Ethyl polyphosphate

In all cases the reaction products are mixtures of ethyl polyphosphates, and, on the basis of elementary analysis, they approximate the empirical formulas given in the above equations. In Equations 3 and 5 the product has been arbitrarily called hexaethyl tetraphosphate, which may contain 8 to 20% of the active tetraethyl pyrophosphate. In Equations 4 and 6 the products have been called technical tetraethyl pyrophosphate, which may contain up to 40% of pure tetraethyl pyrophosphate. Hexaethyl tetra-phosphate has also been made from phosphoric anhydride and diethyl ether by a process recently patented by Adler (1). 

A-cyclopropyl- and N- Xhy -N-(substituted phenyl)aminomethylene-malonates were cyclized in polyphosphoric acid [89EUP332033, 89JAP(K)83068], in ethyl polyphosphate (89USP479490), and in phospho-ryl chloride (89EUP304158). 

Flumequine was prepared when 6-fluoro-2-methyl-1,2,3,4-tertrahydro-quinoline was first reacted with alkylidene malonates and trimethyl orthoformate in THF in the presence of p-toluenesulfonic acid, and then the products, alkylidene (6-fluoro-2-methyl-1,2,3,4-tetrahydroquinolin-1 -yl) methylenemalonates, were cyclized in xylene on the action of polyphos-phoric acid or ethyl polyphosphate at 110-115°C for 1 hr (89EUP310849). 

Aliphatic and aromatic sulphonic acids have been reduced to symmetrical disulphides in almost quantitative yields using potassium iodide and ethyl polyphosphate... 

KI (8.0 g, 48 mmol) and TBA-I (0.58 g, 1.5 mmol) are added to the sulphonic acid (6 mmol) and ethyl polyphosphate or polyphosphoric acid (48 mmol) [or P4O 0 (36 mmol)] in the appropriate solvent (20 ml) (CHC13 for ethyl polyphosphate sulpholane for polyphosphoric acid MeCN for P4O10) and stirred under reflux for ca. 5 h. H20 (10 ml) is added and the mixture is refluxed for a further 1 h and then poured into PhH (100 ml). The organic phase is separated, washed with H20 (3 x 50 ml) and aqueous Na2S203 (0.5M, 2 x 100 ml), dried (Na2S04), and evaporated to yield the disulphide. 

The product obtained from 2-aminopyridine and ethyl 2-methylaceto-acetate in ethyl polyphosphate was described by Mullock et al.6 as 1,8-naphthyridine, but it was shown later by Bowden and Brown82 to be 2.3-dimethyl-4-oxo-4/f-pyrido[l,2-n]pyrimidine (36 R1 = R2 = Me, R = H). 2-Acetylbutyrolactone (43) and its 5-substituted derivatives have also been used as )3-oxo ester component49-65-83 85. 

Conversion of amides into nitriles may be effected by treating them with a variety of dehydrating reagents. Among those that have been employed are phosphorus pentoxide, phosphorus pentachloride,170 ethyl polyphosphate,171... 

In a 50-ml three-necked flask are placed the carboxylic acid (0.01 mol), ethyl polyphosphate (6g, PPE) and purified chloroform (5 ml). The mixture is cooled in an ice bath and the flask is connected to a balloon containing ammonia gas ( 3 litres). Air in the flask is replaced with ammonia and the mixture is mechanically stirred at 0-5 °C for 30 minutes and then at room temperature for one and a half hours whereupon the mixture turns very viscous (1). The balloon is removed and PPE (10 g) is added. The stirring is continued at 80 °C until the reaction is complete (usually within several hours) the dehydration is monitored by t.l.c. analysis (1). The mixture is stirred with aqueous 25 per cent sodium carbonate solution (150 ml), and then extracted with benzene (3 x 40 ml CAUTION). The combined organic extracts are dried with sodium sulphate and evaporated. The residual oil is passed through a short column packed with silica gel ( 20g) and the product eluted with benzene. The eluate is evaporated and the residue purified by short path distillation under reduced pressure (Kugelrohr apparatus). 

Aminopyridines were treated with cyclic fi-oxo esters to give the tricyclic compounds 244. Cyclocondensation was carried out in diethylbenzene, ethylene glycol monomethyl ether,acetic polyphosphoric acid, - " ethyl polyphosphate, a mixture of phos-phoryl chloride and polyphosphoric or in the presence of... 

Aguirre, J. M., Alesso, E. N., Ibanez, A. F., Tombari, D. G., Moltrasio Iglesias, G. Y. Reaction of 1,2-diarylethylamides with ethyl polyphosphate (EPP) correlation of the von Braun, Ritter and Bischler-Napieralski reactions. J. Heterocycl. Chem. 1989, 26, 25-27. 

Nucleoside synthesis.3 This reagent is superior to p-toluenesulfonic acid, ethyl polyphosphate, or zinc chloride for the preparation of nucleosides by fusion of purines with fully acetylated pentoses or hexoses. An example of the method4 is the fusion of purine (1) with tetra-O-acetyl-D-ribofuranose (2) at 174-180° (at the water pump vacuum) to give the two nucleosides (3) and (4). The main product (3) is the triacetyl derivative of a naturally occurring nucleoside antibiotic nebularine. 

Instead of one or two ester groups, the /J-carbon atom of the vinyl side chain may bear oxo-,202 or one203 or two204 nitrile groups. In the latter case, cyclization is effected by ethyl polyphosphate, which will at the same time ethylate the 5-imino group resulting from ring closure with a nitrile function ... 

Ethyl polyphosphate is obtained by reacting phosphorus pentoxide with diethyl ether in chloroform solution. 

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