Cooling solvent

Phase Inversion (Solution Precipitation). Phase inversion, also known as solution precipitation or polymer precipitation, is the most important asymmetric membrane preparation method. In this process, a clear polymer solution is precipitated into two phases a soHd polymer-rich phase that forms the matrix of the membrane, and a Hquid polymer-poor phase that forms the membrane pores. If precipitation is rapid, the pore-forming Hquid droplets tend to be small and the membranes formed are markedly asymmetric. If precipitation is slow, the pore-forming Hquid droplets tend to agglomerate while the casting solution is stiU fluid, so that the final pores are relatively large and the membrane stmcture is more symmetrical. Polymer precipitation from a solution can be achieved in several ways, such as cooling, solvent evaporation, precipitation by immersion in water, or imbibition of... 

Ensure that cooling solvent temperature is sufficiently low to operate outside flammable limits... 

Rinse filter and cake with cool solvent prior to opening filter... 

A solution of 2.9 g (7.3 mmol) MnBr(CO)5 and 2.9 mL (3.4 g, 8.4 mmol) Sn(SC6H5)(n-C4H<,)3 in 40 mL of THF in a 100-mL round-bottom flask (Nz inlet, reflux condenser) is heated at reflux for 6 hr. The solution is allowed to cool. Solvent volume is reduced to 5 mL in vacuum cooling at -15° causes the orange crystalline product to precipitate from solution. This species is separated by filtration and air dried, yield 1.7 g, 93%. Recrystallization can be carried out using hexane. 

The compound [(PEt3)2HPt(/i-H)PtH(PEt3)2] [BPhJ is a white crystalline, air-stable solid when pure, which melts with decomposition above 130°C. The solid is fairly stable at room temperature, but it is light sensitive and is best stored in a refrigerator. It is soluble in acetone and dichloromethane. The solutions are relatively unstable at room temperature and thus are best prepared just before use employing pre-cooled solvents. The decomposition... 

A hot solvent usually can hold more solute than a cool solvent can. When a saturated solution cools, some of the solute usually falls out of the solution. But if a saturated solution is cooled slowly, sometimes the excess solute remains dissolved for a period of time. Such a solution is said to be supersaturated, because it contains more than the normal amount of solute. 

These are "Thermos" bottles made out of heavier glass than your coffee Thermos and are evacuated to about 10 atmospheres. Household type vacuum bottles should not be used around vacuum lines, because the temperature differences encountered are sufficient to cause most to crack in a short while. The common cooling material is dry ice, and the cooling solvents are isopropanol (-89.5 °C) and acetone (-94 C), isopropanol being preferred because it is not as combustible and is less likely to dissolve the synthetic materials from which clothes are frequently made. 

The clean moist soil was prepared for experiments by placing it in the 500 ml round bottom flask and spiking it with a solution of tetrachloroethylene to a concentration of either 9.28 or 957.3 ppm. The flask was sealed and rotated in an ice bath for 3 hr to homogenize the soil and the spike by tumbling. At the end of this tumbling period, the flask was attached to a water-cooled solvent-recovery condenser. The side leg of the condenser was placed in a chilled receiver containing approximately 10 ml of pesticide grade hexane, A Tenax trap was placed on the gas outlet port of the condenser to trap uncondensed vapors. 

Although exchange of hydrogen for chlorine is rarely used in the laboratory purely for the purpose of preparing chlorinated alkanes, chlorination of alkanes is of great technical importance. The large amounts of heat liberated can be removed in the gas phase by working with an excess of alkane or by admixture with an inert gas, and in the liquid phase by cooled solvents. Photochemical, catalytic, and thermal processes are all used. In all cases di- and poly-chlorina-tion occur as competitors of the monochlorination that is usually desired. 

Eastman has examined the perylene-o-bromanil system and he was able to make a 1 1 charge complex (35). When it was slowly crystallized out of a cool solvent, it had no spin signals and was a perfectly normal charge transfer complex. It shows this behavior in solution as well. However, if the quinone (o-bromanil) is sprayed onto the perylene crystals so that a two-phase system exists, the charge can actually separate when the transfer occurs and then the concomitant spin signals appear, conductivity is enhanced, the positive ion radical spectrum appears, etc. 

Condensate—Liquid solvent resulting from cooling solvent vapors. It is the clean solvent that condenses on the cooling coils of a vapor degreaser or still. 

A 5 mg (0.0068 mmol) porphyrin (8a) was dissolved in 0.5 mL 1,2-dichlorbenzene, then 4.5 mL DMF, 7 mg (0.015 mmol) ytterbinm acetylacetonate (3) and 5 mg lithium chloride were added. The mix was maintained for 15 min at 145°C and power 650 w in microwave oven. When reaction mass was cooled solvents were deleted at lowered pressure, and porphyrin complex was isolated by preparative chromatography on silica gel plates in chloroform. Weight 4 mg (58.4%). UV-vis 417.6 553.4 590.4 mn. Luminescent spectrum, 1. 980 nm (DMSO). 

Spray-cooling Solvent-free Low production volume... 

Above the cold heat transfer coils, cooled solvent vapor is heavier than the ambient air above it, and no longer rises to penetrate the air. 

An adhesive is a material which is applied to form a thin interlayer between solid substrates, with sufficient adhesive and cohesive strength to form a strong and durable bond. When applied, adhesives are fluid, because their flow units are independent or only weakly connected. By means of cooling, solvent evaporation or chemical crosslinking, they set to form viscoelastic solids. In both liquid and solid forms, adhesives are rheologically interesting materials. To understand the rheology of adhesives, therefore, it is necessary to study colloidal and polymeric systems in both fluid and solid states. This chapter will deal fully with fluid properties fortunately, much of the theory is equally applicable to the solid state. 

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