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Life in the Drug Labs

No Water, No Problem

I have some colleagues who are evaluating these “no flowing water” condensers for reactions. Anyone out there have any experience with them? It’s for sure that there have been a lot of lab floods over the years from condenser hoses that pop off, and the expense of all that water can be a problem, too. (And I can’t mention water hoses in the lab without bringing up this classic technique, which I’m very glad to have witnessed).

There are a lot of products that are designed for chemists to be able to walk away from long-running reactions in (relative) safety – water flow monitors, temperature cutoff alarms, over-engineered pressure vessels. When you think about it, chemistry tends to be conducted at somewhat inconvenient time scales by human standards, in the “several hours to several days” range. There are plenty of faster reactions, of course, and no doubt innumerable slower ones that no one bothers to even note or discover, but we sure do have a lot of multihour processes.

Perhaps not all of them need to be. I’m pretty sure that if you did a full-text breakdown of all the published experimental sections in the organic chemistry literature, there would be spikes in the number of reactions with overnight and over-the-weekend durations – and a corresponding dip in the inconvenient intervals like 11 hours. (A comparison of sources between industrial and academic research groups might be illuminating in this case). My wife’s molecular biology background has always had her rolling her eyes at the cavalier way that I and other chemists just leave things running in a “few more hours won’t hurt it” way, since in biology a few more hours will often hurt things a great deal. Luxury!

50 comments on “No Water, No Problem”

  1. Lyle Langley says:

    They are called Findensers and are awesome. No flowing water in our labs for the past year or so.

    And to your “a few more hours won’t hurt it”…you see many more 14, 24 and even 72 hour reactions in J. Med. Chem. Industry people usually don’t work weekends.

  2. skarah says:

    Towards the end of my PhD I used the no-water findenser and had no problems with it, I was however, in a lab in the north of England do wonder if they would work so well in a warmer lab environment. After 3.5 years of fumehood floods and not being able to leave refluxing reactions overnight – due to my hood’s water pressure being directly controlled by the nearby sink…anyone switching the tap on then off again always sent a surge of water through my hood which the maintenance guys decided would be too much of an inconvenience to fix – I was very glad of a water-free alternative!

  3. Calvin says:

    Hmmmm. Radleys. I expect this to be a nice piece of kit that works(ish) but is hardly cheap. We used to run all our refluxed reactions in a set number of fumehoods with the right fire suppression systems where all the consensers were hooked up in series to a chiller. Worked just fine. As long as you planned ahead you could always get a space and we never had leaks once we set the flow rate and temp just right. Saved a fortune on water. We used the same system for our Buchis as well.

  4. anonymous says:

    At Astrazeneca we use findensers regularly (it was invented here after all) and they work rather well, the only drawback is that they are rather heavy, and a pain to get fixed if they break/chip

  5. John Wayne says:

    I don’t have any experience with these air cooled condensers (look neat), but I have used recirculating chillers quite a bit; they work pretty well. It you can get by with coolant temperatures above 0 Centigrade they aren’t terribly expensive (especially if you buy them used).

    1. A Nonny Mouse says:

      Or buy a beer chiller for 10th the price (I won’t advertise any specific brands here, though).

  6. a. nonymaus says:

    On reaction times, I’ve heard it summarized that the literature can be broken into reactions that are done on mixing, reactions that are done over five minutes, reactions that are done over tea, reactions that are done over lunch, reactions that are done overnight, and reactions that are done over the weekend. And really, if the reaction needs precise timing on a scale of hours to get optimal yield, that optimum isn’t going to be so high.

    I definitely don’t miss working in a desert climate where all I had was a water cooled rotovap attached to a water aspirator. The worst part was that in summer the tap water temperature got warmer so the condenser wouldn’t condense anything low-boiling and the aspirator wouldn’t pull off anything high-boiling.

  7. Yusef says:

    Are these Findensers pricey?

  8. Scott E says:

    I looked into these just recently and spoke to a couple of colleagues who own some findensers. They are pretty expensive and very heavy, and require the reaction temperature to be well above ambient to work effectively. It’s not uncommon for our lab to be running 3-6 refluxing reactions at a time, which would be a big investment. The best solution we’ve found is to daisy chain multiple condensers to a small pump in a bucket and to use twist ties to fasten the tubes to the condensers. This way, you only need to assemble everything once, you can hang the tubing in the back of the hood so researchers can easily connect/disconnect without disturbing other reactions. Blowing out a line is still a possibility, but we put new twist ties on each year during our “lab Spring cleaning” and have never had a blowout.

  9. anon says:

    Standard air condenser does the trick for many solvents without the need for more expensive kit.

