Mixtures separation into two phases

A mixture of 46 grams of Tmethyl-4-piperidinol (0.4 mol), 49.4 grams of benzhydryl bromide (0.2 mol) and 100 ml of xylene was refluxed for approximately 24 hours. The reaction mixture separated into two phases with the upper phase containing the desired... 

Figure 8.17 Vapor fugacity for component 2 in a liquid mixture. At temperature T, large positive deviations from Raoult s law occur. At a lower temperature, the vapor fugacity curve goes through a point of inflection (point c), which becomes a critical point known as the upper critical end point (UCEP). The temperature Tc at which this happens is known as the upper critical solution temperature (UCST). At temperatures less than Tc, the mixture separates into two phases with compositions given by points a and b. Component 1 would show similar behavior, with a point of inflection in the f against X2 curve at Tc, and a discontinuity at 7V...

If we could prevent the mixture from separating into two phases at temperatures below Tc, we would expect the point of inflection to develop into curves similar to those shown in Figure 8.17 as the dotted line for /2, with a maximum and minimum in the fugacity curve. This behavior would require that the fugacity of a component decreases with increasing mole fraction. In reality, this does not happen, except for the possibility of a small amount of supersaturation that may persist briefly. Instead, the mixture separates into two phases. These phases are in equilibrium so that the chemical potential and vapor fugacity of each component is the same in both phases, That is, if we represent the phase equilibrium as... 

Table XVI is a summary of typical results observed for cyclotrimerization of propionaldehyde to give 2,4,6-triethyl-1,3,5-trioxane (176). In catalysis by H3PMo12O40, the reaction mixture separates into two phases during the course of the batch reaction. The products are present in the upper layer and the catalyst in the lower layer, so that the catalyst solution can be used repeatedly without a catalyst isolation step. Selectivities exceeding 97% and turnovers exceeding 300 moles of product per mole of catalyst have been obtained.

Phase equilibrium resulting in a UCST is the most common type of binary (liquid + liquid) equilibrium, but other types are also observed. For example, Figure 14.5 shows the (liquid + liquid) phase diagram for (xiH20 + jc2(C3H7)2NH. 7 A lower critical solution temperature (LCST) occurs in this system/ That is, at temperatures below the LCST, the liquids are totally miscible, but with heating, the mixture separates into two phases. 

A mixture of 46 g of l-methyl-4-piperidinol (0.4 mol), 49.4 g of benzhydryl bromide (0.2 mol) and 100 ml of xylene was refluxed for approximately 24 hours. The reaction mixture separated into two phases with the upper phase containing the desired ether compound dissolved in xylene. The lower phase consisted of the hydro bromide salt of the excess l-methyl-4-piperidinol. The upper phase was separated from the lower phase and the desired benzhydryl ether recovered in the crude state by distilling off the xylene under reduced pressure. The crude benzhydryl ether was a clear reddish oil. It was dissolved in 75 ml of 20% hydrochloric acid and the aqueous acid solution then washed three times with 50 ml portions each of ethyl ether. The aqueous acid solution was then decolorized with activated carbon and thereafter slowly admixed with 75 ml of 28% aqueous ammonia. The benzhydryl ether separated as an oily material and was removed from the aqueous mixture by extraction with three 50 ml portions of ethylether. On evaporation of the ethyl ether from the ethyl ether solution, the benzhydryl ether was recovered as a pale yellow oil. The benzhydryl ether was dissolved in 60 ml of isopropanol and the isopropanol solution acidified to a PH of 3 with dry hydrogen chloride-methanol solution. The acidic propanol solution was then diluted with ethyl ether until a faint turbidity was observed. In a short time, the crystalline hydrochloride salt of the benzhydryl ether separated from the propanol solution. The crystallized salt was recrystallized once from 75 ml of isopropanol with the aid of ethyl ether in order to further purify the material. 

For instance, denaturation and partial hydrolysis of proteins oppositely influence their incompatibility with other biopolymers (Tolstoguzov 1991). Most biopolymers are polyelectrolytes. Factors such as pH and salt concentration affect their interactions with one another, with the solvent and their compatibility. For instance, when the pH is shifted to their isoelectric point (lEP), the thermodynamic incompatibility of proteins is usually enhanced by self-association of the protein molecules. Generally, protein-neutral polysaccharide mixtures separate into two phases when the salt concentration exceeds 0.15 M. 

