Ammonium bromide-ethanol-water system

Table IV. Isobaric Vapor—Liquid Equilibrium Data for the Ammonium Bromide—Ethanol—Water System at x = 0.206 (755 4 Torr)...

Because of the wide range of fixed x values for which data had been taken, it was possible to use interpolated data from Table II to construct a family of vapor-liquid equilibrium curves for the ammonium bromide-ethanol-water system at various constant salt concentration values—the condition most closely representing that existing from tray to tray in a... 

Figure 3. The ammonium bromide-ethanol-water system at various jixed-salt concentrations and saturation...

Table VII. Values of the Salt Effect Parameter at Various Values of x for the Ammonium Bromide-Ethanol—Water System...

A comparison of the dependence of the improvement factor on the salt concentration for the ammonium bromide-ethanol-water system at x = 0.246 (Figure 3) and that observed by Jaques and Furter (3) for ammonium chloride-ethanol-water at x = 0.223 reveals many similarities between these two systems. Their k values are similar, they both yield good correlation with Equation 1, and in both systems an inflection can be detected in the experimental plot of improvement factor vs. salt concentration at 0.05 mole fraction salt. The inflection probably can be attributed to a change in the solvent structure owing to the presence of salt. 

Although Johnson and Furter (1,2), among others, observed a surprising insensitivity of k to mixed-solvent composition in many alcohol-water-inorganic salt systems, such does not appear to be the case with ammonium bromide-ethanol-water. A linear dependence of k with x was observed and is demonstrated in Figure 4. The slope of this dependence is 2.63 and the intercept with the y-axis occurs at approximately a value of unity. This extrapolated salt effect when x = 0, that is, with water as the single solvent, is consistent with Raoult s Law in that the vapor pressure of the aqueous salt solution depends directly on the salt concentration. However the same behavior has not been observed for the ammonium chloride-ethanol-water system (3) as seen in Table VIII its salt effect parameter shows essentially no dependence on the liquid composition. Therefore the two systems differ in this respect. 

Figure 2. Salt effect of ammonium bromide on the ethanol-water system at x = 0.246...

The data in Tables I-XVI (see Appendix for all tables) show the isobaric vapor-liquid equilibrium results at the boiling point for potassium, ammonium, tetramethylammonium, tetraethylammonium, tetra-n-propylammonium, and tetra-n-butylammonium bromides in various ethanol-water mixtures at fixed liquid composition ratios. The temperature, t, is the boiling temperature for all solutions in these tables. In all cases, the ethanol-water composition was held constant between 0.20 and 0.35 mole fraction ethanol since it is in this range that the most dramatic salt effects on vapor-liquid equilibrium in this particular system should be observed. That is, previous data (12-15,38) have demonstrated that a maximum displacement of the vapor-liquid equilibrium curve by salts frequently occurs in this region. In the results presented here, it should be noted that Equation 1 has been modified to... 

An examination of Figures 1-6 indicates that Equation 1 is valid under conditions of constant x for potassium, ammonium, and tetramethylammonium bromides in ethanol-water mixtures. All three salts show an ability to salt out ethanol from these mixtures (i.e., increase its concentration in the equilibrium vapor) which is verified by their k values shown in Table XVIII. Also, the results for tetra-n-propylammonium bromide and tetra-n-butylammonium bromide in ethanol-water mixtures reveal that Equation 1 can be used to predict the salt effects of these systems however, these two salts demonstrate a propensity to salt in ethanol (i.e., decrease its vapor concentration) in ethanol-water mixtures. On the other hand, Figures 7-9 and the data in Table XVIII reveal that Equation 1 cannot be used to correlate the salt effects of tetraethylammonium bromide in ethanol-water. For this system, a linear dependence of log aja vs. z is observed initially however, a gradual levelling off occurs at higher concentrations. 

This paper is a follow-up of the previous study (Ref 7) whereby the adsorption of the carbon-14-labeled quaternary salt, stearyltri-methyl ammonium bromide (STAB), from soln by HMX was investigated in more detail. A solvent system for STAB, consisting of 90% water and 10% ethanol, yielded improved adsorption isotherms on 10-micron size powdered HMX. The data was shown to be quantitative and reproducible with a std deviation of O.Olmg... 

In a 12-liter flask fitted with a stirrer, addition funnel, gas inlet tube, and reflux condenser is placed 8 liters of 90% ethanol. The reaction system is placed in a hood and ammonia is run in with constant stirring until the flask has gained about 300 gm. Then 68.S gm (0.5 mole) of purified n-butyl bromide is added rapidly. Then, while a slow stream of ammonia is passed through the flask, an additional 1438.5 gm (lO.S moles) of /i-butyl bromide is added continuously at a rate of approximately 17 gm/hr. After the addition has been completed, the flask is stirred for an additional 2 days. Then the reaction mixture is distilled to remove ethanol, and, after approximately 4 liters of ethanol have been distilled off, the flask is cooled and the precipitating ammonium bromide is separated. Another 4 liters of ethanol are then distilled off and more ammonium bromide is filtered off. About 1 liter of solution remains in the flask. To this is added 1 liter of water and the last traces of ethanol are removed by distillation. If necessary, this step is repeated until all of the ethanol has been removed. 

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. 

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