  10. CMCguy says:

    After many floods in our dept due to water lines popping off my grad lab switched to cheap set-up of buckets with a fish tank/pond pump recirculation to feed condensers that worked really well and never had another line come loose (so have always assumed real problem was often at night the lab water pressures increased when there was little draw on the systems). On real hot days we would add ice to the buckets to aid cooling power and on at least one occasion used for warmed water source in a jacketed vessel. Of course a few people never occasionally cleaned out or added a touch of bleach to their buckets and was easy to see the green water flows (yet was very disgusting to see).

  11. Semichemist says:

    We looked at the Findensers recently but couldn’t really believe a water-jacketed heat sink would cool better than our 5 °C chiller setup. Perhaps we should revisit the option…

  12. A Nonny Mouse says:

    I have been using a similar Jencons product for years (1995ish) which has the condenser filled with water which then circulates through the aluminium fins. This just seems to be a more modern version.

    I agree with the above; I use fish pond pumps an a bath which either has a cold finger in it or it runs through a beer chiller (10th the price of the lab equivalent).

    Additionally, if you are using the Radley’s metal baths for heating (unknowingly bought about 50 from a Pfizer auction for £32) then air condensers work fine as the temperature is controller just at the boiling point.

  13. paul koovits says:

    We’ve got a couple in our lab. They work really well. One guy in our lab even had a really vigorous DCM reflux going overnight and it hardly lost any solvent.

    They are pretty heavy though.

  14. anaonandon says:

    Try the Asynt condensyn air condensers. I have been using one for the last two months. Lighter than the findensers, no water, no pump, no ice, no loss of solvent.

    1. Chemystery says:

      The Asynt Condensyn ( is an all glass version. We have a few so far, although not with enough time yet to thoroughly comment, although their evaluation conducted in a UK university is reasonably convincing.

  15. Greener says:

    Before any expensive investment, you might want to read this paper:

    “Static Fluid Condensers for the Containment of Refluxing Solvent” from Dow scientists
    ACS Sustainable Chem. Eng. 2013, 1, 1502−1505

    Works quite well for us 😉

  16. Asynt says:

    May be worth taking a look at the Condensyn air cooled condenser from Asynt. Very cost effective, light weight and easy to clean. By using a unique glass forming technique we have been able to manufacture a high surface area air condenser which is robust and effective.
    Performance of the CondenSyn is equivalent to a Leibig type condenser being used with tap water.
    No issues with water leakage, and potential flooding
    By not using water the environmental impact is reduced as is the costs of water usage.
    A tidy setup, clear visibility of reflux and easy to clean.

  17. Irish chemist says:

    I was writing a shopping list and all I have on it is Asynt Condensyn multiple times.
    I have been brain washed reading this thread

  18. Semichemist says:

    Does anyone moderate this blog aside from Derek? Can we get all this Asynt b.s. removed?

  19. JC says:

    My hood neighbors’ hose popped off, flooded over to my area, went down my sink area and down to the 1st floor from the 3rd. Caused a pretty big problem in the vivarium with trashed walls. I got the heat from the boss, even though my hoses were securely clamped.

  20. dylan says:

    Intriguing, but what I really want is a lighter alternative product that works just as well. Does anyone know a company that makes a more cost effective lighter product?

  21. I had a sink back up, of course I was on the second floor with another company below us. Completely trashed the other company’s office.
    My company, HEL, has just developed a thermoelectic condenser using Peltiers to provide the cooling. The Peltiers cool to ~10°C and are clamped onto a metal condenser. The current ones are are quite small and are designed for a 100ml bioreactors however I don’t see why this technology could not be scaled to larger condensers.

  22. AOK says:

    Coming from an API process development lab, we were offered a free trial on these, but I don’t think anyone took up on the offer. The main objection was that their size was slightly incompatible with our existing flask/overhead stirrer combinations, and we were not ready to overhaul everything all at once. If there is a smaller one on the market, it’d be interesting to try one. I’m all for developing greener lab technologies, however, and painfully aware of the huge carbon footprint I’ve already amassed during my academic and industrial career…

  23. loyboy says:

    I second the use of condensers as described by Greener above. They work great, and only use ethylene glycol. I’ve been using these for going on two years now. They’re not very heavy, and so are easy to pop on and off.

  24. Mark Thorson says:

    Graham, I see a problem with scaling up Peltier coolers. They’re terribly inefficient, in the single digits of %. Not good if you want to move lots of heat. A heatpipe or thermosiphon would do much better.

  25. mg says:

    I have used the findensers and agree with the comments about them being heavy and I really don’t like them on small (<200ml) flasks. And running the risk of cracking/breaking the glass always puts me off. As for the asynt, I tried out one of those recently but they are incredibly long and just like giant vigreux. So I took myself down to the basement to our glassware graveyard (I work in an old established industrial chemistry facility where there used to be a few pilot rigs) and hey presto, I found some pretty decent sized vigreux condensers which work surprisingly well if you're not going mad with vigorously refluxing.

