Solvent occluded

Surface Coating. A dense surface coating (encapsulation) that contains no occluded solvent decreases interparticle attraction provided that the coating has a Hamaker constant intermediate between the particle and the Hquid. This is called semisteric stabilization (ST). The energy of interaction between coated spheres is as follows (26) ... 

Mixed solvents are generally unsatisfactory for use in the determination of polymer molecular weights owing to the likelihood of selective absorption of one of the solvent components by the polymer coil. The excess of polarizabilit f of the polymer particle (polymer plus occluded solvent) is not then equal to the difference between the polarizabilities of the polymer and the solvent mixture. For this reason the refractive increment dn/dc which would be required for calculation of K, or of i7, cannot be assumed to equal the observed change in refractive index of the medium as a whole when polymer is added to it, unless the refractive indexes of the solvent components happen to be the same. The size Vmay, however, be measured in a mixed solvent, since only the dissymmetry ratio is required for this purpose. 

Gross volatility differences in the components of a submitted sample may give misleading results. Occluded solvent is often the worst... 

V,/V-Diphenylacetamidine [621-09-0] M 210.3, m 131°. Crystd from EtOH, then sublimed under vacuum at ca 96° onto a "finger" cooled in solid CO2/MeOH, with continuous pumping to free it from occluded solvent. 

Except for LiC104, which is stable for some distance above its melting point, no molten salt densities seem to have been measured. Most ambient- temperature measurements are of fairly low accuracy. The most reasonable values have been listed for convenience. These are obtained either experimentally (usually pycnometrically, by displacement of a liquid such as CC14) or calculated from X-ray data. Solids frequently exhibit voids and/or occlude solvent so that reported values may scatter considerably. X-ray values are those for a perfect lattice and thus are only approximate guides to densities of real crystals. Whenever recent data are not available, the evaluation from International Critical Tables has been accepted. 

Cole, M. D., Occluded solvent analysis as a basis for heroin and cocaine sample differentiation . Forensic Sci. Rev., 10, 113-120 (1998). 

Occluded solvent A solvent found in a drug sample following crystallization, which can be either chemically bound to the crystal itself or trapped in the interstitial spaces of the crystal lattice. 

It has been recently shown44 that dendritic fragments with a hydroxymethyl group at the focal point form stable monolayers on the surface of water. The n A isotherms showed a strong dependence on the molecular weight of the dendrimer and the compression rate. The latter is due to the characteristic ability of dendritic macromolecules to occlude solvent molecules. 

As is usually the case, it is desirable for solvants to be cheap, noncorrosive, annflammable, tionexpto-sive, nontoxic, ensily removable, and easily recoverable. In the case of heterogeneous extractions, the external solvent and the occluded solvent must be immiscible. In soma cases the solvent should be selective bet when extracts with belauced flavors are desired, selectivity with respect to important flavor components is undesirable. It obviously may be impossible to meet all these objectives. 

The solids moistare content may be adjusted to minimize fines production. When nonaqueous solvouts are used, drying a solid before extraction may facilitate extraction. On the other hand, whea a heterogeneous extraction is to be carried out and water is the occluded solvent, the solid may have to be steamed or otherwise moistened prior to extraction,... 

Structural information has been obtained for solid HfL4 (L = tropolone, iV-benzoyl-, or JV-nitroso-iV-phenylhydroxylamine) complexes by obtaining the nuclear quadrupole interactions of Ta, produced by the p-decay of isoRf Xwo Ta sites were observed for the last two ligands suggesting that they exist in two isomeric forms. For the tropolonato-complex, a rapid interconversion between isomeric forms appears possible, and [Hf(tropolone)4]-CHCI3 seems to involve an interaction between the occluded solvent molecule and the ligand aromatic rings. °... 

In the solid form the stability of pristinamycin 11 depends strongly on the residual impurities (for example occluded solvent). Pure pristinamycin 11 is stable on storage at 50 ° for several months. 

Occluded solvents such as microdroplets in the crystal these are often difficult to extract. Generally, they can escape when the crystal is being dissociated ... 

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