Monomer preparation procedure

Example Procedure for Preparation of Halo-Terminated Intermediate Monomer/Oligomer Mixtures... 

A spontaneous polymerization of glucose methacrylate, however, is observed during the monomer preparation without gel formation and a very hydrophilic water soluble polymer with high viscosity is obtained by precipitation in acetone. This procedure requires further improvement. 

Our standard procedure in preparative experiments of isotactic polymer is that used in earlier work, where the temperature during initiation was carefully controlled. We initiated the polymerization by mixing initiator solution and monomer solution already thermostatted to a predetermined temperature, usually that chosen for the polymerization. At 230 with t-BuMgBr in THF-toluene mixtures this led to a trimodal distribution with the high molar-mass peak in the 106 range (l.,2). More recent work, shown in Figure 2, has confirmed that trimodal distributions arise when the mol fraction of THF is below ca 0.3. 

Craft Copolymers with Low Backbone-Polymer Content. The procedure for preparing this kind of graft copolymer is based on the dissolution of the backbone polymer in the monomer, dispersion of this solution in water, and polymerization by means of an organic peroxide. It applies only to soluble backbone polymers, such as most EPR s. As the handling of a too-viscous vinyl chloride/backbone polymer solution is impractical, this procedure is normally used for preparing end products of the type VC/backbone polymer (95-5) or (90-10). 

Phenolic resins contain oUgomeric and polymeric chains as well as monomeric methylol-phenols, free formaldehyde, and unreacted phenol. The contents of both monomers have to be minimized by the proper preparation procedure. Various preparation procedures are described in the Kterature and in patents [108-117],... 

The following procedure to prepare the specific poly(l,4-a-D-ghicane) -which we will call as neoamylose in the present paper - is described in a batch reactor 20 % by weight of sucrose was dissolved in sodium citrate buffer at pH 6.5. The temperature was set to 37 C and the reaction was started by adding 20 ST units/ml of amylosucrase to the sucrose solution under stirring at 200 rpm. The duration of the reaction was 72 hours. The reaction yields a crystalline precipitate and fructose monomer. 

Chemical coupling via silanization reactions of electroactive silanes to electrode surfaces is a useful procedure for preparing monolayer coatings/" This principle has been extended to the preparation of polymeric films by using bis-tri-alkoxysilylated monomer derivatives of viologen and cobaltocenium that can couple to the electrode surface and form polymeric films by subsequent cross-linking. 

The absence of control of the incorporation of monomers into the polymeric chain implies that many macroscopic properties carmot be influenced to a large extent. Therefore, much effort has been directed toward the development of controlled radical polymerization (CRP) methods for the preparation of various copolymers (for a review, see Reference 31). CRPs offer the possibility of producing polymers with relatively well-defined properties, while at the same time maintaining the simplicity of radical processes.These methods are based on the idea of establishing equilibrium between the active and dormant species in solution phase. In particular, the methods include three major techniques called stable free-radical polymerization, degenerative chain transfer technique, and atom transfer radical polymerization, pioneered by Ando et and Matyjaszewski et Although such syntheses pose significant technical problems, these difficulties have all been successively overcome in the past few years. Nevertheless, the procedure of preparation of the resultant copolymers with controlled monomer sequence distribution remains somewhat complicated. 

The procedure for preparing fibrillar/microporous polypyrrole membranes is illustrated schematically in Figure 2.. The membrane-coated convex Pt disk working electrode (Figure 3) is immersed into a solution containing the monomer (pyrrole), which is electropolymerized as described above. Ideally (see below) polypyrrole is only synthesized in the pores of the host membrane a Nuclepore/polypyrrole conductive composite membrane is obtained (Figure 2). Polymerization was terminated before the conductive polymer fibrils reached the Nuclepore/solution interface. 

With the specific objective here being the preparation of redox-active films of ferrocene covalently bonded to polypyrrole, the first task is to attach the ferrocene moiety to either the 3-alkyl or the 1 -alkyl of pyrrole and the second task is to copolymerize the ferrocene derivatized pyrrole (Fc-P) with pyrrole. The synthesis of a typical ferrocene-3-alkyIpyrrole monomer is described elsewhere [151] and Merz and co-workers [152] give a procedure for preparing A -(4-ferrocenyl-butyl)pyrrole (PFc04). 

