Chloride ion attachment

In each of these complex ions there are six groups (water molecules and chloride ions) attached to the chromium ion. Chromic ion can be oxidized to chromate ion or dichromate ion by strong oxidizing agents, such as sodium peroxide in alkaline solution. 

The nitro group has a strong dipole, and therefore chloride ion attachment is a possibility. 

Fig. 5 shows a comparison based on extracted ion current profiles of ionization efficiencies for Nifedipine. Included are positive ion APCI and ESI, along with negative ion chloride ion attachment APCI. As predicted. Nifedipine can be readily ionized by all three LC/MS ionization processes. The mass spectra of Nifedipine obtained using these three ionization processes are shown in Fig. 6. Positive ion ESI and APCI both show [M + H] at m/z 347 (note the [M + Na] ion at m/z 369 in the ESI spectrum) with some fragmentation (the ion at m/z 315 likely results from loss of methanol from one of the methyl ester groups). The negative ion chloride ion attachment spectrum shows the anticipated [M + Cl] at m/z 381, along with a [M + Cl - HCl] ion at m/z 345. Note that there is also a relatively small [M + TFA] (TFA) ion at m/z 459. If TFA is present in the HPLC...

Fig. 5 Extracted ion current profiles from LC/MS analyses of equal quantities of Nifedipine (A) m/z 347 from positive ion APCI (B) m/z 347 from positive ion ESI (C) m/z 381 from negative ion chloride ion attachment APCI.

HPLC-APCI/MS Weakly polar to medium polar, small to medium sized molecules With chloride ion attachment poorly ionizable molecules with strong net dipoles Gas phase ionization [M -P H]+, M+, [M - H] Can be used with chloride ion attachment... 

FIGURE 5 Negative ion attachment (Cl ) mass spectra at retention time 13.7 minutes (top), and with background subtraction (bottom). Note chloride ion attachment pseudomolecular ion at m/z 262 with correct isotope ratio for a single chlorine. 

Norwood, D. L., Feinberg, T. N., Cain, T. C. and Lennon, J. D. Applications of chloride ion attachment LC/MS in pharmaceutical development. Presented at the 50th Southeastern Regional Meeting of the American Chemical Society, November 4—7, Research Triangle Park, NC, 1998. 

You see, the formula NaCl only shows us the ratio by which the anions and cations can be found in the crystal. The fact that there are no subscripts in the formula tells us that for every 1 sodium ion in the crystal, there is 1 chloride ion. If we have a crystal of CaCl2, we don t really have 2 chloride ions attached to or combined with each calcium ion in some type of special bond. All that formula really tells us is that the ratio of calcium ions to chloride ions is 1 2. 

Cole, R. B. Zhu, J. H. Chloride ion attachement in negative ion electrospray ionization mass spectrometry. Rapid Commun. Mass Spectrom. 1999,75(7), 607-611. Appfel, a. Chakel, J. A. Fischer, S. Lichtenwalter, K. Hancock, W. S. Analysis of oligonucleotides by HPLC-electrospray ionization mass spectrometry. Ana/. Chem. 1997, 69(7), 1320 1325. 

Cole, R. B. Zhu, J. Chloride ion attachment in negative ion electrospray ionization mass spectrometry. Rapid Commun. Mass Spectrom. 1999,13, 607-611. 

CoCl3(NH3)3] consists of three ammonia molecules and three chloride ions attached to a central Co ion it is electrically neutral. The name of this neutral complex is triamminetrichloridocobalt(III). 

Carbonyiation of butadiene gives two different products depending on the catalytic species. When PdCl is used in ethanol, ethyl 3-pentenoate (91) is obtained[87,88]. Further carbonyiation of 3-pentenoate catalyzed by cobalt carbonyl affords adipate 92[89], 3-Pentenoate is also obtained in the presence of acid. On the other hand, with catalysis by Pd(OAc)2 and Ph3P, methyl 3,8-nonadienoate (93) is obtained by dimerization-carbonylation[90,91]. The presence of chloride ion firmly attached to Pd makes the difference. The reaction is slow, and higher catalytic activity was observed by using Pd(OAc) , (/-Pr) ,P, and maleic anhydride[92]. Carbonyiation of isoprcne with either PdCi or Pd(OAc)2 and Ph,P gives only the 4-methyl-3-pentenoate 94[93]. 

The shape of a vessel determines how well it drains (Figure 53.7). If the outlet is not at the very lowest point process liquid may be left inside. This will concentrate by evaporation unless cleaned out, and it will probably become more corrosive. This also applies to horizontal pipe runs and steam or cooling coils attached to vessels. Steam heating coils that do not drain adequately collect condensate. This is very often contaminated by chloride ions, which are soon concentrated to high enough levels (10-100 ppm) to pose serious pitting and stress corrosion cracking risks for 300-series austenitic stainless steel vessels and steam coils. 

For example, Pt/Si02 catalysts are conveniently made by impregnating a silica support vith a basic solution (pH 8-9) of platinum tetraammine ions, Pt(NH3)4 (dissolved as chloride). As the silica surface is negatively charged, the Pt-containing ions attach to the SiO entities and disperse over the surface. The pH should be kept belo v 9 because other vise the silica surface starts to dissolve. 

Before crystallization, each particle of solute is solvated. As a simple example, a chloride ion in water is attached to six water molecules, as [C1(H20)6] . Being bound to a solute species limits the freedom of solvent molecules, that is, when compared with free, unbound solvent. 

As detailed in chapter 17, biological membranes are basically lipid—think fat or oil—in nature with some attached proteins. As such, these thin sheets of phospholipids and proteins are nearly impermeable to charged particles such as sodium, potassium, or chloride ions. While the isolation of the cell interior from the exterior ionic environment is critical in many ways, it is also true that controlled permeability to ions may be critical. In fact, it is the near-impermeability of biological membranes to ions that permits control of ion transport across them by certain, specific proteins. 

Ligand (264) has been prepared and complexed with Ru" to give [Ru(264)(4-Metpy)] + which protonates on the cyclam N atoms to give a series of species up to [Ru(H3264)(4-Metpy)] +. In aqueous solution, the system acts as a selective luminescent sensor for ATP (with respect to phosphate, sulfate, and chloride ions). Oxaaza macrocycles attached to the 4 -position of tpy either directly or with a spacer as in (265) have been synthesized in addition, l,10-diaza-18-... 

Scheme 6 Electrode assembly with a droplet of nitrobenzene containing dissolved iodine attached to a graphite electrode. The electrode is immersed in an aqueous electrolyte solution containing chloride ions [162].

The halide sequence is completely reversed chloride ion > bromide ion > iodide ion. This has caused us some problem, but as yet we have no explanation for it. In both cases there is enough evidence from other kinetic investigations and deuterium labelling to realize that the metal with the attached organic group R... 

The electronegativity difference between boron and nitrogen (2.0 and 3.0, respectively, on the Pauling scale) results in a polar B-N bond. The regio-selectivity of the reactions of borazines with electrophiles and nucleophiles can be understood in this context. Thus the reaction of borazine with three equivalents of HCl produces (C1HBNH2)3 in which the proton seeks out the nitrogen centres and the chloride ions become attached to boron. ... 

Figure 27-2 shows a colloidal particle of AgCI growing in a solution containing excess Ag+, H+, and N03. The surface of the particle has excess positive chaige due to the adsorption of extra silver ions on exposed chloride ions. (To be adsorbed means to be attached to the... 

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