Preparation Of Intermediates For Monomers Used For Auxetic Linear Aromatic Polyamides

Auxetic material is a special kind of functional material developed in the lastdecade. It can exhibit negative Poisson’s ratio effect, i.e., it will expand in the lateraldirection when stretched longitudinally and become thinner when compressed. Thereare some shortcomings for those man-made auxetic materials processed by specialtreatments on commodity materials, such as high porous, low modulus and lowstrength. Solutions for these problems need to design and synthesize materials withauxeticity at the molecular level.Researches on auxetic material at the molecular level are mostly based upon thedesign of networks with special geometry and arrangement. Our previous work showsthat the inverted honeycomb-like structures of hydrogen bonding self-assembledlinear aromatic polyamide can acquire negative Poisson’s ratio. Yet their preparationneeds to synthesize new monomers. The main goal in this paper is to synthesize a newcompound,4’’’-ethoxycarbonyl-quaterphenyl-2,6-dicarboxylic acid, whose synthesis isvital for these monomers.Three routes were designed in order to synthesize the target compound and onewas chosen as the focus after being carefully compared. In this route terphenyl wasused as the starting compound. Through series of reaction (Acylation, Oxidation,Esterification and Bromination) ethyl4’’-bromo-terphenyl-4-carboxylate wassuccessfully prepared. Then it reacted with2-bromoisophthalic acid. So series ofintermediates were prepared during this route, including4-acetyl-terphenyl,4-carboxy-terphenyl, ethyl-terphenyl-4-carboxylate, ethyl4’’-bromo-terphenyl-4-carboxylate,2-bromoisophthalic acid and4’’’-ethoxycarbonyl-quaterphenyl-2,6-dicarboxylic acid. The reaction yield is74.6%,82.4%,77.3%,59%,88.7%and28.7%, respectively. By melting test, infraredspectrum, high performance liquid chromatography, nuclear magnetic resonance, thinlayer chromatography and other methods, each product has been characterized and confirmed. Also the detailed discussion of each reaction conditions has beenaccomplished, especially on improving and optimizing theethyl-terphenyl-4-carboxylate,2-bromoisophthalic acid and4’’’-ethoxycarbonyl-quaterphenyl-2,6-dicarboxylic acid’s steps, and their yield andpurity can be improved effectively. Besides, some proposals on how to improve thereaction conditions of synthesis of4’’’-ethoxycarbonyl-quaterphenyl-2,6-dicarboxylicacid was forwarded.