Chloride retention

Stainless steel surfaces swabbed with trichloethane immediately before insertion in the XPS spectrometer, consistently showed evidence of chloride retention in their Cl(2p) spectra, even after exposure to a spectrometer vacuum of 10 Pa for 2A hours at 3A-A0°C. Figure 5(a) shows such a spectrum. From the Cl(2p) spectral envelope, two sets of Cl (2p 3/2-1/2) doublets were derived by deconvolution. The more intense doublet "1" is assigned to organically-bound chlorine, being close in energy to chlorine bound in some aliphatic hydrocarbons. The Cl(2p 3/2) line labelled "2" corresponds closely to the binding energies. . ... 

Answer 4.15 (i) The chemicals are readily available. The chloride is fairly insoluble in organic solvents and it is possible that chlorine is retained in the product, (ii) There is no need to make the alkali metal alkoxide, as the alcohol is the starting material. The metal may need careful cleaning and there may be the need for heating and a catalyst. One product is a gas. (iii) The lanthanide silylamide has to be prepared first. Because of the bulky nature of the ligand, it may be inert to substimtion, but there are no problems with chloride retention and the reaction should be clean. 

Synthesis of alkoxides from LnCls is often complicated by chloride retention from the starting material, and for this reason they are often made by alcoholysis of Ln(N(SiMc3)2)3. 

Many alkoxides in particular have been known since the 1960s, but interest in them has been stimulated recently by their potential use as precursors for deposition of metal oxides using the sol-gel or MOCVD process. A review covering the literature to 1990 has appeared. " Traditionally, alkoxides are made by salt-elimination reactions of lanthanide chlorides with alkali metal alkoxides (or aryloxides) which sometimes causes chloride retention... 

Figure 8.1 Chromatogram of ethyl chloride (retention time 1.22 min) and internal standard n-propanol (retention time 1.96 min.) on an Rtx-BACl column (30 mx 0.32 mm i.d., 1.8 pm). Static headspace sampling following a 5-min equilibration time at 70 °C and isothermal GC separation at 45 °C for 3.5-min. Note that ethyl chloride and ethanol have the same retention time.

Table 6.9. Relationship of chloride retention time and the affinity of the acid eluent for the resin. ...

The intrinsic activity of the bifunctional system has been increased by balanced improvements to both the Pt metal centres by increasing their dispersion, and improved stability of dispersion through improvements to the defect structure and purity of the alumina support, especially iron and sodium levels, for instance, by using alumina derived from the Zeigler process.90 This led to better acid site strength distributions, and improved chloride retention. In addition, reduced levels of iron led to lower rates of coking. 

Amacher, M.C., H.M. Selim, and I.K. Iskandar. 1990. Kinetics of mercuric chloride retention in soils. J. Environ. Qual. 19 382-388. 

Budde RA and Crenshaw TD (2003) Chronic metabolic acid load induced by changes in dietary electrolyte balance increased chloride retention but did not compromise bone in growing swine. J Anim Sci 81 197-208. 

Vinyl chloride Retention of superior electrical properties while increasing softening point to 215°C... 

Membrane retentions to inorganic ions q>an the entire spectrum. Sodium chloride is used universally as a test solute, and membranes are available commercially with < 10% to >99% sodium chloride retention. Most other ions have higher retentions on a given membrane than does sodium chloride, and calcium, magnesium, sulfate, and other divalent ions always are retained to a much higher degree than is sodium chloride. 

A much higher resolution between fluoride and chloride is obtained by using a CarboPac PAl-type stationary phase. Compared to nanobead-agglomerated anion exchangers such as lonPac AS4A-SC, this separator column, which was initially developed for the analysis of carbohydrates, exhibits a signiflcantly higher capacity. As a result, chloride retention increases to more than 20 min. 

The successfiil isolation of tiie first lanthanide alkyls reported in 1973 had to await recognition tiiat bulky alkyl groups such as CH2Ph, CH2SiMe3, and CH(SiMe3)2, which also blocked j8-elimination patiiways, were necessary. Even so, it has not always been possible to isolate compounds of these groups across file lantiianide series. A further key step has involved the recognition that in many cases, alkyls cannot be obtained by direct synthesis from a lantiianide halide and a metal alkyl (e.g., RLi), in some cases, because of chloride retention in the reaction product, so that alternative synthetic pathways have been devised, often unique to each family of alkyls. 

Heat coagulation requires slight acidity and an electrolyte. Normal urine may provide the latter by its 1 per cent, content of NaCl, but urine from subjects of chloride retention may be so deficient in NaCl that any protein present will not coagulate on heating. To avoid this serious fallacy the modified form of the heat coagulation test has been devised, and should be used in all routine urine analysis. 

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