Solvent grade

Polychloroprene polymers also vary in the degree of branching in the polymer. Polychloroprenes with little or no branching are called sol polymers, whereas those with considerable branching are referred to as gel polymers. Sol polymers are soluble in aromatic solvents. All of the solvent-grade polychloroprene polymers (except Neoprene AG) are sol polymers. The gel content in the polychloroprene affects the cohesive strength, resilience, elongation, open tack time, resistance to permanent set, and oil swell. 

Once the <5 and y values of a given blend are determined, the values are positioned in the graphic chart given in Fig. 37 [77]. The blends that fall within the kidney-shaped area yield good solutions with all solvent grade polychloroprene types, except for Neoprene AH, and those which fall outside that area will not dissolve the polychloroprene. The solvent blends which fall within the shadow area, may or may not dissolve the polychloroprene depending on the amount of toluene. 

Solvent-grade benzene was dried over sodium wire prior to use. If a voluminous sludge forms on drying, the solvent should be distilled from sodium. 

Solvent grade dichloromethane was dried and stored over Linde type 4A molecular sieves. 

Cyclodctanol is available from Aldrich Chemical Company, Inc. A redistilled solvent grade of acetone is satisfactory. 

C/cIohexane is a colorless, water-insoluble, noncorrosive liquid having a really pungent odor. Its flammable like any naphtha product, and it is shipped in tank cars, tank trucks, barges, and drums. Red DOT shipping labels are required. In commerce, trade is usually done on the basis of Technical Grade (either 95 or 99% purity) or Solvent Grade (85% minimum purity). 

In a 5-1. round-bottomed flask are placed 3 1. of tj.s.p. solvent grade ether, 450 ml. of diethylene glycol monoethyl ether (Note... 

In 2001, Rai first reported such a transformation.14 The work specifically noted that the reaction favors aprotic solvents such as THF. This statement was challenged by Komatsu shortly thereafter, who found no reactivity in THF but high conversions in CH2CI2 or benzene for the same reaction.15 Solvent grade or quality may play an important role less likely but still possible, the grade or quality of silver nitrate used may also be a factor. 

Solvent grade dichloromethane was dried over calcium hydride, refluxed and distilled freshly before use. 

A Co-Mo-AlgOs catalyst (Harshaw CoMo 0402T, 3% CoO - 15% M0O3) was used In some experiments either with or without potassium carbonate. Pyrlte Isolated from coal was also used as a catalyst with potassium carbonate In some experiments. Anthracene oil obtained from Crowley Tar Products Company was used as the start-up solvent. In the recycle runs with Sheridan Field Coal (W-74-45), 80% of the anthracene oil was gradually replaced by coal-derived oil after nine recycles. The benzene and pentane used for separation of oil, and asphaltene were Fisher solvent grade. 

Table 1.5 Advantages and disadvantages for alternative solvents, grades 1 (poor) and 5 (very good) for five different categories to give a maximum overall score of 25. ... 

Diethyl ether, solvent grade Solid C02-methylated spirit freezing bath Procedure... 

Properties Colorless liquid fragrant odor. Bp 104-105C, mp 2.6C, d 0.8672 (20/20C), refr index 1.4211 (20C), flash p 77F (25C) (TOC). Miscible with water soluble in most organic solvents. Grade Technical, 95% min. 

The following chemicals were obtained from the Aldrich Chemical Company, Inc., and were used without further purification p-acetamidoben2enesulfonyl chloride, 97% acetone, 99.9+%, HPLC grade sodium azide, 99% ethyl acetoacetate, 99% triethylamine, 99% rhodium(ll) acetate dimer phenylacetylene, 98%. The following solvents were obtained from Fisher Scientific and were used without further purification toluene, certified A. C. S. ethyl ether (Solvent grade. Concentrated) petroleum ether, certified A. C. S. Dichloromethane was distilled from calcium hydride. 

Solvent grade A modification of the solvent grade could potentially impact the obtained separation. For example, the variation of the water content of the organic solvent used under normal phase conditions could modify the activity of silica. It is therefore suggested to keep the same solvent grade between the development and the production stage. 

D 4126 Vapor-Degreasing Grade and General Solvent Grade 1,1,1 -T richloroe thane... 

Improperly stabilized methylene chloride, perchloroethylene, 1,1,1-trichloroethane, and trichloroethylene are subject to decomposition under vapor degreasing conditions to form corrosive acid by-products. For this reason, only solvent grades suitably stabilized for vapor degreasing applications should be used. 

ASTM D 4126-95. Standard specification for vapor-degreasing grade and general solvent grade 1,1,1-trichlraoethane. 

Most of the applications are performed under typical reversed-phase HPLC conditions. Nondeuterated solvents such as MeOH or MeCN are used. Great care in selecting the appropriate solvent grades is important since most solvents contain small impurities such as stabilizing chemicals, which will not be detected in UV but will cause interferences in the LC/ NMR spectra. Water is usually replaced by D2O, which is a relatively cheap deuterated solvent, and gives better quality spectra. 

During this experiment, you will need to use anhydrous diethyl ether, which is usually contained in metal cans with a screw cap. You are instructed in the experiment to transfer a small portion of this solvent to an Erlenmeyer flask. Be certain to minimize exposure to atmospheric water. Always recap the container after use. Do not use solvent-grade ether because it may contain some water. 

Ethanol is often present in solvent-grade diethyl ether. If this grade rather than anhydrous were used, what effect would the ethanol have on the formation of the Grignard reagent ... 

Why is it possible to use solvent-grade diethyl ether in the work-up procedure, whereas the more expensive anhydrous form must be used to prepare the Grignard reagent ... 

Optional Measures If some solid material remains after the addition of aqueous acid is complete, the entire mixture may be transferred to a screw-cap centrifuge tube. Sequentially add solvent-grade diethyl ether and water in 0.5-mL portions to the centrifuge tube. After each addition, cap the tube and shake it to dissolve the solids. Continue the extraction as described, using appropriately sized conical vials or screw-cap centrifuge tubes. 

Work-Up, Isolation, and Purification After the excess dry ice has completely sublimed, most of the ether will have also evaporated, so add 20 ml of solvent-grade diethyl ether to the reaction flask. Combine about 5 g of ice and 10 mL of cold 3 M sulfuric acid in an Erlenmeyer flask, and add this cold acid to the reaction mixture slowly to avoid excessive foaming. If the ether evaporates appreciably during this operation, more solvent-grade diethyl ether should be added so that the total volume of ether is about 20-25 mL. Verify that the aqueous layer is acidic if it is not, add cold 3 M sulfuric acid dropwise until the layer is acidic. 

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