Norbornene imides

To synthesize hetero-telechelic poly(norbornene imide) via sacrificial synthesis, two different sacrificial acetal monomers were employed to build the initial... 

A-Hydroxy-5-norbornene-2,3-dicarboxylic acid imide [21715-90-2] M 179.2, m 165-166", 166-169", pKesi-6 Dissolve in CHCI3, filter, evaporate and recrystallise from EtOAc. IR (nujol) 1695, 1710 and 1770 (C=0), and 3100 (OH) cm. 0-Acetyl derivative has m 113-114° (from EtOH) with IR bands at 1730, 1770 and 1815 cm only, and the 0-benzoyl derivative has m 143-144° (from propan-2-ol or C6H6). [Bauer and Miarka J Org Chem 24 1293 1959 Fujino et al. Chem Pharm Bull Jpn 22 1857 1974],... 

The earliest reported ring-opening polymerizations of functionalized norbornenes were carried out in protic solvents (alcohol, water) using iridium, ruthenium, or osmium salts. Thus, norbornenes substituted with ester (93-95), hydroxy (95), chlorine (96), alkoxy (97), and imide (93) groups have been polymerized via metathesis using noble metal catalysts. 

To improve the processability of PI and to alleviate or eliminate volatiles, work began in the late 1960 s under NASA Lewis sponsorship (23), to end-cap oligomers with reactive groups. The first report involved the use of 3,6-endomethylene-l,2,3,6-tetrahy-drophthalic anhydride (5-norbornene-2,3-dicarbo ylic anhydride, nadic anhydride) and alkyl derivatives thereof (e.g. citraconic anhydride) and 1,2,3,4-tetrahydrophthalic anhydride (4-cyclohexene-1, 2-dicarboxylic anhydride) as the reactive end group on imide oligomers (23-25). This initial effort led to the development of P13N [with T for polyimide, 13 for Mn of 1300g/mole and N for nadic end cap] whose structure is shown below. 

Analogous methyl azidoformate forms with norbornene a thermal unstable triazoline.251 The decomposition products are 40% aziridine and 55% imide. Furthermore it has been observed that the rate of nitrogen evolution of the triazoline from methyl azidoformate increases threefold when triglyme and 20-fold when dimethyl sulfoxide are substituted for 1,1-diphenylethane as solvents. This fact supports a betaine intermediate in the thermal decomposition reaction. The triazoline from 2,4-dinitrophenyl azide and norbornene could just be isolated, but from picryl azide only the aziridine was obtained.252-254 Nevertheless, the high negative value of the activation entropy (—33.4 eu) indicates a similar cyclic transition state for both reactions. 

HONB iV-Hydroxy-5-norbornene-2,3-dicarboxylic acid imide... 

SYNS BICYCLO(2.2.1)HEPTENE-2-DICARBOXYUC ACID, 2-ETHYLHEXYLIMIDE ENDOMETHYLENE-TETRAHYDROPHTHALIC ACID, N-2-ETHYLHEXYL IMIDE ENT 8,184 N-(2-ETHYLHEXYL)BICYCLO-(2,2,l)-HEPT-5-ENE-2,3-DICARBOXIMIDE N-2-ETHYLHEXYUMIDEENDOMETHYLENETETRAHYDR OPHTHALIC ACID N-(2-ETHYLHEXYL)-5-NORBORNENE-2.3-DICARBOXIMIDE 2-(2-ETHYLHEXYL)-3a.4,7,7a-TETRAHYDRO-4,7-METHANO-1H-ISOINDOLE-1,3(2H)-DIONE MGK-264 OCTACIDE 264 N-OCTYLBICYCLO-(2.2.1)-5-HEPTENE-2,3-DICARBOXEvnDE PYRODONE SYNERGIST 264 VAN DYK 264... 

Using a similar approach, through [2+3] dipolar cycloaddition reactions, the syntheses of 532 and 533 were accomplished from thiocarbonyl y-imides 531 and norbornene-3,4-dicarboxylate or /ra r-cycloctene <2000T4231>. 

The pre-polymer has a very low DP (x < 3). The norbornene-ended polyimide (norbornene-2,3-dicarboxylic imide also known as nadic imide) is further polymerized by heating it at about 300 C. The thermosetting process of norbornene-ended polyimide can be investigated by Py-GC/MS. For example, the crosslinking of norbornene-ended polyimide PMR-II, was investigated using Py-GC/MS [20] (the pre-polymer PAR-11 structure is shown below) ... 

The PMR range of resin materials utilize a two-step reaction, in which a norbornene-terminated prepolymer is formed in situ by the condensation reaction of low molecule weight diamines with norbornene-capped imides or acid esters [37]. The PMR-15 designation refers to polymerization of monomeric reactants, with a mixture of diaminodiphenylmethane and a dimethyl ester and a norbornene-containing monomethyl ester, to form a condensation prepolymer having molecular weight approximately equal to 1500. PMR resins are used as matrix materials in high performance composites in the aerospace industry. 

Wong and coworkers. [82, 83] used solution and solid-state NMR to study the cure of the norbornene end-capped poly(imide)s 2NE/DDM and PMR-15. At lower cure temperatures, exo-endo isomerization was observed to be a major product [84]. Loss of cyclopentadiene was suggested to result in initiation of the partner maleimide, as well as Diels-Alder addition of cyclopentadiene with norbornene. There was no evidence of internal double bonds formed by incorporation of the cyclopentadiene into the polymer backbone. The solid-state spectra were very poorly resolved, but did allow confirmation of the mechanism of reaction [83]. Spectra obtained at higher fields did not show improved resolution, indicating that the dominant mechanism for line-broadening in these materials is the dispersion of isotropic chemical shifts resulting from frozen conformations. In later work, Milhourat-Hammadi and coworkers [84, 85] reported solution-state and NMR studies of PMR-15 prepolymers. 

After 5 hr at 170°C, endo-N-phenyl-5-norbornene-2,3-dicarbox-imide failed to undergo isomerization and remained unchanged. Similarly, no isomerization of the exo adduct was detectible by IR analysis after 5 hr at 170 C. However, after 30 min at 260 C, the exo or endo adduct was converted to a 40/60 endo/exo equilibrium mixture, which remained unchanged after 2 hr at 260 c. 

N-(2-Ethylhexyl)-5-norbornene-2,3-dicarboximide 2-(2-Ethylhexyl-3a,4,7,7a-tetrahydro-4,7-methano-1H-isoindole-1,3(2H)-dione MGK 264 N-Octyl bicycloheptene dicarboximide N-Octylbicycio (2.2.1)-5-heptene-2,3-dicarboximide Classification Imide Empirical C17H25NO2... 

Prepolymeric imides with norbornene end groups, I, cross-link during normal polymerization, and those with acetylene end groups, II, presumably cross-link by trimerization to benzene rings ... 

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