Arthur Dent
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Soxhlet question
I got myself a spiffy-looking soxhlet at my favorite shop last Friday, but something's missing!
See the photo below, the bottom part has a standard 24/40 taper, but the head has a ginormous 45/40 joint!
Never seen such a big taper joint! Normally, in a standard soxhlet setup, the head is fitted with a condenser, but the shop had no piece of glassware
with a male 45/40 joint. Fortunately, I found at that shop a couple of jars with monster-size 45/40 glass stoppers, so I bought one. You see the
stopper hovering above the soxhlet, it's a perfect fit but I'm sure I can't use the soxhlet that way.
For those who know that particular model, what piece of glassware would fit the head of my soxhlet?
On the plus side, it's a HUGE soxhlet, so I guess the thistles are gonna be a bitch to hunt down, or is there a ghetto way to make thistles for that
thing?
Robert
[Edited on 1-5-2011 by Arthur Dent]
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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mr.crow
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All soxhlets have a huge size joint so you can fit the material in. There are specialized condensers that fit the top or you can get an adapter
Double, double toil and trouble; Fire burn, and caldron bubble
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The WiZard is In
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Quote: Originally posted by Arthur Dent  | I got myself a spiffy-looking soxhlet at my favorite shop last Friday, but something's missing!
See the photo below, the bottom part has a standard 24/40 taper, but the head has a ginormous 45/40 joint! |
45/40? 45/50 is a normal Soxhlet size for a 85 ml capacity
extractor*. Followed by — 50/50, 55/50 - preceded by — 34/45,
40/50. If you are using a low BP fluid e.g., petroleum ether ... you
a really large capacity condenser.
*Capacity to top of siphon.
Byda — you could buy a reducer and use a longer condenser.
Analine bulb condensers are preferred due to the large volume
of distillate moved.
A 5 000 ml capacity extractor has a 145/60 top joint - 55/50 bottom.
There also dobe a relationship between the capacity of the boiling
flask, which sets the size of the upper stuff. Soxh- extractors are
commonly sold based on boiling flask size.
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Arthur Dent
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well, actually, I have a friend who has a soxhlet with a tiny extraction chamber, the size of a large test tube. And the top part and bottom parts
have both 24/40 joints. So I guess i'll have to look-out for a 24/40 to 45/40 adapter!  
A good analogy would be a wheel-less Ferrari on cinder blocks... I can revv the engine but I ain't goin' nowhere! LOL
EDIT: Yeah you're right, it's 45/50... the stopper I bought is 45/40 though.
Robert
[Edited on 1-5-2011 by Arthur Dent]
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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Magpie
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Here's a picture of an Allihn condenser with a fitting for a Soxhlet extractor. That's what's normally used. The particular one shown has a 40/50
taper which is rare. Usually they are 45/50, so you are lucky there.
The single most important condition for a successful synthesis is good mixing - Nicodem
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aonomus
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A cheap workaround to lack of a cellulose thimble is to use cotton wool stuffed in the bottom of the soxhlet.
As for the adapter, you'll find one eventually. The opening has to be so big so that you can insert the sample thimble and remove it easily.
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peach
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Here's what you're after
Where the heck is this SHOP selling use laboratory glass locally?  I wouldn't
have thought there'd be much interest in it from the general public.
You'll likely want an allihn or coil condenser to go on the top of there, particularly if you can't keep the water cold or the solvent of choice has a
low boiling point; to stop it gradually escaping over time.
Thank you for the message in the other thread as well! I'm sure I have you on my facebook. There are about 80 photos of the benzene thing on there, if
you click my profile it should still be on the wall. I'll be making a litre or three next week and probably re-distil it at the weekend.
The QuickFit adaptors are about £15 new. <--- link to a UK shop
Prices vary  <--- probably without the VAT on it as well, £15 is about
the best it'll get for genuine QuickFit new.
United glass has some in the US size 45/50, which should also work fine <--- another shop
And here's a slightly cheaper US one on eBay for $24
US tapers will fit the Euro tapers, they're both the same shape, it's only their length that differs slightly. Mixing them together, sometimes the
male will poke a few mm out the other end of the female (ouch) or vice versa, not far enough; and then she'll leave him for a guy with a ferrari.
Generally, all glass is designed so it doesn't matter; e.g. the coil in a condenser will start a bit after the tapers because it's easier to make them
that way.
It's also not universally true that all US glass has a longer taper than the Euro glass. I have glass from the US that has shorter tapers than the
UK's QuickFit. I find it makes very little, if any, difference to how well it seals; it's far more important that there aren't little bits of solid
shit stuck in the grease if a really tight seal is needed.
The adaptors show up on eBay used, but they tend to be around the $10 area. So, if you're not up for searching, doing the whole bidding thing and just
want it working, may as well grab one for $24 and have done with it.
The same with the allihn condensers. The ones specific to the soxhlets turn up sometimes and there is usually less interest in them because they won't
easily fit other setups; one end of said condensers often doesn't have a taper on it, but a stem (as per magpie's pic). But it means sitting around
waiting and waiting and then possibly loosing out.
If I see either show up, I'll send you a message. But it's probably easier to buy the adaptor new and use the condenser you already have; if it's a
liebig / west, maybe consider the condenser option instead.
[Edited on 1-5-2011 by peach]
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Arthur Dent
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Hi Peach, thanks for your reply!
Yup, that place I discovered is truly useful... they buy surplus stocks from labs or buy out bankrupt laboratories, they have ton of glassware, and
stuff that ranges from the most modest stirplate to the fanciest mass spectrometers, and the prices are awesome. They also have all sorts of
electronics, industrial tools and other fun stuff!
I have an excellent Allihn condenser with 24/40 joints at both ends, a graham condenser, two liebig and a cool-looking Vigreux, I'm keeping my eye on
a Friedrich condenser at that shop although one of the ports has a hairline crack in it...
I'll check out your Benzene experiment, thanks!
The adapters you suggest are excellent, it will be worth it! But as you mentioned, a condenser with a 45/50 joint would be indeed even better.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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