Hydrochloric Acid → 2-Methyl-5-pyrazin-2-yl-2h-[1,2,4]triazole-3-carbaldehyde dihydrochloride monohydrate

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Reaction Conditions

Reaction Steps

The acetal from step 2, 2-[5-(diethoxymethyl)-1-methyl-1H-1,2,4-triazol-3-yl]pyrazine (44.5 g, 0.17 mol) was dissolved in water (150 mL) and conc. HCl (30.0 mL of 12 M, 0.36 mol, ˜2 equiv). The solution was degassed with nitrogen for 2 min and heated in an oil bath at a bath temperature of 60° C for 2 h, resulting in complete hydrolysis of the acetal group. The volatiles were removed in vacuo, affording a yellow solid (49.8 g). This was suspended in dichloromethane (1 L), refluxed under nitrogen for 1 h, then filtered while still hot. The filter cake was washed with dichloromethane and dried in vacuo at 50° C. for 4 h, affording the title product (41.0 g, 81%) as a hygroscopic yellow solid. 1H NMR (300 MHz, DMSO-d6): δ 4.21 (s, 3H), 8.50 (br s, 4H), 8.75 (m, 2H), 9.27 (s, 1H), 10.01 (s, 1H). MS (APCI) calcd for C8H7N5O: 189.07, found (M+H+): 190.1, 208.1 (hydrate); Anal. Calcd. For C8H11Cl2N5O2: C, 34.30; H, 3.96; N, 25.00; O, 11.42; Cl, 25.31. Found: C, 33.43; H, 3.98; N, 24.70; O, 11.17; Cl, 25.44.

Provenance & Evidence