The Synthesis Of A New Phenolic Ester Antioxidant And Its Properties

Hindered phenol, function as main antioxidants, have been extensively used in industrial and automotive lubricating oils and greases. In this research, a new phenolic ester antioxidant 143 with two hindered phenol groups was designed and synthesized. The two hindered phenol groups in the molecule provide it with good antioxidant property, and the relatively large molecular weight together with symmetric molecular structure endows the antioxidant with good thermal stability.The study includes three segments. Firstly, the antioxidant 143 was synthesized through a three steps reaction. Methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (140) is a significant intermediate to many antioxidants. Its synthetic procedure was optimized. The hydrogen bond was found from its crystal structure which might play an important role in improving property of the molecule. According to this analysis, the ester group of 140 was reduced to a hydroxyl to strengthen this hydrogen bond and the molecule 142 was subsequently obtained. To further enhance its thermal stability, the 143 was synthesized by reacting 140 with 142 through esterification. It’s a three steps reaction, the first step, the raw material 2,6-di-tert-butylphenol reacted with α, β-unsaturated compound methyl acrylate to generate the intermediate 140 in high yield (80%). The second step, the intermediate 140 was reduced into a phenolic alcohol 142 in excellent yield (97%). Then, the final product 143 was synthesized according to an esterification reaction of 140 with 142 in high yield (85%).Secondly, all of the synthesized compounds were characterized by NMR, IR, HPLC and melting point apparatus.Finally, their thermal stability and antioxidation properties were tested by TG, PDSC and RBOT. What’s more, a comparison in properties was made between 143 with another antioxidant YP017B which has been commercially available and is one of the best selling phenolic ester antioxidant.The results of the characterization indicated that the products generated from experiment are target compounds. On the aspect of property test, the TG data shows that the thermal stability of final product 143 is far better than 140,142 and YP017B, with the initial decomposition temperature of 196℃ and the complete decomposition temperature of 322℃. The data of PDSC and RBOT proved that 143 has good antioxidation property, better than YP017B and has a remarkable improvement in comparison with intermediate 140. Besides, the reduction product 142 is also a good antioxidant except for its relatively lower thermal stability, with initial decomposition temperature of 114℃ and the complete decomposition temperature of 230℃, respectively.