Alcohol continued miscibility

If the solubility of either component in the other is unlimited ( free miscibility, as with alcohol and water), there may be an infinite number of solutions, lying between the two pure substances as limiting cases. The solubility may be limited in one or both directions. Thus, water and salt form a series of solutions extending indefinitely towards pure water as one limit, but bounded by saturated salt solution as the other limit water and ether form a continuous series of solutions bounded on one side by a saturated solution of ether in water, and on the other side by a saturated solution of water in ether. In the region of continuous miscibility all the properties of the solution vary... 

This review has presented an overview of the impact of tuning both the surface properties and pore architectures of solid acid and base catalysts on their performance in biodiesel synthesis. Plant-oil viscosity and poor miscibility with light alcohols continue to hamper the use of new heterogeneous catalysts for continuous biodiesel production from both materials and engineering perspectives. Thus, the design of... 

Figure 1 compares data reduction using the modified UNIQUAC equation with that using the original UNIQUAC equation. The data are those of Boublikova and Lu (1969) for ethanol and n-octane. The dashed line indicates results obtained with the original equation (q = q for ethanol) and the continuous line shows results obtained with the modified equation. The original equation predicts a liquid-liquid miscibility gap, contrary to experiment. The modified UNIQUAC equation, however, represents the alcohol/n-octane system with good accuracy. 

Figure 4a represents interfacial polymerisation encapsulation processes in which shell formation occurs at the core material—continuous phase interface due to reactants in each phase diffusing and rapidly reacting there to produce a capsule shell (10,11). The continuous phase normally contains a dispersing agent in order to faciUtate formation of the dispersion. The dispersed core phase encapsulated can be water, or a water-immiscible solvent. The reactant(s) and coreactant(s) in such processes generally are various multihmctional acid chlorides, isocyanates, amines, and alcohols. For water-immiscible core materials, a multihmctional acid chloride, isocyanate or a combination of these reactants, is dissolved in the core and a multihmctional amine(s) or alcohol(s) is dissolved in the aqueous phase used to disperse the core material. For water or water-miscible core materials, the multihmctional amine(s) or alcohol(s) is dissolved in the core and a multihmctional acid chloride(s) or isocyanate(s) is dissolved in the continuous phase. Both cases have been used to produce capsules. 

Among the properties sought in the solvent are low cost, avadabihty, stabiUty, low volatiUty at ambient temperature, limited miscibility in aqueous systems present in the process, no solvent capacity for the salts, good solvent capacity for the acids, and sufficient difference in distribution coefficient of the two acids to permit their separation in the solvent-extraction operation. Practical solvents are C, C, and alcohols. For industrial process, alcohols are the best choice (see Amyl alcohols). Small quantities of potassium nitrate continue to be produced from natural sources, eg, the caUche deposits in Chile. 

The continuous reaction system could be combined with solid acid-catalyzed in situ racemization of the slow-reacting alcohol enantiomer [149]. The racemiza-tion catalyst and the lipase (Novozym 435) were coated with ionic liquid and kept physically separate in the reaction vessel. Another variation on this theme, which has yet to be used in combination with biocatalysis, involves the use of scC02 as an anti-solvent in a pressure-dependent miscibility switch [150]. 

Water is the main ingredient of the continuous phase of most emulsion paints. It is also used alone, or blended with alcohols or ether-alcohols, to dissolve water-soluble resins. Any type of resin can be made water-soluble by incorporating sufficient carboxylic groups into the polymer. The advantages of water as a solvent are its availability, cheapness, lack of smell, nontoxicity, and nonflammability. However, it is not an ideal paint solvent because of its limited miscibility with other organic solvents, and because film formers designed to be dissolved or dispersed in water usually remain permanently sensitive to water. 

Water as diluent has obvious advantages and has been developed for many free-radical polymerizations. Thus suspension polymerization involves the dispersion of the non-miscible monomer in water as droplets (0.1-5 mm diameter) by means of agitation and protective colloids or dispersing agents (e.g. polyvinyl alcohol, PVAL), and adding a monomer-soluble initiator. The polymer ends up approximately the same size as the original droplets and the system can be viewed as many small bulk polymerizations. As water is the continuous phase the viscosity remains constant and good heat transfer occurs. This process is used for PVC. 

Sol-gel synthesis is the process of formation of porous, three-dimensional, integrated solid network (gel) of either discrete particles or network potymers from the conversion of monomers into stable suspension of colloidal solid particles or pol miers (sol) in a continuous liquid phase. Most popular precursors for the synthesis of colloids are metal alkoxides and alkoxysilanes. Tetramethoxysilane (TMOS) and Tetraethoxysilane (TEOS) are commonly used alkojq silanes, which form silica gel. The remarkable property of these silanes is that they readity react with water in the presence of shorter chain alcohol such as ethanol and ammonia to form monodispersed silica particles [7]. The size of silica particles formed is between 50 and 200 nm and depends on the silica ester used, type of alcohol, and molar ratios of water and alkoxysilane [32]. In this process, alcohol acts as a homogenizing solvent between alkoxides and water as both are immiscible but can be easily dissolved in alcohol. With the presence of this homogenizing agent, hydrolysis can be facilitated [33] due to the complete miscibility. However, aluminates borates and titanates often mixed with TEOS or TMOS are commonly used in sol-gel process. The hydrolysis of alkoxysilane proceeds according to Stober s process (Fig. 18.6). 

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