P chloride

A few methods exist for the formation of 1,2-cis isomers. Protic adds such as HC1 or AcOH in conjunction with thionyl chloride (SOCl2) furnish P-chlorides from... 

A much more systematic approach involves the use of p-chlorides carrying non-participating groups at C-2 as is exemplified by the Wolfrom synthesis of p-isomaltose octa-acetate from 1,2,3,4-tetra-O-acetyl-p-D-glucopyranose and 3,4,6-tri-0-acetyl-2-0-nitro-p-D-glucopyranosyl chloride In this work silver carbonate was used as acid acceptor and soluble silver perchlorate was fmmd to exert valuable catalytic influence, but later the perchlorate itself was used in an application to a tiisacchar-ide s mthesis which incorporated the trityl ether modification 2 ). 

Cl ] w.c = Chloride deposition rate determined using Wet Candle method [Cl ] D p = Chloride deposition rate determined using Dry Plate method... 

In this study they condensed the a-glycosyl bromide (243) with the disaccharide (245) in the presence of silver carbonate — silver perchlorate to give the a-linked tri-saccharide (241) in 58% yield or the bromide (244) with the disaccharide (246) in the presence of the mixed silver catalysts to give the a-linked trisaccharide (242) in 63 % yield. In the earlier approach, the preparation of the P-chloride (237) required a previous treatment of the a-bromide with tetraethylammonium chloride under carefully controlled conditions. 

T(ense) state to the R(elaxed) state with the liberation of protons, organic phosphate modulator (like DPG in mammalian RBCs, or ATP or GTP in fish RBCs, indicated by a bar), chloride ions, and heat. (B) 02 saturation curves for Hb showing the right shift (decrease in 02 affinity) with increases in temperature (T) and in concentrations of organic phosphate (shown as P), chloride, or protons. (C) Hill plots for 02 saturation curves in (B), showing the decreased 02 affinity in the T state induced by increased temperature or increased concentrations of organic phosphate modulator, chloride, or protons (compare 1 /KT vs 1 /KR values). Modified from Weber (1995). 

The isomeric o-aimnophenylmercurie acetate is difficult to separate from the larger amount of the p- compound which would separate with it if the filtrate from the initial crop of the p- acetate were allowed to stand. Dimroth found, however, that there was a considerable difference m the solubilities of the chlorides, so the filtrate is treated with an excess of sodium chloride solution, precipitating p-aminophenylmercuric chloride in the amorphous state, while the o-ammo chloride separates in crystalline form. The mixture is sucked off, dried, and the 0- derivative extracted with not too much warm alcohol, separating as leaflets after the solution is chilled and allowed to stand The amorphous residue of p- chloride may be boiled with alcohol or benzene, and separates from the cold solution as leaflets melting at 1880, with decomposition. 

Yasushi, O., Y. Shoji, and K. Masaki, 2004. Metal pattern formation by selective electroless metalli2ation on polypyrrole films patterned by photochemical degradation of iron (P) chloride as oxidizing agent. Synth Met 144 265. 

P-Eliminations (Equation 10.1) are the most common type of elimination reaction from transition metal complexes, and p-hydrogen eliminations from metal-alkyl complexes are the most common type of p-elimination reactions. p-Hydrogen elimination from aUcoxo and amido complexes has also been observed in a few cases. p-Alkyl elimination, p-aryl elimination, p-aUcoxide elimination, and p-chloride elimination have also been observed and have been studied carefully because of their importance as side reactions in catalytic chemistry. Although P-hydrogen elimination from metal-alkyl complexes occurs almost exclusively by migratory de-insertion pathways, p-hydrogen ehmmation from alkoxides has been shown to occur by several different pathways. 

Several examples of p-chloride elimination are shown in Equations 10.24-10.29. Reaction of vinyl chloride with cationic zirconocene-alkyl complexes (Equations 10.24a and 10.24b) forms propylene and the corresponding zirconocene-chloride complex as the initial products. Tlie final products result from polymerization of the propylene by the starting zirconocene-alkyl species, and generation of a dinuclear cationic chloride species from the resulting cationic chloride complex and a zirconocene dichloride by a less-defined pathway. The propylene is formed by the process shown in Equation 10.24b. Insertion of vinyl chloride into the zirconocene methyl, followed by p-chloride elimination from the p-chloroalkyl intermediate generates propylene and a cationic chloride complex. 

Simpler p-halide eliminations occur from late transition metal catalysts for olefin polymerization (Equations 10.25 and 10.26). Reactions of the cationic palladium-alkyl complexes occur in a similar fashion to the reactions of the cationic group 4 complexes, despite the softer nature of these species. In this case, propylene and the metal chloride are formed. Even a neutral nickel-hydrocarbyl complex (the salicaldimine complex in Equation 10.26) undergoes reactions with vinyl chloride that involve insertion followed by P-chloride elimination. 

The generally applied esterification method (Scheme 2/B) suffers from certain drawbacks, especially the use of relatively expensive P-chlorides (e.g., 5) and also the use of a base to remove the hydrogen chloride formed as the by-product. Hence, this method is not atomic efficient and environmentally not friendly. It was thus a challenge for us to try the direct esterification of phosphinic acids with alcohols under MW conditions. It was our delight that a series of phosphinic acids underwent esterification with alcohols with longer chain at around or above 200°C on MW irradiation (Scheme 3) [33-37]. 

The reaction of equimolar quantities of 1,8-bistrimethylstannylnaphthalene and GaCb in toluene yields a stannogallacycle (34) namely bis()i-l,8-naph-thalenediyl)(p-chloride)methyltin(IV)chlorogallium(III). This has a folded... 

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