Sciencemadness Discussion Board - Which extraction method to use for plants

Which extraction method to use for plants

Quince - 7-12-2006 at 00:57

There seem to be many extraction methods for essential oils, and I don't know which one to choose. Is there any advantage to doing steam distillation over solvent extraction? This far I've used methylene chloride in a first extraction, then alcohol to separate the oils from the waxy extract. However, I find that there is a characteristic smell left regardless of what types of plants I extract, which is the same with some commercial extracts I've tried, so I can't help but wonder if the methylene chloride reacts with something, or the 80*C reached when evaporating the alcohol is too much (I guess I could evaporate it under vacuum, if the landlady is away or I'd get killed for the water usage). I can't do supercritical CO2 since I don't have the equipment. Does anyone here have experience with different methods and can make a recommendation? I've been thinking of trying the steam distillation, but I want to ask first if there's any advantage. I also read about "controlled instantaneous decompression" as an extraction method, but didn't find much detailed information with Google, other than what's in this abstract.
BTW when extracting with alcohol from the waxy first extract by DCM, is it OK to use methanol or propanol instead of the commonly specified ethanol? Ethanol is harder for me to obtain in high concentration.

[Edited on 7-12-2006 by Quince]

unionised - 7-12-2006 at 11:56

It rather depends what you are extracting and why.
Extraction with DCM is great for things that are not thermally stable but, unlike steam distillation, it takes all the waxes and fats too.
Ethanol has one huge advantage if you are making extracts to use as food additives or pharmaceuticals- it's essentially non toxic. *
Methanol and IPA have fairly similar solvent properties; if you are trying to get rid of waxes I'd go for methanol unless your product is unusually non-polar. Methanol is easier to evaporate off afterwards but IPA is usually thought of as less toxic.

*Yes, I know, ethanol is responsible for more cases of poisoning than just about any other chemical

Quince - 7-12-2006 at 15:00

What I'm trying to extract is essential oils. Some for the smell (vanilla and a ton of others), some for other stuff (for example, nepatalactone is a good non-toxic mosquito repellent, and I can get plenty of free catnip).
Do you think the DCM or alcohol could be reacting with something in the plants? I always find that the results of such solvent extraction have an additional smell to them I don't like, and like I said in the first post, I've found this in some commercial extracts as well. Or perhaps it's extracting some component that other methods do not...
Now would steam distillation in this case necessarily need the steam to be at 100*C? I don't know much about the process so I'm not sure about this. I know that water vapor doesn't condense right away when it's cooler than that.

I take it you haven't heard about that "controlled instantaneous decompression" extraction? They steam the material for a few minutes, then instantly drop the pressure near zero, and claim it gets 90-97% of the oils. Since I could only access the abstract, I still didn't understand how they physically separate the oils from the plant material afterwards. Just squeezing it out perhaps?

XxDaTxX - 8-12-2006 at 06:19

Quote:

Originally posted by Quince
What I'm trying to extract is essential oils. Some for the smell (vanilla and a ton of others), some for other stuff (for example, nepatalactone is a good non-toxic mosquito repellent, and I can get plenty of free catnip).
Do you think the DCM or alcohol could be reacting with something in the plants? I always find that the results of such solvent extraction have an additional smell to them I don't like, and like I said in the first post, I've found this in some commercial extracts as well. Or perhaps it's extracting some component that other methods do not...
Now would steam distillation in this case necessarily need the steam to be at 100*C? I don't know much about the process so I'm not sure about this. I know that water vapor doesn't condense right away when it's cooler than that.

I take it you haven't heard about that "controlled instantaneous decompression" extraction? They steam the material for a few minutes, then instantly drop the pressure near zero, and claim it gets 90-97% of the oils. Since I could only access the abstract, I still didn't understand how they physically separate the oils from the plant material afterwards. Just squeezing it out perhaps?

Its use is limited to specific industrial processes. It is not feasible for either of the following adaptations:

1. When done in a batch process, ie all at once, you would probably need something around the order of 20,000L of volume to hold your 800mL of DCM (assuming a final temp of ~-70C) w/o pulling DCM into your vacuum. You'd need a pump that could pull 10mbar, and a vessel that can handle the extreme pressure and temperature drop to get good efficiency.

2. A modified version exists where this can be adapted to a semi-continuous process, however you would need a cryogen to condense the vapor @10bar. I'm sure you have a LN2 tap somewhere ..... oh yes here it is! =P

On a side note, do your essential oil extractions like everyone else. There is a reason why only industrial extractions vary from this procedure: steam distill, partition with DCM, filter organic phase, dry, heat/distill off DCM and you can get back to whatever it was that you were going to do with the essential oil...

Quince - 9-12-2006 at 08:57

The reason I skip steam distilling is because by extracting directly with DCM I don't expose the material to high temperature. I also need a minimum amount of DCM, whatever's needed to reach high enough level in the Gregar, which is a continuous extractor. I'm not sure what the point of the steam distillation is, and that's in fact part of my initial question. Why is steam distillation used, instead of using an organic solvent from the beginning?

Quote:

heat/distill off DCM and you can get back to whatever it was that you were going to do with the essential oil.

As unionised mentioned, that also extracts waxes, so alcohol extraction is still needed.

pantone159 - 9-12-2006 at 10:45

Quote:

Originally posted by Quince
The reason I skip steam distilling is because by extracting directly with DCM I don't expose the material to high temperature. Why is steam distillation used, instead of using an organic solvent from the beginning?

With steam distillation, you don't expose the material to temps over 100 C, so that also counts as low temperature a lot of the time.

With a straight extraction, without the steam distillation, you may also pick up non-volatile compounds, which you usually don't want.

One example from my experience: I have tried extracting eugenol from cloves, both with solvent extraction (I used alcohol and then let it evap before continuing), and with steam distillation. In both cases, the crude extracts were separated via an acid/base extration using DCM/NaOH/HCl. (This is a common lab experiment.)

With steam distillation, I got fairly pure eugenol, only lightly yellow-brown colored. With solvent extraction, I got a much darker colored product, which was obviously not pure. Apparently, cloves contain some non-volatile colored component which follows phenols around in the extractions. (High MW polymerized phenols???). Steam distillation left the brown junk behind, solvent extraction picked it up.

It does depend on your plant. Some things work well with solvent extraction, some don't.

Quince - 9-12-2006 at 11:04

I guess then the question is when does it not work.

XxDaTxX - 9-12-2006 at 14:56

Quote:

Originally posted by Quince
The reason I skip steam distilling is because by extracting directly with DCM I don't expose the material to high temperature. I also need a minimum amount of DCM, whatever's needed to reach high enough level in the Gregar, which is a continuous extractor. I'm not sure what the point of the steam distillation is, and that's in fact part of my initial question. Why is steam distillation used, instead of using an organic solvent from the beginning?

