Carbon disulfide, solvent effect

The problem of finding a suitable solvent is more serious in the infrared region, where it is difficult to find one that is completely transparent. The use of either carbon tetrachloride or carbon disulfide (health effects aside) will cover the most widely used region of 2.5 to 15 tm (see Figure 16.4). Water exhibits strong absorption bands in the infrared region, and it can be employed only for certain portions of the spectrum. Also, special cell materials compatible with water must be used rock salt is usually used in cells for infrared measurements because glass absorbs the radiation, but rock salt would dissolve in water. The solvents must be moisture-free if rock salt cells are used. 

It has been proposed that aromatic solvents, carbon disulfide, and sulfur dioxide form a complex with atomic chlorine and that this substantially modifies both its overall reactivity and the specificity of its reactions.126 For example, in reactions of Cl with aliphatic hydrocarbons, there is a dramatic increase in Ihe specificity for abstraction of tertiary or secondary over primary hydrogens in benzene as opposed to aliphatic solvents. At the same time, the overall rate constant for abstraction is reduced by up to two orders of magnitude in the aromatic solvent.1"6 The exact nature of the complex responsible for this effect, whether a ji-coinplex (24) or a chlorocyclohexadienyl radical (25), is not yet resolved.126- 22... 

The effects of adsorption and desorption on the performance of fluidized beds are discussed elsewhere. Adsorption of carbon disulfide vapors from air streams as great as 300 nr/s (540,000 ft3/min) in a 17-m- (53-ft-) diameter unit has been reported by Avery and Tracey ( The Application of Fluidized Beds of Activated Carbon to Recover Solvent from Air or Gas Streams, Tripartate Chemical Engineering Conference, Montreal, Sept. 24, 1968). 

Cardiovascular Effects. In a cohort mortality study of workers in a large rubber and tire manufacturing plant, Wilcosky and Tyroler (1983) found a significant increase in mortality from ischemic heart disease in phenol exposed workers. Of the 25 solvents used in the plant, phenol exposure showed the strongest association with mortality from heart disease, greater even than that observed for exposure to carbon disulfide, the only known occupational cause of atherosclerosis. 

So-called peripheral neuropathies can result from excessive exposure to certain industrial solvents such as carbon disulfide (CS2, used in the rubber and rayon industries) and hexane (CgHn, once used in certain glues and cleaning fluids). Over-exposure to acrylamide, an important industrial chemical, and chronic alcohol abuse can also induce this effect. As the name implies, it involves attack of the chemical on and damage to axonal portions of neurons. Typical symptoms of peripheral neuropathies include weakness or numbness in the limbs, which are more or less reversible depending upon the specific agent and the intensity of exposure. 

The solvents most commonly employed are water, ethyl and methyl alcohol, ether, benzene, petroleum ether, acetone, glacial acetic acid also two or three solvents may be mixed to get the desired effect as described later. If you still cannot dissolve the compound, try some of these chloroform, carbon disulfide, carbon tetrachloride, ethyl acetate, pyridine, hydrochloric acid, sulfuric acid (acids are usually diluted first), nitrobenzene, aniline, phenol, dioxan, ethylene dichloride, di, tri, tetrachloroethylene, tetrachloroethane, dichloroethyl ether, cyclohexane, cyclohexanol, tetralin, decalin, triacetin, ethylene glycol and its esters and ethers, butyl alcohol, diacetone alcohol, ethyl lactate, isopropyl ether, etc. 

Surprising effects can also be observed when solvent mixtures are used to dissolve a polymer. There are examples where mixtures of two non-solvents act as a solvent vice versa, a mixture of two solvents may behave like a non-solvent. For example, polyacrylonitrile is insoluble in both, nitromethane and water, but it dissolves in a mixture of the two solvents. Similar behavior can be observed for polystyrene/acetone/hexane and poly(vinyl chloride)/acetone/carbon disulfide. Examples of systems where the polymer dissolves in two pure solvents but not in their mixture are polyacrylonitrile/malonodinitrile/dimethylforma-mide and poly(vinyl acetate)/formamide/acetophenone. These peculiarities are especially to be taken into account if one wants to adjust certain solution properties (e.g., for fractionation) by adding one solvent to another. 

Carbon disulfide quenches the fluorescence of anthracene quite efficiently,145,149 but seems to have little effect on its triplet lifetime.147 Diphenylanthracene in benzene fluoresces with a quantum yield of 0.8 and shows a high sensitivity to the oxygen concentration in photooxygenation reactions. With about 1 vol% of CS2 present, AC>2 is practically independent of [02] (> 10"5 mole/liter). In jjoth cases, where carbon disulfide was either used as solvent or was added to an otherwise strongly fluorescent solution, the quantum yields of photooxygenation followed... 

Mixed Solvents. In general, polar compounds usually show low recoveries from charcoal. By adding several percent of a polar solvent to the carbon disulfide desorbent solvent, recovery is often improved by 10 to 20% (16,17,18). Methanol is the most frequently added polar solvent, and it is usually effective as long as it does not interfere with... 