The final step is termination of chain growth mostly by radical transfer reaction to monomer [306], whereas combination or disproportionation are observed only to a small extent. The monomer radical is able to start a new chain. The most widely used procedures for preparation of commercially PVC resins are, in order of their importance, suspension, emulsion, bulk, and solution polymerization. A common feature of the first three methods is that PVC precipitates in liquid VC at conversions below 1%. The free polymerization of VC in a precipitating medium exhibits an accelerating rate from the beginning of reaction up to high conversion [307]. This behavior is called autoacceleration and is typical for heterogeneous polymerization of halogenated vinyls and acrylonitrile [308]. 

Whatever route of monomer preparation has been used purification processes are then necessary and these are usually the dominant element in the cost of butadiene production. Such purification is usually achieved by an extractive distillation procedure using such chemicals as cuprous ammonium acetate, furfural, acetonitrile, N-methyl pyrrolidone and dimethyl formamide. 

Work is proceeding to spin fibers with properties exceeding the values given in Table 9.3 for early experimental samples of the new [42] fiber. Details on convenient laboratory scale procedures to prepare the monomers and the polymer have been published [34], alternative routes intended for scaling up were worked out as well [21,25,30]. 

It is however much more difficult to prepare the cyclic monomer. The general procedures for preparing cyclic disulfides involves depolymerizing high molecular weight polymers [115-118], treatment of organic thiosulfate with cupric salts followed by steam distillation [119], reaction of the dibromide with an alcoholic solution of sodium disulfide [120] and oxidation of dithiols [121,122]. Polymeric species are also formed in the oxidative reaction [123]. Hence precautions must be taken to prevent polymerization during the synthesis. 

Ari DIDC Monomers Preparation and Properties. The general procedure is detailed for 2,6 TDA-DIDC. The following components were placed in a 500 ml 3-neck round bottom flask equipped with N2 purge, mechanical stirrer and a dean-stark trap TMA (25.0556 g 0.13 moles) DMF (75 ml). The mixture was heated to 60°C for 1 hour to dissolve the TMA. Then 2,6TDA (7.941 Ig 0.065M), DMF (25 ml) and mXylene (20 ml) were added to the reaction mixture and the dean-stark trap was filled with mXylene. The temperature was raised to 190°C and water (2.5-3.0 ml)... 

Prepare allyl ethyl carbonate, required for the allylation reactions, according to the detailed published procedure (75 Prepare the condensing agent 5-(4-nitrophenyl)-lH-tetrazole as previously described (75). Synthesize 3, 5 -0-(tetraisopropyldisiloxane-1,3-diyl)-6-(2,6-dichlorophe-noxy)purine riboside and 3, 5 -0-(tetraisopropyldisiloxane-l,3-diyl)-2-chloro-6-(2,6-dichlorophenoxy)purine riboside, required as starting materials for the synthesis of the 2 -0-allyl A and G monomers, respectively, according to the detailed published procedures (15). 

Nemoto et al. [371] describe a procedure for preparation of fibers of another Kevlar composite, P(Py)/Kevlar, but using the classic sorbed-monomer route. In their method, fibers are wet-spun firom Kevlar/pyrrole solution in DMSO into an aqueous FeClj coagulating bath, which serves as the oxidant-cum-dopant as well. Conductivities as high as 10 S/cm are claimed for the fiber, but no mechanical data are given. 

A considerable effort goes into improving the procedures for preparing controlled methacrylates both in terms of utilising new monomers and in terms of obtaining higher molar mass. A number of studies were concerned... 

Several oxygen- and sulfur-substituted boranes have been reported (125—130). 1,3,2-Benzodioxaborole [274-07-7] (catecholborane, CB) (15) is the one best studied. It is commercially available or can be prepared by the reaction of catechol with borane-THF (57,131), or by other procedures (132). The product is a Hquid existing as a monomer, remarkably stable to disproportionation. No... 

Condensation ofDianhydrides with Diamines. The preparation of polyetherknides by the reaction of a diamine with a dianhydride has advantages over nitro-displacement polymerization sodium nitrite is not a by-product and thus does not have to be removed from the polymer, and a dipolar aprotic solvent is not required, which makes solvent-free melt polymerization a possibiUty. Aromatic dianhydride monomers (8) can be prepared from A/-substituted rutrophthalimides by a three-step sequence that utilizes the nitro-displacement reaction in the first step, followed by hydrolysis and then ring closure. For the 4-nitro compounds, the procedure is as follows. 

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