Dimethyl 2,6-naphthalenedicarboxylate

CHDA CHDM DMCD EG IPA N NDA PCT PCTA PCTG PET PETG TMCD TPA cis/trans-1,4-cyclohexanedicarboxylic acid cis/trans-1,4-cyclohexanedimethanol dimethyl cis/trans-1,4-cyclohexanedicarboxylate ethylene glycol isophthalic acid dimethyl 2,6-naphthalenedicarboxylate 2,6-naphthalenedicarboxylic acid poly(1,4-cyclohexylenedimethylene terephthalate) dibasic-acid-modified PCT copolyester glycol-modified PCT copolyester poly(ethylene terephthalate) CHDM-modified PET copolyester c .S / ra .v-2,2,4,4-tetramethyl-l,3-cyclobutancdiol terephthalic acid... 

CHDM-BASED COPOL YESTERS WITH DIMETHYL 2,6-NAPHTHALENEDICARBOXYLATE... 

Although PEN is a fifty-year-old polyester product it is only now just beginning to make a major appearance into the marketplace. It was first synthesized as a laboratory curiosity in 1948 by ICI scientists [4], Dimethyl-2,6-naphthalenedicarboxylate (NDC) is the primary starting monomer, along with glycol. The key to further development of PEN is to produce the diacid, 2,6-naphthalenedicarboxylic acid (NDA), on a commercial scale. This is a major... 

Since it is also a poly condensation polymer, the preparation of PEN from dimethyl 2,6-naphthalenedicarboxylate (NDC) is similar to the preparation of PET from dimethyl 1,4-terephthalate (DMT) by combining a diacid ester (NDC) with ethylene glycol. In view of the fact that the commercial-scale production of PEN resin starts with 2,6-NDC, the production process is similar to that used for the production of PET from DMT. There are two main steps for the process (Scheme 10.1) [11]. 

C12H12 2,6-dimethylnaphthalene 581-42-0 1.126E-H10 96.260 26987 1 C14H1204 dimethyl-2,6-naphthalenedicarboxylate 840-65-3 1.570E-I-10 126.670... 

Valence Isomerization of the 2-Thiabicyclo[3.2.0]heptadiene Moiety In principle, a valence isomerization of thiabicyclo[3.2.0]heptadiene skeleton would lead to a thiepin ring system. Wynberg et al. 23) reported that the photochemical adduct (28) from benzo[6]thiophene and dimethyl acetylenedicarboxylate was not thermally stable. When heated in diglyme, it loses sulfur to give dimethyl 1,2-naphthalenedicarboxylate. This reaction presumably proceeds via ring opening of 28 to 2,3-dimethoxycarbonylbenzo[6]thiepin (29) which readily eliminates sulfur. This synthetic route was successfully applied to the reaction of electron-deficient acetylenes with enamines of 2,3-dihydrobenzo[fe]thiophen-3-ones in which the enamine moiety constitutes part of a thiophene system. When 3-pyrrolidin-l-yl-benzo[6]thiophene (30) was allowed to react with dimethyl acetylenedicarboxylate... 

The monomer used for the preparation of PEN is dimethyl-2,6-naphthalenedicar-boxylate (NDC) or 2,6-naphthalenedicarboxylic acid (NDA). During the long development time, several synthetic methods were developed and the manufacturing processes were improved, which finally reduced the cost for the commercialization of PEN [5-10], The main synthesis routes are described in the following. 

A novel 1,8-photoaddition of dimethyl 1,4-naphthalenedicarboxylate and 1,4-dicyanonaphthalene to alkenes, a formal [3-1-2] cycloaddition, was reported by Kubo and co-workers. Although yields of the desired products were low, Cu(OAc)2 showed a profound impact on the reaction by increasing the yields considerably [85]. 

PC = polycarbonate PET = polyethylene terephthalate) PEEK = poly (aryl-ether-ether-ketone) PO = poly(oxy-1,4-pheny lene) PPS = poly (thio-l,4-phenylene) PPO = poly(oxy-2,6-dimethyl-l,4-phenylene) PEN = poly(ethylene-2,6-naphthalenedicarboxylate) PBT = poly... 

Pyridin-3-yl)-l(27/)-phthalazinone with dimethyl l-(2-bromopyridin-4-yl)-6,7-dimethoxy-2,3-naphthalenedicarboxylate gave 2-[4-(6,7-dimethoxy-2,3-dimethoxycarbonylnaphthalen-1 -yl)pyridin-2-yl] -4-(pyridin-3-y 1)-1 (2H)-... 

The reactions of simple phthalazine A -oxides with dialkyl acetylenedicarbox-ylates have been studied in detail. For example, phthalazine 2-oxide (261) with dimethyl acetylenedicarboxylate (262) gave a separable mixture of l,2-dimethoxycarbonyl-2-phthalazinioethenolate (263) (or equivalent formulation) (4%), trimethyl pyrrolo[2,l-a]phthalazine-l,2,3-tricarboxylate (264) (11%), dimethyl 2-hydroxy-1,3-naphthalenedicarboxylate (265) (24%), dimethyl l,2-dihydro-l,2-epoxynaphthalene-2,3-dicarboxylate (266) (7%),... 

A soln. of dimethyl 3,5,6,7,8,8a-hexahydro-5,5,8a-trimethyl-l,2-naphthalenedi-carboxylate in triethylene glycol dimethyl ether heated 14 hrs. at 200° dimethyl 5,6,7,8-tetrahydro-5,5-dimethyl-l,2-naphthalenedicarboxylate. Y ca. 100%. J, C. Loperfido, J. Org. Chem. 38, 399 (1973). 

---