Monoliths ROMP-derived

Monolithic ROMP-derived columns for size-exclusion chromatography ... 

Scheme 16 In situ functionalization of a ROMP-derived monolith...

Table 2 Functional monomers used for in situ grafting of ROMP-derived monoliths...

Scheme 17 Immobilization of a NHC precursor on a ROMP-derived monolith via in situ grafting...

Scheme 18 Immobilization of a metathesis catalyst on a ROMP-derived monolithic support...

Figure 7.11 ROMP-derived monolith based on tris(methyl carboxylate)ethane (a) containing PONBE and PNBE, and (b) containing PONBE and poly(cyclooctene) (PCC ). (c) Neo-glycopolymer synthesized via tandem ROMP-hydrogenation.

Scheme 11.9 Loading of the ROMP-derived monolithic supports with Pt-based nanoparticles for continuous hydrosilylation reactions.

Figure 13 Structural variations in ROMP-derived monoliths.

Despite the high mechanical and thermal stability of these stmctures, which are by far sufSdent for short- and medium-term analytical applications as wdl as applications in heterogeneous catalysis, " tert-allylic carbons located at the surface of a monolithic stmcture tend to be oxidized, resulting in a slow change of surface polarity of such monolithic columns. Consequently, the typical long-term stability of NBE-based, ROMP-derived columns is limited to less than 1000 injections. To solve this problem, a novel monomer/ cross-linker system had to be introduced. For these purposes, Buchmeiser et al. devdoped a polymerization system based on... 

Some important differences between COE- and NBE-based, ROMP-derived monolithic supports were identified and need to be outlined. Figures 15(a) and 15(b) illustrate the different structure of an NBE- and COE-based ROMP-derived monolith using the same amounts of monomers, cross-linkers, and poro-gens. Figure 15(c) illustrates the fast separation (<150 s) of a mix of proteins, that is, ribonuclease A, lysozyme, insulin. 

Figure 16 IP-RP-HPLC separation of an oligodeoxynucleotide (dT)i2-is on a ROMP-derived NBE-based monolith (3 x 60 mm). Mobile phase 100 mmol f triethylammonium acetate at pH 7.0 linear gradient, 11-16% acetonitrile in 10min flow rate, 2mlmin 7"=20 C detection, UV 264 nm sample (dT)i2-i8, 0.1 pg of each oligodeoxynucleotide.

Miniaturized systems ROMP-derived monolithic capillary columns ... 

Contributing to ongoing efforts toward the miniaturization of analytical devices and to develop systems applicable to the coupling to highly sensitive quantification methods such as mass spectroscopy, Buchmeiser et al. reported on an extension of the concept of ROMP-derived monolithic supports to the synthesis of capillary columns. Transferring the synthetic concepts, methods, and procedures elaborated for semipreparative scale separations to 0.2 mm i.d. capillaries, high resolution was achieved in the separation of the oligodeoxynucleotides (dT)i2-i8 (2.27 [Pg.619]

It is worth mentioning that the TONs obtained with these two supported versions exceeded all published data on TONs of supported well-defined metathesis catalysts at that time. Equally important, the contamination of the products with mthenium was (at that time) unprecedented low, that is, 1.8 ppm. The same group also reported on an extension of this work by immobilizing 1,3-dimesityltetrahydropyrimidin-2-ylidene-based on ROMP-derived monolithic supports. 

Scheme 33 Synthesis of ROMP-derived monolithic membranes (left) and monolithic membrane after I2 extraction. Buchmeiser, M. R. J. Sep. Sci. 2008, 31,1921. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission.

Scheme 34 Synthesis of 7-oxanorborn-2-ene-based, ROMP-derived monoliths.

Another group active in this field of research is led by Michael Buchmeiser, who has reported NHC-supported, catalyst systems anchored to both monolithic polymer and silica supports. The first example from this group involved the preparation of the norbornene-functionalized NHC salt 13, and the subsequent tethering of this molecule to a Runorbornene-derived monolithic material (14 Scheme 5.1) using ROMP [25]. The free carbene was then generated on the support and treated... 

However, the acrylate-derived supports that were post-grafted with ROMP-based monomers functioned more efficiently with higher TONs in Suzuki couplings than with purely ROMP-based monoliths [71]. 

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