Acyl‐ und Alkylidenphosphane. XVII. Triacetylphosphan aus Tris(trimethylsilyl)phosphan

Abstract

Tris(trimethylsilyl)phosphan und Acetylchlorid im überschuß reagieren bei 0°C in Cyclopentan zu Chlortrimethylsilan und Triacetylphosphan 3a. Im Unterschied zum entsprechenden 2,2‐Dimethylpropionyl‐Derivat (Z)‐5 b sind die intermediär gebildeten Verbindungen (E)‐ und (Z)‐Acetyl‐[1‐(trimethylsiloxy)äthyliden]phosphan 5 a thermisch sehr instabil und konnten nicht rein isoliert, sondern nur NMR‐spektroskopisch charakterisiert werden. Die Isomeren unterscheiden sich kaum in ihren chem. Verschiebungen, aber stark in ihren Kopplungskonstanten. Bei unzureichender Kühlung der Lösung bilden sich in verstärktem Ausmaß diacetyl‐[1‐(trimethylsiloxy)vinyl]phosphan 7 und die Keto‐Enol‐Tautomeren des Diacetylphosphans K‐E‐2 a. Die Zuordnung der im 1H‐NMR‐Spektrum auftretenden Signale zu den 31P‐NMR‐Resonanzen und die sichere Identifizierung aller Phosphane wurde erst mit 1H‐{31P}‐Indor‐Experimenten möglich. Auch die Nebenprodukte 2a und 7 setzen sich mit überschüssigem Acetylhalogenid im Laufe von Tagen bei +20°C zu Triacetylphosphan 3a um.

Synthesis of acyl(chloro)phosphines enabled by phosphinidene transfer

“…Acylphosphines and their oxides are used as photoinitiators for radical-initiated polymerization [1][2][3][4] reactions used in the manufacture of consumer goods such as automotive coatings, adhesives, latex composition kits, and various dental and orthodontic materials. [5][6][7][8][9][10][11][12][13][14] Known methodologies for the synthesis of acylphosphines employ nucleophilic sources of phosphorus such as tris(trimethylsilyl)phosphine (P(TMS) 3 , TMS ¼ trimethylsilyl), [15][16][17] which is volatile, pyrophoric, toxic, expensive, and difficult to handle. 18 Transition metal-supported phosphines and phosphides have been used as a platform in niche syntheses of acylphosphines, though scope is limited and products remain bound to the metal center.…”

Symmetrical and Mixed Tris(acyl)phosphines: Synthesis, Oxidation and Photochemistry

“…We decided to work with the sodium t butylate aggregate NaPH 2 (NaO t Bu) x 1 ( x ≈2.5) [3,17] as an inexpensive and conveniently to use source of phosphorus for the synthesis of acylphosphines. Silyl phosphine TMS 3 P has severe drawbacks because it is a pyrophoric, toxic and expensive liquid [5,7,9,12,13] . Compound 1 was prepared in situ from red phosphorus, three equivalents of elemental sodium and an equimolar amount of t butanol as proton source.…”

“…In 1977, Becker prepared tris(pivaloyl)phosphine as side product with 23 % yield by reacting tris(trimethylsilyl)phosphine (TMS 3 P) with pivaloyl chloride [12] . Four years later, the same authors reported tris(acetyl)phosphine in a similar manner by reacting TMS 3 P with acetyl chloride [13] . Mislow and co‐workers studied the synthesis of tris(benzoyl)phosphine in 1979 and reported 13 C‐ and 31 P‐NMR spectra, which also contained resonance signals of the oxidized derivative [14] .…”

“…[12] Four years later, the same authors reported tris(acetyl)phosphine in a similar manner by reacting TMS 3 P with acetyl chloride. [13] Mislow and co-workers studied the synthesis of tris(benzoyl)phosphine in 1979 and reported 13 Cand 31 P-NMR spectra, which also contained resonance signals of the oxidized derivative. [14] A patent on the synthesis of orthosubstituted aroylphosphines and their subsequent conversion to the corresponding TAPOs was claimed by Ciba-Geigy in 1996.…”

Tris(Trimethylsilyl)Phosphine and Lithium Bis(Trimethylsilyl)Phosphide.Bis‐(Tetrahydrofuran)

“…In reactions with alcohols and water bis(trimethylsilyl) and (trimethylsilyl)phosphine can be synthesized;9 acetyl chloride in a molar ratio of 1:3 gives triacetylphosphine. 10 For the important reaction with 2,2-dimethylpropionyl chloride see Section 49.…”