Gas chromatographic and nuclear magnetic resonance determination of linear formaldehyde oligomers in formalin

Abstract

tems considered could be a result of anomalous behavior of the systems or the inherent crudeness of a first-generation model. I t appears, for example, that the model should fit the data for systems where KGLC = K = KNMR, such as is likely for aliphatic alcoholln-electron donor hydrogenbonded complexes (16). T h a t , in itself, would be noteworthy. Nevertheless, in addition to the inconsistencies described above, it presently lacks the support of independent experimental evidence (even inferential) for the existence of local aggregates of A and S in the mixed solvent, or separate clustering of A and S about D when solute is added. A similar two-phase thermodynamic model has been used to interpret solute activity coefficients in nematic liquid-crystalline solvents (32). In t h a t case, however, there was some supporting evidence for solvent clustering from x-ray and light scattering experiments. In short, more experimental evidence and additional refinement are needed before a compelling case can be made for the model. ACKNOWLEDGMENTStimulating discussions and correspondence with J. H.

On the synthesis and structure of resorcinol-formaldehyde polymeric networks – Precursors to 3D-carbon macroassemblies

“…The most abundant single species detected was methane diol, followed by methanol. Indeed, aqueous formaldehyde is often referred to as being in equilibrium with methane diol and having a significant methanol impurity present (with the latter often deliberately included as a polymerization inhibitor) [27]. However, what the NMR analysis indicates is that the reality is even more complex; even in the presence of methanol, formaldehyde readily dimerizes and polymerizes to form a complex mixture of species.…”

Methanol and Formaldehyde Oxidation by an Autotrophic Nitrifying Bacterium

“…The NMR spectrum obtained from 1 m~-[l~C]forrnaldehyde showed a signal at 6 = 82.1, attributable to hydrated formaldehyde, plus a minor signal at 6 = 62.8. Formaldehyde solutions contain self-addition compounds in equilibrium with the monomer (Dankelman & Daemen, 1976); the minor signal was at a chemical shift appropriate for the dimer, HOCH20CH20H. On addition of equimolar hydroxylamine the signal from hydrated formaldehyde disappeared, being replaced by a signal at S = 140.6.…”

Quantitative high-resolution on-line NMR spectroscopy in reaction and process monitoring

“…Thermodynamic and kinetic data are needed to develop predictive models of the physicochemical properties of formaldehyde containing solutions which are used in the design of reactors and separation equipment, like formaldehyde distillation and absorption columns [23,49,50]. For this purpose quantitative information on chemical equilibria and reaction kinetics of all species is needed.…”