Synthesis of Some N,N-Methylacyl Derivatives of 4-Aminoantipyrine
Abstract Generated abstract
This paper reports the application of an acylation method for introducing acyl residues into 4-N-methylaminoantipyrine, a secondary amine of the pyrazolone series. Instead of using acid chlorides, the procedure reacts 4-methylaminoantipyrine with free carboxylic acids in anhydrous benzene in the presence of phosphorus trichloride, followed by alkaline workup and recrystallization. Six previously undescribed N,N-methylacyl derivatives of 4-aminoantipyrine were synthesized, including dinitrobenzoyl, methoxybenzoyl, fluorobenzoyl, capronoyl, and stearoyl derivatives, with reported yields, melting points, empirical formulas, and nitrogen analyses.
Full Text
Synthesis of Some N,N-Methylacyl Derivatives of 4-Aminoantipyrine
E. V. Shmidt, G. M. Stepnova, N. S. Grigorevskaya
(Presented by the scientific-methodological seminar of the CTF)
To obtain acyl derivatives of 4-aminoantipyrine, we previously used the reaction of 4-aminoantipyrine with free carboxylic acids in the presence of phosphorus trichloride in an inert solvent medium [1–3]. In the present work, the results are set forth of applying this reaction to introduce acyl residues into a secondary amine of the pyrazolone series—4-N-methylaminoantipyrine. According to the literature, for this purpose the usually difficult-to-obtain and expensive acid chlorides of carboxylic acids were used [4–6].
Experimental Part
0.1 g-mol of 4-methylaminoantipyrine and 0.1 g-mol of a carboxylic acid are placed in a reaction flask equipped with a stirrer, reflux condenser, and dropping funnel. Forty ml of anhydrous benzene are added. The mixture is heated with stirring to 60–70° and, dropwise over 10 minutes, 2.5 ml of phosphorus trichloride dissolved in 10 ml of benzene is added. The mixture is boiled for 3 hours. The benzene is distilled off; the reaction mass is treated with a 10% solution of sodium carbonate, filtered, washed with water and ether, and recrystallized from alcohol. The yield of the acyl derivative is determined. The yields and characteristics of the obtained N,N-methylacyl derivatives of 4-aminoantipyrine are given in Table 1.
Table 1
| Name of acyl | Yield, % | m.p., °C | Found, % nitrogen | Empirical formula | Calculated, % nitrogen |
|---|---|---|---|---|---|
| 3,5-dinitrobenzoyl | 79 | 215–216 | 17.11 | C₁₉H₁₇O₆N₅ | 17.03 |
| 2,5-dinitrobenzoyl | 70.5 | 177–178 | 16.96 | C₁₉H₁₇O₆N₅ | 17.03 |
| 3-methoxybenzoyl | 75.8 | 168–169 | 12.40 | C₂₀H₂₁O₃N₃ | 11.97 |
| 3-fluorobenzoyl | 81.5 | 148–149 | 12.13 | C₁₉H₁₈O₂N₃F | 12.38 |
| Capronoyl | 73.5 | 82–83 | 13.83 | C₁₈H₂₅O₂N₃ | 13.33 |
| Stearoyl | 83 | 79–81 | 9.01 | C₃₀H₄₉O₂N₃ | 8.69 |
Conclusions
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A method has been applied for introducing an acyl radical into the secondary amine of the pyrazolone series using free carboxylic acids in the presence of phosphorus trichloride.
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Six \(N,N\)-methylacyl derivatives of 4-aminoantipyrine not described in the literature have been synthesized.
Literature
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