Experimental procedure monomer synthesis

Monomer Synthesis. The synthesis of 1 was based on the published procedure of Reppe for the divinyl ether of triethylene glycol (11) The reaction conditions given in the Experimental were those found to give the best yields of 1 with this method. Some variations in reaction time and temperature as well as catalyst concentration were examined in attempts to improve the yield. Milder conditions reduced the rate of reaction without increasing the final yield, while harsher conditions led to extensive decomposition. Several additional mono- and divinyl ethers of oligo-oxyethylenes have been synthesized with this procedure and in general, yields were low. 

This section will describe some of the synthetic methods of selected PTs and PSTs. Examples of the different synthetic routes that are used to aehieve thiophene-based polymers with variable properties will be noted. The latter examples will also include monomer synthesis as this leads into the synthetic path chosen in many of the cases. The experimental procedures and characterization details will be included. 

It is generally accepted that the translation of solution-phase reactions to solid-phase procedures for the production of compound libraries is usually time-consuming and not always successful. The most robust solid-phase synthesis instrumentation has operational temperature and solvent compatibility limitations that impinge on the direct translation of solution-phase chemistries to the solid phase. These instrument restrictions necessitate a considerable investment in experimentation to rcdclinc the solution-phase reaction protocol for the solid phase. In spite of this apparent obstacle, a substantial number of reactions for solid-phase library production has been pubhshed. Many of these reachons cannot be exploited because the overall product yields are too low (which could lead to ambiguity in the interpretahon of the eventual assay results). Also, some reachons have a restricted range of potential monomers that lead to a hmited diversity of the compounds in the resulting library. 

Among all of the methods of synthesis to produce polypyrrole, the electrochemical procedure is one of the most useful procedures to obtain polypyrroles with high conductivities. The general details are similar to other conducting polymers such as poly(p-phenylene) or polythiophene. The experimental requirements are not difficult, because it is possible to work in aqueous solution at ambient pressure and temperature. The main problem is related to the difficulty in producing large amounts of polypyrrole due to the limitations imposed by the size of the anode. Second, even the most simple electrochemical process of pynole electropolymerization involves different experimental variables in order to optimize polymer properties. These variables can be chemical, such as solvent, monomer concentration, and salt concentration, or physical, such as temperature, nature and shape of the electrodes, cell geometry, or electrical conditions. Commonly, all of these variables are interdependent. 

In order to enhance the sulfonic acidity and therefore improve the polymer proton conductivity, a different synthetic pathway has been elaborated to introduce the sulfonic acids in the ortho position to electron-withdrawing groups (sulfones, ketones). Based on a procedure widely developed by Jan-nasch et al. for the synthesis of proton exchange polyarylethers [82,83], Chen et al. [84] designed an original and interesting monomer (Fig. 9). However, the harsh experimental conditions required (BuLi, gaseous SO2) and relatively low overall yields (24.7%) should preclude the wide development of such monomers. 

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