Quote:

heat/distill off DCM and you can get back to whatever it was that you were going to do with the essential oil.

As unionised mentioned, that also extracts waxes, so alcohol extraction is still needed.

If you are extracting essential oils you use water to steam it out. Honestly, I don't quite know what will persuade you to do it right. If you want the nitty gritty here you go:

1. DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax, and is thus carried over any distillation head.

2. The amount of wax able to dissolve in DCM / oC s not 1:1. Its a higher order function.

3. Water counters the effect that DCM has on the solubility of the wax. By adding water, it interacts with what used to be just DCM:wax so now you have DCM:wax:water. Changing the composition in the still changes the composition of the vapor thus produced in favor of DCM (due to high relative volatility) and against wax (due to insolubility in water, polarity).

4. Just do it and stop arguing. DCM is a prime defatting/dewaxing solvent at higher temperatures. Particularly because a quick temperature swing and solubility goes down, where after it is recovered by centrifuging, and STEAM DISTILLATION, or hot air volatilizing and scrubbing. We use it in industrial applications ALL THE TIME.

5. If you want essential oils, use water. For tincture/organic solvent extraction use alcohol. And for WAX, USE DCM.

[Edited on 9-12-2006 by XxDaTxX]

unionised - 10-12-2006 at 05:27

"DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax, and is thus carried over any distillation head."

What, exactly, does solubillity have to do with distilation?
Water disolves salt as a function of temperature; at higher temperatures it disolves more and more salt.
Nevertheless, salt gets left behind when seawater is distilled to produce fresh water.
I still want to know what this weird wax is- it is very odd that it distills along with DCM.

XxDaTxX - 10-12-2006 at 08:07

Quote:

Originally posted by unionised
"DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax, and is thus carried over any distillation head."

What, exactly, does solubillity have to do with distilation?
Water disolves salt as a function of temperature; at higher temperatures it disolves more and more salt.
Nevertheless, salt gets left behind when seawater is distilled to produce fresh water.
I still want to know what this weird wax is- it is very odd that it distills along with DCM.

It is not odd. It is predictable. The high solubility in high temperatures has to do with their molecular interactions. Those same interactions govern, somewhat, the vapor pressures of the constituents in in your still.

DCM is used to remove waxes from lubricant oils ALL THE TIME, so again NO IT IS NOT ODD that it comes over with DCM. Send it to an analytical lab and they will tell you what it is. Is it worth your $ to know? Probably not. And similarly, it is no longer worth my time trying to persuade people in this thread to do things right.

[Edited on 10-12-2006 by XxDaTxX]

unionised - 10-12-2006 at 14:29

It wouldn't be very $ for me to get a lab to analyse it; I work in one. Of course, since I don't have a sample of it, I can't analyse it. I have analyse plenty of things in my time, some of them waxes.
For the wax to distill at 40C it needs to have a reasonable vapour pressure at 40C. Very few solids do.
As I said, salt dissolves perfectly well in water, but it doesn't distill.

It's news to me that DCM is used to dewax oils (and Google doesn't give any hits about it for "dewaxing oil" dichloromethane).
Last time I checked lube oil mixed freely with DCM. If you chilled it well enough you might get the wax out, but any solvent could be used for that. It still has nothing to do with the idea that a wax would distill at 40C

[Edited on 10-12-2006 by unionised]

[Edited on 10-12-2006 by unionised]

XxDaTxX - 10-12-2006 at 20:16

Quote:

Originally posted by unionised
It wouldn't be very $ for me to get a lab to analyse it; I work in one. Of course, since I don't have a sample of it, I can't analyse it. I have analyse plenty of things in my time, some of them waxes.
For the wax to distill at 40C it needs to have a reasonable vapour pressure at 40C. Very few solids do.
As I said, salt dissolves perfectly well in water, but it doesn't distill.

It's news to me that DCM is used to dewax oils (and Google doesn't give any hits about it for "dewaxing oil" dichloromethane).
Last time I checked lube oil mixed freely with DCM. If you chilled it well enough you might get the wax out, but any solvent could be used for that. It still has nothing to do with the idea that a wax would distill at 40C

[Edited on 10-12-2006 by unionised]

[Edited on 10-12-2006 by unionised]

If you work in a lab then ask your teacher.

Read some books on Raoult's Law as it governs (somewhat) the composition of your distillate.
Here is an intro.

Now if you have understood that then model a vapor pressure diagram for DCM, your wax, and water. (It should have three axes)

Due to specific interactions between DCM and the wax (as can be seen from the temperature dependant solubility) you have a non-ideal mixture.

Adjusting for positive deviations for the wax's vapor pressure, and negative deviations for DCM's vapor pressure, redraw your vapor pressure diagram.

Remember that mol fraction of in the lower phase is severely limited by its solubility, but it does affect it significantly.

I will not tell you how to compute the actual deviations because one can devote a complete post-doc career in it, however I will tell you that it gets more and more complex.

What you have from there is a rough estimate of how water changes vapor pressures. Deviations can be calculated within the framework of a particular model, each having specific applications of non-ideal mixtures.

Congratulations, you have now seen what happens ...... IN THE LOWER PHASE ONLY!

..... Read a book if you want to see what goes on in biphasic equilibrium. Google is not the place to look. Try industrial chemistry literature.

Here's a reference on using DCM to dewax oils.

unionised - 11-12-2006 at 04:07

My teachers may well be retired if not dead by now, it's been a couple of decades or so since I left University. I actually work in a real analytical lab.
I'm well enough aquainteed with Raoult's law to know that it refers to the vapour pressures of the components of the mixture- I trust that you are too.
The point that you have been steadfastly ignoring is that, unless the vapour pressure of a component is reasonably high, it never gets into the vapour phase (to any significant extent) so it doesn't distill over.

What I am asking is "what is this wax with a high vapour pressure at 40C? because most solids don't have high vapour pressures."
Do you understand that the rarity of volatile (at 40C) waxy solids makes this stuff a real oddity?
Most solids, like the salt in seawater, don't distill with steam and they are even less likely to do so with DCM vapour at 40C.

It's interesting to note that the reference you give for dewaxing with DCM points out that a whole slew of other solvents can be used (as I sugested) and also, that by steam strippping or distillation, the DCM can be recovered from the wax. They point out explicitly that distillation separates wax from DCM. I'm saying it's odd that in the case we have been discussing the wax distills over with the DCM and that I would have expected the distillation to separate them because the difference in boiling poinst between very volatile DCM and (usually very involatile ) wax is huge.
You seem to think it's perfectly normal for these two components to co-distill. I don't and nor does the reference you cite.

