31P-NMR

Similar conclusions were obtained from lH and 31P NMR and also from IR studies of egg phospholecithin reversed micelles in benzene by Boicelli et al. 58 61). According to the results of these experiments the water structure within the reversed phospholecithin micelles alters considerably compared with water in bulk. This becomes evident from the shortening of the relaxation time T, of the water protons split into two relaxation times T1A and T1B, indicating that there are at least two... 

The 31P NMR spectrum in solution [47] is in accordance with a square planar structure (Figure 2.6). 

P NMR spectra indicate the T-shape geometry is retained in solution at -30°C but that the molecule is fluxional at room temperature. Rh(PPh3)3 undergoes a range of addition reactions with Lewis bases (CO, PF3, NH3) to afford various 16- and 18-electron species (Figure 2.14). 

The 31P NMR spectrum of wer-RhCl3(PMe3)3 is shown in Figure 2.62 again two of the ligands are equivalent, so the spectrum is a doublet for... 

The 31P NMR spectrum of RhH2Cl(PBu2)2 is shown in Figure 2.69 the triplets show coupling with two equivalent hydrogens, split further by coupling with rhodium (/(Rh-P) 110.3 Hz /(P-H) 14.9 Hz). 

In the 31P NMR spectra, there is a significant difference in, for example, the 195Pt-3lP coupling constant [155]. Therefore, for c -Pt(PBu3)2Cl4, /= 2070 Hz trans-isomer, J = 1462 Hz). 

PMe3)2H] + (12) with NaH (Eq. 5) [37]. The conformation for these complexes as deduced from 31P NMR spectroscopic data are depicted above. Interestingly the cationic derivative [Co(Bu2Cp)(PMe3)2Me]+ (13) possesses a molecular plane of symmetry. 

More recently, Grubbs et al. obtained a refined mechanistic picture of the initiating step by conducting a 31P NMR spectroscopic study of the phosphine exchange in precatalysts 12-A. These investigations revealed that substitution of the phosphine proceeds via a dissociative-associative mechanism, i.e., a 14-electron species 12-B is involved that coordinates the alkene to give a 16-electron species 12-C (Scheme 12) [26a]. Increased initiation rates are observed if the substituents R and the phosphine ligands PR3 in precatalysts... 

P NMR showed that the filtrate contained none of the desired product. 

It is of interest to examine the development of the analytical toolbox for rubber deformulation over the last two decades and the role of emerging technologies (Table 2.9). Bayer technology (1981) for the qualitative and quantitative analysis of rubbers and elastomers consisted of a multitechnique approach comprising extraction (Soxhlet, DIN 53 553), wet chemistry (colour reactions, photometry), electrochemistry (polarography, conductometry), various forms of chromatography (PC, GC, off-line PyGC, TLC), spectroscopy (UV, IR, off-line PylR), and microscopy (OM, SEM, TEM, fluorescence) [10]. Reported applications concerned the identification of plasticisers, fatty acids, stabilisers, antioxidants, vulcanisation accelerators, free/total/bound sulfur, minerals and CB. Monsanto (1983) used direct-probe MS for in situ quantitative analysis of additives and rubber and made use of 31P NMR [69]. 

As may be seen from Table 3.22, MTBE does not extract additives from PA6, as opposed to dissolution in the expensive solvent HFIP. It is also evident that in these conditions intact Ultranox 626 is not observed the hydrolysis product 2,4-di-f-butylphenol (2,4-DTBP) is observed instead. 31P NMR confirms hydrolysis of Ultranox 626. The results do not discriminate between hydrolysis during mixing or analysis. As also SFE does not detect Ultranox 626 hydrolysis is likely to occur in the mixing step. Dissolution with HFIP and SFE (after optimisation) give identical results. In this case the added value of SFE extraction consists in a considerable cost reduction. 

Quantitative analysis with internal standard (for H or 31P NMR) or polymer ( H NMR)... 

Organophosphate Ester Hydraulic Fluids. Absorption rates of TOCP were measured in chickens after subcutaneous injection by measuring the apparent disappearance of TOCP from the site of injection with 31P NMR spectroscopy (Carrington et al. 1988). Five chickens were injected with single,... 

The derivatives 15a-i exhibit characteristic 31P NMR spectroscopic data (see Table I), which are distinctly different from those observed for the P-organo-substituted derivatives 12 and 13 (8(3IP) = 65.8-136.0).27 However, the similar Si chemical shifts and. /(Si, P) coupling constants observed for 12,13, and 15 clearly show the identical electronic nature of the low-coordinate silicon centers in these derivatives. 

---