Materials and Methods. The isomeric compositions of the four polybutadienes used are listed in Table I. Samples were prepared for infrared measurement from solutions of the polymer without further purification. Most films were cast from carbon disulfide solutions on mercury or on glass plates, but a few films were cast from hexane solutions to determine whether or not the solvent affected the radiation-induced behavior. No difference was observed for films cast from the different solvents. The films were cured by exposure to x-rays in vacuum. (Doses were below the level producing detectable radiation effects.) They were then mounted on aluminum frames for infrared measurements. The thicknesses of the films were controlled for desirable absorbance ranges and varied from 0.61 X 10 s to 2 X 10 3 cm. After measuring the infrared spectrum with a Perkin-Elmer 221 infrared spectrophotometer, the mounted films were evacuated to 3 microns and sealed in glass or quartz tubes (quartz tubes only were used for reactor irradiations). 

The 1H NMR spectra of the polymers were obtained with a Varian HR-300 spectrometer, at 110-120° C, using 5-10% solutions of polymer in hexachloro-butadiene. The effect of temperature and solvent on the H NMR spectrum of a cationically prepared poly(4-methyl-l-pentene) was investigated. Figure 1-3 show the results obtained with carbon disulfide, carbon tetrachloride, o-dichloro-benzene, p-dichlorobenzene, and hexachlorobutadiene. 

Since medium effects may be expected for any resonance, the solvent must be mentioned when 13C shift values are tabulated. In this work, all 13C shifts are given relative to TMS. Those shifts which were originally reported relative to other references (e.g. carbon disulfide, <5CS2, or 1,4-dioxane, <5C4hho2)> have been converted into shifts relative to TMS (t>TMs) using the known shift difference between common reference substances, as... 

The absorption of ultrasonic energy is also influenced by relaxation effects. At the frequencies of near 100 MHz that are employed, the relaxation times are of the order of ns, rather than the ps for dielectric relaxation. The relevant quantity is the absorption coefficient, a, divided by the square of the frequency, f2. Values of a//2 in 10-15 s2 nr1 have been measured for many solvents near 25 °C at the frequency of 104 to 107 MHz (Heasall and Lamb 1956 Krebs and Lamb 1958) and are shown in Table 3.10, being considered accurate within 2%. For a few solvents the ratio a//2 depends strongly on the frequency as it decreases somewhat for all solvents, e g., for carbon disulfide a//2/ (10-15 s2 nr1) = 2068 at 104 MHz and 776 at 189 MHz and for dichloromethane it decreases from 779 at 107 MHz to 550 at 193 MHz... 

The addition of singlet oxygen to 2-methyl-2-pentene oeeurs via a concerted ene-type mechanism as shown in Eq. (5-46). This is entirely consistent with the small solvent effect observed for this reaction [138], When the solvent is changed from methanol to carbon disulfide, the rate changes by a factor of seven. Thus, it would appear that the activated complex does not involve much charge separation [138],... 

Thermal Desorption Thermal desorption is an alternative GC inlet system particularly used for VOC analysis. However, the analytes subjected to thermal desorption must be thermally stable to achieve successful analysis. Otherwise, decomposition occurs. This technique is mainly used for determination of volatiles in the air. Such a methodology requires sample collection onto sohd sorbents, then desorption of analytes and GC analysis. Traditionally, activated charcoal was used as a sorbent followed by extraction with carbon disulfide. However, solvent desorption involves re-dilution of the VOCs, thus partially negating the enrichment effect. Therefore, the sampling method is to pump a sample of gas (air) through the sorbent tube containing certain sorbents in order to concentrate the VOC. Afterwards, the sample tube is placed in thermal desorber oven and the analytes are released from the sorbent by application of high temperature and a flow of carrier gas. Additionally, desorbed compounds are refocused in a cold trap and then released into the GC column. Such a two-step thermal desorption process provides a narrow chromatographic band at the head of the column. 

Naphthalene can be acetylated by acetyl chloride in the presence of aluminum chloride. The orientation of substitution is determined by the particular solvent used predominantly alpha in carbon disulfide or solvents like tetrachloroethane, predominantly beta in nitrobenzene. (The effect of nitrobenzene has been attributed to its forming a complex with the acid chloride and aluminum chloride which, because of its bulkiness, attacks the roomier beta position.)... 

Dossing and Ranek reported on liver damage in chemical workers exposed to low levels of carbon disulfide, isopropanol, toluene, and other chemicals in trace quantities. The researchers suggested that the liver injury was caused by the combined action of organic solvents and compared it to the known synergistic effect of isopropanol on the hepatotoxic-ity of carbon tetrachloride. I26 ... 

Occupational exposure to mercury (0.08) and chemical solvents, including styrene (2.95), tetrachloroethylene (3.40), /j-hexane (3.90), toluene (2.73), and carbon disulfide (1.94), has been shown to impair color vision in exposed workers J48l Color vision impairment was also observed for those exposed to solvent mixtures at levels below TLV values. I49l No explanation was offered by the authors for the observed mixture effect. 

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