Handling solvents

CH3)2N]3P0. M.p. 4°C, b.p. 232"C, dielectric constant 30 at 25 C. Can be prepared from dimethylamine and phosphorus oxychloride. Used as an aprotic solvent, similar to liquid ammonia in solvent power but easier to handle. Solvent for organolithium compounds, Grignard reagents and the metals lithium, sodium and potassium (the latter metals give blue solutions). 

Degreasing small parts can be achieved with solvent sprays. Chlorinated hydrocarbons such as trichloroethylene (tricho) are sometimes used, normally in a heated vapor bath, although special handling, solvent recovery, and disposal methods are required. 

Extrinsic wastes are more functional in nature and are not necessarily inherent to a specific process configuration. These may occur as a result of unit upsets, selection of auxiliary equipment, fugitive leaks, process shutdown, sample collection and handling, solvent selection, or waste handling practices. Extrinsic wastes can be, and often are, reduced readily through administrative controls, additional maintenance or improved maintenance procedures, simple recycling, minor... 

Dissolve one vial of heavy isotope, cleavable ICAT reagent (Applied Biosystems) in 20 pi acetonitrile (use a fume hood for handling solvents). Dissolve a second vial containing the normal isotope ICAT compound in 20 pi acetonitrile. Vortex mix each vial to dissolve. 

An important source of error in nonaqueous conductance measurements is the presence of water in the system. As little as 1 X 10 "4 M water (2mg/l) may cause errors in many solvents. The difficulties faced in maintaining anhydrous conditions are formidable. Closed cell systems for handling solvents and salts have been described earlier. The most widely used method for measuring the water content of a solvent at low levels is still the Karl Fischer titration. 

The significant, often decisive, influence of the solvent in chemical reactions similarly is valid for electrochemical reactions too, for example, due to protic or aprotic and electrophilic or nucleophilic properties. If an excess of reactants can be used as solvent, a particularly uncomplicated operation will be possible. An additional solvent should be inert. The requirements for the solvent in dissolving power for reactants and products and the criteria regarding an easy separation of the products from the reaction mixture, for example, the boiling point, are comparable for chemical and electrochemical conversions. Generally, there is an interest to use, as far as possible, inexpensive, nontoxic, and easy to handle solvents. 

Safety glasses must be worn in the laboratory at all times. Safety gloves should be worn when handling solvents. 

As a general rule, the use of organic solvents in chromatographic processes should be minimized, because of the requirement for specialized flameproof equipment which can be extremely costly compared with the equivalent item for a safe area. Where unavoidable, a separate flameproof room for handling solvent-based materials is recommended, with the appropriate specification for mechanical and electrical equipment, controls and room fittings including lights, switches, and telephone systems. 

Hazardous features to be considered will include pressure relief handling of hazardous materials such as acids and alkalis protection from steam and other high-temperature fluids and electrical classification for handling solvents or protection from water ingress, high speed rotating machinery, and noise levels. 

In a similar manner, easy-to-handle solvents/reagents for electrophilic iodochlorination and iodobromination have been demonstrated.[11]... 

While working with solvents, observe that all personal protective equipment is suitable for the particular chemical substance in the solvent. Provide safety information to workers handling solvents and improve their... 

Cyrel FAST, an offering that eliminates the need for solvents in the process of making the plates used in certain printing processes. Because solvents require particular handling, specialty job shops or printers primarily owned the earlier equipment and produced the plates. With the new equipment and no need to handle solvents, graphic design businesses and others became a whole new market for the system ... 

Size-exclusion chromatography (SEC) has become the technique of choice in measuring the molar-mass distributions of polymers that are soluble in easily handled solvents (Dawkins, 1989). The technique as widely practised is not an absolute method and a typical SEC system must be calibrated using chemically identical polymers of known molar mass with a narrow distribution unless a combined detector system (viscosity, light scattering and refractive index) is employed. 

The value of VbA may be the true value or, if necessary, estimated from equation (1-48), or from the data of Table 1.2, except when water is the diffusing solute, as noted above. The association factor for a solvent can be estimated only when dif-fusivities in that solvent have been experimentally measured. There is also some doubt about the ability of the Wilke-Chang equation to handle solvents of very high viscosity, say 100 cP or more. 

When handling solvent-laden air, as is common in activated charcoal recovery plants, it is normal to operate with a flammable solvent content in the range of 25-40% of LEL. If information on the flash point of a mixture is not available the great majority of solvents have an LEL of 10,000 ppm (1%) with a few In the range of 7000-10,000 ppm. The flash point of straight run hydrocarbon solvents (e.g. white spirit) can be estimated from their initial boiling point (IBP)... 

From a practical standpoint, the water based silicone provides material of lower viscosity than pure silicone elastomers and free of hazards associated with handling solvent dispersion. 

When handling solvents, the odor can be regarded as a preliminary warning sign but cannot replace necessary safety measures. Relatively high solvent concentrations may irritate the mucous membranes. It must be pointed out, however, that some mildly smelling solvents may present more of a health hazard than other, strongly perceptible products. 

Ordinary steel pipe is suitable for handling solvents. Underground piping should be welded. Surface piping may be screwed, flanged or welded. Compressed-cork gaskets are suitable for pipe flanges. 

Orthophthalic, isophthalic, bisphenol, and chlorinated or brominated polyesters exhibit poor resistance to such solvents as acetone, carbon disulfide, toluene, trichloroethylene, trichloroethane, and methyl ethyl ketone. The vinyl esters show improved solvent resistance. Heat-cured epoxies exhibit better solvent resistance. However, the furan resins offer the best all-around solvent resistance. They excel in this area. Furan resins are capable of handling solvents in combination with acids and bases. 

Gravity separators can be designed to handle solvents denser or less dense than water provided that there is a density difference between the phases of... 

At water temperatures of 60 C or more water hardness will be deposited at low concentrations and make-up should therefore be softened in hard water areas. Clearly this temperature can be reached quite easily if the condenser is handling solvents which have a boiling point of 100 C or more. 

Achieving the required separation of solvent from residue at the safe operating temperature is likely to involve the use of reduced pressure, particularly towards the end of a batch when the mole fraction of volatile solvent becomes low and that of the involatile residue becomes high. Because this situation is present all the time in a continuous operation, it is likely to be under vacuum. This presents no insuperable problem for handling solvents with high boiling points since it is still possible to condense their vapours with cooling water or ambient air with an adequate temperature diiference in the condenser. 

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