21906-68-3Relevant academic research and scientific papers
Oxocarbons and related compounds, 30 [1]. On the reaction of squaric acid with pyrazolinones
Schmidt, Arthur H.,Schreck, Timo,R?tz, Ralf,Von Freytag-Loringhoven, Sarah
, p. 311 - 319 (2008/01/27)
Heating of squaric acid (1) with the 1-aryl-3-methyl-5-oxo-2,5-dihydro-1H- pyrazoles 3a-j and the 1,3-disubstituted pyrazolinones 7a-d in the molar ratio of 1:2 in a mixture of n-BuOH/toluene afforded the bis(pyrazolyl)-squaraines 4a-j and 8a-d, respectively. Reaction of an excess of 1 with the pyrazolinone 3j yielded 4j and the 3-hydroxy-4-pyrazolyl-cyclobutene-1,2-dione 6 as a byproduct. In contrast to disubstituted pyrazolinones, the trisubstituted pyrazolinones 9a-e reacted with squaric acid (1) to give the hydroxy-oxopyrazolyl-cyclobutenediones 10a-e.
