Trivalent phosphorous compounds

The use of silver (II) salts, particularly argentic picolinate, as reagents for hydroxyl oxidation has also been disclosed recently. The reaction may be run in acid, neutral or basic media in aqueous or polar organic solvents at room or slightly elevated temperatures. Primary alcohols may be oxidized to aldehydes or acids depending on the conditions used. Amines and trivalent phosphorous compounds are more sensitive to oxidation with this reagent than are hydroxyl groups. 

Act to decompose hydroperoxides into stable molecules such as alcohols and ethers, before they can react with light to form free radicals. Main chemical classes are trivalent phosphorous compounds and thio-synergists (esters of thiodipropionic acid). Sulfur-based organic antioxidants decompose hydroperoxides by non-radical reactions. Typical peroxide decomposers are Irgafos 168, Ultranox 626, Irganox PS 800 and others. 

The addition of finely dispersed solid particles improves the IR absorption of the polymer and positively influences blowing of the preforms. Such solid particles can be obtained by the reduction of Sb3+ to metallic antimony during polycondensation by the addition of trivalent phosphorous compounds such as phosphonic acid or its esters (phosphites). However, only a slight improvement in properties could be achieved by this approach [35],... 

Pilgram et al. tried to intercept the proposed thioacyl azide with trivalent phosphorous compounds and they isolated 2,2-dihydro-l,3,4,5,2-thiatriazaphosphorines <71JHC951> but it is not possible to distinguish between a direct attack on the heterocyclic ring and attack on the thioacyl azide formed by ring opening. 

A trivalent phosphorous compound phosphene can abstract hydrogen from a C—H bond with a formation of two radicals. Thus, BAPO can produce up to four radicals upon absorption of one photon. (One absorbed einstein can lead up to four moles of reactive radicals.) This unusual feature makes BAPO a very efficient PI. °... 

Other initiators that have been used for AN polymerization include trivalent phosphorous compounds dialkylaminotita-nium, allyl molybdenum, and tungsten compounds and metal-free ammonium salts of malonates and carbazo-lides. ° °° ° All of these initiators produce PAN less efficiently with varying degrees of molecular weight and MWD control. The side reactions can be classified as given in... 

Scheme 22 Anionic poiymerization of AN using (i) anions and (ii) trivalent phosphorous compounds as initiators.

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Mitsunobu, O., Yamada, M., Mukaiyama, T. Preparation of esters of phosphoric acid by the reaction of trivalent phosphorus compounds with diethyl azodicarboxylate in the presence of alcohols. Bull. Chem. Soc. Jpn. 1967,40, 935-939. 

The thiirane part of the Dewar thiophene is not desulfurized by triphenylphosphine but isomerization to the thiophene occurs. This reaction with trivalent phosphorus compounds which are not substituted with electronegative groups is typical of Dewar thiophene. Therefore, a mechanism involving electron transfer from the phosphorous compound to the sulfur atom of the Dewar thiophene has been proposed. The reaction of Dewar thiophene with diphenylchlorophosphine proceeds via an intermediate which was isolated (124)129). 

As implied by Equation 14b, a polymer with multiple hydroxyl groups will react with pentavalent or trivalent phosphorous electrophiles to crosslink the polymer if a molar excess of the phosphorus compound is present. This was verified by Doughty, who found that phosphorous halide or sulfide/lignin reactions with a greater than 1/1 mole ratio produced insoluble products (183). If the number of moles of phosphorous compound are equal or less than the moles oflignin in the reaction, the soluble reaction product can be further reacted with mono and polyhydroxy compounds to produce flame retardant resins with film- forming capacity (185). 

The absorption and emission bands of Eu + ions show strong changes from one host crystal to another. For instance, Eu + ions emit in the violet region when incorporated into the Sr2P207 compound, while they emit in the green region in SrAl204 phosphor. This behavior is opposite to the practical insensitivity of the absorption and emission spectra of the trivalent europium ion to different host crystals. 

Phosphoric acid is a co-ordinated compound with the co-ordination number 4, and may accordingly be written H3[P04] (see section on Phosphorus in Combination ). Although the trivalent ion seldom is actually present, except perhaps in solid Na3P04, etc., it is written... 

A different approach to the synthesis of aldosyl phosphates involves the intermediacy of aldosyl phosphites [470], The reaction of the anomeric hydroxyl group, with a trivalent phophitylating reagent, furnished an anomeric phosphorochloridite, which is able to react with a hydroxyl-containing compound, to generate a phosphorous triester which, upon oxidation gives the corresponding aldosyl phosphoric triester (O Scheme 83). 

The addition of an ether linkage in the alkyl chains of dialkylphosphoric acids has been found to increase its extractive power for trivalent actinides, resulting in an extractant that is more effective from acid solutions than is HDEHP (69). Bis(hexoxy-ethyl)phosphoric acid (HDHqEP) is a compound of this type that has been studied extensively (70,71). The ether linkage may contribute to the coordination of the metal ion, resulting in the formation of a seven-membered ring. 

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