## Results and Discussion
### Synthesis of Liquid-Phase Phosphine Reagent (2)  
A concern with the original reagent **1** was the carbamate ester moiety incorporated as a linker between the triarylphosphine and the PEG support. The known base and acid sensitivity of the urethane linkage, coupled with worries about its lability in the presence of Lewis acids and metallating reagents, linked any further exploitation of PEG-supported triarylphosphines to an immediate replacement of this carbamate ester group. An aryl-alkyl ether moiety was chosen as the replacement linker, the chemical stability of which is comparable to that of the poly(ethylene oxide) backbone, therefore reagent **2** became the functionalized polymer of choice [19]. The synthetic strategy towards **2** involves an initial concise preparation of the key hydroxyphosphine **3**[20], followed by its attachment to PEG _via_ the dimesylate **4**[21]. 4-Bromo-phenol **5** was protected as the TBDMS ether **6**, that was then phosphinylated under standard conditions [22] to give the triarylphosphine **7**. The silyl ether was removed and the resultant hydroxyphosphine **3** was obtained in 87% yield for the three steps. Mesylate **4** was obtained by heating (50'C) a neat solution of PEG\({}_{3400}\)**8** in methanesulfonyl chloride. No base was required under these conditions, which had the benefit that the purification of **6** was simplified from its original preparation [21]. Etherification between **4** and **3** was performed in rigorously degassed DMF. Phosphine **2** was then isolated by addition of the reaction mixture into degassed diethyl ether, followed by filtration and sequential washing of the polymeric precipitate with _i_-Pr alcohol (to remove salts) followed by diethyl ether to give reagent **2** in 92% yield, based on the weight of polymer isolated. Figure 1:The oxidation state of the phosphine termini of **2** was routinely quantified by \({}^{31}\)P NMR after certain periods of storage. This revealed that even after prolonged exposure to air (2-3 weeks) little oxidation to the phosphine oxide (\(<5\%\)) occurs. The derivatization level of the polymer is also determined by inspection of the \({}^{1}\)H NMR of **2**. The chemical shift of \(\alpha\)-methylene protons of PEG and its derivatives is a function of the moiety attached to the termini hydroxyl groups. For undervatized PEG\({}_{3400}\), the chemical shift of these \(\alpha\)-protons is \(\delta\) 3.8 ppm, for PEG-mesylate **4**, this changes to \(\delta\) 4.35 ppm (also detectable are the \(\beta\)-methylene protons \(\delta\) 3.74 ppm) and for the phosphine terminated polymer **2** this changes to \(\delta\) 4.16 ppm (\(\beta\)-methylene protons \(\delta\) 3.64 ppm). Inspection of the \({}^{1}\)H NMR of **2** shows that no mesylate **4** remains. Therefore there is high confidence that the polymeric phosphine **2** is quantitatively substituted with terminal triarylphosphine residues (\(ca.\) 0.5 mmol g\({}^{-1}\)). The ease of NMR-characterization of soluble polymer reagent **2** offers a considerable advantage over its solid-phase homologue which, in order to determine the oxidation state of the phosphine center, must involve either gel- or solid-phase NMR, or single-bead FTIR techniques [23]. _Liquid-Phase Ozonide Reduction_  
Figure 2: A) \({}^{1}\)H and \({}^{31}\)P NMR spectra of PEG-supported triarylphosphine **2**. B) \({}^{1}\)H and \({}^{31}\)P NMR spectra of PEG-supported triarylphosphine **9**. As an entry level into the utility of **2** in organic chemistry, the mild chemical decomposition of ozonides was selected. Ozonolysis of alkenes has a broad scope of application in organic chemistry, and the range of methods for destruction of the intermediary ozonides is equally broad. However, the two major methods of choice: Zn/acetic acid or dimethyl sulfide have limitations, a result of potential chemical substituent sensitivity in the former case, or noxious reagents and high-boiling point byproducts in the latter. For these reasons PPh\({}_{3}\) is an excellent alternative [24].