Suppose, for example, that a mixture of ammonia and water that is 40% NH3 by mass is contained in a closed vessel at 140°F and 1 atm. Point A on Figure 8.5-2 corresponds to this condition. Since this point lies between the vapor and liquid equilibrium curves, the mixture separates into two phases whose compositions are found at the extremities of the 140°F tie line (points B and C),... 

For the extraction of proteins, aqueous two-phase systems (ATPS) are preferred over organic solvents, which usually denature the proteins and render them biologically inactive. They consist of polyethylene glycol (PEG), and a salt (e.g., potassium phosphate) or dextran in water. At concentrations above a critical value, the mixture separates into two phases—one rich in PEG and the other in dextran or salt. In industrial systems, salts are more commonly used because they are relatively inexpensive as compared to dextran. The MW, charge and surface properties of the protein decide how the protein partitions in the system. The nature of the phase components, the MW of the polymer, and the concentration and type of salt used also affect the distribution. ... 

Consider now the results of the model calculations. As shown for path I in Fig. 4.18, the confined mixture separates into two phases (shaded region) at temperatures below T 30°C. Volume density profiles for a 3.5nm slit-pore are shown in Fig. 4.20 for four different temperatures. It is seen that water is preferentially adsorbed at the pore walls. Figure 4.20(a) and (b) show the situation in the single-phase region at T = 70°C and 50°C, whereas the graphs in Fig. 4.20(d),(c2) and (dl),(d2) illustrate the density profiles for the two-phase region at 25 C and 10°C. The mean mass fraction of phase (1) [i.e., see Fig. 4.20(dl)j is lower and that of phase (2) [i.e., see... 

When a mixture separates into two phases, it is important to know the compositions and the amounts of the two phases in equilibrium. A tie line links the two conjugated compositions in equilibrium. This means that any composition located on the same tie line will separate in the same two phases, the compositions of which are defined by the points of contact of the tie line with the phase boundary. 

Solubility of solids is defined as the concentration of the compound in a solution that is in equilibrium with the solid phase at the specified temperature and one atmosphere pressure. For liquids whose water mixtures separate into two phases, the solubility given here is the concentration of the specified compound in the water-rich phase at equilibrium. In the case of gases (i.e., compounds whose vapor pressure at the specified temperature exceeds one atmosphere) the solubility is defined here as the concentration in the water phase when the partial pressure of the compound above the solution is 101.325 kPa (1 atm). Values for gases are marked with an asterisk. 

Dimerization of butadiene was studied extensively in the 1970s [1]. Since then, few studies have been reported. Beller and co-workers studied the telomerization of butadiene with MeOH, and found that the Pd-carbene (XVI-1) complex was an excellent catalyst and the linear telomer 6 was obtained with 99 % chemoselectivity and 98 % yield at 90 "C. In addition, they claimed that TON = 267 000 was attained with this catalyst. Also they showed that Pd(OAc)2/3PPh3 is a good catalyst for the telomerization [2]. Telomerization in the presence of water to give 2,7-octadien-l-ol (7) proceeded in an ionic liquid (l-butyl-3-methylimidazolium tetrafluoroborate) at 70 °C. The reaction mixture separated into two phases when it was cooled. After separation of the product, the ionic liquid phase is recycled [3]. 

Add the DCM in a 2 1 ratio to the supernatant in a separatory funnel, shake well, and let the mixture separate into two phases. 

LPS may be extracted from intact cells by a variety of procedures. Treatment with chelating agents, such as EDTA, releases about one-third of the LPS. Generally LPS is obtained by a phenol-water extraction. In essence the bacterial cells are treated for Ih with 45 per cent (w/v) aqueous phenol at 68°C. On cooling the mixture separates into two phases, a lower phenol layer and an upper aqueous phase, in which the LPS is located. This treatment extracts up to 90 per cent of the LPS which can then be subjected to chemical analysis. 

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