Diphenol, solvents

Aroma isolation, 11 516-521 distillations for, 11 519 solvent extraction for, 11 518 Aroma perception, taste and, 11 522-523 Aroma therapy, 18 354 Aromatic-(poly)cycloaliphatic diphenols, interfacial condensation of, 23 723-724... 

Polysulfone supports are well suited for the fifth method listed in Table 1. In this approach. Method E, the support film is saturated with a water solution containing diamines, polyamines or diphenols, plus other additives such as acid acceptors and surfactants. The saturated film is contacted with a nonmlscible solvent containing di- or triacyl chloride reactants. A condensation polymer forms at the interface. The film is dried to bond the thin Interfacial film to the support surface. In some... 

Homopolycarbonates based on 1 and 2 have been prepared by several groups. The interfacial polycondensation typical for the synthesis of aromatic polycarbonates is not useful with alditols, including 1, because they are water-soluble and less acidic than diphenols. The 1-based homopolycarbonate was prepared by phosgena-tion of the sugar diol, with phosgene or diphosgene in pyridine-containing solvent mixtures at low temperatures. The polycondensation of the isosorbide bischloro-formate in pyridine is an alternative approach. 

Phenolic esters are obtained similarly. The presence of a nitro group in the aromatic nucleus and the use of pyridine as solvent facilitates the reaction. This reaction is recommended for the characterization of phenols. 2,4,5-Trichlorophenyl-, pentachlorophenyl-, 4-nitrophenyl- and thiophenyl esters of N-acylamino acids are prepared in this manner. These aromatic esters are used in the stepwise lengthening of peptides, du Vigneaud and coworkers synthesized lysine vasopressin from a nonapeptide which they prepared stepwise using the nitrophenyl ester method. Room temperature esterification of dicarboxylic acids and diphenols are also carbodiimide mediated using the 1 1 complex derived from DMAP and p-toluenesulfonic acid as catalyst Methacrylic acid is also esterified with phenols using carbodiimides and DMPA to mediate the reaction. ... 

F. Minisci, F. Recupero, A. Cecchetto, C. Gambarotti, C. Punta, R. Paganelli, G. F. Pedulli, F. Fontana, Solvent and temperature effects in the free radical aerobic oxidation of alkyl and acyl aromatics catalysed by transition metal slats and N-hydroxyphatUmide New processes for the sysnthesis of p-hydroxybenzoic acid, diphenols, and dienes liquid for liquid crystals and cross-linked polymers, Org. Proc. Res. Devel. 8 (2004) 163. 

Levulinic acid can be converted by known processes to the solvents, tetrahydrofuran and 2-methylfuran, to succinic acid, to 5-aminolevulinic acid for weed control (see Chap. 11) and to diphenolic acid. Diphenolic acid may be useful in waterborne epoxy coatings and other resins. If a suitable acid catalyst that can be left in the resin can be found, it may be possible to convert diphenolic acid, by self-acylation, to an analogue of phenol-formaldehyde resins, thus eliminating the use of the carcinogenic... 

More useful as monomers than the dicarboxylic acids are the corresponding imide diphenols (6a,b-10a,b) and their bisacetates, because their Tms are lower and their solubility in inert organic solvents is higher. Yet, even in the case of the bisacetates which are free of any H-bonds the Tms maybe as high as 500 °C (e.g. the bisacetate of 6b, see Table 1), so that it cannot be used in melt polycondensations [36]. Even in the case of 7b and 8b the Tms of the bisacetate are so high that they start to decompose in the melt mainly due to a Fries rearrangement [45]. However, the bisacetate of 5b disolved readily in the melt of silylated dicarboxy-lic acids (11 and 12a-d) below 300 °C, so that successful polycondensations were feasible [36]. For all polycondensations of acetylated imide diphenols, silylated dicarboxylic acids were used as reaction partners to reduce the initial reaction temperature below 300 °C and to avoid proton catalysed side reactions. 

