Condensation polymerization possible products

Polyester polyols (Scheme 4.4) are prepared by condensation polymerization of dicarboxylic acids and diols. An excess of diol ensures OH functional product, minimizing die possibility of residual acid groups which react with isocyanates to generate C02 and act as inhibitors in catalyzed urethane reactions. The reactants are heated at 200-230°C under vacuum to remove the water by-product and drive the reaction to completion. The most common coreactants include adipic... 

There are innumerable industrially significant reactions that involve the formation of a stable intermediate product that is capable of subsequent reaction to form yet another stable product. These include condensation polymerization reactions, partial oxidation reactions, and reactions in which it is possible to effect multiple substitutions of a particular functional group on the parent species. If an intermediate is the desired product, commercial reactors should be designed to optimize the production of this species. This section is devoted to a discussion of this and related topics for reaction systems in which the reactions may be considered as sequential or consecutive in character. 

In addition, isosorbide and other l,4 3,6-dianhydrohexitols (isomannide derived from D-mannose, isoidide derived from L-fructose) are also attractive to serve as monomers for polymer production due to their rigidity, chirality, and non-toxicity (Fig. 6). Such features may introduce special properties into the polymers formed, such as enhanced Jg and/or special optical properties. Their innocuous nature also opens the possibility of applications in packaging or medical devices. As a bifunctional monomer, isosorbide can be polymerized with other bifunctional monomers via condensation polymerization. A recent review described various isosorbide-based polymers synthesized, including polyesters, polyamides, poly(ester amide)s, poly(ester imide)s, polycarbonates, polyurethanes, and so on [308], and the present... 

There are also indications that coal may be a system of peri-condensed polymeric structures in contrast to the suggestion of coal being predominantly kata-condensed. The occurrence of anthracene in the thermal products of coal processing has, on many occasions, been cited as evidence for the predominantly condensed nature of the aromatic systems in coal. Be that as it may, and there is some degree of truth to this supposition, there is also the distinct possibility that such anthracene systems in the thermal products are, to a degree, thermal artifacts that are formed by various dehyrocyclization reactions. 

Further condensation reactions of keto imides and keto amides may yield to many possible products oxypyridone, isocianate, uracil, malonamide, ketones, and so on. A scheme of the most probable side reactions in the anionic polymerization of lactams with a methylene group next to the carbonyl is given in Figure 5, ta ken from a comprehensive review of Sebenda (38). As already men- tioned, a complete and detailed kinetic scheme for the anionic polymerization of lactams cannot disregard the complex role of si de reactions, which contribute also to the formation of additional growth centers. For these reasons, only simplified kinetic equations with very limited validity have been proposed so far (J3). 

If the equilibrium constant K has a value between 1 and 10, less than a thousandth of the total amount of water formed in the reaction mixture is sufficient to prevent the formation of really high-molecular-weight condensation polymers. Hence it follows that it is extremely important to remove as completely as possible the low-molecular-weight reaction products, for example, water, eliminated during a polycondensation. In principle, these equilibriums are also known in stepwise addition polymerizations (polyaddition) like the back-reactions of urethane groups. Since they mostly occur at higher temperatures only, they can be neglected. 

Electrolytic polymerization or electrolytically initiated polymerization, or shortly electro-initiated polymerization or electropolymerization, generally means initiation by the electron transfer processes which occur at the electrodes of an electrolytic cell containing monomer and electrolyte, in that by controlling the electrolysis current it is possible to control the generation of initiating species. Under appropriate conditions it may proceed by a free radical, anionic or cationic mechanism. In addition to the electrolytic addition polymerization, production of polymers through condensation reaction by electrolytic means should also be covered. Examples of each of these propagation mechanisms have now been reported in the literature. 

Condensation of Dianhydrides with Diamines. The preparation of polyetherimides 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 possibility. Aromatic dianhydride monomers (8) can be prepared from IV-substituted nitrophthalimides 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. 

The qualities of the styrene product and toluene by-product depend primarily on three factors the impurities in the ethylbenzene feed-stock, the catalyst used, and the design and operation of the dehydrogenation and distillation units. Other than benzene and toluene, the presence of which is usually inconsequential, possible impurities in ethylbenzene are Cj-Cm nonaromatics and C Cm aromatics. The condensed reactor effluent is separated in the settling drum into vent gas (mostly hydrogen), process water, and organic phase. The organic phase with polymerization inhibitor added is pumped to file distillation train. 

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