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Synthesis Of 2,6-Naphthalenedicarboxylic Acid And Preparation Of New Aromatic Polyamides Containing Phthalazinone

Posted on:2007-03-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:P WangFull Text:PDF
GTID:1101360182960793Subject:Materials science
Abstract/Summary:PDF Full Text Request
2,6-Naphthalenedicarboxylic acid(2,6-NDA) is an important monomer for making high-quality polymers, and also could be used as an intermediate in the field of dye, fluorescent brightening agents. It has been commercialized in some developed countries such as American and Japan, but only a little research has been done in China, and up to date, no appropriate technology route is available for synthesis of 2,6-NDA in large scale.In the first part of this paper, 2-methyl 6-propionylnaphthalene(2,6-MPN) was synthesized in homogeneous liquid phase system from 2-methyl naphthalene(2-MN) with nitrobenzene as solvent and aluminum trichloride(AlCl3) as catalyst. The main factors of acylation were discussed with propionic anhydride and propionyl chloride as the acylating agents. The propionyl chloride was found to be the appropriate acylating agent in terms of the cost. The obtained best conditions are as follows: The better dropwise method is for adding the solution of the propionic chloride, AlCl3 and nitrobenzene to the nitrobenzene solution containing 2-MN, and n(2-MN):n(propionyl chloride):n(AlCl3) is 1:1.4:1.7 in mole; the acylation was conducted at 20℃ for 5h. The molar yield of the 2,6-MPN under the conditions mentioned above could reach up to 93% with a purity of 90% by GC. The crude 2,6-MPN was purified by recrystallization with the aqueous solution of 90% methanol. The yield and purity of recrystallized product was 85% and 89 wt%. The purified product was studied by FT-IR, ~1H NMR, two-dimensional NMR, MS, etc.Secondly, a self-designed setup was used for oxidizing 2,6-MPN to 2,6-NDA by liquid-phase catalytic oxidation, in which the involved mechanism is found to be that the propionyl group in naphthalene ring is firstly oxidized to carboxyl group, then the methyl group is oxidized in the presence of a mixed solvent containing cobalt, manganese and bromine and the acetic acid.At the same time, the optimum oxidizing conditions by particular experiments were obtained with the better co-catalyst 1,1,2,2-tetrabromoethane at flowing air of 3 L min~-1, m(HAc):m(2,6-MPN)=15:l, reaction temperature, 210℃; reaction pressure, 2.2MPa; reaction time, 30 min. The yield and purity of the oxidation was 91.7% and 97.6% withm(Co):m(Mn):m(Br):m(HAc) = 0.1%:0.2%:0.5%:l. The structure of 2,6-NDA was characterized by FT-IR, MS and *H NMR.The applications of 2,6-NDA in preparation of new aromatic polyamides were also studied. Two new aromatic diamines, 2-(4-aminophenyl)-4-[2-methyl-4-(4-amino-phenoxy) phenyl]-2,3-phthalazin-l-one(MM-DA),2-(4-aminophenyl)-4-[3-methoxy-4-(4-amino-phenoxy)phenyl]-2,3-phthalazin-l-one(OO-DA) were synthesized and characterized by FT-IR and *H NMR etc.Two series of new aromatic polyamides from OO-DA and MM-DA were synthesized with three different aromatic diacids using Yamazaki phthosphorylation method and their structures were also confirmed by FT-IR and *H NMR etc. All the polyamides exhibited good thermostability and mechanical properties and showed good solubility in polar solvents such as NMP, DMAc, Py etc. and could be solution-cast into strong and tough films.New copolyamides with higher inherent viscositiy were prepared from MM-DA and mixed dicarboxylic acids of NDA/Terephthalic acid (TPA) or NDA/4,4'-Oxybis(benzoic acid) (OBBA). New copolyamides have good solubility, thermostability and mechanical performance, which is of potential as low cost resins with high performance.Other new copolyamides were also prepared from 2,6-NDA and mixed diamines of MM-DA/p-Phenylenediamine(PPD) or MM-DA/4,4'- Diaminodiphenyl ether (DAPE). The solubility of copolyamides was determined by the content of MM-DA, which obviously increased with the increasing of the MM-DA content. The thermal properties of copolyamides are excellent, which leads one to believe that the twisted and noncoplanar phthalazinone units in backbone play a key role in improving the solubility and at the same time, keeping good thermostability of aromatic copolyamides remained unchanged.
Keywords/Search Tags:2,6-naphthalenedicarboxylic acid, liquid-phase catalytic oxidation, phthalazinone, aromatic polyamides, solubility
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