DIY Soxhlet and Condenser

[kaos.underwave]

Hey since soxhlets are damn expensive here in the uk [£170 250ml]
I thought about making my own, but there are a few things I'm still fuzzy on...it seemed crazy at first...

The plan is to use a 1000ml measuring cylinder as the base for both soxhlet and condenser.
The condenser part should be relatively easy - I'm thinking just wrapping the top half of the cylinder with tubing to pump water through. Maybe reduce the opening to ensure no solvent escapes.

The soxhlet part is a little more difficult. Using a drill, a water bath and diamond drill bits I should be able to open holes in the cylinder at the correct points for the siphon and distillation arms. Obviously drilling holes in glass is pretty tricky, but it can be done with the correct tools, practice and caution [I can see me needing a lot of practice at this]. This is the most dubious element of the process. From what I can tell, drilling flat glass is hard enough.

For, the arms themselves, I figured tygon tubing would work fine. I have a feeling just melting the tubing to the glass might not work as well as I first hoped, what would be the best way to seal these joints? I have silicone sealant lying around...

A wine/vodka bottle or small demijohn seem to be good cheap replacements for a flat bottom flask. The tygon arms would simply fit into the top of the bottle, through a two-way adaptor that plugs the top. I think the siphon arm should have a smaller inner diameter than the distillation arm, is this generally how it is?

Ideally all this would create a 500ml Soxhlet apparatus, which would cost less than
£25 - drill and bits
£30 - tygon tubing [15m x ID 4mm]
and it'll cost me nothing to make the next one, since I have another cylinder lying around

I'm hoping the people with actual real soxhlets/organic chemistry skills can point me in the right direction here. Any problems with this plan?

If I can do it, I will, and not a botch job either, just until I can afford some real glassware; work it up into a diy tek for those of us who dream of soxhlet extractions but have no cash.

 

[benzyme]

the soxhlet is a beast to try to make. they operate on pressure/volume relationships. ever put your hand on the condenser port when it cycles? vacuum

I honestly don't see a rigged one working well. :?

 

[Faust]

I believe this place ships worldwide Soxhlet Extractors, then there is just EB to buy a flat bottomed boiling flask of the appropriate size. Water pump and tubing.

 

[kaos.underwave]

k, thats kinda what I was expecting. it is a mission.

could you expand on the pressure/volume relationships please? As a layman, I just guessed it siphons because the solvent level reached the top of the siphon arm, then moved down it, pulling the rest through. Now Ive put that into words it does seem like I dont have a clue.

If these relationships arent extremely precise, perhaps they could be replicated to a certain degree by simply replicating the dimensions of an actual soxhlet? Is the diameter of the main chamber important too?

please keep in mind that I dont expect it to work perfectly...just to function would be good

thanks for the input man,

 

[benzyme]

yes

know of that store, it's definitely a good one.

 

[benzyme]

k, thats kinda what I was expecting. it is a mission.

could you expand on the pressure/volume relationships please? As a layman, I just guessed it siphons because the solvent level reached the top of the siphon arm, then moved down it, pulling the rest through. Now Ive put that into words it does seem like I dont have a clue.

If these relationships arent extremely precise, perhaps they could be replicated to a certain degree by simply replicating the dimensions of an actual soxhlet? Is the diameter of the main chamber important too?

please keep in mind that I dont expect it to work perfectly...just to function would be good

thanks for the input man,

no problem

of course, you'd have to account for both the volume of the flask, and the volume of the extractor. since it's an open system (would have to be...or else it would be a bomb), pressure is exerted when the liquid boils (gas is still escaping). it's cooled once it hits the condenser, and fills up the extractor body. once it gets to the top level of the small siphon-arm (if you rig this, you'd need to figure out the diameter, in about 2 to 4mm), it cycles over...and the solvent rushes back to the rbf, pulling vacuum with it.
the larger side siphon may also need to be proportionately larger in diameter than the small siphon.

 

[kaos.underwave]

Thanks for the tip Faust, I checked out the site a while ago and loved the prices but assumed they either didnt ship here, or that shipping charge would be way high.

dont know why I didnt bother dropping them an email before...doh...we'll see, I really hope they do, cos those things are like a third of the price they go for over here!

 

[kaos.underwave]

hmm ok Benzyme, that makes sense...

so apart from the size of the tubing diameters, what else could mess the process up?
If I can get one cheap from the link Faust posted I might just do that for now, and consign this project to the long term.
After all, the prices they have without shipping are about what I was prepared to spend on my bumbled effort.

thanks for the help anyway...I just made a basic separatory funnel from a gallon jug and thought I could take on the world with my diy!

 

[benzyme]

hehe
DIY is good when on a budget.

but a soxhlet is like an investment.
you could use it to make aromatherapy products, flavorings, tinctures.. all sorts of homeopathic products.
and they're aesthetically pleasing, like chemist's sculpture

a glass one will be easier to clean than a rigged one

 

[kaos.underwave]

Yeah definitely, that's what got me started on all this, after my first couple of A/B extractions I realised the process and materials aren't that dissimilar for so many different products...and that a soxhlet would be ideal. I just don't have the money to invest at uk prices.

