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Chemistry Department, AN-Najah National University, P.O. Box 7, Nablus, Palestine
Molbank 2010, 2010(4), M709;
Submission received: 15 October 2010 / Accepted: 26 November 2010 / Published: 2 December 2010


A new 2-(diphenylphosphino)ethyl propyl ether as hemilabile hybrid ether-phosphine ligand [Ph2PCH2CH2OCH2CH2CH3] was made available. The structure of the titled compound was characterized by elemental analysis, IR, 31P-NMR, 1H-NMR, 13C-NMR, UV-visible spectroscopy and EI-MS.

Graphical Abstract

1. Introduction

In recent years, there has been a considerable interest in the design and use of so-called hemilabile ligands [1,2,3,4,5]. They contain a soft donor (e.g., phosphorus) closely coordinated to the transition metal with a hard donor (e.g., oxygen) forming only a weak contact to the metal center. Due to this feature, the (ether) oxygen atom can easily be displaced by an incoming substrate. In addition, the oxygen function, which may be regarded as an intramolecular solvent, is able to stabilize a transition-metal fragment after substrate dissociation, and therefore, decomposition is suppressed [4,5,6,7,8,9]. Thus, ether phosphines are capable of making available and protecting vacant coordination sites and lead to an improvement in both catalytic and stoichiometric reactions [5,6,7,8,9] The strength of the metal oxygen bond in (ether phosphine)ruthenium complexes depends on the O nucleophilicity of the ether moiety, the ring size of the cyclic ether, the number and position of the oxygen atoms in the ring, and the basicity at the metal.

2. Result and Discussion

The desired ether-phosphine [2-(diphenylphosphino)ethyl propyl ether,Ph2PCH2CH2OCH2CH2CH3] hemilabile ligand was made available in a very good yield as displayed in Scheme 1.
The structure of the Ph2PCH2CH2OCH2CH2CH3 ligand was confirmed by elemental analysis, IR, UV-visible spectroscopy and EI-MS, as well as 31P-NMR, 1H-NMR, 13C-NMR as shown in Figure 1 and Figure 2.

3. Experimental

3.1. Preparation

A solution of n-BuLi in n-hexane (25 mL of a 1.6 M solution, 2.56 g) was added dropwise to a solution of diphenylphosphine (7.44 g, 40.0 mmol) in dry THF (100 mL) at –5 °C over a period of 5 h. The red solution consisting of Ph2PLi was stirred for 2 h at ambient temperature. Then a solution of ClCH2CH2OCH2CH2CH3 (4.94 g, 40.0 mmol) in dry THF (50 mL) was added dropwise within 30 min, until all the red color disappeared, the reaction temperature was kept constant at 0 °C during the addition. Subsequently, the solution was stirred for another 30 min under reflux to ensure completion of the reaction, then it was cooled to 20 °C. To the colorless mixture, a degassed aqueous solution saturated with NH4Cl (100 mL) was added and the organic layer was separated. The solution was dried with Na2SO4 and separated from the solid residue. After evaporation of the volatile materials under vacuum, the crude product was distilled to yield a highly viscous colorless air-sensitive oil.
Boiling point: 374 K (5 mbar).
Yield: 8.93 g (83%).
MS (EI): m/z = 272.2 (M+).
IR (KBr, cm−1): 3180 (vPhH) and 2970 (vCH). 1540 (vC=C).
UV-visible absorption: λmax = 240 nm.
31P{1H} NMR (CDCl3): δ (ppm) –20.7.
1H NMR (CDCl3): δ (ppm) 0.9 (t, J = 7.2 Hz, 3H, CH3), 1.5 (m, 2H, CH2CH3), 2.4 (t, J = 7.9 Hz, 4H, PCH2), 3.3 (t, 2H, J = 6.9 Hz, PCH2CH2O), 3.6 (q, J = 7.5 Hz, 2H, OCH2CH2CH3), 6.6–7.7 (4 m, 26H, Ph-H).
13C{1H} NMR (CDCl3): δ (ppm) 10.9 (s, 1C, CH3), 23.2 (s, 1C, CH2CH3), 29.1, 29.3 (d, 1C, PCH2), 68.1, 68.5 (d, 1C, PCH2CH2O), 72.9 (s, 1C, OCH2CH2), 128.7–138.8 (4 m, 12C, Ph).
Elemental analysis: Calculated for C17H21OP. C, 74.98; H, 7.77%. Found: C, 74.73; H, 7.65%.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3


I would like to thank AN-Najah National University for their financial support.


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Scheme 1. The synthetic route to the title compound.
Scheme 1. The synthetic route to the title compound.
Molbank 2010 m709 sch001
Figure 1. 31P-NMR of Ph2PCH2CH2OCH2CH2CH3 in CDCl3.
Figure 1. 31P-NMR of Ph2PCH2CH2OCH2CH2CH3 in CDCl3.
Molbank 2010 m709 g001
Figure 2. 1H-NMR of Ph2PCH2CH2OCH2CH2CH3 in CDCl3.
Figure 2. 1H-NMR of Ph2PCH2CH2OCH2CH2CH3 in CDCl3.
Molbank 2010 m709 g002

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Al-Nuri, M. Diphenyl(2-propoxyethyl)phosphine. Molbank 2010, 2010, M709.

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Al-Nuri M. Diphenyl(2-propoxyethyl)phosphine. Molbank. 2010; 2010(4):M709.

Chicago/Turabian Style

Al-Nuri, Mohammed. 2010. "Diphenyl(2-propoxyethyl)phosphine" Molbank 2010, no. 4: M709.

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