Acyclic-diene metathesis polymerization

Figure 7.4-2 Acyclic diene metathesis polymerization (ADMET) reaction carried out in the...

Scheme 2 Different modes of the olefin metathesis reaction cross metathesis (CM), ringclosing metathesis (RCM), ring-opening metathesis (ROM), acyclic diene metathesis polymerization (ADMET), and ring-opening metathesis polymerization (ROMP)...

Brzezinska KR, Deming TJ (2001) Synthesis of ABA triblock copolymers via acyclic diene metathesis polymerization and living polymerization of alpha-amino acid-N-carboxyanhy-drides. Macromolecules 34 4348 354... 

K. Nomura, H. Morimoto, Y. Imanishi, Z. Ramhani, and Y. Geerts, Synthesis of high molecular weight rra i-poly(9,9-di- -octylfluorene-2,7-vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts, J. Polym. Sci., Part A Polym. Chem., 39 2463-2470, 2001. 

Acyclic diene metathesis polymerization (ADMET) is a related polymerization in which an unconjugated diene polymerizes with loss of ethene [Lehman and Wagener, 2002, 2003 Schwendeman et al., 2002], ADMET is carried out using the Schrock and Gmbbs initiators at about 40-80°C. The process is a step polymerization, not a ROP chain reaction. The reaction is reversible, and high polymer MW is achieved by removal of ethene (usually by reduced... 

Acyclic carbenes, with palladium isocyanides, 8, 258 Acyclic diene metathesis polymerization alkynes, 1, 191 characteristics, 1, 138 in ionic liquids, 1, 869... 

ADMET polymerization, see Acyclic diene metathesis polymerization... 

Dienes are cyclized by intramolecular metathesis. In particular, cyclic alkenes 43 and ethylene are formed by the ring-closing metathesis of the a,co-diene 46. This is the reverse reaction of ethenolysis. Alkene metathesis is reversible, and usually an equilibrium mixture of alkenes is formed. However, the metathesis of a,co-dienes 46 generates ethylene as one product, which can be removed easily from reaction mixtures to afford cyclic compounds 43 nearly quantitatively. This is a most useful reaction, because from not only five to eight membered rings, but also macrocycles can be prepared by RCM under high-dilution conditions. However, it should be noted that RCM is an intramolecular reaction and competitive with acyclic diene metathesis polymerization (ADMET), which is intermolecular to form the polymer 47. In addition, the polymer 47 may be formed by ROMP of the cyclic compounds 43. 

This intramolecular reaction results in the formation of a cyclic system, and therefore it is called ring-closing metathesis (RCM). In this process a diene 36 is treated with a metal alkylidene 37. Two competing pathways are available via the intermediate metal alkylidene 38 A) RCM will occur to afford cyclic adducts 39 and B) intermolecular reaction can occur to form polymeric structures 40 (acyclic diene metathesis polymerization (ADMET)). The reaction is also complicated because of the possibility of ring-opening metathesis (ROM), the retro reaction of path A, and ring opening metathesis polymerization (ROMP) (path C).13... 

A new acyclic diene metathesis polymerization method has been developed using 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)benzylidene mthenium(II) dichloride as catalyst. This reaction catalyst was used for preparing oligomers and polymers containing amino acids or polypeptides. 

ROMP Ring-opening metathesis polymerization ADMET Acyclic diene metathesis polymerization ALTMET Alternating diene metathesis polycondensation MCLCP Main chain liquid crystalline polymer SCLCP Side chain liquid crystalline polymer mru molecular repeating unit... 

ADMET polymerization acyclic diene metathesis polymerization CT... 

Olefin metathesis is a unique carbon skeleton redistribution in which unsaturated carbon-carbon bonds are rearranged in the presence of metal carbene complexes. With the advent of efficient catalysts, this reaction has emerged as a powerful tool for the formation of C-C bonds in chemistry [1]. Olefin metathesis can be utilized in five types of reactions ring-closing metathesis (RCM), ring-opening metathesis (ROM), respective ringopening metathesis polymerization (ROMP), cross-metathesis (CM), and acyclic diene metathesis polymerization (ADMET). 

Fig. 14 Acyclic diene metathesis polymerization of 9 to give polymer 10.

Olefin metathesis (OM) has proven to be one of the most important advances in catalysis in recent years based on the application of this chemistry to the synthesis of polymers and biologically relevant molecules [1-10]. This unique transformation promotes chain and condensation polymerizations, namely ring opening metathesis polymerization and acyclic diene metathesis polymerization (ADMET). Applications of metathesis polymerization span many aspects of materials synthesis from cell-adhesion materials [11] to the synthesis of linear polyethylene with precisely spaced branches [12]. 

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