<![CDATA[Crystal, IR and NMR data for (4-(Ethoxycarbonyl)-1H-pyrazol-5-olate)sodium (14): NaOMe (0.5 M in MeOH; 1.81 mL, 0.903 mmol, 1.00 equiv) was added with stirring to pyrazolone 5 (141 mg, 0.903 mmol, 1.00 equiv) in MeOH (5.0 mL) at 65 °C. The mixture was heated at reflux for 30 h, cooled to room temperature and the mixture was co-evaporated to dryness with Et2O (4 x 15 mL). The precipitate was suspended in Et2O, collected by filtration and dried in vacuo. Na-pyrazolone complex 13 (147 mg, 0.825 mmol, 91%) was obtained as a white solid, essentially pure by its 1H NMR spectrum. Crystals suitable for X-ray crystallography were obtained by slow evaporation from a MeOH solution of complex 14.
1H-NMR (400 MHz, CD3OD): δ (ppm) = 7.46 (s, 1H), 4.17 (q, J = 7.1 Hz, 2H), 3.35 (s, 1H), 1.29 (t, J = 7.1 Hz, 3H).
13C{1H}-NMR (101 MHz, CD3OD): δ (ppm) = 167.7, 167.4, 142.4, 93.5, 59.5, 15.0.
IR (Diamond-ATR, neat) νmax (cm-1) = 3294, 1664, 1577, 1433, 1327, 1252, 1128, 917, 781, 656.
HRMS (ES-ToF) m/z: [M + H + CH3CN]+ calc. for (C8H11N3O3Na)+: 220.0693, found: 220.0430.
m.p.: >265 °C (MeOH) (decomp.).
Anal. Calcd for C6H7N2NaO3 ∙ 1.2 NaOH ∙ 0.25 MeOH: C, 32.06; H, 3.96; N, 11.97. Found: C, 32.31; H, 4.06; N, 12.15.]]>
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