Tetraketopiperazine

Tetraketopiperazine
Names
	Preferred IUPAC name Piperazinetetrone
	Other names 2,3,5,6-Piperazinetetrone
Identifiers
CAS Number	49715-78-8 ;
3D model (JSmol)	Interactive image;
ChemSpider	245865;
PubChem CID	279250;
UNII	3RT8Z7D4Q8 ;
CompTox Dashboard (EPA)	DTXSID10964366 ;
	InChI InChI=1S/C4H2N2O4/c7-1-2(8)6-4(10)3(9)5-1/h(H,5,7,9)(H,6,8,10) Key: IXRCBQCSNZKFHS-UHFFFAOYSA-N;
	SMILES C1(=O)C(=O)NC(=O)C(=O)N1;
Properties
Chemical formula	C4H2N2O4
Molar mass	142.070 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Tetraketopiperazine is a chemical compound with a molecule containing a six member heterocyclic ring with two nitrogen atoms. Each carbon is doubly bonded to oxygen.^[1]

Production

Reacting sodium oxamate (the sodium salt of oxamic acid) with hydrochloric acid yields some tetraketopiperazine. A higher yield result from reacting ethyl oxalate with sodium ethoxide.^[1] Yet another way to make tetraketopiperazine is a condensation of oxamide with ethyl oxalate with sodium ethoxide present.

Excessive nitration of 2,6-diaminopyrazine ends up with tetraketopiperazine.^[2]

Reactions

The nitrogen atoms in tetraketopiperazine are slightly acidic losing their hydrogen atoms as ions. Salts of tetraketopiperazine exist. Tetraketopiperazine reacts with sodium bicarbonate to yield a monosodium salt. A disodium salt results from reaction with sodium hydroxide or sodium alkoxide. These are likely to be tautomeric with a hydrogen moving to an oxygen atom. Potassium salts also exist. A monosilver salt can be made from a silver compound and a dissolved tetraketopiperazine potassium salt. Ammonia and mercury salts of tetraketopiperazine also exist. Tetraketopiperazine also can form a monohydrazone.^[1]

Reduction of tetraketopiperazine yields trikeopiperazine and then 2,5-diketopiperazine. Glyoxalic acid and oxamide are side products.^[3]

Properties

When heated tetraketopiperazine does not melt, but turns black at 250°C.^[1]

Tetraketopiperazine is slightly soluble in water and more so in boiling acetic acid. The solid form has monoclinic prismatic crystals.^[1]

pK_a is 4.8 and the second pK_a2 is 8.2.^[3]

References

^ ^a ^b ^c ^d ^e de Mouilpied, Alfred Theophilus; Rule, Alexander (1907). "XVI.—Tetraketopiperazine". J. Chem. Soc., Trans. 91: 176–183. doi:10.1039/CT9079100176.
^ Bellamy, A. J.; Golding, P. (2007). "The Study of Some Potential New Synthetic Routes to LLM-105 (2,6-Diamino-3,5-dinitropyrazine 1-oxide)". Central European Journal of Energetic Materials. 4 (7): 33–57.
^ ^a ^b Owens, J.L.; Dryhurst, G. (November 1976). "Electrochemical reduction of tetraketopiperazine". Analytica Chimica Acta. 87 (1): 37–50. Bibcode:1976AcAC...87...37O. doi:10.1016/S0003-2670(01)83118-4.

[tkp-1] ^ ^a ^b ^c ^d ^e de Mouilpied, Alfred Theophilus; Rule, Alexander (1907). "XVI.—Tetraketopiperazine". J. Chem. Soc., Trans. 91: 176–183. doi:10.1039/CT9079100176.

[2] Bellamy, A. J.; Golding, P. (2007). "The Study of Some Potential New Synthetic Routes to LLM-105 (2,6-Diamino-3,5-dinitropyrazine 1-oxide)". Central European Journal of Energetic Materials. 4 (7): 33–57.

[owens-3] Owens, J.L.; Dryhurst, G. (November 1976). "Electrochemical reduction of tetraketopiperazine". Analytica Chimica Acta. 87 (1): 37–50. Bibcode:1976AcAC...87...37O. doi:10.1016/S0003-2670(01)83118-4.

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