Steam Distillation

G.Patton

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Introduction.

Steam distillation is analogous to simple distillation, the main difference being that steam (or water) is used in the distilling flask along with the material to be distilled. Experimentally the setups are arranged more or less the same (Fig.1), with small differences being how the steam is added to the flask: either indirectly if a steam line is available in the building, or directly by boiling water in the flask.
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The most common use of steam distillation is the extraction of natural products from plant materials. This is the main industrial method for obtaining plant essential oils, used in fragrances and personal hygiene products. As so many products can be isolated in this way, this technique is regularly performed in drug labs. An extraction of Ayahuasca potion plants and Cannabis allow obtaining a row of psychoactive substances.

Steam Distillation Procedure.

A steam distillation apparatus is shown in Fig.2 that uses boiling water in the distilling flask. An apparatus using a steam line is shown in Fig.3. It is assumed that readers have previously performed a simple distillation, so in this section are described differences between simple and steam distillations.
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Prepare the Setup:

1. Place the plant material to be extracted into a large round bottomed flask with a 24/40 joint (wide mouth), no more than half full. A large amount of material is often necessary as the bulk of plants is cellulose, not oil. Use of a 14/20 flask (more narrow mouth) would make it difficult to remove the plant materials after distillation.

2. Use an extension clamp to secure the large flask to the ring stand or latticework. If desired, further secure the setup with a platform (e.g. ring clamp and wire mesh as in Fig.2).

3. Add water to the distilling flask to just cover the plant material.

4. Always use a Claisen adapter in the setup, as plant materials commonly foam with heating and there is often a great amount of turbulence in the distilling flask (see splashing in the flask in Fig.3).

5. Two variations of steam distillation are regularly used: one where steam is directly generated by heating water in the distilling flask with a Bunsen burner (Fig.2), and another where steam is indirectly generated by a steam line in the building (Fig.3). Although burners are not commonly used with the distillation of organic compounds, they are relatively safe in steam distillations because: a) the majority of the vapor produced by the solution is typically water rather than organic compounds, so the vapor is not particularly flammable, b) The distillate may be somewhat flammable, but is a distance away from the heat source.

6. To the top of the Claisen adapter, connect one of the following, depending on the variation of distillation used:
a) If water will be heated in the distilling flask along with a burner: Attach a stopper to close the system (indicated by the arrow in Fig.4) if the quantity of water will be sufficient for the distillation. Attach a 125ml separatory funnel (which must have a ground glass joint below the stopcock) if it is anticipated that water will need to be replenished during the distillation. Clamp and partially fill this separatory funnel with water (Fig.2).
b) If a steam line will be used: Insert a steam inlet tube, and position it, so the outlet is just raised above the bottom of the flask. Connect this tube to a separatory funnel trap attached to the steam line (Fig.3).

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7. The receiving flask can be a graduated cylinder, Erlenmeyer flask, or round bottomed flask.
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a) Waving the burner to heat the distilling flask (with mint), b) Draining the water from the steam trap after opening the steam line, c) Steam bubbling through the distilling flask (with orange peels).
Begin Distilling.
8.
Begin heating the flask:

a) If using a Bunsen burner, initially heat the flask at a rapid rate (it takes a lot of energy to boil water), but once the solution is boiling or foaming, turn down the burner and/or wave the burner to moderate the distillation rate (Fig.5 a).
b) If using a steam line, open the stopcock in the separatory funnel steam trap. Turn on the steam, and allow the water in the steam line to drain through the funnel and into a container (Fig.5 b). Close the stopcock when it appears that most of what is coming out of the steam line is steam and not water. Adjust the steam rate so that the steam bubbles vigorously through the liquid in the distilling flask (Fig.5 c).
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a+b) Distillate with organic oil atop water (orange oil in both), c) Milky distillate (clove oil)

9. Collect distillate at a rate of 1 drop every second. The distillate will contain both water and oil, and may look one of two ways.
a) A second layer may form, or the distillate may appear to have oily droplets clinging to the sides of the flask. This happens when the oil is very nonpolar (e.g. Fig.6 a+b show the distillate of orange oil, which is almost entirely composed of hydrocarbons).
b) The distillate may also appear cloudy or "milky" (Fig.6 c shows the cloudy distillate of clove oil). A cloudy mixture forms when tiny insoluble particles are dispersed throughout the suspension. This tends to happen when the oil is water-insoluble but contains some polar functional groups (e.g. large compounds with a few alcohol or ether functional groups).


10. If using a steam line, the steam rate will need to be reduced once the distillation begins.

11. If not use a steam line, be sure to replenish the water in the distilling flask if the level gets too low (if the liquid in the distilling flask is getting thick). Heating a solution which is too concentrated can sometimes cause sugars in the plant material to caramelize, making cleanup difficult. To replenish water, either:
a) Temporarily open the stopper on the Claisen adapter and add water via wash bottle.
b) If using a separatory funnel on the Claisen adapter, turn the stopcock to gradually pour in water. If water is drained too quickly so that it pools in the Claisen adapter, it will be difficult to drain into the distilling flask for the same reason that a separatory funnel doesn't drain with its stopper in place. Draining water from the separatory funnel slowly prevents this from happening.


