Carbon tetrachloride, as a solvent

One patent (64) describes an extraction method to remove both trichloropropane and tetrachloropropyl ether from the dichi orohydrin solution by the use of carbon tetrachloride as a solvent. In this way the by-products are removed from the aqueous phase iato an organic phase from which they can be separated by distillation and disposed of ia a safe and proper manner. 

Prior to our original report7 on this method, acceptable and general preparative routes to a-iodocycloalkenones had not been described. Treatment of a p-substituted cycloalkenone with trimethylsilyl azide and a mixture of iodine and pyridine sequentially in dichloromethane has now been reported as a method for the preparation of p-substituted-a-iodocycloalkenones.8 The combination of iodine and pyridinium dichromate has also been reported to provide a-iodoenones from enones as well as from ethynyl carbinols.9 10 Some successes have also been achieved with enones and iodine azide (IN3)11 and iodine/ceric ammonium nitrate.12-14 The submitters first variant5 of the present procedure used carbon tetrachloride as a solvent. In this procedure this solvent has been replaced with the more benign diethyl ether. 

To elevate / -selectivity in the nitration of toluene is another important task. Commercial production of p-nitrotoluene heretofore leads with a twofold amount to the unwanted o-isomer. This stems from the statistical percentage of o m p nitration (63 3 34). De-laude and co-authors (1993) enumerate such a relative distribution of the unpaired electron densities in the toluene cation radical ipso 1/3, ortho 1/12, meta 1/12, and para 1/3. As seen, the para position is the one favored for nitration by the attack of NO (or N02) radical. A procedure was described (Delaude et al. 1993) that used montmorillonite clay-supported copper (cupric) nitrate (abbreviated as clay cop) in the presence of acetic anhydride (to remove excess humidity) and with carbon tetrachloride as a solvent, at room temperature. Ni-trotoluene was isolated almost quantitatively with a 23 1 76 ratio of ortho/meta/para monon-itrotoluene. 

II. Moisture Determination in Propellants and Explosives by Distillation Method 102.1.3, Prescribed by MIL-STD-286B (1 Dec 1967). Although this procedure is similar to the one described under Dynamite in Vol 5, p D1620-R, we are describing it because it uses trichloroethylene (in lieu of carbon tetrachloride) as a solvent and a lOOg (in lieu of 50g) sample. 

The use of carbon tetrachloride as a solvent in diketone irradiations is dangerous since intermediate radicals can abstract chlorine giving trichloromethyl radicals which can result in formation of complex mixtures. In a study 146) of the irradiation of 68 in CCI4, products included (inter alia) reduced 68 and the trichloromethyl compound 186. 

Indirect determinations of the formal oxidation potential of Bk(IV)-Bk(III) couple in sulfuric and nitric acids have been made by tracer measurement. From the Bk(IV)/Bk(III) ratios and the corresponding Ce(IV)/Ce(III) ratios at equilibrium conditions one can calculate the oxidation potential of the Bk(IV)-Bk(III) couple. The Bk(IV)/Bk(III) ratio can be determined by extracting Bk(IV) by an appropriate organic solvent. The formal oxidation potentials of the Bk(IV)-Bk(III) couple in IN and 0.5N sulfuric acid were found to be 1.42 and 1.44 volts using trilaurylmethylammonium sulfate in carbon tetrachloride as a solvent. In 6N nitric acid the oxidation potential of the couple was found to be 1.56 volts by using 0.18M tributylphosphate. Whereas, in IN to 2N nitric acid berkelium was not oxidized by cerium(IV). 

The pH value for which 50% of metal as its chelate is extracted, i.e., D = 1, and for [H2L] = 1, is equal to log Kex)/n- This is termed pH 1/2, and has a value characteristic for the particular reagent, solvent, and the metal ion being determined. For example, in the case of metal extraction in the form of dithizonates using carbon tetrachloride as a solvent, the pHj/2 values for Pb(II), Zn(II), In(III), and Bi(III) are 8.0, 5.0, 3.8, and 2.0, respectively. Similar considerations apply to other chelating reagents as, e.g., 8-hydro-xyquinoline, acetylacetone, and thenoyltrifluoroace-tone. Such relationships are often presented in graphical form (Figure 9). 

