Toluene solvent system, dilute solution

Jikei et al. [158] reported the synthesis of a new AB2 monomer (Table 4, entry 2) with a sulfone linkage and prepared hb-PAESs and studied their properties. It was found that the reaction conditions affected the DB of the resulting polymers. Selfcondensation of the AB2 monomer to form hb-PAES was explored in three different ways First, self-condensation of the AB2 monomer was performed in the presence of a base such as K2CO3 in a DMAc/toluene solvent system. Second, the AB2 monomer was polymerized using cesium fluoride (CsF) in DMAc as solvent by stirring the mixture at 160°C for 10 h. Third, self-condensation of the AB2 monomer was performed by using low monomer concentration in the presence of DMAc as solvent in a highly diluted solution. The structure of the AB2 monomer was elucidated by H-NMR and C-NMR spectra and the peaks confirmed the proposed structure. 

In the case of polystyrene blends with poly(vinyl methyl ether) two phase behaviour was found for blends from various chlorinated solvents whereas single phase behaviour was found for blends from toluene The phase separation of mixtures of these polymers in various solvents has been studied and the interaction parameters of the two polymers with the solvents measured by inverse gas chromatography It was found that those solvents which induced phase separation were those for which a large difference existed between the two separate polymer-solvent interaction parameters. This has been called the A% effect (where A% = X 2 Xi 3)-A two phase region exists within the polymer/polymer/solvent three component phase diagram as shown in Fig. 2. When a dilute solution at composition A is evaporated, phase separation takes place at B and when the system leaves the two phase region, at overall... 

Such an analysis has been also extended to several solvent-poljnner systems. A simil U approach has been applied to polyisoprene in dilute solution in toluene [15]. The maximiim value of the relaxation time is found to be independent of polymer concentrations ranging firom 0.58 to 1 it is equ il to 20 s 1. This result shows that the effective number of interacting protons does not depend on the polymer concentration interactions between protons located on different chain segments can be neglected. 

Rouse and Sittel have investigated the applicability of the theory to real systems, in particular, dilute solutions of polystyrene in the good solvent toluene. Their results are reproduced in Figure 3-15. The agreement between theory and experiment is excellent. However, in a sense a certain amount of "curve fitting" is involved, since the friction factors and a have been adjusted to fit the data through the method outlined in deriving equation (3-84). 

In general the same principles apply to mixtures of two polymers in a common solvent. Theoretical calculations of the spinodals show that the incompatibility depends on the interaction parameter x 23 (polymer-solvent 3) at high polymer concentrations. Conversely, the difference between the interaction parameters x 12 and x 13 becomes important at low concentrations. If these interaction parameters differ greatly, a very strong solvent influence on the incompatibility will be observed in dilute solutions. The poly(styrene) / poly(vinyl methyl ether) system is, for example, compatible in toluene, benzene, or perchloroethylene, but not in chloroform or methylene chloride. Conversely, at high polymer concentrations, incompatibility in one solvent is normally accompanied by incompatibility in all other solvents. 

Dobry and Boyer-Kawenoki (1947) investigated the phase relationships existing in ternary systems polymer (l)-polymer (2)-mutual solvent (3). They prepared dilute solutions of polymers in common solvents, and then mixed the two solutions of interest. All of the polymer pairs studied were found to undergo phase separation at only 5-10% polymer concentration. For instance, cellulose acetate and polystyrene were immiscible at 5% concentration in toluene. These investigators concluded that incompatibility of two polymers even highly diluted is the normal situation. 

With this system, the conversions after the same reaction time were higher with high olefin concentrations in chlorobenzene (15 w/w solvent) than in toluene (12 w/w solvent) and higher still in the more dilute olefin solutions in chlorobenzene (39 w/w solvent). 

The principle of extraction method used to separate PTC and product is based on solubility of quaternary ammonium salt in alkaline aqueous solution. " For example, tetrabutylammonium bromide is soluble to the extent of 27% in dilute (1% NaOH) aqueous solutions, but when the solution is made more concentrated (15% NaOH), the solubility of Bu4N Br decreases to 0.07%. When the products are obtained in PTC system, they can be usually separated from PTC by distillation method. PTC catalyst in the distillation residue may sometimes be reusable. With quaternary ammonium salts as catalysts, temperatures above 100-120 C usually result in partial or total decomposition of the quaternary salts to trialkylamines and other products. Mieczynska et al. and Monflier et al. investigated the hydrogenation and hydroformylation under phase transfer catalytic conditions. They found that the yield of aldehydes obtained in hydroformylation of 1-hexene strongly depends on solvent 24% in toluene, 53-86% in toluene-water-ethanol mixture and 77-94% in water-ethanol solution. The mixture of water-ethanol as a solvent was also found to be the best for hydrogenation of 1-hexene (96% of hexane). Conversion of Ph2PCH(CH3)(COOH) phosphine into sodium salt Ph2PCH(CH3)(COONa) yields aldehyde in toluene, 92% in toluene-water and 94% in toluene-water-ethanol mixture. 

Also the paint industry, formerly the main end-user of solvents, attempted to produce a quantitative solvent power data system [5]. This related solvency to certain standard solutes, used in their industry. These could either be a well-known natural (Kauri-resin) or later a synthetic (nitrocellulose) paint binder. The result was the introduction of the Kauri-Butanol number, which applies to hydrocarbon solvents only and the NC-dilution ratio which is used for oxygenated solvents. Another test, used in conjunction with hydrocarbon solvents, is based on the fact that aniline is hardly miscible with aliphatic hydrocarbons but mixes very well with aromatics. The Kauri-Butanol (KB) number as defined in ASTM D 1133 is a measure of the tolerance of a standard solution of Kauri resin in -butanol to hydrocarbon diluent. Standard hydrocarbon solvents used to calibrate the Kauri solution are toluene (KB-number 105) and a 75% v -heptane/25% v toluene blend (KB-number 40). The KB-value increases from approx. 20 to over 100 in the order ... 

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