  26. steve says:

    I havent refluxed a reaction for years. If a reaction say calls for refluxing toluene, I do it at 105 C on a temperature controlled bath with a air condenser as a back up. Reflux is just a hang up from the days before temperature control.

  27. Dieter Weber says:

    Not a chemist here, but won’t such a condenser couple your rig’s operating point to air temperature and air flow as well as introduce crosstalk if you run a couple in close vicinity? Why not using a water-cooled equipment together with a regular chiller or even a closed-loop cooling water infrastructure for the entire lab? That gives stable temperature and flow independent of the environment. That’s the standard solution for the equipment I am used to, electron microscopes, sputter tools and such. I’m astonished that anybody is still using tap water for cooling.

  28. Mark Thorson says:

    An advantage of using tap water (or a Findenser) over a circulator is that it tolerates power interruptions. Tap water seldom goes out, but electricity can. What are the consequences if your reflux apparatus loses cooling during an overnight or overweekend run?

  29. Bob says:

    How much do these things cost? Lets say for 500 mL scale condensor?

  30. steve says:

    I’m a biologist, not a chemist, but this “no flowing water” condenser always worked for me.

  31. milkshaken says:

    dry ice condensers are 100% water-free

    1. A Nonny Mouse says:

      The name was given to me in the first year at university when I forgot to put my name on an assignment by a physical chemistry prof (MR Ashe- he was proud that he was the only MR on the teaching staff. Rumour has it that his thesis somehow got ruined and he couldn’t be bothered getting it re-done).

      I’m in the UK and the Airflux were obtained when a lab was closing down, so they were free for me!

  32. Matt says:

    This is a really interesting read and is something close to my heart. Chemistry isn’t the most environmentally friendly activity so if we can reduce any impact thats great! Personally I have been looking at this for quite a few years and I use a variety of solutions. I rejected chillers / circulators as I wanted an entirely passive system. That’s not to say they aren’t effective, I just wanted ‘free’. Here (UK) the airflux is more expensive than the findenser and asynt solutions so I don’t use it. I have used vigreux columns with great result but there are limitations in terms of scale and solvent boiling point. I have found the findenser covers all aspects of what I require and I have even had 2L of ether on the boil for a few weeks with one. I did find they weren’t suitable for a jacketted vessel though so couldn’t try larger volumes. The downside is the weight as previously mentioned. I was concerned about its stability in a small volume flask but I find that with the flask neck clamped and the flask in an aluminium heating block it is sufficiently stable. You can always clamp it as the body is just smaller than the limit of a lab clamp. I really like the look of the Asynt solution but I haven’t tried it (yet) and I would love to see how it compares with a vigreux and how it copes with larger scale (ie can it match the 2L of ether expt?). I’m always happy to discuss or share my results but I’m unsure if I can be contacted via this website.

    Putting the whole ‘which solution’ debate to one side, it’s great to see such debate. It clearly demonstrates that the chemistry community is considering it’s impact. Long may this continue!

    On a personal note, I love the names used. Nonny mouse made me laugh. 🙂

  33. Matt says:

    I jsut thought I’d add a note of caution with the static fluid condensers. I’ve tried it and they work well. However, if you put a lot of heat into them I got breakthrough and managed to crack a couple. Perhaps I shouldn’t have used them sealed! Hope that helps.

  34. Xanthate says:

    “An advantage of using tap water (or a Findenser) over a circulator is that it tolerates power interruptions. Tap water seldom goes out, but electricity can. What are the consequences if your reflux apparatus loses cooling during an overnight or overweekend run?”

    Not much, given the power is out?

  35. Mark Thorson says:

    If you have a liter of boiling solvent on a heater, and suddenly no condensor cooling and no fume hood ventilation, could that be a problem? I suppose it depends on the solvent. Could be fun when the power comes back on.

  36. NoDrugsNoJobs says:

    When I first joined industry more than 20 years ago, one of the associates in my lab asked me why I was using a water condensor and he showed me his set up of a simple kulgerohr bulb that he refluxed up into – Not thinking it adequate, I simply stacked 3 on top of each other and never looked back again. For small reactions I did every thing in sealed tubes and they worked great as well. I hated condensors and was so glad to get away from them.

    I thought the ideal thing would be to couple a temp/solvent sensor to the top bulb of the air trap and have that feedback to the oil bath to reduce the temperature when the solvent front gets too high in the air trap. I was totally convinced that could work superbly – not sure what a findensor is, maybe something like that?