[Edited on 11-12-2006 by unionised]

Quince - 11-12-2006 at 04:43

Well, next time I get a can I'll check the company and post the name here, so anyone interested can contact them for an MSDS, which should list the mystery ingredient.

My own feeling is that, though the head temperature did not exceed 40*C, the flask most certainly did, and not all the wax vapors condensed in the Vigreux, but some got through (after the steam distillation mentioned in the other thread, about 5%).

[Edited on 11-12-2006 by Quince]

XxDaTxX - 11-12-2006 at 07:49

Quote:

Originally posted by unionised
My teachers may well be retired if not dead by now, it's been a couple of decades or so since I left University. I actually work in a real analytical lab.
I'm well enough aquainteed with Raoult's law to know that it refers to the vapour pressures of the components of the mixture- I trust that you are too.
The point that you have been steadfastly ignoring is that, unless the vapour pressure of a component is reasonably high, it never gets into the vapour phase (to any significant extent) so it doesn't distill over.

What I am asking is "what is this wax with a high vapour pressure at 40C? because most solids don't have high vapour pressures."
Do you understand that the rarity of volatile (at 40C) waxy solids makes this stuff a real oddity?
Most solids, like the salt in seawater, don't distill with steam and they are even less likely to do so with DCM vapour at 40C.

It's interesting to note that the reference you give for dewaxing with DCM points out that a whole slew of other solvents can be used (as I sugested) and also, that by steam strippping or distillation, the DCM can be recovered from the wax. They point out explicitly that distillation separates wax from DCM. I'm saying it's odd that in the case we have been discussing the wax distills over with the DCM and that I would have expected the distillation to separate them because the difference in boiling poinst between very volatile DCM and (usually very involatile ) wax is huge.
You seem to think it's perfectly normal for these two components to co-distill. I don't and nor does the reference you cite.

[Edited on 11-12-2006 by unionised]

I already explained that it was non-ideal and the wax has a positive deviation from raoult's predicted vapor pressure.

If you want the theory behind it, thats more simple:

Let's assume that intermolecular forces between wax molecules in a pure liquid is some value "x" ... then assume that the intermolecular forces for DCM in a pure liquid is some value "y".

Then when you mix them, BECAUSE THEY ARE SUBSTANTIALLY DIFFERENT like I said before, they become non-ideal.

Intermolecular forces between DCM and the wax are less than DCM : DCM or wax : wax interactions.

In this way you can see that because the intermolecular attraction between the two components decreases upon mixing, their respective vapor pressure also changes because they are less "bound" to the liquid phase due to lowering of intermolecular attractive forces.

The reason for the water is two fold: first it should produce a compensating negative deviation for the wax, while having little to no effect on the polar DCM.

Your salt and water example is one of negative deviations. The intermolecular forces set up in the mixture, ionic, increase the amount of energy needed to vaporize its components. In this way it is non-ideal as a negative deviant of Roult's law.

Interactions between components create non ideal mixtures, and corresponding non ideal vapor pressures.

BTW, I certainly hope that someone in your "real analytical lab" knows more than the introductory material on Raoult's law. Positive and negative deviations are the first thing explained past the undergraduate courses in chemistry ... and I would hate to know that there is an analytical lab run by undergrads .... oh wait .... thats like what I have to deal with .... back to scolding these undergrads.

[Edited on 11-12-2006 by XxDaTxX]

Reference Information

solo - 11-12-2006 at 09:00

An original solvent free microwave extraction of essential oils from spices
Marie Elisabeth Lucchesi, Farid Chemat,* and Jacqueline Smadja
FLAVOUR AND FRAGRANCE JOURNAL Flavour Fragr. J. 2004; 19: 134–138

ABSTRACT:
Attention is drawn to the development of a new and green alternative technique for the extraction of essential oils from spices. Solvent-free microwave extraction (SFME) is a combination of dry distillation and microwave heating without added any solvent or water. SFME and hydrodistillation (HD) were compared for the extraction of essential oil from three spices: ajowan (Carum ajowan, Apiaceae), cumin (Cuminum cyminum,
Umbelliferae), star anise (Illicium anisatum, Illiciaceae). Better results have been obtained with the proposed method in terms of rapidity (1 h vs. 8 h), efficiency and no solvent used. Furthermore, the SFME procedure yielded essential oils that could be analysed directly without any preliminary clean-up or solvent exchange steps.

KEY WORDS: solvent-free; microwave; dry distillation; essential oil; ajowan (Carum ajowan); cumin (Cuminum cyminum); star anise (Illicium anisatum)

[Edited on 11-12-2006 by solo]

Attachment: An original solvent free microwave extraction of essential oils from spices .pdf (103kB)
This file has been downloaded 1634 times

Reference Information

solo - 11-12-2006 at 09:10

Kinetics of Isothermal and Microwave Extraction of Essential Oil Constituents of Peppermint Leaves into Several Solvent Systems
Michael Spiro and Sau Soon Chen
FLAVOUR AND FRAGRANCE JOURNAL, VOL. 10, 259-272 (1995)

Abstract
The rates and extents of extraction have been measured for three major constituents of peppermint oil, namely l,&cineole, menthone and menthol, using the leaves of the black mint (Menthu X piperitu L.). The solvents used
were hexane, ethanol and mixtures of composition 90mol% ethanol + 10mol% hexane and 90mol% hexane + 10mol% ethanol. The extractions were carried out isothermally at 25, 35 and 45°C as well as in an electrically
and mechanically modified domestic microwave oven where the temperature increase vaned from c. 10 to 30°C.
The rates of both isothermal and microwave extractions were sensitive to the solvent employed and decreased in the order 90mol% hexane > 90mol% ethanol > hexane > ethanol. The rates of microwave extraction were also
affected by the microwave power output and the size of the sample load. The activation energies for the extractions were in the range 30-90kJ mol-', again dependent on the solvent used. Scanning electron microscopy on the spent leaves provided evidence of a link between the kinetics of extraction and structural changes on the glands.