Not that I can be bothered to sell much, but it would pay for itself by saving me and my friends a lot of money on our favourite homeopathic products

lightening quick replies guys, if I could +rep you I would

 

[lowjackal]

I was wondering if a possible buy/sell/trade section on the nexus forum was ever thrown around to help certain people like the first person thats wanting to make a not all that expensive setup like the soxhlet setup yo buy one legally from their fellow nexus members?

Of course, a deep line in the sand of what can and cant be bought,sold,traded would need to be moderated with strict guidelines. But glassware and possibly cuttings and seeds all legal would be the only right way to do a section like this. But I just wondered cuzz I have a few nice soxhlet setups , a few with Graham condensers and a few with Allihn condensers that I got for next to nothing in comparison to his UK price.
I was just wondering. If this is out of the question then all I have to say is open an ebay account and get your ass watching for lab closing auctions and always get a good quality stirring hotplate. Without that, your soxhlet apparatus isnt gonna work worth a shit.

My opinion and questions have been entered. thanks. this place rocks.

 

[Faust]

I was wondering if a possible buy/sell/trade section on the nexus forum was ever thrown around to help certain people like the first person thats wanting to make a not all that expensive setup like the soxhlet setup yo buy one legally from their fellow nexus members?

Of course, a deep line in the sand of what can and cant be bought,sold,traded would need to be moderated with strict guidelines. But glassware and possibly cuttings and seeds all legal would be the only right way to do a section like this. But I just wondered cuzz I have a few nice soxhlet setups , a few with Graham condensers and a few with Allihn condensers that I got for next to nothing in comparison to his UK price.
I was just wondering. If this is out of the question then all I have to say is open an ebay account and get your ass watching for lab closing auctions and always get a good quality stirring hotplate. Without that, your soxhlet apparatus isnt gonna work worth a shit.

My opinion and questions have been entered. thanks. this place rocks.

What exactly about a stirring hotplate makes the Soxhlet apparatus work worth a shit, and compared to using one that does not stir?

 

[lowjackal]

What exactly about a stirring hotplate makes the Soxhlet apparatus work worth a shit, and compared to using one that does not stir?

Well I suppose my opinion is just that my opinion, but, assuming that the soxhlet is setup securely with ring stand and a clamp holding the flask and another clamp holding the condenser, I'd say that having to physically grab the apparatus and swirl it around several times every few minutes is ghetto and not worth the hassle doing, IMO. I'd stress getting a stir plate/hotplate with a good stir bar and having it stirring the solvent continuously all while having it clamped in place securely is the only way to go. Using a toastmaster style hotplate and having to watch the extraction the entire time waiting to manually declamp and stir with one hand on the condenser and the other on the increasingly heating up flask isn't necessary and shitty in my eyes, and thus my remark. I mean you have this technical glassware only to use it not as its intended to be used...why?

Dont get me wrong before swim splurged on a $40 digital fisher stir/hotplate (ebay all the way) Swim was doing just what I described (via toastmaster). But isn't $40 worth the convenience of not having to babysit the extraction process that has the advantage of being able to be left to do its thing (indefinitely if needed) without the worry that extraction from an unevenly toastmaster style hotplate heated, and shotilly two handed stirred soxhlet extraction would require?

You decide and go with what you know.

Lowjackal

 

[benzyme]

What exactly about a stirring hotplate makes the Soxhlet apparatus work worth a shit, and compared to using one that does not stir?

for one, it assists in quickly getting the solvent to a boil
it also aids in preventing bumping

it's not absolutely necessary though

 

[lowjackal]

What exactly about a stirring hotplate makes the Soxhlet apparatus work worth a shit, and compared to using one that does not stir?

for one, it assists in quickly getting the solvent to a boil
it also aids in preventing bumping

it's not absolutely necessary though

Your right, it's not absolutely necessary at all. Neither is doing any type of extractions via the soxhlet apparatus. But when it's all said and done the individual with the proper heating equipment will have several advantages over the non-stirring hotplate equipped individual.

Plus the chemical gods wont bless your soxhlet extractions without a stir/hotplate. :lol:

 

[Faust]

What exactly about a stirring hotplate makes the Soxhlet apparatus work worth a shit, and compared to using one that does not stir?

for one, it assists in quickly getting the solvent to a boil
it also aids in preventing bumping

it's not absolutely necessary though

Your right, it's not absolutely necessary at all. Neither is doing any type of extractions via the soxhlet apparatus. But when it's all said and done the individual with the proper heating equipment will have several advantages over the non-stirring hotplate equipped individual.

Plus the chemical gods wont bless your soxhlet extractions without a stir/hotplate. :lol:

So it must be done. :shock: