Osmometric molecular weight

The presence of the P4 molecule was indicated by osmometric molecular weight determinations, mass spectrometry, and by the easy displacement, even at -78°C, of the intact P4 unit by carbon monoxide or phosphane ligands. The infra-red and Raman spectra showed bands attributable to a bound P4 molecule under 3 or Cg... 

The high activating power of the furoxan ring in nucleophilic addition has also been observed by Bailey et al.2 9 in 7-nitro-l,2,5-oxadiazolo[3,4-c]-pyridine 3-oxide, a nitropyrido[3,4-c]furoxan that easily undergoes covalent addition of water by nucleophilic attack at the position para to the nitro group. The structure of the covalent hydrate is supported by elemental analysis, osmometric molecular weight determination, and H-NMR spectra in DMSO-[Pg.429]

The cyclic structure of 16 is supported by osmometric molecular weight determination (found 1466 g/mol) and by NMR studies. Attempts failed to cleave the exocyclic phenyl groups of 16 selectively by its reaction with Ph2SnCl2 or I2, respectively. Further studies on this subject are envisaged. 

The authors acknowledge gratefully the contributions of J. G. Cobler and Miss C. Kleeman for the ultracentrifuge particle size measurements, E. B. Bradford for the electron microscope particle size measurements. Miss D. L. Dickens, A. S. Teot, and N. Sarkar for the critical coagulation concentration experiments, R. D. Van Dell for the SDS adsorption experiments, the East Main Analytical Laboratory for the osmometric molecular weight and nitrogen adsorption measurements, the Chemical Physics Laboratory for the X-ray fluorescence measurements, and J. B. Shaffer in the preparation of the latexes. 

Criterion 3. All of the polyisoprenes and poly(a-methylstyrene-f focfc-iso-prene-b/ocfc-a-methylstyrene) block copolymers prepared using the isoprene chain-extended derivative of 6 exhibited monomodal molecular weight distributions as observed by SEC. In addition, the triblock copolymers prepared using this initiator exhibited polydispersities (M /M ) equal to 1.07, based on light scattering and osmometric molecular weight determinations. 

Optically active propylene oxide was polymerized by potassium hydroxide as a catalyst and the polymer of an osmometric molecular weight of 3200 was obtained [5]. Optical rotation of the polymer was measured in 35 different solvents at ambient temperature at a fixed concentration of 2.5 g/100 ml. 

Reported temperatures for this polymerization vary somewhat depending on the metal cation. With Cu(II), a maximum temperature of I05°-110°C was employed (SS). Temperatures as high as 260°C were used in other cases (76). With Be(II), this method has yielded very high molecular weight, soluble polymer. Fractionation of the product obtained from Be(II) and 4,4 -di(aceto-acetyl)diphenyl ether yielded a fraction with an osmometric molecular weight of 126,000 (76). A product with an intrinsic viscosity of 1.2 was obtained from sebacoyl diacetone and Be(Il) using a melt, bulk procedure (86). 

---