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Abstract: This paper presents two alternatives for the synthesis of acetylsalicylic acid, by replacing the acetic anhydride with ethyl acetate and acetic acid. In both cases, the synthesis of acetylsalicylic acid was confirmed by the X-ray diffraction analysis, FT-IR and UV spectra, ^sup 1^H-NMR and ^sup 13^C-NMR.
Keywords: acetylsalicylic acid, original methods, synthesis, characterization
INTRODUCTION
Acetylsalicylic acid, commonly known as aspirin, is one of the most widely used nonsteroidal anti-inflammatory medications worldwide [1]. Plants rich in salicylic acid (willow tree) were used to treat pain for more than 2000 years, while after the synthesis of aspirin in 1897, it was used on large scale for its analgesic, antipyretic and anti-inflammatory actions [2, 3, 4]. Presently, the low-dose aspirin is used also for its cardio protective, anticoagulant and immunoregulatory effects [1, 5, 6, 7]. Moreover, recent researches suggest that acetylsalicylic acid may reduce the risk of oncological maladies, but the overall benefits are unclear due to its association with bleeding and stomach pain [8-15]. The new derivatives of acetylsalicylic acid offers improved gastric protection, controlled release or targeted delivery [2, 16, 17].
There are several methods for the synthesis of salicylic acid [13-16]. Commercially, the acetylsalicylic acid is synthetized in two steps: i) synthesis of salicylic acid from phenol by the Kolbe-Schmitt reaction ii) acetylation of salicylic acid using acetic anhydride in presence of acid catalysts, generally concentrated sulphuric and phosphoric acids [19-22]. With the increase of the manufacture and consumption of acetyl salicylic acid, new, eco-friendly methods of synthesis based on the use of alternative catalyst as solid acids were developed [23,24].
In this paper, two synthesis methods used to obtain acetyl salicylic acid are described.
The obtained compounds were characterized by UV spectrometry, Fourier Transformed Infrared (FT-IR) spectroscopy, X-Ray diffraction analysis (XRD), Proton Nuclear Magnetic Resonance (1H-NMR) and Carbon-13 Nuclear Magnetic Resonance (13C-NMR).
The obtained acetyl salicylic acid can be used in food industry as preservative, bactericide and antiseptic. The acetylsalicylic acid can be also assimilated from natural sources, like berries, almonds and peanuts.
In large quantities, acetylsalicylic acid can cause gastric intestinal toxicity, urticarial, angioedema, rhinitis and bronchial asthma.
EXPERIMENTAL SECTION
The synthesis of acetylsalicylic acid by the classical method [30] was carried out by mixing 10 g (72.46 mmol) salicylic acid...