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In a currently retracted* manuscript by Tomas Hudlicky [1, Retraction Watch] the following has been noted:

  1. Fifty years ago professors took an active part in all laboratory instructions and they taught advanced techniques to research undergraduates, graduate students, and even postdocs. During my postdoctoral stay in Geneva Professor Oppolzer personally showed me how to distill 3 mg of an oil after I commented that it could not be done. Such practices are all but absent at present. Students are not taught by professors, most of whom have not been at the bench for decades, but by more senior personnel in the research laboratory.

Does anyone know or can suggest a plausible method used by Prof. Wolfgang Oppolzer to distill milligram amounts of oil, considering this demonstration has likely took place between 1977 and 1978 (according to this CV)?

I flipped through the distillation handbook of that time [2], especially focusing on section 5.1.1 Micro- and semi-micro-distillation, and I suppose it was possible that some version of an extremely miniaturized distillation apparatus combined with a set of spinning band columns or concentric tube columns operating under reduced pressure could've been used:

The separation of essential oils with spinning band columns at 4 to 13 torr has been reported by Spiegelberg [9]. Examples of separations of high-molecular organic compounds with a concentric tube column are given by Jantzen and Witgert [3] and Fischer [7].

Bonus question: how relevant mastering this distillation technique would be these days? Are there better alternatives and what are they? (Gas chromatography, I presume?)


* Thanks to M. Farooq for drawing my attention towards the article and motivating to find and actually read the original paper.

References

  1. Hudlicky, T. “Organic Synthesis—Where Now?” Is Thirty Years Old. A Reflection on the Current State of Affairs. Angew. Chem. 2020, ange.202006717. DOI: 10.1002/ange.202006717. (Retracted 2020-06-05)
  2. Krell, E. Handbook of Laboratory Distillation: With an Introduction into the Pilot Plant Distillation, completely rev. 2nd ed.; Techniques and instrumentation in analytical chemistry; Elsevier Scientific Pub. Co. ; Elsevier North-Holland: Amsterdam; New York, 1982. ISBN 978-0-444-99723-4.
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    $\begingroup$ During the 1970's we used a homemade Kugelrohr for non-fractionating distillation of small amounts of liquid under reduced pressure. Today there are hi-tech Kugelrohrs: en.wikipedia.org/wiki/Kugelrohr $\endgroup$ – user55119 Jun 8 at 23:39
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    $\begingroup$ Today, in order to purify 3 mg sample, one would do a semi-preparative liquid chromatography or supercritical fluid chromatography (preferred). It is not a big deal today. GC columns have very poor capacity. $\endgroup$ – M. Farooq Jun 9 at 0:23
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    $\begingroup$ @Andselisk, If you search microdistillation in ACS Analytical Chemistry, you will find plenty of apparatus descriptions until the 1960s. $\endgroup$ – M. Farooq Jun 9 at 0:31

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