Abstract
Objective:Cinnamic acid and its derivatives have a numerous potential applications in many different fields such as pharmacy, organic “building blocks”, and corrosion inhibitors.Method:It is well-known that Verley-Doebner modification is a high efficient method for the preparation of cinnamic acid derivaties, especially with the compounds containing electron-donating subtituents at para position in aromatic ring. In this paper, 4-ethoxy-cinnamic acid was synthesized according to Verley-Doebner reaction with the use of pyrine acting as catalyst and solvent. The effect of the β-alanine concentration on the conversion of the starting material of 4-ethoxy-benzaldehyde was thoroughly investigated using high performance liquid chromatography. The results showed that consuming of 8% of β-alanine would convert 100% of 4-ethoxy-benzaldehyde to 4-ethoxy-cinnamic acid.Result:The structure of the obtained 4-ethoxy-cinnamic acid was also confirmed using Fourier transform infrared spectroscopy, Raman spectroscopy, and Gas chromatography-Mass spectroscopy.Cinnamic acid and its derivatives have numerous potential applications in many different fields such as pharmacy, organic “building blocks”, and corrosion inhibitors. It is well-known that Verley-Doebner modification is a high efficient method for the preparation of cinnamic acid derivaties, especially with the compounds containing electron-donating subtituents at para position in aromatic ring. In this paper, 4-ethoxy-cinnamic acid was synthesized according to Verley-Doebner reaction with the use of pyrine acting as catalyst and solvent. The effect of the β-alanine concentration on the conversion of the starting material of 4-ethoxy-benzaldehyde was thoroughly investigated using high performance liquid chromatography. The results showed that consuming 8% of β-alanine would convert 100% of 4-ethoxy-benzaldehyde to 4-ethoxy-cinnamic acid. The structure of the obtained 4-ethoxy-cinnamic acid was also confirmed using Fourier transform infrared spectroscopy, Raman spectroscopy, and Gas chromatography-Mass spectroscopy.
Highlights
Cinnamic acid is an anti-bacteria and anti-mould organic compound which has been widely used in cosmetic and food industries
Different types of catalysts including acidic and basic catalysts were used in this approach, which showed a prospective potential for the synthesis of many types of cinnamic acid derivaties, especially compounds with the electron-donating subtituents at para position in the aromatic ring
The peaks at 1.87 min and 2.39 min correspond to the desired product of 4-ethoxy-cinnamic acid and the reactant of 4ethoxy-benzadehyde, respectively
Summary
Cinnamic acid is an anti-bacteria and anti-mould organic compound which has been widely used in cosmetic and food industries. In order to obtain a rather good conversion of benzadehyde, long reaction time (8 h) and high temperature (180 °C) should be applied [16] This reaction is unsuitable for the synthesis of cinnamic acid derivatives with electron-donating substituents in the aromatic ring. In order to obtain relatively good yields of cinnamic acid derivaties with electron-donating subtituents at the para position in the aromatic ring, many literatures have focused on the Knoevenagel modification using malonate ester, malonic acid or acetic acid insteads of malonic anhydride [17,18,19,20,21,22,23,24]. With the proposed experiment procedure, the yield of 4-ethoxy-cinnamic acid was high (>98.2%) with the short reaction time
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