2-acetyl benzimidazolyl-glycin schiff base preparation method
A technology of acetyl benzimidazole glycine Schiff base and acetyl benzimidazole is applied in the field of preparation of 2-acetyl benzimidazole glycine Schiff base, and can solve the problem of long reaction time and less than 90% Yield, serious pollution in the reaction process, etc.
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Embodiment 1
[0019] Embodiment 1 The synthetic method of precursor 2-acetylbenzimidazole
[0020] Step 1: Synthesis of 2-(1'-hydroxyethyl)benzimidazole:
[0021]
[0022] In a 100ml three-neck flask, dissolve 10g of o-phenylenediamine in 25ml of 4mol / L HCl, stir until completely dissolved, adjust the pH to 2 with HCl, and then add 0.1g of catalyst FeCl 3 ·6H 2 O and 13ml lactic acid, heated to reflux for 4 hours, cooled, slowly added solid Na 2 CO 3 Neutralize the powder and stir vigorously until the pH is close to 7, then add 20% Na 2 CO 3 Adjust until the solution changes from black-red to yellow-green, and a large amount of precipitates are formed, which is left to stand and filtered with suction to obtain the crude product. Recrystallize directly with water, add activated carbon for decolorization, filter while hot, and precipitate 13.5 g of white crystals after cooling, with a yield of 80% and a melting point of 180.4-181.0°C (literature value of 177-179°C).
[0023] Step 2: ...
Embodiment 2
[0025] Example 2 Preparation of 2-acetyl benzimidazole glycine Schiff base
[0026] Glycine (0.7507g, 0.01mol) and KOH (0.56g, 0.01mol) were dissolved in 25mL of methanol, stirred for about 15 minutes until dissolved, filtered, and 2-acetylbenzo Imidazole (1.602g, 0.01mol) in 20mL of methanol solution, after reflux for 5-14 hours, the color of the solution changed from yellow to dark brown red, part of the methanol was evaporated, cooled, a precipitate formed, suction filtered, washed with methanol and chloroform respectively, Dry it under infrared light, place it in a concentrated sulfuric acid desiccator to obtain a khaki powder.
[0027] 1 H NMR hydrogen spectrum (400MHz, CD 3 OD): δ7.6(q, 2H, a Coupling peak on H-Ar), δ7.3(q, 2H, b Coupling peak on H-Ar), δ5.311 (d, 1H, H-N), δ2.582 (s, 2H, -CH 2 -), δ1.652(s, 3H, CH 3 ).
[0028] Infrared (cm -1 )(KBr) 1643(C=N), 1570(ν as COO - ), 1428 (ν s COO - )
[0029] Raman (cm -1 ): 1644.76 (C=N), 1566.93ν as COO -...
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