In the previous section, the C=C unit of an alkene reacted as a Br0nsted-Lowry base with a Br0nsted-Lowry acid. These are, of course, acids that have a proton (see Chapter 6, Sections 6.2.1 and 6.2.4). Can the alkene react as a Lewis base The answer is yes (see Chapter 6, Section 6.4.5). With this in mind, consider the following experiment. When cyclohexene is mixed with elemental bromine in carbon tetrachloride as a solvent, the product is frans-l,2-dibromo-cyclohexane (38) isolated in 57% yield. In this case, quite a bit of unreacted cyclohexene is recovered. 

Draw the product formed when cyclohexene reacts with diatomic bromine in carbon tetrachloride as a solvent. 

When classes of hydrocarbons, such as olefins, need to be measured, techniques such as bromine index are used. ASTM Test Method D1492, Bromine Index of Aromatic Hydrocarbons by Coulometric Titration, continues as a useful method, but D1491, Bromine Index of Aromatic Hydrocarbons by Potentiometric Titration, was withdrawn in 1985 because of health concerns regarding its use of carbon tetrachloride as a solvent. It was eventually replaced by D5776, Bromine Index of Aromatic Hydrocarbons by Electrometric Titration, which is based on D2710, Bromine Index of Petroleum Hydrocarbons by Electrometric Titration, but uses the less toxic l-methyl-2-pyrrolidinone as a solvent. 

As we saw when discussing allylic brommation m Section 10 4 N bromosuccm imide (NBS) is a convenient free radical brommatmg agent Benzylic brommations with NBS are normally performed m carbon tetrachloride as the solvent m the presence of peroxides which are added as initiators As the example illustrates free radical bromi nation is selective for substitution of benzylic hydrogens... 

What problem is encountered with spectra interpretation when a solution of the analyte in a particular solvent is analyzed Why does the use of carbon tetrachloride as the solvent minimize... 

Uses Carbon tetrachloride is a clear, colorless, volatile liquid with a characteristic sweet odor. It is miscible with most aliphatic solvents and is itself a solvent. Its solubility in water is low. Carbon tetrachloride is nonflammable and is stable in the presence of air and light. In the presence of flame or hot metal, carbon tetrachloride partially converts into phosgene—a highly poisonous war gas. Carbon tetrachloride is a solvent for fats and oils, and is extensively used in a variety of products such as soaps and detergents, textiles, and rubber cements. Decomposition may produce phosgene, carbon dioxide, and hydrochloric acid. 

The bromination of bicyclo[3.2.1]oct-2-ene (46) with A -bromosuccinimide under conditions which promote radical chain reactions (carbon tetrachloride as the solvent activation by UV light gave the expected allylic bromination product exo-4-bromobicyclo[3.2.1]oct-2-ene (47). On the other hand, when the related bicyclo[3.2.1]octa-2,6-diene (48) was treated with N-bro-mosuccinimide under comparable conditions (carbon tetrachloride as the solvent activation by benzoyl peroxide and visible light) no product 49 of allylic bromination was formed. Instead, the bromination resulted in the formation of ejco-6-bromotricyclo[3.2.1.0 ]oct-3-ene (50), due to participation of the C6 to C7 double bond in 48. - ... 

Esters of 3-nitropyridyl-2- and 4-pyruvic acids were examined spectroscopically (UV, IR, NMR) for possible tautomerism. Esters of 3-nitropyridyl-2-pyruvic acids exist in the solid state and in solution almost exclusively in the enol form 115 (R1 = H, OMe R2 = Me, Et). Its 4-substituted analog 116, however, exists in chloroform, dioxane and carbon tetrachloride as a mixture of 116a and 116b and exclusively as enol 116b in pyridine. The more polar solvents, as expected, favor the enol tautomer (74KG389). 

A technical palmitic- stearic acid mixture has been sulfonated thus at 25-60 C on a commercial scale, using carbon tetrachloride as sulfonation solvent. 

Tsai and Chou carried out the indirect electrooxidation of cyclohexanol by using a double mediator consisting of ruthenium and chlorine redoxes in the multiphase system. Table 13.3.24 shows that the current efficiency had the highest value at 83% using carbon tetrachloride as organic solvent. The current density decreased in order, carbon tetrachloride > chloroform > toluene > cyclohexane. The selectivity was 100% except when toluene was used as organic solvent. For this case, the concentration of cyclohexanol in carbon tetrachloride is higher than that of the other solvents. 