KEY WORDS Extraction kinetics; microwave extraction; solvent extraction; rate constants; essential oils; peltate glands; peppermint (Mentha x piperita L.); 1,8-cineole; menthone; menthol; dielectric properties

Attachment: Kinetics of Isothermal and Microwave Extraction of Essential Oil Constituents of Peppermint Leaves into Several Solvent (1.1MB)
This file has been downloaded 908 times

unionised - 11-12-2006 at 09:55

XxDaTxX
I guess that you are used to dealing with undergrads- you have my sympathy on that matter. Perhaps that's why you aren't used to dealing with someone who is sufficiently familiar with Raoult's law and deviations from it that he doesn't need to quote chapter and verse on it.
DCM and water form an azeotrope. Raoult's law predicts that no azeotropes exist.
Clearly, there are deviations from it, I already knew that. You can rest assured that someone in my lab knows about it; I do. (Incidentaly, I also know that distilation isn't used much in analytical labs these days so it wouldn't be the end of the earth if nobody knew about Raoult's law. In addition many, if not most mixtures don't know about it anyway, they certainly don't follow it)
Simply stating that "I already explained that it was non-ideal and the wax has a positive deviation from raoult's predicted vapor pressure." doesn't really help unless you can tell me what sort of thing has this great a deviation.
The most volatile solid I could find the data for in a quick search was camphor; I estimate that it has a vapour pressure of a couple of mmHg at 40C. At that temperature DCM has a vapour pressure of roughly 760mmHg. If they started off equimolar then the mixture coming over, if it followed Raoults law, would be something like 0.3% camphor (the usual crass aproximations have been made here).

What you are talking about is a deviation from Raoult's law of an order of magnitude or 2. As far as I'm aware, that sort of thing doesn't happen unless something really weird is going on.

XxDaTxX - 11-12-2006 at 10:29

Quote:

Originally posted by unionised
XxDaTxX
I guess that you are used to dealing with undergrads- you have my sympathy on that matter. Perhaps that's why you aren't used to dealing with someone who is sufficiently familiar with Raoult's law and deviations from it that he doesn't need to quote chapter and verse on it.
DCM and water form an azeotrope. Raoult's law predicts that no azeotropes exist.
Clearly, there are deviations from it, I already knew that. You can rest assured that someone in my lab knows about it; I do. (Incidentaly, I also know that distilation isn't used much in analytical labs these days so it wouldn't be the end of the earth if nobody knew about Raoult's law. In addition many, if not most mixtures don't know about it anyway, they certainly don't follow it)
Simply stating that "I already explained that it was non-ideal and the wax has a positive deviation from raoult's predicted vapor pressure." doesn't really help unless you can tell me what sort of thing has this great a deviation.
The most volatile solid I could find the data for in a quick search was camphor; I estimate that it has a vapour pressure of a couple of mmHg at 40C. At that temperature DCM has a vapour pressure of roughly 760mmHg. If they started off equimolar then the mixture coming over, if it followed Raoults law, would be something like 0.3% camphor (the usual crass aproximations have been made here).

What you are talking about is a deviation from Raoult's law of an order of magnitude or 2. As far as I'm aware, that sort of thing doesn't happen unless something really weird is going on.

What I already explained is the theory behind what he is seeing. I don't know how else to explain it, but that is how it works. If you look at phase diagrams for non-ideal mixtures you will see severe changes when intermolecular forces change sharply between pure liquids and their respective multicomponent mixtures..... after all, what else do you think is holding them in the liquid phase, but those intermolecular forces and the pressure above them?

There are few examples better at explaining this phenomena than dipole-dipole DCM and London Dispersion Wax .... being combined to lose those interactions, thus making it easier to leave the liquid phase. The fact that it affects the wax's vapor pressure more than the DCM has to do with the fact that LD is a weak force to begin with, destroy that and what else is a wax to do but vaporize.

[Edited on 11-12-2006 by XxDaTxX]

Quince - 11-12-2006 at 11:04

Thinking back to the extraction of HNO3 with DCM, the patent claims that the two form a bond of sorts. Is something analogous possible with the wax? That is, not just a simple solution of the wax into the DCM?

Also, I want to stress again that, although the head remained at 40*C, the flask was much hotter. That not all the wax vapors condensed in the Vigreux could have been simply because I was distilling too fast.

A final question: if I get another batch of paint stripper, should I just do the steam distillation, or do I need regular distillation first to remove other things such as the methanol?

[Edited on 11-12-2006 by Quince]

unionised - 11-12-2006 at 11:23

Those weak forces are normally enough to keep it together at 40C unless it's a wax that boils below 40C in which case I really want to know what it is.
There are 3 sets of forces to consider you have missed out the dipole- induced dipole force ie between DCM and wax. This is generally stronger than the London force. If the wax can be melted without boiling then the relatively weak London forces are sufficient to keep the stuff in the liquid phase rather than the vapour. The forces holding it back in solution rather than vapourising ie the induced dipole interactions are stronger so the deviation ought to be negative. Similarly, the relatively strong dipole dipole interactions in pure DCM are destroyed because the wax molecules get in the way. If anything this means that the DCM should be easier to distill out than Raout's law would suggest. (of course, this is offset- the DCM is less strongly held to the wax, but the wax is heavier so there is some chance of the DCM escaping as a dimer but little chance of a wax+DCM molecule doing so).

Anyway, if your point holds for wax and DCM it will also hold for "oily fatty crap" +DCM so you cannot evaporate DCM from oily stuff to recover it. More interestingly, it would also hold for "the stuff I just synthesised in any of a whole bunch of practical experiments and the extracted into ether". That means I cannot extract my product into ether and then evaporate off the ether to collect my product.
This is news to me, and, I suspect, to many others on this site.
(BTW, if you want to refer to this post please don't quote the whole lot- doing so just takes up more storage space and bandwidth)

[Edited on 11-12-2006 by unionised]

Maya - 11-12-2006 at 11:43

Why don't we put down the nice theoretical discussions and simply find out what the heck you got in the wax?

You know ? some simple organic micro-qualitative testing for functionality?

my god that would be so easy and tell you exactly how to purify....

I learned that first year organic chem , its easy....

Quince - 11-12-2006 at 11:50

Well look who's here... the Hindu creator of the universe!

Not possible for me, for the simple reason that I never took chemistry in university. Indeed, my specialty couldn't be further from it.

[Edited on 11-12-2006 by Quince]

Maya - 11-12-2006 at 11:56

yes but you ARE dealing with chemistry, you have to try and understand some of the principles involved otherwise you'll be beating your head on the wall, and ours on the internet, everytime that you don't understand something.

really, it is very easy. DUDE, this is the first page I got when i googled "organic qualitative analysis" and it looks like a good one out of many...........

http://chemserv.bc.edu/ugrad/lab/org/QualAnal.pdf

Quince - 11-12-2006 at 11:58

Quote:

Originally posted by Maya
beating your head on the wall, and ours on the internet

If so, I'm amazed neither head nor wall has broken this far...

Maya - 11-12-2006 at 11:59

Here's an even better one

http://bcs.whfreeman.com/mohrig2e/content/cat_010/techniques...

