From what I can find Googling - they've been around commercially for some time (10 or more years?); I found very little in written SOP's, but the discussion on researc- gate I've seen several comments that if not handled correctly, the results can be energetically problematic.

See https://www.toptionlab.com/Hydrothermal-synthesis-reactor/teflon-lined-hydrothermal-reactor.html for an example of a reactor.

So questions for the group:

Does your institution have specific guidance on using these such as limiting the size of reaction chambers?  

Do you have minimum engineering controls for containment (blast shielding, etc.)?  

Does your institution explicitly prohibit using them?

Two critical administrative controls I've seen are:

1) not overfilling the reaction chamber, allowing headspace for gas formation.  For hydrothermal reactions, this seems pretty well established since water expands about 25% at the temperatures these are operating at (190-220C).  For solvents, it doesn't seem to be as straight forward.  For example, I've not been able to find an expansion factor for dimethylformamide (DMF).

2) not heating and cooling too fast.  The instructions I've seen with reactors say things like don't heat or cool faster than 5C/min.  But I've seen instructions that go outside those guidelines (8C/min) and several that say "cool naturally" i.e. not at 5C/min (I've also seen discussions that specifically advise against quenching them).  

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