Solvents action

Diethyl ether is a mobile, colourless liquid having b.p. 35° and dy 0720. It has a characteristic odour, and a burning taste. It is used chiefly as a solvent, and was formerly widely used as an anaesthetic owing to its chemical non-reactivity, it is very seldom used actually as a reagent, except in the preparation of Grignard reagents (p. 280) where probably its chemical properties reinforce its solvent action. 

For purification, transfer the acid to a 150 ml. flask containing 60 ml. of water, boil the mixture under reflux, and then add acetic acid in 5 ml. portions down the condenser until almost all the solid has dissolved avoid an excess of acetic acid by ensuring that the solvent action of each addition is complete before the next portion is added. A small suspension of insoluble impurity may remain. Add 2 g. of animal charcoal, boil the solution again for 10-15 minutes, and then filter it through a preheated Buchner funnel. Cool and stir the filtrate, which will deposit pale cream-coloured crystals of the acid. Collect as before and if necessary repeat the recrystallisation. Yield of pure acid, 9 g. m.p. 227-229°. 

No cresol is obtained if sodium hydroxide alone is used, presumably because the fused sodium hydroxide has no solvent action upon the sodium p-toluene-sulphonate. Potassium hydroxide alone gives excellent results, as do also mixtures of Sodium and potassium hydroxide containing not less than 28 per cent, of potassium hydroxide. The experimental details utilise the minimum amount of potassium hydroxide for the salce of economy. 

Tetrahydrofurfuryl alcohol is a solvent and coupling agent for a phosphate-type insecticide used to control the gypsy moth. Esters of tetrahydrofurfuryl alcohol are used in preparations employed as insect repeUents. Tetrahydrofurfuryl alcohol is also used as a solvent—carrier for an EPA-approved paper sHmicide formulation. In this appHcation, the exceptional solvent action of tetrahydrofurfuryl alcohol prevents separation of the... 

Flaking paint is treated by infusion of an adhesive in the areas where needed, followed by resetting the flakes on the substrate the softening of the paint needed to bend it back is effected through solvent action or heat. Losses can only be filled and inpainted. Inpainting may also be necessary when cracks become so wide as to seriously affect the visual appearance of the painting. 

In unalloyed steel containers formamide discolors slowly during shipment and storage. Both copper and brass are also subject to corrosion, particularly in the presence of water. Lead is less readily attacked. Aluminum and stainless steel are resistant to attack by formamide and should be used for shipping and storage containers where the color of the product is important or when metallic impurities must be minimized. Formamide attacks natural mbber but not neoprene. As a result of the solvent action of formamide, most protective paints and finishes are unsatisfactory when in contact with formamide. Therefore, formamide is best shipped in containers made of stainless steel or in dmms made of, or coated with, polyethylene. Formamide supphed by BASF is packed in Lupolen dmms (230 kg) or Lupolen canisters (60 kg) both in continental Europe and overseas. 

C its solubihtyis only 14-15 mg/L. As the temperature increases, so does the solubihty until at 100°C solubihty reaches 30-40 mg/L. This faint solubility at elevated temperatures accounts for the accretion of a primarily CaCO scale in steam boilers. Carbon dioxide exerts a mild solvent action on... 

A number of materials exist which neither attack the polymer molecule chemically nor dissolve it but which cannot be used because they cause cracking of fabricated parts. It is likely that the reason for this is that such media have sufficient solvent action to soften the surface of the part to such a degree that the frozen-in stresses tend to be released but with consequent cracking of the surface. 

Solvent Action. Materials that tend to respond well to extraction by pressing will be more effective in solids removal when solvents are used. The complication is that it becomes necessary to separate not only the solids and the containing liquid from the finished process, but the solvent as well. 

The solvent action of mineral oil base stocks can cause skin problems and prolonged exposure may have been the origin of a few skin cancers . The use of additives that might be in any way harmful to health, e.g. ortho-tricresyl phosphate (anti-wear) and sodium mercaptobenzothiazole (anticorrosion) has been discontinued where skin contact is likely. 

In view of its position in the e.m.f. series ( °aj3+/ai = 166V (SHE)), aluminium would be expected to be rapidly attacked even by dilute solutions of relatively weak acids. In fact, the rate of chemical attack is slow, owing to the presence on the aluminium of a thin compact film of air-formed oxide. When a voltage is applied to an aluminium anode there is a sudden initial surge of current, as this film is ruptured, followed by a rapid fall to a lower, fairly steady value. It appears that this is due to the formation of a barrier-layer. Before the limiting thickness is reached, however, the solvent action of the electrolyte initiates a system of pores at weak points or discontinuities in the oxide barrier-layer. 