Quince - 11-12-2006 at 12:14

I'll just track down the MSDS. That's the easiest solution. I just have to go to the hardware store again. Thanks for the links anyway though.

[Edited on 11-12-2006 by Quince]

Maya - 11-12-2006 at 12:24

No worries, Let us know what the top 4 -5 components are. You've got us wondering now as well.........

unionised - 11-12-2006 at 12:26

I doubt that there are fewer than a hundred components in that wax. Good luck!

Maya - 11-12-2006 at 12:30

well , he calls it wax for want of a better discriptor. I actually doubt it's a wax per se at all

Simple test for parrafins would tell

unionised - 11-12-2006 at 13:11

Well, beeswax isn't a hydrocarbon. Nor are plant waxes. Anyway, we won't find out by guesswork.

XxDaTxX - 11-12-2006 at 14:18

Quote:

Originally posted by unionised
Those weak forces are normally enough to keep it together at 40C unless it's a wax that boils below 40C in which case I really want to know what it is.

The the length of the chain has alot to do with it. 1 molecule of whatever chain length will have induced dispersion forces almost propotional to its chain length (plus a constant) ....

Quote:

Originally posted by unionised
There are 3 sets of forces to consider you have missed out the dipole- induced dipole force ie between DCM and wax. ...

You are missing the point. Here let me put it simply once again.

Pure liquids
DCM : DCM attractive force is some value X
Wax : wax attractive force is some value y

In a mixture
DCM : wax attractive force for DCM with an ajacent molecule is x-dx
Wax : dcm attractive force for wax with an adjacent molecule is y-dy

dy and dx have to do with relative molar fractions in the mixture, and the corresponding intrinsic differences between the two molecules. Thats it. Go argue with a text book if you want. I am not making this up. I don't know why you continue to argue with me.

And when you try to explain deviations between non-ideal mixtures and their vapor pressures, you generally speak of the strongest interactions broken and made, and the effects that mixing has on them... not all the interactions. Not that there is no effect on the ones not mentioned, but the strongest interactions made/broken are the ones that generally prevail.

The forces holding wax in liq phase in pure liq are LD forces, which, upon mixing, do not contribute due to the relative seperation between wax:wax molecules (ie DCM is in between).

The fact that DCM does not distill out easier by the same token is not that it isn't true, but that it is not noticeable. Dipole dipole forces are several times stronger than LD forces, so that although they are diminished slightly, it is not noticed as much.

[Edited on 11-12-2006 by XxDaTxX]

unionised - 11-12-2006 at 22:55

"I don't know why you continue to argue with me. "

Because, by your argument, I can't recover a product by ether extraction and distilling off the ether.
When theory and practice don't agree it isn't reallity that needs changing.

XxDaTxX - 12-12-2006 at 08:25

Quote:

Originally posted by unionised
"I don't know why you continue to argue with me. "

Because, by your argument, I can't recover a product by ether extraction and distilling off the ether.
When theory and practice don't agree it isn't reallity that needs changing.

But theory and practice did agree. As you can see he posted that it did work. The VERY slight amount that did come over was because he did not centrifuge first.

Are you talking about his wax when you say ether extraction?? Or about something else?

For binary ideal mixtures (ether+whatever it is that you are talking about), provided that their vapor pressures in the pure state are significantly different, extraction and evaporation is relatively easy, and efficient. Thats Raoult's Law for ideal mixtures. If they are non-ideal and intermolecular forces change significantly then thats different. And I already went through that.

Keep in mind that deviations because of changes in intermolecular interactions has alot of relativity that must be taken into account. Dipole Dipole interaction is less affected by a non polar component, as opposed to a LD/Induced Dipole being affected by a polar component.

Relative mol fractions also have alot to do with why one is affected more than the other, not to mention its obvious influence on vapor pressure ratios, as well as many other things. Like I said, go learn it yourself.

There is nothing wrong with the theory, we use the same theories to build large processing facilities. I think we'd notice if there was something wrong.

At simple applications of theory such as this one, theory and practice practically ALWAYS agree .... when they don't .... it's usually a matter of whether or not you understand enough theory to comprehend reality, or whether or not you had the foresight to compensate for factors that get presented to you.

If today a novel reaction is discovered that is not explained by current mechanisms, and tomorrow they come out with a mechanism, it does normally negate the prior, rather it adds to it.

The theories that govern this set of equilibria are simple to say the least. You should see more complex models. Each one has a workable theoretical framework by which one can understand it.

[Edited on 12-12-2006 by XxDaTxX]

unionised - 12-12-2006 at 10:28

OK, Sorry, I'm getting 2 threads muddled but Quince wrote
"After distillation through a vigreux into ice water, I realized that even though I did not let the head go above 40*C, a good deal of the gelling agent/thickener came over... "
Here
https://sciencemadness.org/talk/viewthread.php?tid=7161&...

I was generalising the point that you made, like DCM, ether is a volatile, fairly polar water immiscible solvent. I used it as an example because it's very commonly used as an extraction solvent. It doesn't matter much. The point I was making works just as well with extracting a product int DCM and then distilling off the solvent- this too has been done countless times my masses of students for a huge variety of products.

Since we don't know anything much about the wax that was the origin of this discussion we ought to assume that it's nothing particularly weird. If it's just some run of the mill chemical then the same argument that you made for the wax distilling over would also apply in lots of other cases.
Just go through your text and replace "wax" with "product"- all the stuff about London forces and such still applies (except if we are talking about really polar products). For example your arguments would work for olive oil just as well as they work with this wax, not because there's anything magic about olive oil- plenty of other materials would do as examples. The problem is that if I get some olive oil and add DCM to it, I can then distill the DCM out of the oil.
It works; the oil gets left behind.

When the mixture of wax and DCM was distilled it didn't work- the wax distilled over in spite of the still head not reaching 40C as indicate above, copied from the other thread.

That's a real difference and I'd still like an explanation.

When you distill the oil and DCM some tiny trace of the oil will come over, broadly in proportion to the vapour pressures of DCM and the oil. Of course, eventually the oil will distill over but the temperature at the still head won't be anything like 40C at that point.
You talk of simple theories.
I can't see one much simpler than this;

If the stuff has a low vapour pressure at 40C then it won't distill over at 40C because, if it tried to, it would condense out on the thermometer bulb and get stuck.

I am fully aware of the fact that the vapour pressure of a material above a solution might be higher than predicted by Raoult's law. I have known that for a long time and I understand the reasons for it.
What I'm saying is that the deviations are usually small- you seldom get more than a doubling of the vapour pressure. If a significant amount of this wax distilled over then something odd happened. I'd like to know what.

