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Chemistry and Industry of Forest Products ›› 2016, Vol. 36 ›› Issue (6): 49-55.doi: 10.3969/j.issn.0253-2417.2016.06.008

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Synthesis and Antioxidant Acticity of Stearoyl Tannic Acid Ester Based on Hydroxyl Protection

LI Yan, AN Li-ping, GUO Yu-chen, JIN Li-e   

  1. College of Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, China
  • Received:2015-12-29 Online:2016-12-25 Published:2016-12-23

Abstract: In order to solve the high water-solubility and low oil-solubility of tannic acid(TA), stearoyl tannic acid ester (C18-TA) as a kind of natural antioxidant was synthesized from tannic acid and stearic anhydride through three steps in the present study. At first, the phenolic hydroxyl of tannic acid was partially protected by benzyl bromide, then the long chain fatty hydrocarbyl was introduced with stearic anhydride as acetylating reagent, pyridine as catalyst and N2 as shielding gas. At last, benzyl group was removed in weak acid and C18-TA was obtained. The synthetic conditions were optimized through uniform design. The chemical structure of C18-TA was characterized by FT-IR, UV and 1H NMR. The antioxidant activity was assayed by·DPPH scavenging and peroxide value (POV) of linseed oil. The results showed that the optimized conditions were the dosage of tannin 1 g, stearic acid 0.6 g, pyridine 1.5 mL, reaction temperature 80℃, and refluent time 265 min. Under the optimized conditions, the yield of C18-TA reached 87.98%. The C18-TA synthesized by hydroxyl protection owned much hydroxyl and excellent surfactivity. The antioxidant activity of C18-TA was higher than tannic acid and butylated hydroxyanisole (BHA). The·DPPH scavenging rate of C18-TA reached 91.96%-97.39% at the mass concentration of 0.05-0.25 g/L. The POVs of linseed oil increased slowly and were 3.82-17.72 mmol/kg in 0-30 d.

Key words: tannic acid, stearoyl tannic acid ester, antioxidant activity

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