Route to poly

Alternative synthetic routes to poly(arylene sulfide)s have been pubHshed (79—82). The general theme explored is the oxidative polymerization of diphenyl disulfide and its substituted analogues by using molecular oxygen as the oxidant, often catalyzed by a variety of reagents ... 

The scope of Wessling route has been extended by Mullen and co-workers to develop a soluble precursor route to poly(anthrylene vinyiene)s (PAVs) [51]. It was anticipated that the energy differences between the quinoid and aromatic resonance structures would be diminished in PAV relative to PPV itself. An optical band gap of 2.12 eV was determined for 1,4-PAV 29, some 0.3 eV lower than the value observed in PPV. Interestingly, the 9, lO-b/.v-sulfonium salt does not polymerize, possibly due to stcric effects (Scheme 1-9). 

The AICI3-catalyzed polycondensation of diphenyl ether with a mixture of terephthaloyl chloride and isophthaloyl chloride is a relatively inexpensive route to poly(ether ketone)s. The polymerizations were carried out in chlorinated solvents... 

This effect has also been observed in polyphosphazenes containing alkyl- or phenyl-carborane as pendent groups.12 A typical synthetic route to poly(phenyl-carboranyl-di-trifluoroethoxy-phosphazene) having pendent phenyl-carborane groups is shown in scheme 4. A substantial improvement in the thermal stability of the polymer was observed. This is attributed to a retardation of the ring-chain de-polymerization mechanism due to steric hindrance effects of the carborane units, inhibiting helical coil formation. 

An alternative route to poly(m-carborane-siloxane) rubbers is via the condensation reaction between w-carborane di-hydrocarbyl-disilanol and a bis-ureidosilane.20 This mild reaction allows the incorporation of desired groups into the polymer via both the dihydrocarbyl-disilanol and the bis-ureidosilane (see scheme 8). The first step involves the formation of the carborane silanol from the butyl lithium carborane derivative. The bis-ureidosilane is prepared from the phenyl isocyanate (see step 2), and the final step involves reacting the dihydrocarbyl-disilanol with bis-ureidosilane. 

At AWE, the Lewis acid-catalyzed bulk polymerization route has been the main synthesis route to poly(m-carborane-siloxane) elastomers. Our selection has been based on considerations of safety, availability of key reagents, and ease of scale-up operations. An understanding of the physical and chemical properties of these materials, and how these properties can be modified through the synthesis process, is essential in order to develop materials of controlled characteristics. 

As mentioned previously, the main drawbacks of the thermal route to poly-borylborazine are (1) the presence of both direct intercyclic bonds and three-atom bridges between the rings, and (2) a difficulty in controlling the polycondensation rate. One solution we investigated to address these drawbacks is a route based on the room temperature reaction of /i-chloroborazine with trialkylaminoborane.31 32 We used 2-methylamino-4,6-dichloroborazine instead of 2,4,6-trichloroborazine to prepare a two-point polymer (scheme 4), which is theoretically less cross-linked. 

Two-step synthetic routes to poly(/i-aminoborazines) from /i-chloroborazines involve initial nucleophilic reaction of the /i-chloroborazine with appropriate linking reagents followed by a deamination reaction of the as-obtained /i-aminoborazine. The 5-tiichloroborazine undergoes nucleophilic attack by ammonia or amine derivatives on the boron atom linked to chlorine atoms. For the same reasons previously quoted a tertiary amine (e.g., Et3N) must be added to precipitate the corresponding hydrochloride. 

Poly-j3-malate is readily degraded completely to L-malic acid under both acid and base conditions [108], and it can also be hydrolyzed by enzymes within the cell [105,106]. Recently, several bacteria were isolated which were able to utilize poly-/i-malate as sole carbon source for growth [109]. Because the polymer is biodegradable and bioadsorbable, it is of considerable interest for pharmaceutical applications, especially in controlled-release drug delivery systems [97,98]. Chemical routes to poly-/ -malate are expected to provide materials with various properties [110]. 

Acetyl-CoA as a central intermediate in the metabolism of all carbon compounds can be dissimilated to generate biologically useful energy or assimilated and used for growth and multiplication. But the shortest and quickest way to store this carbon skeleton is synthesis of poly(3HB) via formation of aceto-acetyl-CoA (Fig. 1). Since the enzymes involved in the metabolic route to poly(3HB) are unspecific, the synthesis of other homopolyesters and heteropolyesters is possible. Such analogues are formed if appropriate prefabricated substrates (which merely need to be activated and incorporated) are offered. Compounds of this type are called related substrates. 

Designing Efficient Routes to Poly-functionality <2000PAC1597> - deals with benzotriazole derivatives ... 

V.P. Conticello, D.L. Gin, and R.H. Grubbs, Ring-opening metathesis polymerization of substituted bicyclo[2.2.2]octadienes a new precursor route to poly(p-phenylene vinylene), J. Am. Chem. Soc., 114 9708-9710, 1992. 

W.J. Swatos and B. Gordon, III, Polymerization of 2,2-di- -hexyloxy-a,a -dichloro-p-xylene with potassium tert-butoxide a novel route to poly(2,5-di- -hexyloxy-p-phenylene vinylene), Polym. Prepr., 31(1) 505-506, 1990. 

Scheme 3. Different routes to poly(tetrafluoro-/)-xylylene).

Ponsart S, Coudane J, Vert M (2000) A novel route to poly(e-caprolactone)-based copolymers via anionic derivatization. Biomacromolecules 1 275-281... 

Vert M (1998) Chemical routes to poly( P-malic acid) and potential applications to this water-soluble bioresorbable poly(P-hydroxy alkanoate). Polym Degrad Stab 59 169-175... 

The phosphoranimine route also allows an alternate route to poly(dichlorophosphazene) by using lV-(trimethylsilyl)-/)/)/>-trichlorophosphoranimine as the monomer. The phosphoranimine route not only efficiently produces alkyl and aryl poly(phosphazene)s but also offers... 

Condensation reactions to polyphosphazenes have been developed that provide an alternative, direct route to ffuoroalkoxyphosphazene polymers and aryl derivatives [eqns (11.31) and (11.32)]. " The development of condensation routes to poly(dichlorophosphazene) has also been reported for example, a promising route that operates at 200 °C has been described [eqn (11.33)]. ... 

Synthetic routes to poly(p-phenylene sulfide) have been reviewed by Cleary71. The route used commercially is the polycondensation of 1,4-dichlorobenzene with sodium sulfide, typically carried out in a polar organic solvent, such as JV-methyl pyrrolidone at temperatures in the range 200 to 300 °C ... 

A more convenient route to poly(p-phenylene vinylene) is via a soluble sulfonium... 

Teyssie, Ph., and G. Smets Polymers and group interactions. II. Friedel-Crafts reactions on polyvinyl chloride, a route to poly-1,3- methyleneindans. J. Polymer Sci. 20, 351 (1956). 

Figure 5.17 The ICI chemoenzymatic route to poly(phenylene) uses genetically altered Pseudomonas putida cells, which consume benzene and excrete the dihydrodiol monomer.

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