Solvent condensation

Finish removers are manufactured in open or closed ketdes. Closed ketdes are preferred because they prevent solvent loss and exposure to personnel. To reduce air emissions from the solvents, condensers are employed on vent stacks. Mild steel or black iron ketdes are used for neutral or basic removers stainless steel (316 or 317) or reinforced polyethylene ketdes are used for acidic removers. The ketdes are heated to increase dispersion of paraffin waxes and aid in the mixing of other ingredients. Electric or air driven motors drive either sweeping blade or propeller mixers that give sufficient lift to rotate and mix the Hquid. Dispenser-type mixers are used to manufacture thick and viscous removers. Ketde, fittings, mixer, and fill equipment must be fabricated with materials resistant to the chemicals in remover formulas. 

Vapor Degreasing. In vapor degreasing, the solvent is vaporized and the cold part is suspended in the vapor stream. The solvent condenses on the part, and the hquid dissolves and flushes dirt, grease, and other contaminants off the surface. The part remains in the vapor until it is heated to the... 

Finally, the extraction of solid or semisolid masses into solvents can be carried out by use of a Soxhlet extractor (Fig. A3.1 lb). The. .ample is placed in a porous cup in the extractor. The boiling solvent condenses into the cup and accumulates until a siphon column is established in the adjacent tube. Then the saturated solvent returns to the boiling flask and fresh solvent distills again, repeating the process. 

In the auto-refrigerated reactor shown below, an exothermic reaction A —> B is carried out using a low boiling solvent C. The heat of reaction is removed from the reactor by vapourising the solvent, condensing the vapour in the reflux condenser and returning the condensate as saturated liquid to the reactor. The total holdup of liquid in the reactor is maintained constant, but the temperature of the reactor is controlled by regulating the mass flow of vapour to the condenser. The example is taken from the paper of Luyben (1960). 

This cycle of vaporisation of the solvent, condensation, extraction, and vacuum-filtration may be repeated any number of times in a solid-fluid serial extractor. The occurrence of an extractive material fluid bed as a result of the flow of boiling hot vapour provides for effective extraction, while pressure filtration provides for short cycle times. This functional principle makes it possible to achieve filtration pressures which are 50-100 times more effective than when using the Soxhlet method, where only the low hydrostatic pressure of the extractive fluid operates. Solid-fluid-vortex extraction according to the proprietary FEXTRA (Feststoff Extraktion) principle is low cost. 

Just about 80% of the reactions in organic lab involve a step called refluxing. You use a reaction solvent to keep materials dissolved and at a constant temperature by boiling the solvent, condensing it, and returning it to the flask. 

Put a suitable heat source under the flask and adjust the heat so that the solvent condenses no higher than halfway up the condenser. You ll have to stick around and watch for a while, since this may take some time to get started. Once the reaction is stable, though, go do something else. You ll be ahead of the game for the rest of the lab. 

This common procedure consists of mixing your reagents with a solvent, boiling the solvent, condensing the vapors, and returning them back to the flask. Observe these rules. 

Finish removers are manufactured in open or closed kettles. Closed kettles are preferred because they prevent solvent loss and exposure to personnel. To reduce air emissions from the solvents, condensers are employed on vent stacks. 

Table 2.1 Thermodynamics of solvent condensation from the vapour to the liquid...

C. R. Clark, J. DeRuiter, and F. T. Noggle, GC/MS identification of amine-solvent condensation products formed during analysis of drugs of abuse, J. Chromatogr. Sci., 30 399 (1992). 

After that the solvents are distilled in apparatus 9. In the system of solvent condensation (cooler 10 and receptacle 11) a vacuum is created (66.6-93.3 GPa). Cooler 10 is filled with cooled water. The solvents (benzene and methanol mixture) are distilled at agitation and a temperature in apparatus 9 not exceeding 45 °C. The solvent vapours are condensed in cooler 10 and collected in receptacle 11. The process of distillation is monitored through a run-down box on the solvent intake line. After the solvents are no longer released, the vacuum is released by nitrogen in cooler 10 and the product is sampled to check its appearance. 

Nonaqueous electrochemistry — Electrochemistry (both interfacial and ionic) related to solutions other than aqueous solutions. This includes the following solvents, condensed gases, gels, and solids, all ensuring electric conductivity either by self-dissociation or by dissolving the appropriate electrolytic salts ... 

As condensation reactions progress, the sol will set into a rigid gel. Since the reactions occur within a liquid alcoholic solvent, condensation reactions result in a three-dimensional oxide network [M-0-M] that contains solvent molecules within... 

Sol-gel processing describes a type of solid materials synthesis procedure, performed in a liquid and at low temperature (typically T< 100 °C). The development of sol-gel techniques has long been known for preparations of metal oxides and has been described many times [30-38, 40-46, 65]. The process is typically used to prepare metal oxides via the hydrolysis of reactive precursors, usually alkoxides in an alcoholic solution, resulting in the corresponding hydroxide. It is usually easy to maintain such hydroxide in a dispersed state in the solvent. Condensation of the hydroxide molecules with loss of water leads to the formation of a network When hydroxide species undergo polymerization by condensation of the hydroxy... 

In the vapor phase osmometer, two matched thermistors are located in a ther-mostatted chamber which is saturated with solvent vapor. A drop of solvent is placed on one thermistor and a drop of polymer solution of equal size on the other thermistor. The solution has a lower vapor pressure at the test temperature (Eq. 2-72), and so the solvent condenses on the solution thermistor until the latent heat of vaporization released by this process raises the temperature of the solution sufficiently to compensate for the lower solvent activity. At equilibrium, the solvent has the same vapor pressure on the two temperature sensors but is at different temperatures. 

Figure 3. Modified Dean-Stark apparatus. The solvent (usually toluene) drips through the sample, dissolving the organic component and leaving the solids behind. The water, which codistills with the solvent, condenses and is trapped in the side arm and measured volumetrically. The solids and organic phases are determined gravimetrically after evaporating the solvent from the sample thimble and the solvent flask.

Dimethylformamide, used in excess as solvent, condenses with an aromatic amine such as (3) in the presence of sodium methoxide at the reflux temperature to give the corresponding formanilide (4). The same reaction conditions are satisfactory O... 

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