If the molar fractions of mononuclear complexes formed in stepwise processes are plotted as a function of the free ligand concentration, in general a single extreme is observed. Exceptions from this fairly general regularity occur in systems where the ratio of the components of the solvent mixture varies during the equilibrium measurement. For example, Vertes et al [Ve 73] employed Mossbauer examinations to follow the interaction of tin tetraiodide and dimethylformamide in rapidly frozen solutions in carbon tetrachloride as inert solvent, and showed that a plot of the sum of the molar fractions of the species SnI and Sn(DMF) J as a function of the dimethylformamide concentration exhibited two extremes. The phenomenon was explained by Nagypal and Beck [Na 75] in that a double effect occurs in the solution with an increase in the dimethylformamide concentration ... 

Bascom and Timmons have studied the hydrolysis of triethylethoxysilane with an amorphous silica surface using carbon tetrachloride as the solvent [57]. They found that no hydrolysis occurred in wet solvent or in the presence of dry filler, but proceeded rapidly at room temperature when water was present on the filler surface. The reaction rate increased abruptly at a water level corresponding to a 1 1 ratio of water to surface silanols, implying that a certain specific arrangement of water molecules is necessary. They believed this to be due to the establishment of a hydrogen bonded network allowing the acidic surface silanol species to catalyse the hydrolysis reaction. 

In a solution with carbon tetrachloride as the solvent, the compound VCI4 undergoes dimerization ... 

NIR spectra of five gases and solutions of the same organic compounds are compared in Figure 21.4. The gas-phase spectra were measured in a 20 m cell. The solution spectra were measured using carbon tetrachloride as the solvent and the concentrations of the solute were adjusted to produce maximum absorptions of 1.0. There are two noticeable differences between the gas and solution spectra the relative band intensities are somewhat different, and some of the bands in the gas-phase spectra are sharper than those in the solution. The intensities of the bands in the C—H overtone... 

Nuclear Magnetic Resonance Spectroscopy ( H NMR and NMR) Proton and carbon nuclear magnetic resonance sp>ectra (iH NMR and NMR, respectively) were obtained in a polynuclear JEOL Eclipse Plus 400 sp>ectrometer (400 MHz), using tetramethylsilane as the reference and deuterated chloroform and carbon tetrachloride as the solvent for NMR and iH NMR, respectively. i3C NMR spectrum were accumulated during 24 hours. 

Firstly, we examined the esterification with metal acetate, benzyl bromide, and catalyst 9c, 15, or 16. The reaction proceeded in the presence of these catalysts, but not in the absence of them. Therefore, their catalytic activity is apparent. The rate constants remained in the same range for all runs. Moreover, the reaction was slow (k=10 — 10 s ) because of the low nucleophilicity of acetate ion. Since the substitution by acetate did not give much information on their catalytic activity, we chose the Williamson ether synthesis with phenol, benzyl bromide, metal hydroxide, and catalyst (see Equation 1), because phenolate has high nucleophilicity and hydrophobicity [24]. In fact, the difference of their catalytic activities clearly appeared in this case as shown in Table III. Catalysts made the reaction markedly faster than that without them. In carbon tetrachloride as a nonpolar solvent, the catalytic activity of 9c increased remarkably when larger ions were used and the maximum rate constant was recorded in the RbOH system. This behavior of 9c resembles that of calix[6]arene derivative 16 because both 9c and 16 have the same affinity for large ions. The other experiments were performed in... 

CH2CI2. A colourless liquid with a chloroform-like odour b.p. 4I°C. Prepared by heating chloroform with zinc, alcohol and hydrochloric acid manufactured by the direct chlorination of methane. Decomposed by water at 200°C to give methanoic and hydrochloric acids. Largely used as a solvent for polar and non-polar substances, particularly for paint removal (30%), dissolving cellulose acetate and degreasing (10%). It is more stable than carbon tetrachloride or chloroform especially towards moisture or alkali. It is somewhat toxic. U.S. production 1981 280000 tonnes. 

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