Spontaneous separation

The sulfoxidation of normal Cl4-CI7 paraffins with sulfur dioxide, oxygen, and water is performed under UV radiation in parallel reactors (1 in Fig. 3). The reaction enthalpy is dissipated by cooling of the paraffin in heat exchangers. The 30- to 60-kW UV lamps are cooled by a temperature-controlled water cycle. The reaction mixture leaving the reactors separates spontaneously into two phases in 2. The lighter paraffin phase is recirculated to the reactors. The composition of the heavy raw acid phase is shown in Table 5. 

As for the former problem, the researchers of GA found that the mixed acid solution produced by the Bunsen reaction separates spontaneously into two liquid phases in the presence of excess amount of iodine [17]. The heavier phase is mainly composed of HI, I2, and H20, and is called "Hix" solution. The main components of the lighter phase are H2S04 and H20. The phenomenon (liquid-liquid (LL)-phase separation) offered an easy way of separating the hydriodic acid and the sulfuric acid. As for the HI processing, some ideas have been proposed by GA [17], RWTH Aachen [18], and JAEA. JAEA studied the utilization of membrane technologies for concentrating the Hix solution to facilitate the HI separation and also for enhancing the one-pass conversion of HI decomposition [19,20]. 

The tetrahydrate readily forms supersaturated solutions and in the above investigation it was never observed to separate spontaneously... 

The most common form of TOT clathrate crystallises as discrete C2 symmetric cavities in the chiral space group 1, implying that the (—)-(M) and (+)-(/") forms separate spontaneously as crystallisation occurs. This property of TOT has been used in an ambitious model experiment designed to test the theory that the parity-violating energy difference (the violation of parity or symmetry in elementary particles), with autocatalytic amplification (in the case of TOT during crystallisation) is responsible for the observed chirality of modern biomolecules. The experiment did not find any evidence to support the theory, with equal amounts of each enantiomeric crystal being isolated.26... 

Aqueous systems containing high polymers such as polyethylene glycols and dextrans may separate spontaneously into two phases (Guan et al., 1993). These... 

Polysaccharide dispersions phase-separate spontaneously, a phenomenon called aging. Phase-separation may be induced in special systems, under controlled conditions (e.g., encapsulation), to industrial and commercial advantage. 

Difficulty separating spontaneous geriatric findings from induced changes... 

At this point the mother liquor should be rich enough in the more soluble Z-diacetate (2) for its isolation. Concentrate the methanol mother liquor and washings from the third crop of 1 to a volume of 4-5 mL, stopper the flask, and let the solution stand undisturbed overnight. The Z-diacetate (2) sometimes separates spontaneously in large rectangular prisms of great beauty. If the solution remains supersaturated, addition of a seed crystal of 2 causes prompt separation of the Z-diacetate in a paste of small crystals (e.g., 215 mg, mp 118-119°C then 70 mg, mp 116-117°C). 

Cover picture Homogeneous catalysis in aqueous phase the yellow catalyst solution separates spontaneously from the colorless phase consisting of butyraldehydes. The underlying molecular model symbolizes the water-soluble ligand of the organometallic complex. The picture was taken at the plant site of Celanese (formerly Ruhrchemie), Oberhausen/Germany (see Chapter 1 and Section 2.1.1). 

An unstable state where the homogeneous solution separates spontaneously into two phases in equilibrium. This state, which is always located within the miscibility gap, is thermodynamically determined by ... 

By this formula the tensile stress at the periphery of the deformation area is infinite 2,.t. on unloading, the released elastic stresses peel the contacting surfaces apart. This analysis tells us that it is possible for weakly adherent surfaces to separate spontaneously on removal of the contact load. But it is not necessarily valid for strong adhesions. Otherwise we would never observe persistent adhesion after contact of bodies under load. 

In addition to their observed homogeneity, true solutions also have certain other characteristics. For example, components of a solution never separate spontaneously, even when a significant density difference exists between the components. Solutions also pass through the finest filters unchanged. 

Dilute, highly purified poliovirus, which would occupy less than 0.03 cm if hexagonally closest packed in a two dimensional array, was emulsified with equal volumes (10 mL) of 0.02 Z, pH 7 buffer and C2CI3F3 in borosilicate extraction tubes at 25°C. The emulsion was allowed to separate spontaneously, which took about 5 min, and the aqueous phase was sampled for residual virus. In Table IX we see only a small decrease in infectivity and radioactivity in the C2Cl3F3-extracted samples, compared to controls run in parallel but not containing C2CI3F3. This experiment was repeated and essentially identical results were obtained. 

Styrene-butadiene block copolymer belongs to the A-B-A type thermoplastic elastomer. The principal structure of this type of polymer involves the thermoplastic rubber molecules terminated by the hard, glassy end blocks. The A and B copolymer block segments are incompatible and, consequently, separate spontaneously into two phases. Thus in the solid state, the styrene-butadiene (S-B-S) thermoplastic elastomer has two phases a continuous polybutadiene rubber phase and the dispersed glassy domains of polystyrene. The styrene plastic end blocks, called domains, act as cross-links locking the rubber phase in place. 

Perfluoroalkanes (hydrocarbon compounds in which every hydrogen atom is replaced by a fluorine atom) and alkanes (hydrocarbons) are incompatible from a certain chain length and separate spontaneously at room temperature. If a hydrocarbon residue is connected to a perfluorocarbon residue, the result is an amphiphilic molecule which is constructed from two incompatible components ... 

From, a critical value of y onwards the curves for AG show two minimum values. Any solution whose composition is represented by a point between the two tangent points t end t (miscibility gap) will separate spontaneously into two layers, the one rich and the other poor in polymer substance. There is nothing remarkable in this result when y has a large positive value. In polymer solutions, however, these minimum values occur at -values which are considerably smaller than in solutions of micromolecules. 

---