The synthesis and characterisation of poly( 14-cyclopentenylene-5,6-ethylidene-2,3-disodium dicarboxy1ate)s and Pendant functional group isomerisation

Monomer sequencing and microstructural analysis on polymers of dimethyl norbornene dicarboxylate and 7‐oxanorbornene dicarboxylic derivatives employing ruthenium catalysts by ring‐opening metathesis polymerization

“…Specifically, one M1 ‐repeat unit can contain a cis ‐double bond on one‐side and a trans ‐double bond on the other side within the same monomer molecule. This finding is unique as a number of earlier studies inferred that blocks of cis and/or blocks of trans double bonds form with ROMP initiators . In particular, the results indicate polyM1‐I2 contain 60% cis ‐ and 40% trans ‐olefinic proton signals.…”

“…Two‐dimensional proton correlation spectroscopy (2D‐proton COSY) was measured in the absolute value mode, and two‐dimensional phase‐sensitive proton Nuclear Overhauser Effect spectroscopy (2D‐proton NOESY) as supplied in the VNMRJ software, using either 200, 300, or 400 ms mixing times were used. Carbon and proton chemical shift assignments were made by comparison to the literature values, and confirmed by 2D‐13C‐1H‐Heterocorrelation, 2D‐1H‐1H‐COSY, and 2D‐1H‐1H‐NOESY experiments. Monomer sequencing was obtained from 2D‐13C‐1H‐HSQC‐TOCSY experiments utilizing 30–80 ms spin‐lock mixing times using a Clean‐MLEV‐17 pulse‐sequence.…”

“…Detailed studies into the tacticity of ROMP polymers were first pioneered by Ivin and Rooney using chiral monomers such as 5‐ or 7‐methyl‐substituted norbornenes to probe the microstructure of the polymer's backbone. However, this approach also incorporated an additional complexity of head‐to‐tail (HT), head‐to‐head (HH), and tail‐to‐tail (TT) arrangements owing to the asymmetrically substituted norbornene in the carbon NMR spectra …”

“…With respect to tacticity studies, there has been a growing number of reports in the literature stating that cis‐ double bonds are predominantly syndiotactic, whereas trans‐ double bonds are primarily isotactic when using Ruthenium initiators . This conclusion has been invoked by stereo‐electronic, steric, and thermodynamic data, Furthermore, it has been generally stated that the exo ‐face is solely attributable for polymerization to occur owing to its higher reactivity observed empirically than its endo ‐counterpart . In addition, when a highly cis or highly trans polymers are produced, then a highly tactic polymer is also produced .…”

“…Dicyclopentadiene (Fisher), maleic anhydride (Aldrich), sodium hydroxide (Aldrich), furan (Aldrich), d 4 ‐furan (Aldrich), Grubbs ruthenium initiators I1 (benzylidene‐ bis (tricyclohexylphosphine)‐dichlororuthenium, Aldrich), I2 (benzylidene[1,3‐ bis (2,4,6‐trimethylphenyl)‐2‐imidazolidinylidene] dichloro(tricyclohexylphosphine) ruthenium, Aldrich), and Umicore initiator I3 (dichloro‐(3‐phenyl‐1H‐inden‐1‐ylidene) bis (tricyclohexylphosphine) ruthenium(II), Strem Chemicals) were used as provided. Exo ‐7‐oxanorbornene‐5, 6 ‐dicarboxylic anhydride M1 , endo,exo ‐norbornene‐5,6‐dimethyl ester M2 , exo,exo −7‐oxanorbornene‐5,6‐dimethyl ester M3 , and endo,exo −7‐oxanorbornene‐5,6‐dimethyl ester M4 38 were synthesized according to the literature procedures. More detailed experimental procedures are provided in Supporting Information material: Synthesis.…”