In Table 4 we present the results of catalytic tests in several conditions using a Ti-Beta prepared by the cogel method. There it can be seen that water is a good solvent from the point of view of activity and selectivity and that it is possible to obtain about equimolecular amounts of catechol and hydroquinone while keeping the selectivity to diphenols above 50 %. 

The reaction rate was shown to be related to the accessibility of the acid sites-H-MFI zeolite was practically inactive and Nafion was the most active catalyst. With all the catalysts, not only the desired p-hydroxybenzophenone (/ -HBP) product but also j3-benzoxybenzophenone (p-BXBP) and o-hydroxybenzophenone (o-HBP) were formed. The para products result from benzoylation of phenol (formed by hydrolysis of PB) or of PB and o-HBP from the intramolecular rearrangement of PB. The selectivity to p-HBP can, therefore, be significantly improved by adding phenol to the reactant mixture [4]. Unfortunately, thermodynamic limitations arising from the low polarity of the medium employed (even with very polar solvents such as sulfolane) seems to preclude the use of a solid acid for the production of diphenol monomers from diphenyl benzoate [4]. 

Main-chain aromatic polysulfonates are disclosed in numerous patents. As in the case of the polyamides, they are mostly prepared by a two-phase polycondensation using an aromatic disulfonyl chloride in a chlorocarbon solvent on the one hand, and an alkaline water solution of a diphenol on the other. The most commonly used diphenol is the industrially available Bisphenol A, in conjunction with aromatic disulfonyl chlorides. Typical cases are reported by Thomson and Ehlers82, e.g. 

The reactions were performed in a domestic microwave oven that was used without any modification and temperature control. Prior microwave irradiation, 0.1 g diacid chloride was ground with an equimolar amount of an aromatic amine or diphenol and a small amount of a polar high-boiling solvent (o-cresol or NMP, 0.05... 

In work [62] it has been shown, that temperature synthesis T increasing at high-temperature polycondensation of polyaiylates, obtained by interaction of diphenols of different chemical stracture with dianhydride of terephthalic acid, results to reaction rate constant growth (the value pj was used for polycondensation first stage up to conversion degree Q 0.30-0.50). The solvent nature, in solution of which synthesis was performed, influences perceptibly on value. So, the value - pj is higher at polycondensation in nitrobenzene enviromnent, than in diphenyloxide enviromnent. The systematic enhancement was found... 

Theoretically chemical reaction rate reduction for ortho-derivative diphenol can be easily explained by steric factors. Within the frameworks of fractal analysis it is supposed, that solvents change at polyarylates syrrthesis should result to interactions polymer-solvent change. In this case the value of macromolecu-lar coil fractal dimension is determined according to the Eq. (12). In its turn, Flory-Huggins interaction parameter can be determined according to the Eq. (10). 

Thus, the stated above results have shown, thatpolyarylates series high-temperature polycondensation kinetics, characterized by the reaction rate constant pi, at different temperatures and solvents is controlled by three main factors process thermal activation (T), diphenol reactiveness (Z r) and macromolecular coil stmc-ture (Dj.). The obtained generalized dependence Ig allows to perform... 

The reaction may be carried out in the presence of pyridine that acts as a catalyst and as an HCl scavenger. Often, a chlorinated solvent is used as a diluent for the pyridine. Phosgene is bubbled through a solution of the diphenol at 25-35 The pyridine hydrochloride precipitates out and, after washing the pyridine solution with dilute HCl and water, the polymer is precipitated with a nonsolvent. 

An interfacial polymerization procedure is also employed in direct phosgenations. A caustic solution of the diphenol is dispersed in an organic chlorinated solvent containing small quantities of a tertiary amine. Phosgene is bubbled through the reaction mixture at 25 °C. When the reaction is complete, the organic phase contains the polymer. It is separated and the product isolated as above. 

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