[Edited on 12-12-2006 by unionised]

XxDaTxX - 12-12-2006 at 13:52

Quote:

Originally posted by unionised
What I'm saying is that the deviations are usually small- you seldom get more than a doubling of the vapour pressure. If a significant amount of this wax distilled over then something odd happened. I'd like to know what.

A simple doubling of the vapor pressure makes a big difference, particularly if the mol fraction of the undesired component is significant.

There are many factors that affect liquid-vapor equilibria, I have highlighted the important ones that, when combined, produce the effect that you see here. Take a graduate course in chemical engineering thermodynamics if you want to be able to quantify, recognize, and focus on each particular interaction that governs the collected distillate in anything other than an ideal distillation.

I am not going to teach you all of it. Again, those are the IMPORTANT ones that produce this effect. I will not type out a whole slew of chapters to tell you ALL the interactions, to what degree they influence the vapor curves, what each is dependant on, and how they change when adding another component.

[Edited on 12-12-2006 by XxDaTxX]

unionised - 14-12-2006 at 11:29

"A simple doubling of the vapor pressure makes a big difference, particularly if the mol fraction of the undesired component is significant."
It almost certainly isn't significant- the thickening agent is likely to be polymeric or, at least, high molecular weight.
As I mentionned elsewhere earlier, solids with any significant vapour pressure are thin on the ground. Even pretty volatile ones like cmphor shouldnt distill much at 40C. Whatever the interactions are (and I already know that thery are many and varied), they are usually small. They are unlikely to do more than double the equilibium vapour pressure compared to the value predicted by Raoult's law. That still leaves the distillation of any significant amount of the thickener as unexpected.

XxDaTxX - 14-12-2006 at 15:44

You aren't getting it .... picture pure wax .... each long chain held together by induced dipoles along its chain length. Those interactions hold it in its solid phase.

Now picture the same molecules of wax .... but mixed in a significant amount of DCM, for simplicity assume completely dissolved .... the dipole interactions are several orders of magnitude stronger than induced dipoles. Now if you see that the wax is evenly dispersed in the DCM, then you see why it is that it takes less energy to vaporize it. The difference in intermolecular forces between the pure wax, and when the wax is in a non-pure mixture is the reason why it does what it does.

Honestly, go argue with a book or something ... it's not like I am just making this up.... on second thought .... here, you want to settle this ... I made the whole thing up. I'm a fraud.

[Edited on 14-12-2006 by XxDaTxX]

Nicodem - 14-12-2006 at 16:09

Quote:

Originally posted by XxDaTxX
Now picture the same molecules of wax .... but mixed in a significant amount of DCM, for simplicity assume completely dissolved .... the dipole interactions are several orders of magnitude stronger than induced dipoles. Now if you see that the wax is evenly dispersed in the DCM, then you see why it is that it takes less energy to vaporize it. The difference in intermolecular forces between the pure wax, and when the wax is in a non-pure mixture is the reason why it does what it does.

The intermolecular interactions in gases are too negligible to have much of an influence on partial pressures in such an intense way as you seem to extrapolate from the interactions in liquids. Molecular interaction in gases do exist, or else every gas would be an ideal gas and no monophasic liquid mixture would ever form azeotropes, but such interactions are magnitudes less than in liquids and you can not wildly extrapolate behavior in gases from the behavior in liquids. Therefore, I agree if by "takes less energy to vaporize it" you meant that the deltaH of evaporation of some paraffin wax out of a solution is lower when compared to the deltaH of evaporation from the solid phase. But I disagree if by that you imply that the vapor pressure above a paraffin wax solution in CH2Cl2 would be considerably higher than above its solid form.

XxDaTxX - 14-12-2006 at 17:51

Quote:

Originally posted by Nicodem

Quote:

I never said anything about intermolecular interactions in the gas phase. The difference in vapor pressures has nothing to do with that, and even if it did, i agree that it is negligible.

I don't know how many times/ways this has to be said.

The amount of energy needed to vaporize 1 mol of wax in the pure state is X because wax : wax interactions. The amount of energy needed to vaporize 1 mol of wax where there are less wax : wax interactions (i.e. in DCM) is X - (some difference). That difference is due to a decrease in wax : wax interactions.

Its like the first thing you go over in distillation of multicomponent systems in an engineering thermodynamics class. Then come the phase graphs and you start quantifying the deviations and all hell breaks loose.

turd - 15-12-2006 at 02:02

Quote:

I don't know how many times/ways this has to be said.

Your repeated hand-waving doesn't change the fact that co-distilling wax with DCM through a vigreux at < 40°C is something that doesn't usually happen in the real world. At least not in my lab.

Instead of repeating the same stuff again and again, you should find a reliable source which states that very high boiling solids come over with DCM in non-negligible amounts or describe an experiment that someone can actually repeat.

XxDaTxX - 15-12-2006 at 09:23

Quote:

Originally posted by turd
describe an experiment that someone can actually repeat.

https://sciencemadness.org/talk/viewthread.php?tid=7161

...or ever distilled the EtOH/H2O azeotrope .... thats another example.

For all you reference whores:
Google: vapor pressure deviations non-ideal intermolecular
Go to "Explaining the deviations"

Theres some hand waving for you .... well ... four fingers shy of a whole hand but its definitely waving at you.

.... honestly though .... I decided to just come back for a quick look at the circles I used to travel in before I took my long vacation in which I was trying to finish up my hand-waving classes, to get my hand-waving degree, and to get into a hand-waving graduate program ... for it was these circles that gave a new flame to my undergraduate research. Now that I look back, not only is the home away from home gone ... but present day constituents are a bunch of spoon feeding, reference mongering slackers whose responses to some advice well given is nothing more than name calling .... "hand waving"?

Seriously, I am just trying to help some of you out. I do it on a daily basis for undergrads who need guidance in lab. Why not do it for you? ..... however all of them together have not amounted to the whining I have heard here. If you don't believe me, look for the answer yourself. You will find something close to what I said at the end of the rainbow.

[Edited on 15-12-2006 by XxDaTxX]

Nicodem - 15-12-2006 at 14:22

What do the vapor pressure deviations from ideality have to do with your claim that when distilling CH2Cl2, with paraffin wax dissolved, the wax would be carried over in the distillate? Don't tell me you believe CH2Cl2 and paraffin wax forms an azeotrope with any considerable concentration of paraffin? That would be in opposition to experience. Except for Quince's post I never heard from anybody else having ever had troubles separating paraffin-like wax from CH2Cl2 by distillation. That simply does not happen. I distilled used dichloromethane several times, even contaminated with greases and it always distilled cleanly. Besides what Quince described is clearly not wax, but some other crap or else it would not separate from dichloromethane simply by stirring the solution with water.

