Molecular weight determination, oxidized

Molecular weight determinations of ECH—EO, ECH—AGE, ECH—EO—AGE, ECH—PO—AGE, and PO—AGE have not been reported. Some solution studies have been done on poly(propylene oxide), and these may approximate solution behavior of the PO—AGE copolymer (33,34). 

M = 3.2 X 10 and 6.67 x 10, were determined, as a function of temperature, from room temperature through the melting point. In both cases full NOEF s were observed at room temperature and in the melt. Schaefer and Natusch have reported essentially a full NOEF, 1.7 0.1, for a 1000 molecular weight polyethylene oxide which is a liquid at room temperature. (35)... 

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]

All the known tetraalkoxides are very easily hydrolyzed by water vapour and the uranium(IV) compounds oxidize rapidly in air, so their preparation must be carried out under nitrogen. Molecular weight determinations (M = Th, U) indicate a considerable degree of polymerization, approximately tetrameric in the case of Th(OR)4 with R = Pr or MeEtCH, but the molecular complexity decreases to about 3.4 for R = Bu, and with R = CEt3 and CMeEtPr the alkoxides are monomers in boiling benzene.653 The plutonium compound Pu(OCMeEt2)4 is volatile at 150 °C/0.05 torr, suggesting a low molecular complexity. 

The propylene oxide complex was rather unstable and dissociated partially to its components in solution as shown by the molecular weight determined cryoseopically in benzene. This instability corresponds to the low electron donating power of the propylene oxide monomer as well as to the low electron accepting power of the catalyst. 

By the end of the nineteenth century, molecular weight determinations carried out by means of vapor density measurements proved that phosphorus(V) and phosphorus(III) oxide in the gaseous state consist of molecules of the compositions P406 (3,86) and P4O10 (87), respectively. However, their molecular structures remained uncertain (see, for example, Ref. 88) until adequate techniques for structure determination such as electron and X-ray diffraction became available (6, 7, 72). 

Tetrakis(triphenyl phosphite)nickel is a white crystalline solid. It melts sharply at 146 to 148° and begins to decompose above 150°. The molecular weight determined cryo-scopically in benzene is normal. The compound is soluble in such solvents as benzene, triphenyl phosphite, chloroform, and cyclohexane and is only slightly soluble in water. It is not readily oxidized. 

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