Piperonyl-piperazine synth. (french)

[pHarmacist]

Shulgin mentioned in PiHKAL that MD correspondents of Bz-piperazine would be intresting. Here is a patent that describes the process of high-yield synthesis of piperonyl-piperazine by reductive amination of piperonal with piperazine. However it's written in French, maybe someone can translate.

Abstract:

Single-stage preparation of piperonyl-piperazine (I) involves reacting piperonal (II) with a stoichiometric excess of piperazine (II) in a volume excess of a polar solvent until (II) is partially converted into the corresponding hemi-animal, then hydrogenating the mixture in presence of a catalyst.

Patent FR2799464

[Rhodium]

See

Post 291455 (missing)

(Nemo_Tenetur: "No effects!", Novel Discourse)

[Osmium]

Oh come on, The experiemntal part is not that hard to translate even if you don't speak French (and of course the whole 17 pages is just too long unless someone is really bored!)

Example 1:

A reactor is charged with 50g piperonal, 114.8g piperazine, 255ml EtOH and 5g Pd/C. While the mixture is heated to 45°C the reactor is purged with N2. The yellow solution is then put under 3 bar of H2 and heating continued to 75°C until H2 absorption ceases. After 3 hours the piperonal will have reacted completely.
Cool solution to 20°C, filter with celite, wash filter cake with 59ml ( why not 60?) EtOH and remove solvent under vacuum at about 40°C. The residue is taken up in 125ml toluene, colled to -10°C for an hour and the precipitated piperazine removed by filtration. To the filtrate 250ml water are added and pH adjusted to 6. The water layer is extracted three times with 75ml toluene, basified to pH=13 and extracted three times with 118ml toluene. The combined toluene extracts are washed with 50ml saturated NaCl solution and the toluene removed under reduced pressure at 40°C. Yield 90%, purity 99.7% by GC, no traces of bis-piperonylpiperazine, piperazine or piperonal detected.

The tables following example 1 are pretty much self-explaining, describing production runs using 50-175kg piperonal.

[Osmium]

Pretty much expected it to be uninteresting. All that nice piperonal wasted for nothing... sigh.

Still, a pretty good example for the usefulness and efficiency of catalytic reductive amination
(Hint: obviously the same can be done to a mixture of EtOH, MDP2P and methylamine)

[Barium]

I´m more curious about the effects of (3,4-methylenedioxyphenyl)piperazine,

Post 301368 (missing)

(toad: "MD-phenylpiperazine", Novel Discourse)