Sandmeyer - 15-12-2006 at 16:42

Quote:

Originally posted by XxDaTxX
Seriously, I am just trying to help some of you out. I do it on a daily basis for undergrads who need guidance in lab.

Poor undergrads... Besides, what's all this bullshit about, too tough on your ego to accept that reality is in conflict with your claim?

XxDaTxX - 15-12-2006 at 16:59

There are simply too many variables in the situations that you are posting.

There are alot of variable to consider if you want to analyze a multicomponent distillation. Most of the time it is not necessary and seperation can be done using crude approximations like Raoult's Law and so forth. ... but when it is necessary, aka. Quince's situation, you then use the dissimilarity between the components to differentially affect the vapor pressure of one component more than the other. I'm sorry, but that is the way that it is taught. If any of you have a PhD and would like to challenge the current model go ahead, but that is the way it is done.

As far as your application of distilling DCM away from contamination ... I assume you mean byproducts/polymerization etc. In that case, not only is the mol ratio different from Quince's, but so is the identity of the component being carried over. Like I said, if you want to be able to quantify ALL situations so you can apply this theory that you think I have made up, then take an engineering thermodynamics class and you will understand. There is more to it then, "oh so if that is your answer for this ... then how come it doesn't work here?" The answers you are getting from me are the most pertinent outcomes of the application of thermodynamic equilibria of multicomponent systems. Not the whole damn course.

XxDaTxX - 15-12-2006 at 17:03

Quote:

Originally posted by Sandmeyer

Quote:

Originally posted by XxDaTxX
Seriously, I am just trying to help some of you out. I do it on a daily basis for undergrads who need guidance in lab.

Poor undergrads... Besides, what's all this bullshit about, too tough on your ego to accept that reality is in conflict with your claim?

Its not my claim. It is the current model, and has been tried and tested by many, most of which are lightyears beyond you and even me in this field. I study the books, it wouldn't offend me at all if you were to disprove them, because they were mot my claims to begin with. I am merely bringing up the pertinent information that one would be taught in the appropriate course.

And if you noticed in the other thread ......

Quote:

Originally posted by Quince
Worked, but yield wasn't good. Quite a bit of the DCM evaporated

....so you can take your claims about it not being reality elsewhere. I warned him about the difficulty in trying to condense the vapors, and that he shouldn't try it unless he could fine tune the input feed, or unless he had sufficient cooling for the condenser.

..... oh BTW ... Why are you guys still asking me questions ... I though I told you I made the whole thing up!

.... oh well ... back to my hand-waving. I have a research coordination committee to answer to in a few weeks.

You guys can go on arguing with well established models. You can go to the library ... in the chemistry sections they have alot of models/theories there ... why don't you open a book and try calling them names. Maybe you will prove them wrong too. Have fun.

[Edited on 16-12-2006 by XxDaTxX]

unionised - 16-12-2006 at 07:57

"picture pure wax .... each long chain held together by induced dipoles along its chain length. Those interactions hold it in its solid phase.
Now picture the same molecules of wax .... but mixed in a significant amount of DCM, for simplicity assume completely dissolved .... the dipole interactions are several orders of magnitude stronger than induced dipoles. Now if you see that the wax is evenly dispersed in the DCM, then you see why it is that it takes less energy to vaporize it. The difference in intermolecular forces between the pure wax, and when the wax is in a non-pure mixture is the reason why it does what it does."
On the contrary, I see the wax molecules now tied down by, as we have both accepted, dioplar interactions that are stronger than the London forces. Since it was not volatile as a solid, I can't see why it should be any more volatile from a solution where it is trapped by those forces.

"There are simply too many variables in the situations that you are posting."
Fair enough, lets come down to a nice simple system.
A straight chain hydrocarbon wax, in solution in DCM.
I think that it should be trivially simple to distill the DCM away from the wax.

Now lets' make it slightly more complicated by considering other solutes.
If the wax were, for example, beeswax which is largely (I believe) a mixture of high molecular weight esters, I would expect much the same result. Similarly, if it were a silicone based on poly(dimethyl siloxane) I wouldn't expect any problem recovering DCM from it. Even a polyether like poly(ethylene oxide) would, as far as I can judge, behave in the same way.
In fact, I cant think of any wax that would co-distill with DCM.
Furthermore, many people on this site have discussed isolation of DCM from paint stripper where DCM was found to distill perfectly satisfactorily from various (unspecified) matricies. I believe that their collective experimental evidence outweighs any theory you might have.

Thus I stand by my original point that the original result is odd.

I'm well enough aware of things like Raoults law (which tends to back my point since, with a high molecular weight, the wax would have a comparatively low mole fraction so contributing less to the vapour) and the deviations from it (which are generally small) and the reasons for those deviations (for example that the polar interactions of DCM with the wax might well make it less volatile than would be expected compared to (for example) the molten state where the relatively weak London forces would be the only ones involved).
I also think that the quote "Worked, but yield wasn't good. Quite a bit of the DCM evaporated" rather sugests that it's the DCM that's volatile rather than the wax.

I'm still asking because, as I said a while back, I'd like to know what this strangely volatile wax is. Whether or not you are a fraud couldn't influence that.

[Edited on 16-12-2006 by unionised]

XxDaTxX - 16-12-2006 at 20:11

Quote:

Originally posted by unionised
On the contrary, I see the wax molecules now tied down by, as we have both accepted, dioplar interactions that are stronger than the London forces. Since it was not volatile as a solid, I can't see why it should be any more volatile from a solution where it is trapped by those forces.

Wax tied down by polar interactions ? ... wow ... do you have intermolecular forces screwed up.

Quote:

Originally posted by unionised
I also think that the quote "Worked, but yield wasn't good. Quite a bit of the DCM evaporated" rather sugests that it's the DCM that's volatile rather than the wax.

So why then did it come over the first time he distilled it.

Quote:

Originally posted by unionised
I believe that their collective experimental evidence outweighs any theory you might have.

Once again its not my theory. I am just giving you the pertinent information regarding stripping DCM from wax. He called it wax, so I addressed it as wax. This is how they do it. Whatever it may be, I don't really care. Industries do this continuously, so no ... the experimental evidence SUPPORTS what I said. Let me guess ... you thought I made this up?

