Di‐tert‐butyl(methyl)phosphine

[6002-40-0] C9H21P (MW 160.24) 1S/C9H21P/c1-8(2,3)10(7)9(4,5)6/h1-7H3 InChIKey = JURBTQKVGNFPRJ-UHFFFAOYSA-N (mainly used as a ligand in coordination compounds or in transition-metal-catalyzed reactions; some examples of its use as precursor of ylides, bidentate ligands, and frustrated Lewis pairs) Alternate Name: di-tert-butyl(methyl)phosphane. Physical Data: bp 170–172 °C; 58 °C/12 mmHg; d 0.824 g cm-3. Stability: soluble in most organic solvents; slightly soluble in H2O. Form Supplied in: tBu2MeP is available as a colorless liquid. Also available as the corresponding tetrafluoroborate salt: tBu2MeP·HBF4. (the structure of tBu2MeP·HCl crystals has been determined1) Analysis of Reagent Purity: tBu2MeP gives a singlet in 31P NMR at δ 10.8, while its 1H NMR consists of doublets at δ 1.07 (tC4H9, 3JPH = 10.3 Hz) and at δ 0.90 (PCH3, 2JPH = 3.7 Hz). The 13C NMR spectrum of tBu2MeP (10% v/v in vinyl chloride) shows doublets at δ 29.5 (tC4H9 methyls; 2JPC = 14.1 Hz), δ 30.5 (quaternary; 1JPC = 21.0 Hz), and δ 4.5 (PCH3, 1JPC = 19.3 Hz).2, 3 Preparative Methods: tBu2MeP was initially prepared4 by reaction of tBuMgCl with PCl3, followed by reduction of tBu2PCl with LiAlH4. The so obtained tBu2PH was allowed to react with CH3I followed by basic treatment to convert the phosphonium iodide to the free base. In more recent procedures, tBu2MeP was obtained from tBu2PCl and MeLi or MeMgI.5, 6 Handling, Storage, and Precautions: can be stored at room temperature indefinitely under an inert atmosphere. Oxygen should be strictly excluded to avoid oxidation; the corresponding phosphine oxide is therefore a typical contaminant of the reagent. tBu2MeP is pyrophoric and causes severe skin burns, eye, and mucous membranes damage. Not much is known about toxicology, therefore all possible precautions should be taken to avoid inhalation or absorption through the skin.