Chloride ions opening

The ideal size of the cation relative to the size of the anion for each of the voids can be determined by trigonometry. For example, a cation will fit snugly into an octahedral void if it is 0.41 times the size of the anion. If it is significantly larger than that, it may not be possible to fit the cation into the closest-packed array. This is the case for compounds such as cesium chloride, where the cation has an ionic radius of 1.67 A and the anion has a radius of 1.84 A (thus, the ratio is 0.91). In this solid, the chloride ions open up to form the simple cubic packing shown in Figure 16. 

The reaction of 6-0-acetylsucrose with sulphuryl chloride in chloroform/pyridine gave, after dechlorosulphation and acetylation, a mixture of (19) and (20). The chlorine atoms at C-4 in these compounds were postulated to be derived from the chloride ion opening of the isomeric C-3, epoxides. Compound (20), after... 

Preparation of Pillared Clay Catalysts. PAG products are used for the preparation of zeolite-like catalysts by intercalation, the insertion of Al polycations molecules between the alurninosiHcate sheets of clay (3,33). Aqueous clay suspensions are slowly added to vigorously stirred PAG solutions, and the reaction mixture is aged for several hours. The clay is separated from the PAG solution and washed free of chloride ion. The treated clay is first dried at low temperature and then calcined in air at 450—500°G, producing a high surface area material having a regular-sized pore opening of about 0.6 to... 

The azidohydrins obtained by azide ion opening of epoxides, except for those possessing a tertiary hydroxy group, can be readily converted to azido mesylates on treatment with pyridine/methanesulfonyl chloride. Reduction and subsequent aziridine formation results upon reaction with hydrazine/ Raney nickel, lithium aluminum hydride, or sodium borohydride/cobalt(II)... 

OKO-l,3,7-triazanaphthalene (450) forms acyloxy derivatives in situ with phosphorus oxychloride and pentasulfide which undergo nucleophilic displacement with chloride ion and with a complex sulfide ion, respectively, to form the 4-chloro and 4-thioxo derivatives. The 4-carboxymethylthio compoimd failed to undergo the ring-opening reaction (see below) characteristic of more activated azino- and diazino-pyrimidines, but it did yield about 10% of the 4-0X0 displacement product. 

A) Preparation of 1-Methyl-2-Picolinium Chloride 98 ml of cx-picoline is dissolved in 200 ml of methanol, cooled and 85 ml (at -68°C) of methyl chloride is added. The solution is charged to an autoclave, sealed and the nitrogen pressure of 300 psig is established. The mixture is heated at 120° to 130°C for 2 hours, cooled and opened. The resulting solution is then evaporated to dryness in vacuo, yielding a residue of 110 g. This residue is then dissolved in 50 ml of water and extracted with two 50 ml portions of ether. The aqueous phase is then diluted to 150 ml with water and an assay for ionic chloride is performed which indicates the presence of chloride ion equivalent to 721 mg/ml of 1-methyl-2-picolinium chloride. 

Sintered PVC separators for open stationary batteries are produced in the same way as the corresponding starter battery version (Sec. 9.2.2.2). Their brittleness and thus difficult processability are disadvantages, as is their relatively low porosity the concerns about release of chloride ions and subsequent increased corrosion are to be considered here as well. On the other hand,... 

The induced reduction of chlorate can be inhibited by iodide, bromide and chloride ions. The effectiveness of these ions is about 400 10 1 in the given order. The order and the magnitude of the effect agree fairly well with the catalytic activity of these ions in the arsenic(III)-cerium(IV) reaction. This inhibition by halides is presumably connected with the opening of a new two-electron route for the arsenic(III)-cerium(IV) reaction. 

A variety of ie.so-epoxidcs could be selectively ring-opened this way with e.e. s as high as 97% [28], The azides can be converted to 1,2-amino alcohols, which are very desirable synthetic intermediates. Surprisingly, the mechanism of the ARO (asymmetric ring-opening) was more complicated than expected [29], First, it turned out that the chloride ion in Cr-salen was replaced by azide. Secondly, water was needed and HN3 rather than Me3SiN3 was the reactant nucleophile. Thirdly, the reaction rate was found to be second order in catalyst concentration, minus one in epoxide (cyclopentene oxide), and zero order in HN3 [30],... 

Benzodiazepines reduce fibrinogen binding and platelet aggregation Central Nervous System Acts as sedative-hypnotic, opens ion channel, chloride ion... 

A more detailed evaluation of the diverse structures proposed for the secondary species goes beyond the scope of this review. We mwely emphasize that the ESR results provide detailed evidence for the nature of the radical center, but fail to elucidate the cationic site. The identity of this center is left to secondary considerations or speculation. We also note that any alternative structure has the virtue of not contradicting the ab irutio calculations the potential c ture of chloride ion has precedent in the nucleophilic substitution at a cyclopropane carbon (see Section 7). Another type of ring-opened structure has been postulated as an intermediate in the aminium radical cation catalyzed rearrangement of l-aryl-2-vinylcyclopropanes (see Section 5). 

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