Ring-opening metathesis polymerization described

The living character of the ring opening metathesis polymerization described earlier in this review enables a simple preparation of functionalized norbornene-based monoliths. Adding one more in situ derivatization step that involves functional norborn-2-ene and 7-oxanorborn-2-ene monomers that react with the surface-bound initiator, the pores were provided with a number of typical functional groups such as carboxylic acid, tertiary amine, and cyclodextrin [58,59]. 

Aqueous ring-opening metathesis polymerization (ROMP) was first described in 1989 (90) and it has been appHed to maleic anhydride (91). Furan [110-00-9] reacts in a Diels-Alder reaction with maleic anhydride to give exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3—dicarboxylate anhydride [6118-51 -0] (24). The condensed product is treated with a soluble mthenium(Ill) [7440-18-8] catalyst in water to give upon acidification the polymer (25). Several apphcations for this new copolymer have been suggested (91). 

In this chapter I will cover only well-defined or well-characterized compounds. Results will be included that have appeared since reviews in 1991 on alkylidene and metalacyclobutane complexes [41] and in 1993 on ring-opening metathesis polymerization [30], but an overview of prior results that are especially relevant to olefin metathesis in particular will also be included. (An excellent and comprehensive text also has been published recently [1].) The terms well-defined or well-characterized originally were meant to imply that the alkylidene complex is isolable and is essentially identical to that in a catalytic reaction except for the identity of the alkylidene. These terms have been watered down from time to time in the literature, even to the point where they are used to describe a catalyst that is formed from a well-characterized transition metal precursor complex, but whose identity actually is not known. In this article I... 

Efforts towards the synthesis of strained polycyclic hydrocarbons have been described. These compounds are of interest as fuels and fuel additives for advancedpropulsion. Chemistry has been devised for the attachment of azido functionality to the strained hydrocarbon nucleus. Highly unsaturated substituted cubanes have been synthesized. Ring-opening metathesis polymerization of basketene and 2,3-diazabicyclo[2.2.1]hept-2-ene has been studied. 

Basically, COCs can be manufactured by ring opening metathesis polymerization (ROMP) as described in the chapter about metathesis polymers. However, ROMP offers disadvantages as main chain double bonds must be hydrated after polymerization. Therefore, COCs are more conveniently straightforwardly prepared by addition polymerization. 

There are a limited number of photochromic polymers as a result of the relatively harsh methods used to prepare them. A mild method for preparing these materials using ring-opening metathesis polymerization at ambient temperature is described. 

Enholm [13] has also described the synthesis of soluble designer supports by the ring-opening metathesis polymerization (ROMP) of norbornyl derivatives. Reduction of norbornene-l-carboxaldehyde 88 to the corresponding alcohol 89, followed by treatment with either 2-bromopropionic acid or 2-bromo-2-phenylacetic acid in the presence of DCC, provided the esters 90 or 91 respectively (Scheme 19). Polymerization of 90 and 91 was carried out with Grubbs catalyst and halted after 25 s by capping with excess ethyl vinyl ether to give polymers 92 and 93 respectively. 

Water-soluble polymers have been obtained via C-C couplings in biphasic reactions by means of Pd/TPPMS catalysts (see Section 3.3.10.1 [166]). These reactions include aqueous ring-opening metathesis polymerizations (ROMPs eq. (8) [167, 258]) as described by Novak and Grubbs [168], and other oligo-or polymerizations [188, 191] Section 2.3.3). 

Grubbs and co-workers reported the ring-opening metathesis polymerization (ROMP) of norbornene derivatives in water using Ru(H20)6(ts)2 as the catalyst [127, 128]. More recently, these authors have described the first example of a homogeneous living polymerization in water using a water-soluble ruthenium carbene [Eq. (24)] [129]. 

A third example of a polymeric ligand with pH-sensitive solubility is 97. This ligand was prepared by ring-opening metathesis polymerization of the 1,4,7-triazacyclononane-containing monomer 96 by the chemistry shown in Eq. 40 [132]. This polymer was capable of forming Mn(IV) complexes that oxidize alkenes and cycloalkanes with hydrogen peroxide. This basic polymer s solubility is affected by pH, as is the case with the other polymers 93 and 95 described above. 

Several acronyms are used to describe these polymerizations Reversible Addition-Fragmentation Transfer (RAFT), Group transfer polymerization, Ring Opening Metathesis Polymerization (ROMP), Group Transfer polymerization. 

In 1991 we introduced olefin metathesis as a tool for direct synthesis of PV polymers and copolymers [2]. In general, two ways exist for a metathesis chain growth process ring opening metathesis polymerization of a cyclic olefin (ROMP) and metathesis polycondensation of an acyclic diene (ADMET). We have tested both possibilities (s. Eqs. 1 2) [2-5]. A stable, tungsten based Schrock-type alkylidene complex W(=NPh - ) (=CHPh"- ) [OCMe(CF3)2l2 (THF) (described by Grubbs et al [6]) served as catalyst (Scheme 1). 

If reaction had proceeded in the same manner as Ziegler-Natta polymerization of ethylene and substituted ethylenes (Section 29.6B), a 1,2-addition polymer would have been formed. What is formed, however, is an unsaturated polymer in which the number of double bonds in the polymer is the same as that in the monomers polymerized. This process is called ring-opening metathesis polymerization, or ROMP, after the olefin metathesis involving reaction of acyclic alkenes and nucleophilic carbene catalysts described in Section 24.6. 

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