Chloride impurity

Acetic 31 6 L stainless steel Excess acetic anhydride in glacial acetic acid can accelerate corrosion chloride impurities (ppm levels) can cause pitting and stress-corrosion cracking... 

Heating must be terminated when two-thirds of the nitrate has decomposed since explosive nitrogen trichloride may be formed from traces of ammonium chloride impurity. 

Given the strontium chloride crystal, write the defect reaction(s) expected if lithium chloride is present as an impurity. Do likewise for the antimony chloride impurity. Also, write the defeet reactions expected if both impurities are present in equal quantities. 

It is also reported that anions can be preferentially adsorbed in the CBD process, which leads to different levels of impurities. Hashimoto et al.28 compared the iodide and chloride impurities in the CBD CdS thin films when the films were deposited from an aqueous solution of iodides and chlorides, respectively. The CdS films deposited using iodide contained 3% iodine, whereas the CdS grown from chlorides contained less than 1% chlorine. 

Dyson et al. also showed that it is important to account for the chloride concentration in the ionic liquid [87]. These authors proved that chloride impurities, resulting from the synthesis of the ionic liquid, have a strong influence on hydrogenation activity. This was demonstrated by a comparison of hydrogenation activity in [BMIM][BF4] which was made via the classical ion-exchange reaction (metathesis route, Scheme 41.2 (1)), with a chloride concentration of 0.2 mol kg-1, and the same ionic liquid which was made by direct conversion of... 

Due to chloride impurities of the ionic liquids in use, all selectivities were lower than the selectivities in pure water. Surprisingly, the selectivity increased from 76 to 90% and from 85 to 90% with reuse of the ionic catalyst solution based on [BMIM][BF4] and [BPy][NTf2], respectively. 

Halide impurities may have a negative effect on the rate of a hydrogenation reaction, as was observed by Cobley et al. These authors studied the asymmetric hydrogenation of 2-methylenesuccinamic acid using [(S,S)-(Et-DuPHOS)Rh-(COD)]BF4 as catalyst [76]. They were able to obtain a 30-fold acceleration upon removal of a chloride impurity from the substrate (Scheme 44.9). 

Dyson recently warned that chloride impurities present in ionic liquids prepared by the classical metathesis reaction may cause severe catalyst inhibition. This may be aggravated by the fact that metal-chloride dissociation is disfavored in ionic liquids, in spite of their polar nature [77]. 

D.8.2. F Impurity. It has been observed that [MIMjSbFg produced a small amount of fiuoride ion over time because of its sensitivity to air. Furthermore, residual chloride impurities have been found to exert a large influence on the physical properties of ionic liquids 115). 

D.8.3. Cl Impurity. Trace amounts of chloride impurities, which may be present at levels between 0.1 and 0.5mol/kg, have significant effects on the physical properties of ionic liquids, such as viscosity and density. Increases in viscosity are of particular concern in biphasic processes because of the formation of emulsions that affect the interface between the two phases 88). 

Potassium tetracyanoplatinate may be prepared as described elsewhere in this volume,3 or commercial material may be used after chloride impurities are eliminated by two recrystallizations from distilled water. An aqueous solution at... 

Two impurities are apparent in the product, iron (III) chloride and hexachloroethane. Both are more volatile than zirconium tetrachloride. Nevertheless, if both are to be removed from the product, considerable product inevitably sublimes beyond K. The amount of hexachloroethane impurity is roughly a function of temperature, since runs made at 450° yield virtually none, whereas if the furnace is allowed to go much above 500°, appreciable quantities are formed. The amount of iron (III) chloride impurity depends on the purity of starting materials. ... 

Redox Processes. Among the most serious impurity problems for electrochemical applications is the contamination of electrolytes with halides. Since they easily react anodicaUy they can be expected to reduce the size of the electrochemical window drastically but the readiness of their anodic decomposition can be used for a decontamination procedure. This was recently described by Li et al. [133] for chloride impurities. They found that, in combination with a subsequent removal of the gaseous product Qi by absorption, electrochemically pure ionic liquids can be obtained. Ethylene was bubbled through the solution to absorb the chlorine gas. Without such an absorption step, the soluble complex CI3 - was formed which could not be removed by vacuum distillation. Both formation and subsequent removal of the complex Cl j can be easily followed spectrometrically due to a strong band of this species at 302 nm. 

In the fresh electrolyte a first anodic step starts at 1500 mV. This could be a hint for chloride impurity. Since this signal almost vanished for the regenerated ionic liquid, it can be assumed that the procedure presented is suitable also for purifying fresh ionic liquids. 

Both steps require high temperature and considerable reaction time but give 80-90 percent yields. The major problem areas are chloride impurities in the final product and the excessively fine particle size of the final product. Because TATB is highly insoluble in most solvents, it is difficult to purify the... 

The introduction of the novolac epoxy corrected the Tg problem and partially corrected the moisture resistance problem. Advances in the novolac epoxy technology have continued to improve the moisture resistance, as noted earlier in Figures 2 and 3. Corrosion due to chloride impurities, however, continued to be a very severe problem until the introduction of low chloride resins and hardeners by the Japanese resin suppliers. Figure 4 (Bates, Vm., Horton-Thiokol,... 

The reaction can be carried out more conveniently and in equally good yields by substituting zinc cyanide for the hydrogen cyanide (70-SK)%)/ Potassium chloride impurity in this catalyst is necessary/ Sodium cyanide has also been used/ With these modifications, phenols and ethers as well as hydrocarbons react (cl. method 140). 

Argentiometric procedures cut across the classification boundaries to some extent, in that volumetric, gravimetric or colorimetric methods may be applied to the analysis of particular silver salts. However, the argentiometric methods for the determination of phosgene are specific to the chloride ion, and as such are susceptible to other chloride impurities (especially dichlorine or hydrogen chloride). The details of these methods have been reviewed elsewhere [1255], and since they are neither specific to phosgene, nor in any obvious way amenable to automation, they will not be reviewed here. 

Thus, over a period of eighty years, no single study of the COClj-AlClj system has agreed with any other clearly, a fresh examination of the problem is required. However, the interaction between aluminium(III) chloride and phosgene has formed the basis of two patents for the purification of aluminium(III) chloride by removal of iron(lll) chloride impurities, which apparently are not soluble in the COClj-AlClg system [174b,2199a]. 

H2S can have significant effects on dense Pd membranes resulting in some instances in complete membrane failure in short periods of time. Short of replacing Pd with other metals, it is imclear at this point how one overcomes the problem of Pd sensitivity to sulphur and chloride impurities, which are unfortunately present in many industrial hydrocarbon streams. 

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