Dear all, I'm stuck with a technical problem. I have developed a working air-free synthesis, in which products are relatively stable and be exposed to small quantities of oxygen. Now, based on the same procedure I'm trying to synthesize products very oxygen sensitive. This implies not being able to use syringes or rubber septa anymore. Everything is being done in a one-pot synthesis, conducted in air-tight and vacuum resistant Schlenk/ Kjeldahl reaction apparatus. Previously, I could just put a rubber septum in one of the necks and stick a thermocouple trough, this is now not an option anymore. I've searched for multiple necks air-tight systems, but this only brings the problem of how to put the TC in, again no rubber septa possible. I tried to use an oil bath with silicone oil or mineral oil and measure their temperature, but they start to smoke at around 230°C and they did not reach the desired temperature of 320°. The best solution I've had so far is actually to stick the TC in the interstice between the inside vessel of the heating mantel, but I'm oblivion whether this is ok, ok-ish, not that good, or absolutely wrong. So, do any of you either know if the system i plan to use actually works or has a more experienced solution to the problem of measuring the T of a solution without putting a TC inside the vessel?
Could you bring a sketch of your vessel with dimensions and materials used for the different parts ? What you intend is right under conditions depending on the design of your fixture thus the need to have a better look than a qualitative description.
Bruno - you can fit your thermocouple into this adapter which is equipped with O-rings (interior and exterior) for an air-tight seal between adapter and flask joint and between thermocouple and adapter. This will let you still probe the solution temperature directly, which is by far the best way.
https://www.fishersci.com/shop/products/adapter-thermocouple-14-20/50872868
Dear all,
Thanks for the suggestions.
Eventually, I ended up purchasing such products (attachments).
Usually, they come already with a hole in the rim to accommodate for the TC, in case the hole will not be present I will simply bore a hole on the rim and use that to measure with the TC.
IT is not as good as measurements directly inside the vessel but is by far the simpler system.
Thanks again for all the answers.
Best
Bruno
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