Ammonium bromide-ethanol-water

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. 

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... 

Add 8.0g (10.0ml, 0.15 mol) of redistilled acrylonitrile (Expt 5.161, Note (1)) to a stirred solution of diethyl propylmalonate (30.2 g, 0.15 mol) (Expt 5.132) and of 30 per cent methanolic potassium hydroxide (4.0 g) in t-butyl alcohol (100 g). Keep the reaction mixture at 30-35 °C during the addition and stir for a further 3 hours. Neutralise the solution with 2 M-hydrochloric acid, dilute with water and extract with ether. Dry the ethereal extract with anhydrous sojdium sulphate and distil off the ether the residue [diethyl (2-cyanoethyl)-propylmalonate 11 g] solidifies on cooling in ice, and melts at 31—32 °C after recrystallisation from ice-cold ethanol. Boil the cyanoethyl ester (10 g) under reflux with 40 ml of 48 per cent hydrobromic acid solution for 8 hours, and evaporate the solution almost to dryness under reduced pressure. Add sufficient water to dissolve the ammonium bromide, extract several times with ether, dry the ethereal extract and distil off the solvent. The residual oil (4.5 g, 66%) soon solidifies upon recrystallisation from water, pure 2-propylglutaric acid, m.p. 70 °C, is obtained. 

The filtrate is concentrated to dryness in vacuo and the residue is taken up in 25 cc of ethanol. The residual ammonium bromide is removed by filtration and to the filtrate there is added sufficient diethylamine to change the pH to 6.4. The mixture is warmed to 60°C and then cooled to room temperature. It is then allowed to stand overnight to effect complete crystallization. It is then cooled to 0°C and the product is isolated by filtration, washed with methanol and air dried. The product (a-hydrazino-a-methyl-p-(3,4-dihydroxyphenyl)-propionic acid) is recrystallized once from water using a proportion of 15 cc water per gram of product. 

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

To a solution of 145 g. (0.52 mol) of cobalt(II) sulfate 7-hydrate in 180 ml. of water contained in a 1-1. beaker is added 300 ml. of 10% ethylenediamine (0.50 mol). The mixture is stirred for 10 minutes and is allowed to oxidize by standing undisturbed and exposed to air. A dark red-brown precipitate begins to form within a few hours. The reaction mixture should be allowed to stand undisturbed for three or four days. The product is filtered, washed successively with water (until the washings are pink), ethanol, and ether, and then air-dried. The yield is usually 25 to 31 g. (17 to 21%) of the pink sulfate 5delds as high as 50 to 60% have sometimes been obtained. A suspension of 18 g. of the pink sulfate (0.022 mol) and 50 g. of ammonium bromide (0.51 mol) in 50 ml. of water is warmed (about 50°) until all of the complex dissolves. The deep purple solution is allowed to cool in the refrigerator overnight. The piu-ple crystalline solid which precipitates is filtered, washed with ethanol, and air-dried. The yield of crystalline 1-hydrate is 12 to 18 g. (60 to 90%, based upon... 

Crude cis-[tetraammineaquahydroxochromium(III)] dithionate (2.00 g, 0.0060 mole) is heated for 1 hour and 15 minutes at 100° in an oven to give a violet product of very impure di- i-hydroxo-bis[tetraamminechromium(III)] dithionate. This material is added to 8 mL of a saturated (at room temperature) solution of ammonium bromide, and the suspension is cooled in an ice bath, with thorough stirring, for M. hour. The dithionate salt dissolves and red crystals of di-Ai-hydroxo-bis[tetraamminechromium(III)] bromide tetrahydrate precipitate. The sample is filtered, washed with four 5-mL portions of 50% v/v ethanol-water, and dried in the air. This procedure yields 1.00 g (50%) of an almost pure sample. A pure product is obtained after two further reprecipitations. A 1.00-g quantity is dissolved in 10 mL of 0.01 M hydrobromic acid and reprecipitated from the filtered solution by addition of 10 mL of the saturated solution of ammonium bromide with stirring and cooling in an ice bath. The bromide salt is isolated as above in a yield of 0.75 g (75%). Anal. Calcd. for [(NH3)4Cr(OH)2-Cr(NH3)4]Br4-4H20 Cr, 15.62 Br, 48.00 N, 16.83 H, 5.15. Found Cr, 15.50 Br, 48.16 N, 16.88 H, 4.87. 

The crude dithionate salt (lO.O g, 0.0143 mole) is added to 25 mL of a saturated solution of ammonium bromide and the suspension is kept at room temperature with stirring for I hour. The violet crystals of the bromide salt are filtered and washed with two 25-mL portions of 50% v/v ethanol-water. The product is... 

Alanylglycine 515 7V-(2-Bromopropionyl) glycine was heated with the five-fold amount of 25 % aqueous ammonia in a sealed tube at 100° for 20 min. The solution was evaporated, ethanol was added, and evaporation repeated to remove all the water. When the residue was treated with hot anhydrous ethanol (60 ml/5g of starting material) the ammonium bromide all gradually dissolved. The residual dipeptide was dissolved in the smallest possible amount of hot 50 % ethanol, and the solution was filtered and treated with anhydrous ethanol tot incipient turbidity. The product crystallizes slowly in short needles, m.p. ca. 228° (dec.) (87%). 

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