Seriously ... this thread wont go anywhere. Tell you what ... if you don't believe me, go find your answer elsewhere. Let me know when you find it. I don't need a reference. I have a sinking suspicion I'd have already said what you end up finding.

unionised - 17-12-2006 at 03:09

Ho hum.
"Wax tied down by polar interactions ? ... wow ... do you have intermolecular forces screwed up."
OK what's screwed up about the idea that diople-induced dipole interactions between the DCM and the wax will tend to keep the wax in solution?

I'm not saying that it's specifically your theory; I'm saying that any theory that says "You should expect wax to co-distill with DCM" is wrong; and I'm saying it because lots of people have found it to be wrong.
As an example, here's a quote from that reference you gave.
"The methylene chloride
may be stripped from the oil or wax by distillation
with steam or by passing air through the mixture
heated lo 80” C. (176’ F.)."
So, even the data you cite says that the DCM can be distilled out of the wax.

Of course, the page you cited indicates that you can get (at least some of) the wax out of solution by chilling it. I knew that and it has nothing to do with distillation (apart from the bit I quoted which shows that distillation works). You have referenced a page which shows that the experimental evidence supports the idea that wax can be stripped from solutions in DCM by chilling. I realise that might have quite a lot to do with the original question about getting stuff from plant extracts, but please explain what you think it has to do with distillation?

As for "So why then did it come over the first time he distilled it."
You seem not to have noticed that that is exactly the question I have been asking all along.
Unless someone answers it then you may be right in saying the thread's going nowhere.

Sandmeyer - 17-12-2006 at 05:28

Quote:

Originally posted by XxDaTxX
Industries do this continuously, so no ... the experimental evidence SUPPORTS what I said. Let me guess ... you thought I made this up?

Amazingly, that reference does not "SUPPORT" but refutes what you said.

Quote:

Originally posted by XxDaTxX DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax, and is thus carried over any distillation head.

Ok, you don't have a clue what the hell you're talking about. Can we all at least agree on that?

[Edited on 17-12-2006 by Sandmeyer]

haribo - 17-12-2006 at 06:56

For extracting some oils, for example safrole, steam-distillation does the trick. You can buy stills designed to extract essential oils quite easily. I got a vintage one.

Step 1- Steam distill
Step 2- Fractionally distill

Makes the place smell wonderful as well.

XxDaTxX - 17-12-2006 at 10:58

Quote:

Originally posted by unionised
You have referenced a page which shows that the experimental evidence supports the idea that wax can be stripped from solutions in DCM by chilling. I realise that might have quite a lot to do with the original question about getting stuff from plant extracts, but please explain what you think it has to do with distillation?

It says chill/centrifuge, then steam strip (aka steam distill on lab scale). Exactly what I told him to do.

I recomended steam stripping to take advantage of the shifts in vapor equilibria that it would make on the system.

Quote:

Originally posted by Sandmeyer

Quote:

Originally posted by XxDaTxX DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax, and is thus carried over any distillation head.

Ok, you don't have a clue what the hell you're talking about. Can we all at least agree on that?

What about what I said do you not believe?

"DCM dissolves wax as a function of its temperature, at higher temperatures it dissolves more and more wax":

"and is thus carried over any distillation head": So you mean to tell me that dissolving more wax at a higher temerature (ie during a distillation) has nothing to do with the mol fraction of the liquid, and therefore the mol fraction of the vapor above?

This thread makes my head hurt. Seriously, why are you still arguing with me .... I told you I made it all up. I am a fraud.

[Edited on 17-12-2006 by XxDaTxX]

Nicodem - 17-12-2006 at 11:02

You are unbelievable!

…as well as annoying.

XxDaTxX - 17-12-2006 at 11:05

Quote:

Originally posted by Nicodem
You are unbelievable!

…as well as annoying.

Do you have a reference for that ? HAhaahah

Nicodem - 17-12-2006 at 11:17

All the abominations of the human kind, internet trolls included, will burn in hell.

Reference: The Bible

unionised - 17-12-2006 at 11:56

He is unbelievable and annoying. I cite a reference a few posts up this thread.
I also suspect trolling here ( ref all the times he failed to address the questions asked)

XxDaTxX - 17-12-2006 at 12:20

I give up on this thread ... seriously

[Edited on 17-12-2006 by XxDaTxX]

Sandmeyer - 17-12-2006 at 17:05

Quote:

Originally posted by XxDaTxX
So you mean to tell me that dissolving more wax at a higher temerature (ie during a distillation) has nothing to do with the mol fraction of the liquid, and therefore the mol fraction of the vapor above?

What I meen (and don't expect you to understand) is that your megalomania prevents you from adequately process the information that you read, hence you (miss)lead your self to belive that something that refutes your claim actually supports it.

[Edited on 18-12-2006 by Sandmeyer]

solo - 17-12-2006 at 17:16

Sounds like Indole_Amine is back .................solo

turd - 19-12-2006 at 07:10

Quote:

I give up on this thread ... seriously

But first you have to post a treatise on the VdW-interactions between nitrogen and DCM giving a decreased solubility of wax in DCM so that the amount of wax at the still head is lower when you blow 80°C air through the mix than when you distill at 40°C. Or something like that. For bonus points mention "your" undergads at least three times, n-dimensional phase diagrams, how all this is way over everyones but your head and that it's not your fault that the theory says such things at least once.

XxDaTxX - 19-12-2006 at 13:06

"But first you have to post a treatise on the VdW-interactions between nitrogen and DCM giving a decreased solubility of wax in DCM so that the amount of wax at the still head is lower when you blow 80°C air through the mix than when you distill at 40°C. Or something like that. For bonus points mention "your" undergads at least three times, n-dimensional phase diagrams, how all this is way over everyones but your head and that it's not your fault that the theory says such things at least once."

Well now that you've said it ... I have nothing left to say. Couldn't have said it better.

Quote:

Originally posted by unionised
... I also suspect trolling here...

hehehe ....

::::runs and hides laughing at everyone with a stick up their butt:::

Seriously though .... you REALLY want to know what came over with the DCM? .... heheheh

[Edited on 19-12-2006 by XxDaTxX]

unionised - 19-12-2006 at 14:22

Seriously though .... you REALLY want to know what came over with the DCM?
Yes, I said I did and I'm not a liar. OTOH I realise that theres bugger all chance of you helping find out.

Sandmeyer - 19-12-2006 at 20:53

Quote:

Originally posted by XxDaTxX

::::runs and hides laughing at everyone with a stick up their butt:::

Don't skip that haloperidol, remember three pills every day, morning, afternoon, evening.

[Edited on 20-12-2006 by Sandmeyer]

unionised - 20-12-2006 at 05:43

I'm not sure he needs psychoactive drugs; he may well grow up to be a useful member of society. In the meantime I guess we just have to put up in the same way that we do with crying babies on busses and such like.