Phosphite Structures

Cavity structures are also formed by some phosphites. Large 24-ring channels of cross section 11.0 X 11.0 A are formed in crystalline Zn3(HP03)4[(C4Hi2N)2], for example [170]. Organically tern-plated open-framework structures containing (HP03) anions have been reviewed [171]. 

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The phosphitylation procedure activated by tetrazole led to the phosphite structure (step a) which was effectively oxidized by TBHP to yield the corresponding phosphate (step b). Finally all 2-cyanoethyl protecting group were removed by the action of DBU in the presence of the silylating reagent bis(trimethylsilyl)acetamide BSA (step c). The latter is indispensable to secure total deprotection. 

Hypophosphorous Acid—Phosphorous Acid—Hypophosphites and Phosphites, Structure and Tautomerism—Meta- and Pyro-phosphorous Acids—Detection and Estimation of Phosphites and Hypophosphites—Hypophosphoric Acid—Detection and Estimation of Hypophosphates. 

Catalyst deactivation essentially results from the formation of cyanides, such as Ni(CN) or CuCN. The role of (he phosphite ligands in Ni(0) caralysis is to prevent such inhibition pathways. Tlie phosphite structure is very critical in achieving the best catalytic activity [Ig). Tri(/J / butylphenyl)phosphiie (1) is, for example, much more active than triphenylphosphitc (2). 

Compounds j4 and 5, two of the experimental processing stabilizers listed in Figure 2, remained essentially unchanged when exposed neat to an air atmosphere of 80% relative humidity at room temperature for 50 days. This is in contrast to some of the commercial compounds such as 1 1, and 3 which hydrolyze rapidly under the same conditions (Table V). Hydrolysis tests at 50°C/80% relative humidity show that compounds 4 to 9 inclusive are much more resistant to hydrolysis than 3 (Table VI). Of particular interest in this respect is the dramatic increase in hydrolytic stability of compounds 6 and 9 all of which have tertiary amino functions in their phosphite structures capable of preferentially neutralizing... 

Nickel, diiodotris(trimethyl phosphite)-structure, 45 Nickel, hexaammine-reactions, 27 Nickel, hexaaqua-reactions, 204... 

Dialkyl H-phosphonates furnish in general two types of metal salts alter appropriate treatment. The first type is obtained through deprotonation of the hydrogen atom of the P-H group and has a phosphite structure. 

In this section, the alkaline metal derivatives of the first type of metal salts of dialkyl H-phosphonates are described, namely, those having phosphite structure. The reactivity of these metal salts has been already discussed in the preceding chapters, since in most of the cases they are generated as intermediates and used in situ as phosphorylation reagents. 

The phosphite structures (6.302) are retained only by triesters and a few diester salts. Monoesters and most diesters exist in the tetrahedral phosphonate form. 

PET (75)/PBT (25)/various phosphite condensing agents (0-5 %) Internal mixer at 275-280 °C/GPC/DSC/ torque rheometry/viscometry/selective solvent extraction/phosphoms analysis/ effect of PET end-group concentrations/ FTIR for end-groups concentration/effect of phosphite structure/model study with OH -t COOH-terminated acrylic polymer/ detailed mechanistic study Jacques et al. 1993, 1996a, b, 1997... 

The reaction occurs with stoichiometry 1 1. Only sometimes stoichiometry somewhat differs fktm this ratio. For example, cumyl hydroperoxide oxidizes triphenyl phosphite in the stoichiometric ratio from 1.02 1 to 1.07 1, depending on the ratio of reactants. The reaction is bimolecular, trialkyl phosphites react with ROOM more rapidly that with aryl phosphites (see Table 11.1), and the activation energy depends on the phosphite structure and changes in an interval from 25 to 77 kJ/mol. The structure of hydroperoxide weakly reflects the rate of its reaction with phosphite, which is seen from the data for the reaction (303 K, QH5CN)... 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

Curious products isolated by Bailey and Evans from the reaction of benzotrisfuroxan with triphenyl phosphine have been examined by X-ray crystallography by Cameron and Prout. The structures (44-46) were determined.A molecular complex of trialkyl phosphate with benzotrisfurazan is formed using a trialkyl phosphite as reducing agent. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

Although the phosphorous acid esters are often referred to as such, they are not true phosphites [72]. To be more precise, they exist almost exclusively in the phosphonate form of pentavalent phosphorus, as shown in structures (5) and (6) ... 

X-ray crystallographic analyses of the structures show that the P-S bond distance vary over one-half of an Angstrom (2.36-2.88 A). The derivatives were generated using procedures similar to those utilized to form pentaoxyphosphoranes with P-N bonds, that is (i) the oxidation of sulfur containing cyclic chlorophosphines with a quinone or (ii) treatment of phosphites with the sulfur-containing diol in presence of N-chlorodiisopropylamine. Two typical examples of these synthetic protocols are shown in Scheme 10. 

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