Stop the Distillation:
12. If following a procedure, collect the recommended quantity of distillate. If the distillate is milky, the distillation can be ceased when the distillate dripping from the vacuum adapter clarifies, indicating that only water is condensing.

13. If using a steam line, fully drain the liquid in the separatory funnel steam trap (and leave open) before turning off the steam. If water is in the funnel when the steam line is turned off, suction formed by the trap cooling faster than the distilling flask may pull liquid from the distilling flask into the steam trap (sometimes violently).

Isolate the Oil:
14. If the oil separates from the distillate as in Fig.6 a, it can be removed via pipette, dried with a drying agent (such as Na2SO4) and analyzed directly. If milky as in Fig6 c, the oil must be extracted into an organic solvent, dried with a drying agent (such as MgSO4), and solvent removed with the rotary evaporator. Three extractions are typically necessary to fully extract the oil from a milky distillate into an organic solvent. In the extraction of the milky clove oil distillate from Fig.6 c, notice how the aqueous layer (bottom) remains milky after the first extraction (Fig.7 a). This milky appearance shows that the oil was not fully removed with one extraction. The aqueous layer clarifies with the second extraction (Fig.7 b) demonstrating the importance of multiple extractions.
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a) First extraction of clove oil distillate into ethyl acetate, b) Second extraction
 
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h20

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Hello,
I don't think people here on BB want to distill leaves.
you can find this explanation all over the internet.
I would like to know how you distill chemicals. what temperatures must be respected ?
 

G.Patton

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You will be surprised that CBD can be steam distilled from cannabis leafs! Also, chemicals can be distilled by the same way. In pic. 3 and 4 such apparatus is represented. You can figure out temperature in case you know what do you want to distill. If you can read this article and article about distillation, you will understand what does it mean distillation and won't ask such questions.
 
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h20

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oh, yes, I forgot, you only are welcome here if you know everything.
So you don't have to explane nothing right
 

G.Patton

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I'm sorry if it looks like this. You could be more polite in case you want to get some help...
 

J-man

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You can also pull meth freebase oil over using steam distillation after basifying it in the moscow route after reflux, So what iv heard... Thanks G.Patton for putting this stuff on here, i re learnt a couple of things i forgot as even the simple things can be overlooked or forgotten in time. Hey, can you plz give any good examples of sources that can produce steam? Like pressure cookers etc
 

diogenes

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Hi, Can anyone show an good and efficient setup for steam distillation. I have only just started to explore this area and simply used water in a flask with the only floating on top. This seems to work, but it is very slow, and there are a lot of questions which I haven`t found answer to:
1. What is the ideal proportion of water/oil, if there is such?
2. Is there a more efficient way, e.g. using a cappucino maker or steam cleaner? (If yes, please, explain or show a picture of such setup. I tried creating steam in oine flask and direct it into the flask with the oil, but the steam cooled too much to be efficient.)
3. How do you determine when to end the steam distilation?

thank you for any advice, figuring all this out by experimenting would take ages and I`m sure these questions have already been looked into and figured out by people with more experience.
 

WinterDust

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Hi @diogenes

Here is a good setup for Steam Distillation:

1 - Unneccessary
2 - Collector flask
3 - Vigreux column
4 - Thermometer (0-100C)
5 - Liebeg Cooler
6 - Coldwater inlet
7 - Warmwater outlet
8 - Receiver flask
9 - Vacuum adapter
10 - Angle
11 - Temperature controll
12 - Stirrer controll
13 - Magnetic stirrer with heating plate
14 - Container with water
15 - Organic oil
16 - Container coldwater

POINTERS:

1 - If you are for example steam distilling amphetamineoil from IPA then you don't neex the vigreux column you can just connect it straight to the Liebeg cooler.
2 - If you are for example steam distilling amphetamineoil with distilled water then you need to use the vigreux column.
3 - Oil / Water ratio shold be 1:1 and don't use normal tapwater but use distilled water to not lose yield
4 - How to know when steam distillation is done. One example of this would be there is no more fumes condensating inside of the Liebeg column any more, second recognition is, for example if you steam distill if IPA from amphetamine oil, IPA boilingpoint under pressure is 29-30c, when the thermometer passes the temperature for example to 35c then you know there is no more IPA and steam distillation is done.

I hope this helps, best regards
Rcfin9dbhZ
 

diogenes

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Hi, thank you for your explanation, but the picture is of distillation with a water bath or I just don`t get where the steam enters the oil. Why is the hotplate marked as unnecessary? (No 1.) thanks
 

WinterDust

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If you have amphetamineoil that you want to purify you use distilled water, ratio 1:1.

So if you have amphetamineoil 1l you ad 1l of distilled water. When it heats up under vacuum pressure, the boilingpoint will be approx. 56c which will steam and remove any impurities with it, hence "Steam Distillation".

