Phosphorus acid anhydrides mixed

The preparation of fluonnated acid anhydrides can be done by simple methods Phosphorus pentoxide removes a molecular equivalent of water from tnfluoroacetic acid and tnfluoromethanesulfonic acid and forms the mixed anhydride [Si] (equation 53)... 

Starches have been chemically modified to improve their solution and gelling characteristics for food applications. Common modifications involve the cross linking of the starch chains, formation of esters and ethers, and partial depolymerization. Chemical modifications that have been approved in the United States for food use, involve esterification with acetic anhydride, succinic anhydride, mixed acid anhydrides of acetic and adipic acids, and 1-octenylsuccinic anhydride to give low degrees of substitution (d.s.), such as 0.09 [31]. Phosphate starch esters have been prepared by reaction with phosphorus oxychloride, sodium trimetaphosphate, and sodium tripolyphosphate the maximum phosphate d.s. permitted in the US is 0.002. Starch ethers, approved for food use, have been prepared by reaction with propylene oxide to give hydroxypropyl derivatives [31]. 

Nylen (1930) converted the sodium salt of diethyl phosphonate with diethyl phosphorochloridate (8) and oxidised the mixed phosphorus acid-phosphoric acid anhydride obtained ... 

Like all anhydrides (Section 21.5), the mixed carboxylic-phosphoric anhydride is a reactive substrate in nucleophilic acyl (or phosphoryl) substitution reactions. Reaction of 1,3-bisphosphoglycerate with ADR occurs in step 7 by substitution on phosphorus, resulting in transfer of a phosphate group to ADP and giving ATP plus 3-phosphoglycerate. The process is catalyzed by phospho-gjvcerate kinase and requires Mg2+ as cofactor. Together, steps 6 and 7 accomplish the oxidation of an aldehyde to a carboxylic acid. 

The phosphinic isocyanates (116) and isothiocyanates (117) react with oxygen, nitrogen, and phosphorus nucleophiles by attack at carbon rather than phosphorus. Phenyl phosphonodichloridate has been recommended as a useful reagent for the activation (presumably by mixed anhydride formation) of carboxylic acids for conversion to amides and hydrazides. ... 

Sayah et al. <2000JOC2824> attempted direct cyclization of acid 115a with phosphorus pentaoxide and isolated the expected compound 116 in poor yield (20%). They could improve the yield (57%) of this ring closure via the mixed anhydride 115b which was isolated prior to its cyclization in the presence of BF3 OEt2 (Scheme 18). 

---