Metaphosphoric acid esters

The generation of alkyl-substituted monomeric metaphosphoric acid esters (254) has been described using two different methods and the metaphosphate produced spontaneously self-condensed to give polymeric P—O—P bonds, hi the presence of styrene polymerization is avoided and happing occurs instead to give a diastereomeric mixture of 2-alkoxy-l,3,2-dioxophospholane-2-oxides with (254 R = Me).232 Pyridine A -oxidc-tricthylaminc mixtures individually or together catalyse the phosphorylation of... 

Phosphoric acid amide esters from metaphosphoric acid esters Activation of amino groups s. 13, 354 PO- P(OH)N<... 

Esters of monomeric metaphosphoric acid like 147 are just as unisolable as metaphos-phoric acid itself or its anion. All the metaphosphoric esters described in the previous literature1011 are probably actually mixtures of oligomeric metaphosphoric esters, or well defined compounds such as cyclic trimetaphosphate. 

A further indication of formation of monomeric metaphosphoric esters or monomeric metaphosphoric acid itself by gas phase fragmentation comes from the behavior of 3-oxo-2-butyl phosphates in the mass spectrometer 1U). 

Esters of metaphosphoric acid are known. Ethyl metaphosphate, C2HsP03, was prepared by heating dry ethyl acetate with phosphoric oxide and extracting the product with ether and warm alcohol, from which the ester was precipitated by ether.4... 

Catalysts having a very acid nature such as metaphosphoric acid, arsenious acid, boric acid, or salts of these acids have been proposed. The addition of copper as such or as the formate serves to promote the reaction.190 Reaction chambers extremely resistant to corrosion must be tised. Catalysts such as zinc arsenite. or zinc or chromium metaphosphatc having a highly acidic nature are claimed to be effective in the formation of organic acids from carbon monoxide and alcohols at temperatures of about 300° C. and a pressure of 200 atmospheres. Even with such acidic catalysts considerable quantities of esters are stated to be formed.101... 

D-Glucose and acetone, with a wide variety of catalysts, for example, 1-2% hydrogen chloride, zinc chloride and 85% phosphoric acid, anhydrous copper(II) sulfate, concentrated sulfuric acid, cation-exchange resins, or the ethyl ester of metaphosphoric acid, react to give 1,2 5,6-di-O-isopropylidene-a-D-glucofuranose (24). A comprehensive survey of the evidence, and confirmation of the furanose structure of the diacetal (24) was provided by Anderson, Charlton, and Haworth, nearly 30 years after the initial preparation of the diacetal. The diacetal has been used extensively for the preparation of C-3 substituted D-glucose derivatives and 3-a- and 3- 3-linked disaccharides. 

METAPHOSPHORIC ACID (7664-38-2) A medium-strong acid. Violent reaction with strong bases. Violent reaction if water is added to concentrated acid. To dilute, always add acid to water heat will be generated. Reacts violently with solutions containing ammonia or bleach, azo compounds, epoxides, and other polymerizable compounds. Reacts, possibly violently, with amines, aldehydes, alkanolamines, alcohols, alkylene oxides, amides, ammonia, ammonium hydroxide, calcium oxide, cyanides, epichlorohydrin, esters, halogenated... 

OCCURRENCE AND ISOLATION. Protoveratrine was first obtained by Salzberger (53) from the rhizomes of V. album. This ester-alkaloid may be isolated from plant material by the so-called metaphosphoric acid ... 

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