Reaktion #2459

Reaktionsgleichung

Diethyl chlorothiophosphate

ammonia

tetrahydrofuran

sulphuric acid

→

tetraethyl thioimidodiphosphate

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   FiltrationThe mixture was filtered
2. 2
   Sonstigeto remove
3. 3
   Sonstigeprecipitated ammonium chloride
4. 4
   Einengenconcentrated by distillation of the solvent under reduced pressure to a yellow oil (diethyl thiophosphoramide, 21.0 g, 31P NMR in CDCl3, singlet, 67.4 ppm downfield of H3PO4)
5. 5
   SonstigeWithout further purification
6. 6
   workup.DISSOLUTIONthis amide (8.5 g) was redissolved in tetrahydrofuran (250 cm3)
7. 7
   workup.ADDITIONsodium hydride (13.2 g of a 20% suspension in toluene) was added
8. 8
   workup.STIRRINGwith stirring
9. 9
   workup.ADDITIONdiethyl chlorothiophosphate (9.5 g) was added dropwise during 15 min
10. 10
    workup.STIRRINGThe mixture was stirred
11. 11
    Temperaturand then cooled
12. 12
    Filtrationfiltered
13. 13
    workup.DISTILLATIONThe solvent was distilled under reduced pressure
14. 14
    Sonstigeleaving a yellow oil which
15. 15
    SonstigeThe organic phase was separated
16. 16
    Trocknendried with magnesium sulphate
17. 17
    Filtrationfiltered
18. 18
    Einengenconcentrated by distillation of solvent under reduced pressure

Vorschrift

Diethyl chlorothiophosphate (25.04 g, supplied by Aldrich Chemical Company Ltd.) was added dropwise with stirring to a saturated solution of ammonia in tetrahydrofuran (250 cm3). Stirring was continued for two hr. The mixture was filtered to remove precipitated ammonium chloride and then concentrated by distillation of the solvent under reduced pressure to a yellow oil (diethyl thiophosphoramide, 21.0 g, 31P NMR in CDCl3, singlet, 67.4 ppm downfield of H3PO4). Without further purification, this amide (8.5 g) was redissolved in tetrahydrofuran (250 cm3) and sodium hydride (13.2 g of a 20% suspension in toluene) was added with stirring. When hydrogen ceased to be evolved, diethyl chlorothiophosphate (9.5 g) was added dropwise during 15 min. The mixture was stirred and heated at 65° C. for 2 hr. and then cooled and filtered. The solvent was distilled under reduced pressure leaving a yellow oil which was dissolved in dichloromethane (250 cm3) and stirred with dilute sulphuric acid (1 molar to ensure that the pH of the suspension was less than pH 2). The organic phase was separated, dried with magnesium sulphate, filtered, and concentrated by distillation of solvent under reduced pressure yielding tetraethyl thioimidodiphosphate (11.2 g. 31P NMR in CDCl3, singlet, 56.4 ppm downfield of H3PO4). The purity was determined by titration of a sample dissolved in 50% tetrahydrofuran-water with 0.1M aqueous sodium hydroxide solution for the acidic (NH or SH) proton, which was 50% neutralised at pH 6.1. By this method the purity was found to be 77% of theoretical based on molecular weight 321. The compound of Formula I in which R1 =R2 =R3 =R4 =ethoxy was examined as an extractant for zinc by Tests 1 and 2, with the results listed in Tables 1 and 2, which show that it is a weak extractant for zinc with high selectivity over iron.

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