uemura knows: smaller is better!!!

Have a good night
 
 
 
 
    Rhodium
(Chief Bee)
12-20-01 17:02
No 249409
      Re: DC Results  Bookmark   

Don't use concentrated solution, 5% or less is sufficient with an UV lamp (which can be bought cheaply for detecting fake paper money).
 
 
 
 
    Osmium
(Stoni's sexual toy)
12-20-01 18:38
No 249430
      Re: DC Results  Bookmark   

> Drops have been set via small Pasteur-pipette resulting
> in (undiluted) starting material with diameter < 1mm

Oh my god! WAY WAY WAY too concentrated!
Last time I did TLC I applied ~6L of a diluted solution (1:5) with an adjustable volume (2-20L) Eppendorf pipette, which resulted i a starting point about 3mm in diameter. Yours was so small because of the high viscosity material.
Separation at such a high concentration is abyssmal.
Use melting point capillaries to apply your (diluted!)samples.

> Spot detection was surprisingly easy. Against a plant
> lamp the spots could be easily detected after drying the
> plates. Uemura found that the spots are even easier to
> see when looking at the back of the plate againt the
> lamp. No iodine or real UV lamp seemed required.

Uh oh. You shouldn't be able to see anything at all once they are dried.
Iodine detection isn't the best method around, but it is the easiest. I2 often doesn't detect all components.

> UV lamp (which can be bought cheaply for detecting fake
> paper money).

Commercial overpriced UV lamps for TLC have two wavelenghts which can be used independently from each other, or together. Different compounds might show up at one wavelenght but not readily at the other.
 
 
 
 
    uemura
(Hive Photographer)
12-20-01 23:59
No 249502
      Re: DC Results  Bookmark   


Oh my god! WAY WAY WAY too concentrated!




OOps, still to much substance????

Compared with the results uemura got from a test using chromatography paper, the silica plates worked like the Hubble telecope. Circles of pure substances moved up as a circle of almost same size and did not smear out. Mixed components did seperate clearly.


Uh oh. You shouldn't be able to see anything at all once they are dried.



Under a 'normal' lamp there was indeed almost nothing to see, but the 'plant lamp' uemura has around helped to see the developed spots.


Iodine detection isn't the best method around, but it is the easiest.



Uemura will re-do the above samples and apply your recommendations. For the time being he will try it with iodine and will have a look for a detecting fake paper money device. Thanks for your input so far!


Carpe Diem

Unob! Thanxs for the new title! More pics to come soon...
 
 
 
 
    sunlight
(Pioneer Researcher)
12-21-01 06:05
No 249542
      Re: DC Results  Bookmark   

The faked money detect uv light doesn't show too much, we use the bactericide ones. Keep care with your eyes, I had a problem with them one day testing and H2O2 alkene addition (didn't work for safrol) catalyzed by uv, very irritant.
 
 
 
 
    sunlight
(Pioneer Researcher)
12-21-01 07:53
No 249575
      Re: DC Results  Bookmark   

The bactericide uv lamp has the same size of the others for detecting faked money, so it was armed in the same lamp, and plates are examined like money. Good invention of my friend.
 
 
 
 
    Osmium
(Stoni's sexual toy)
12-21-01 08:20
No 249579
      Re: DC Results  Bookmark   

Can you find out what wavelenght that UV lamp produces?
 
 
 
 
    sunlight
(Pioneer Researcher)
12-21-01 11:41
No 249604
      Re: DC Results  Bookmark   

I didn't remember it but my friend has told me it is 254 nanometres, and acording to him is the exact wave length for this TLC. Plates are Merck silica gel 60 F 254 (yes, 254, the wave length). The disco and money uv light is around 350, and we compared both in a TLC and the money one showed no more than normal light. The invention is that is armed in the money detect apparatus, very nice.
 
 
 
 
    Osmium
(Stoni's sexual toy)
12-21-01 13:59
No 249624
      Re: DC Results  Bookmark   

Aldrich sells spare UV lamps/tubes at obscene prices. They are available in 4, 6 and 8W (with a lenght of 20.3/26/51.6cm resp) and short and long wavelenght (254 and 365nm). The short wavelenght usually costs twice as much as the long wavelenght.

Where else might one get the short wavelenght spares?
 
 
 
 
    terbium
(Old P2P Cook)
12-21-01 14:23
No 249632
      Re: DC Results  Bookmark   

Short wave cost more because it requires a quartz bulb whereas longwave can use glass.

Sources in the US:

http://www.scientificsonline.com/
Search for "uv lamp"
http://www.scientificsonline.com/Products/DisplayProduct.cfm?productid=1853

And then, the motherload though they may no longer sell retail:
http://www.uvp.com/index.html
 
 
 
 
    sunlight
(Pioneer Researcher)
12-22-01 10:12
No 249844
      Re: DC Results  Bookmark   

I'll ask my friend, he bought the whole kit for me, and if I remember correctly the price of the lamp was something like 20 euros.
 
 
 
 
    uemura
(Hive Photographer)
12-23-01 00:37
No 250016
      Re: DC Results  Bookmark   

Hi bees,
uemura did some google research and can confirm the TLC designed lamps are pretty expensive and the low-cost stuff for the fake money seems to be at 360nm or so.
BUT: he found another area where UV lamps are of use: mineralogy He checked out a pdf sheet described a nice UV hand-lamp for about 50$ saying it works in 2 frequencies (should be 254 and 360). Company closed over the holidays frown.
The third type of application, sterilisation of water in ponds and aquarien provides you with type of lamps working in the low UV but these are also expensive and not very handy.

Merry X-Mas to the Bees
 
 
 
 
    sunlight
(Pioneer Researcher)
12-25-01 12:52
No 250419
      Re: DC Results  Bookmark   

I've consulted it and the uv tube 254nm I'm using is used as a germicide-bactericide in aquariums etc..., there are diferent lengths, but this one is exactly the same of the uv tubes for detecting faked money, so it was just substituted, and the price was 20-30 euros. It don't believe it is expensive for anyone.