  37. Steve stroud says:

    We’ve been testing one of these Donjoy recirculating systems in my lab and have been very happy with it. Using 200 ml of actively reflxing toluene, the water temperature of the reservoir stayed under 10 deg C for over 6 hours (it is initially filed with crushed ice and some water). The quick disconnects on the tubing mate perfectly with those already mounted on our condensers. Bonus points from our Safety Department for the entire unit being self contained, with no exposed electronics, and the unit is not in the hood when being used.

  38. anon electrochemist says:

    These work a treat for reactions in gloveboxes. The regular air condensers work, but these protect your atmosphere better.

  39. eugene says:

    Off topic, but I thought this was the best thread to leave this, there is a new video game that is a big pharma simulator. Anyone want to give it a try? Derek maybe has to. Less posts for a week, but a scintillating review afterwards.

    On topic, like many others, I switched to a bucket with a powerful fish tank pump in my postdoc. You can fill the bucket with ice, and periodically drain it, but a full bucket of ice with some water will stay at ~2-3 degrees for overnight without melting. I cannot use parallel condensers since the reactions I do are too different, and frankly, I feel a lot better washing them very well on the inside after every reaction, so I don’t have the connections well clipped. Still, with the right choice of tygon tubing I never had it pop off a condenser. Others in my lab did have that problem, but the flooding was limited only to the contents of the bucket, which is a lot better than what happened in grad school, when someone with a condenser hooked up to the main line had a connection fail overnight, and flooded not only their floor, but the floor below which had an expensive million dollar laser setup. Good thing that the latter lab had insurance. But the payments probably went up after that.

  40. Andy says:

    Oversized flasks work well as air condensers, with a bit of practise.
    Regular condensers work well simply filled with water and sealed.

    Using a reservoir such as a bucket and pumping it round condensers works really well, but it’s difficult to get around the legislation relating to Legionnaires Disease.

  41. Dieter Weber says:

    Is it common practice to use a coolant flow interlock for the heater and a flood sensor interlock for both coolant and heater? For cleanroom equipment that’s always the case because these often run unattended and the damage of overheating or flooding can be extensive. Interlocks make me sleep better!

  42. tangent says:

    Reflux is just a hang up from the days before temperature control.

    Huh. That makes a lot of sense to this non-chemist. Why do people run reactions right at the boiling point of the solvent, other than lack of a temperature controller, anyway?

  43. MK says:

    Findensers are great if you don’t need a very strong reflux – we don’t use then for soxhlets. And they are tough to clean if you soil them badly. For anything else, they are awesome!

  44. Vigreux says:

    Been using a long Vigreux column for that purpose for years, can stack them too. Just add a bit more solvent

  45. Hano3s says:

    Landed a job in industry some 18 years ago and immediately got laughed at by the senior chemists (the ones with 40+ years of prep-synthetic experience) when I started to hook up a water condenser. I was given an in-house air condenser instead that was nothing more than a 3-foot long glass tube of ca. half inch diameter with male and female NS connections on either end. Have rarely used a water condenser since, and when I did it was a super-efficient condenser with jacket AND coil that required only a gentle flow of cooling water.
    With a job in academia now I’ve been trying to convince people to stop using water condensers, in view of the multi-thousand euro damage already done by flooding. One can explain the importance of hose clamps to students, but if they’re in a rush to start celebrating the weekend they’ll just shove tubing onto condensers, construct adapters by shoving different diameters of tubing into each other and more of these horrors, but surely without the mandatory ty-rap or hose clamp. After flooding the NMR facilities (no NMR for three days, can you imagine ?) people started looking into these Findensers but they seem to be kinda hard on academic budgets. Still advocating the use of the simplest air condensers (as above, in fact they are commercially available at ridiculously low prices) I also teach my students to not reflux DCM with an oilbath of 100 deg C. Does not make any sense. Oil at 50 deg C is plenty. As for myself, I hardly use any condenser anymore. Reflux ? Just take a bigger flask, say 100 ml in a 500 ml RB, oilbath at 5 to 10 deg above bp of solvent. No problemo. I do like Greener’s suggestion however. It just might put these dozens of bulb-condensers lying around to good use.

  46. 100%chem says:

    We’ve been using the Asynt Condensyn air cooled condensers and they’re fabulous. We recently had a flood in the lab and the decision was made to switch over to air cooled condensers for overnight reactions. In the grand scale of things, they’re very cost effective and will pay for themselves within around 6 months.
    We also purchased one of the Julabo F1000 recirculating chiller units. This allows us to cool four rotary evaporators from one chiller system.
    Often you can obtain help from your Estates Department to pay for these things. Worth having a chat with them. Some universities also have sustainability leaders who have access to pots of money to help build a more sustainable laboratory.

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