Chloroform, CHCla, is an example of a polar molecule. It has the same bond angles as methane, CH4, and carbon tetrachloride, CCLi- Carbon, with sp3 bonding, forms four tetrahedrally oriented bonds (as in Figure 16-11). However, the cancellation of the electric dipoles of the four C—Cl bonds in CCL does not occur when one of the chlorine atoms is replaced by a hydrogen atom. There is, then, a molecular dipole remaining. The effects of such electric dipoles are important to chemists because they affect chemical properties. We shall examine one of these, solvent action. 

A mixture of hydrochloric and nitric acids (3 1 by volume) known as aqua regia is a very potent solvent largely due to its oxidising character, and the addition of oxidants such as bromine or hydrogen peroxide frequently increases the solvent action of acids. 

It should have no solvent action upon the precipitate, but dissolve foreign substances easily. 

Arsenites may also be determined by this procedure but must first be oxidised by treatment with nitric acid. Small amounts of antimony and tin do not interfere, but chromates, phosphates, molybdates, tungstates, and vanadates, which precipitate as the silver salts, should be absent. An excessive amount of ammonium salts has a solvent action on the silver arsenate. 

The other effect of having a stretched area is a reduction in resistance to stress cracking. Crazing is a possibility in such areas such as in polystyrenes, and environmental stress cracking caused by solvent substances will occur in the stretched areas. This is a particularly important consideration in vacuum formed products used for packaging food that frequently has some solvent action on the plastics. 

Molten TNT has little or no solvent action on Explosive D, and consequently, cast Picratol consists essentially of a physical mixt of crystals of the two expls. Its d is 1.61 to 1.63g/cc, and this permits a wt of charge almost equal to that of Explosive D pressed under 10,000 to 12,000 psi. Picratol has the solubility and reactivity chracteristics of its ingredients. It is hygroscopic to the extent of only 0.02% when exposed to an atm of 90% RH at 30°... 

Begun in 1944 with DDT and in 1947 with parathion, the present report includes analytical data secured from certain chemical, mechanical, and solvent actions on apples, pears, lemons, and oranges. In the absence of established tolerances for these two insecticidal materials, it is hardly possible to interpret the significance of many of these data with respect to consumer hazard. 

This fractionation may be carried out in an ordinary Claisen flask, but there is some difficulty in maintaining the desired pressure due to the solvent action of the hydrocarbons on the rubber stopper. This difficulty may be avoided by the use of a Claisen flask with very long necks and a wide side-tube. The material should be distilled fast enough to prevent it from solidifying in the column and side tube. Prolonged heating of hexamethyl benzene also causes a considerable amount of decomposition to tars. 

Demethylation reactions proceed equally well using dry M-pentane or dry methylene chloride as the solvent for both the ether and the boron tribromide methylene chloride, having by far the more powerful solvent action, is to be preferred. 

The liquid is a mild skin irritant due to solvent action. 

Under the usual conditions of commercial practice, the development reaction does not occur entirely at the silver/silver halide interface. Some reduction of silver ions from solution takes place. Such reduction presumably can occur at any point on the silver/solution interface, and the mechanism should be the same as that for post-fixation physical development. The relative extent of the physical development in comparison with that at the silver/silver halide interface will depend upon the silver halide solvent action of the developing solution and upon the rate of the direct development. 

The silver halide solvent, sulfite ion, is always present in practical developing solutions which employ organic agents. The conventional solutions contain up to 100 g. sodium sulfite per liter. The action of the sulfite is manifold. It is added primarily to decrease the rate of loss of developing agent by aerial oxidation and to prevent the accumulation of quinone or quinonelike oxidation products of the developing agents, A third phase of its activity, the solvent action, is well-known but the extent to which it can alter the nature of the development process under proper conditions is often overlooked. 

A rather extreme example of the alteration of development by solvent action is given by some experiments with the hydroxylamine... 

To account for the sharp drop in rate at the higher sulfite concentrations, it was suggested that the solvent action of the sulfite can isolate the latent image nuclei from the main body of the grains, so that development can proceed only by the slower physical development process. 

The solvent action of sulfite tends to promote fine-grain development, and some of the commercially used fine-grain developers contain as much as 100 grams of sodium sulfite per liter. Some of these developers contain other solvents as well, e.g., thiocyanates and amines. Any of these solvents should cause some shift to occur in the relative rates of the... 

The solvent action of sulfite on silver bromide and the resultant tendency to isolate latent image nuclei from the grain accounts for the failure of sulfite itself to act as a direct developer in spite of the autocatalytic character of its reduction of silver ion. The active nuclei simply are isolated from the grain before development gets under way. The same phenomenon enters to prevent sulfite-containing hydroquinone solutions of low pH (e.g., 8.5) from developing readily even though the thermodynamic conditions are suitable for reaction and the hydroquinone develops readily at the same pH when sulfite is absent. 

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