The reason for the flask being inside a container of water on a hotplate is because it cover largers heating area of the flask rather than just the bottom of it.

(1) - This is some kind of protectionblanket incase you don't use a steel pan as a heat conducter.
 

WinterDust

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Forgot to ad,

A good distillation ratio of flow is one drop every second into the receiver flask. This is because if you Steam Distill to "fast" the distill will take oil with in into the receiver flask, and you will lose some of your product.

Best regards
 

diogenes

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Hi, sorry for another question, just want to clarify what you have said. Steam distillation is recommended under vacuum, so that the temperature is even lower and no oxidation occurs, right? Also in the second post you advice to go 1 drop per second, so about 3ml/minute, otherwise some oil will also come through with the steam. Is this not the main goal of steam distillation, I mean we are trying to get the pue prduct (oil) to come over to the reveiving flask. What am i getttig wrong? thank you
 

G.Patton

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Which oil do you mean? Amphetamine/meth? Steam distillation is assumed that you distill them as azeotropic mixture.
 
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diogenes

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Hi Patton, I was referring to the previous post by ImOutAlso who said that if steam distillation is done too fast, then oil will also come through, which I didn`t understand, because as you say, Amph and Meth bases are also oils, or at least oily substances. Or was he referring to other oils? The orig mixture is supposed to be water:base 1:1 ratio and purification happens because the non-volatile impurities stay in the original flask and only the volatile (oil-base) will come over. This has been my understanding of steam distillation, and it worked when I tried although probably not optimally because I never tried it under vacuum. This was new information to me. Perhaps you can clarify and give some advice about the optimal way to do it?
 

G.Patton

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Actually, it worth to do without vacuum with steam. It would be easy to determine boiling point of target product. In case of vacuum distillation, I recommend you to carry it out without steam by reason that it wold be hard to determine where is pure product and where is side-products (I mean exactly temperature of vapors under vacuum). First option is common and better, I think.
 

diogenes

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In theory boiling point drops to below 100C, right? I have done this without vacuum and the boiling point kept at 98-99. The amph base-water azeotrope has lower boiling point than water alone. On the other hand the small change in boiling point makes it impossible to distinguish between different oils.
e.g. https://chem.libretexts.org/Bookshe...ria/Immiscible_Liquids_and_Steam_Distillation

What I don`t understand is why most sources generate steam in a separate flask. Is it not easier to just put the water and the oil together in one flask, stir and distill? This can be supplemented by an addition funnel to replace water if it runs out while there is still some oil left.
 

diogenes

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The link recommends vigorous stirring to keep the oil/water mix `swirling` continuously, which will prevent the oil from `locking` the water underneath.

In this way the vapour pressure of the water, which is (roughly) 1 bar = 760Hgmm at 100C. Now the overall vapour pressure of your`swirling` mixture will be the sum of the vapour pressure of the oil and water. The oil`s vapour pressure at 100C is nowhere near 760Hgmm so will contribute very little to the sum, and only reduce the boiling point a tiny bit. So in case there is an unwanted, but volatile component in your oil, with similar boiling point as your product, it will be difficult to tell when your desired product and when this undesired product is coming over to the collection flask.

E.g. the vapour pressure of benzaldehyde is 0.074bar at 97C water`s vapour pressure is 0.91 so the sum is just short of 1 bar, and benzaldehyde will distill with the water at 98C. I haven`t found a calculator for amphetamine base vapour pressure, but it is lower than benzadehyde because it`s boiling point is higher and its weight is higher as well. So it will boil between 98 and 100C. There are a lot of factors, such as altitude etc. and these are just estimated values, but the point is that most molecules we are dealing with will boil with water/steam in a narrow temperature range and it not possible to tell what is coming over based on temperature. The steam temperature difference will be minuscule even if the compounds` boiling points are very different e.g. benzaldehyde and methamphetamine. With steam distillation it is only possible to separate the volatile components from the non-volatile `pollutions` in your oil. (Which is what we need as most of the volatile components is our product.)
 

diogenes

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Patton, in short my questions are:

Are there inaccuracies in ImOutAlso`s post about steam distillation? I have 3 points to question:
1. He appears to suggest that `which will steam and remove any impurities with it` which is the opposite of what I had thought: the steam will take the `purities` with it into the receiving flask. Then your pure substance can be extracted from the water. The impurities will stay in the boiling flask.
2. The removal of IPA is not steam distillation, just simple vacuum distillation. Steam distillation can only be done with water.
3. There is no need for a vigreaux coloumn for steam distillation.

These are based on my current (limited) knowledge, so I am putting this out there to have clarification, because it goes against most of what I have ever read about steam distillation.
The 4th question to you is whether steam distillation is better/same/worse than without vacuum? For experts these might be obvious, but for beginners it is important because it is easy to waste a lot of time based on inaccurate information.
 

G.Patton

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Steam just drop boiling point of amines
Сorrect, it worth to do these steps (IPA distilling off and product distillation) separately.
correct
Answered in previous message
 
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