One‐ and two‐dimensional NMR study of resol phenol—formaldehyde prepolymer resins

Abstract

A one-and two-dimensional NMR study was performed on three commercial resol phenol-formaldehyde (PF) prepolymer resins. 'H, "C, CSCM and DQF COSY NMR spectral data, in acetoned, , were obtained on each resin and on PF model compounds: phenol, five methylolphenols, four diphenylmethanes, two formals, two dibenzyl ethers and two dibenzylamines. Gated-decoupled "C experiments, using 2,4,6trimethylphenol as internal standard, were used to quantitate the major components present in each of the three resins. The major chemical differences of the three resins were noted. A DQF COSY method was developed that allowed the qualitative identification of most of the major phenolic components present in each of the PF resins.

A 13C NMR study of the methylol derivatives of 2,4′‐ and 4,4′‐dihydroxydiphenylmethanes found in resol phenol–formaldehyde resins

“…Chemical shift values from other NMR solvents cannot be used in our correlation, as discussed previously. 9 A recent study 15 found both acetone-d 6 and DMSO-d 6 to be good quantitative solvents for 13 C NMR analysis of PF resins with shorter acquisition times available using added Cr(acac) 3 .…”

“…6,9,11 -14 To develop further our comprehensive 13 C NMR method 9 to monitor the early stages of resol PF polymerization, each of the individual methylol isomers of 2,4 0 -and 4,4 0 -dihydroxydiphenylmethanes were needed as model compounds. To this end, an attempt was made to synthesize and isolate each of these compounds, 1-18, shown in Figure 1.…”

“…4,8 Earlier, we reported a 13 C NMR method for the analysis of resol PF prepolymer resins based on nine model compounds. 9 In order to analyze the next cure stage (called prepreg) more comprehensively, it was necessary to extend the range of model compounds to include the methylol derivatives of the dihydroxydiarylmethanes, which are common intermediates found in this cure stage.…”

Neuroprotective Compounds from Salix pseudo-lasiogyne Twigs and Their Anti-Amnesic Effects on Scopolamine-Induced Memory Deficit in Mice

“…Although it was previously reported in an organic synthetic study, this is the first report of its occurrence in nature [10]. The ten known compounds were identified as salicin (3) [13], grandidentatin (10) [14], isograndidentatin (11) [14], and saligenin (12) [15] (l " Fig. 1).…”

Polymers Based on Phenols

“…There are significant differences between the 13 C CP-MAS spectra of the cured resins with a formaldehyde/phenol (FP) ratio = 1.2 and FP = 1.8. There is no peak at 110 ppm in the FP = 1.8 resin, indicating complete substitution at the ortho position 95,96 , unlike in the FP = 1.2 resin. The cured FP = 1.8 resin contains methyl (10 ppm), phenoxy (150 ppm) and carbonyl groups (190 ppm) 3,91 while the cured FP = 1.2 resin does not.…”