Imidodiphosphoric acids

The second group also includes imidodiphosphoric acid,... 

By the loss of the elements of water or ammonia from imidodiphosphoric acid there is formed diimidodiphosphoric acid, or mixed imido-amido-diphosphoric acids also called imido-diphosphamic or imido-diphosphamidic acid ... 

When an aq. soln. of trimetaphosphimic acid, or of one of its salts, acidified with one of the stronger mineral acids, is heated or kept for a long time, decomposition occurs—slowly if cold, rapidly if heated. Orthophosphoric acid and ammonia (ammonium phosphate) are the ultimate products of the decomposition. Several intermediate products have been detected in addition to pyrophosphoric acid, what H. N. Stokes calls diimidotriphosphoric acid, and imidodiphosphoric acid have been found, and he represents the different stages of the decomposition ... 

According to A. Mente, if in the preparation of imidodiphosphoric acid, the products be heated to 290° or 300°, ammonia iB evolved, and a white flocculent powder is formed from which ammonium chloride can be removed by washing with water. The pale yellow residue dissolves in aq. ammonia and when the soln. is acidified with nitric or hydrochloric acid, a white precipitate is formed, and the soln. contains what is thought to be nitrilotrimetaphosphoric acid,... 

Due to the by-reactions (eq. 3-5) alcoholysis of Cl P=N-POCl2 does not yield the desirable "pentaesters" (RO)3P=N-PCj(OR)2. Depending on molar ratio, temperature and time the reaction mixtures contain mono-, di-and trialkoxyphosphazenes, tetrachloride and several esterchlorides of imidodiphosphoric acid. In the presence of a great excess of alcohol the final products are exclusively tetraesters of imidodiphosphoric acid, (RO PO-NH-POCOR. Indeed these can be converted into "pentaesters" by reacting with diazoalkanes (eq. 10)... 

The checker reports that the melting-point determination, run by inserting a capillary tube into a hot bath, gave a liquid at 170° which evolved a gas. X-ray diffraction data showed the absence of imidodiphosphoric acid tetramide, (NH2)2P(0)—NH—P(0)(NH,)s. f The University, Munich, Germany, t Monsanto Chemical Co., Dayton, Ohio. 

Imidodiphosphoric acid tetramide, formation of, from phosphoryl triamide, 6 110, llln. Iodination apparatus, for preparation of chromium(III) iodide, 6 128... 

A dibasic imidodiphosphoric acid, which can be regarded as derived from the last-mentioned compound by the loss of the elements of water, was prepared by warming to about 50° C, a solution of 4 grams ammonium carbamate in 10 grams of phosphoryl chloride.2 Thus... 

Nitrilotrimetaphosphoric acid is said to be formed by heating crude imidodiphosphoric acid to 290°-300° C., washing out ammonium chloride, dissolving the residue in ammonia, acidifying and filtering off the white precipitate. The solution contained this acid,... 

Imidodiphosphoric acid Diamidophoaphoric acid Phosphoramide [phosphoryl amide or phosphorus (V) oxytriamide] Phosphorus 0X3Uiitride (phosphoryl nitride)... 

Acid imidodiphosphate salts can be precipitated when the pH of a normal salt solution is lowered by the addition of acetic acid (7.69). In boiling aqueous solutions, imido and nitrilo compounds are hydrolysed rapidly (7.70) and (7.71). Free imidodiphosphoric acid can be prepared from an aqueous solution of the sodium salt, using a weakly acidic cation exchanger. 

Figure 3.7 Stabilizing CH...JI (blue) and CH...O (red) interactions found in the transition states for the sulfoxidation of thioanisole catalyzed by imidodiphos-phonic acid 21. (From Jindal, G. and Simoj, R. B. Axially Chiral Imidodiphosphoric Acid Catalyst for Asymmetric Sulfoxidation Reaction Insights on Asymmetric Induction. Angew. Chem. bit. Ed. 2014. 53, 4432-4436. Copyright Wiley-VCH Verlag GmbH Co. KGa A. Adapted with permission.)...

Jindal, G. Sunoj, R. B. Axially Chiral Imidodiphosphoric Acid Catalyst for Asymmetric Sulfoxidation Reaction Insights on Asymmetric Induction. Angew. Chem. Int. Ed. 2014,53,4432-4436. 

Imidodiphosphoric acids a single syntt tic step more than phosphoric acids ... 

Scheme 25 Synthetic strategy for C2-symmetric imidodiphosphoric acids...

The dimeric stmcture of C2-symmetric imidodiphosphoric acids enables a highly convergent synthetic approach. The synthesis requires only a single additional synthetic step compared to the synthesis of the corresponding phosphoric acids (Scheme 25) [57]. 

Scheme 27 Bifunctional activation of reactants with Brpnsted acid/base pair in imidodiphosphoric acid catalysis...

Based on this synthetic strategy, three imidodiphosphoric acids 13-15 with bulky substituents on the 3,3 -positions of the two BINOL backbones were reported (Scheme 26) [57]. 

Confined imidodiphosphoric acids provide completely different active moiety and significant increase in the steric demand of the chiral environment, while keeping crucial features of the phosphoric acids C2-symmetry of the anion and a single type of bifunctional active site. Compared to phosphoric acid catalysts, additional two atoms P=N are introduced between the Brpnsted acidic and Br0nsted basic sites (Scheme 27). 

The crystal structure of imidodiphosphoric acid 13 revealed a confined active site placed within a extremely sterically demanding chiral environment (Fig. 1). Top view at the catalytic moiety shows how the two BINOL substituents surround the active site (Fig. lb). From the bottom half, two remaining BINOL subunits completely block access to the imidodiphosphate (Fig. Ic) [57]. 

The first enantioselective synthesis of 5,6-dihydroindolo[l,2-a]quinox-alines (200) has been achieved by using a newly developed Hg-BINOL-lype imidodiphosphoric acid catalyst (201) in the Pictet-Spengler-type reactions of indolyl anilines (198) with ketones (199) to afford the products in high yields (up to 97%) and excellent enantioselectivities (up to 98% ee) (Scheme 53). ... 

A novel imidodiphosphoric acid catalyst (310), including two R)-BINOL frameworks with different 3,3 -substituents has been successfully applied for the first enantioselective synthesis of pyrrolyl-substituted triaiylmethanes (308). This strategy has also been expanded to the synthesis of bis(indolyl)-substituted triaiylmethanes (309) with high enantioselectivities compared to previous reports (Scheme 83). ... 

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