The Acid-Catalyzed Phenol–Formaldehyde Reaction

Lu, Kai‐Tai; Luo, Kuo-Ming; Lin, Sheann-Huei; Su, Shoujin; Hu, Kuang

doi:10.1205/095758204322777651

Cited by 21 publications

(6 citation statements)

References 11 publications

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“…Finally, we need to point out that the acid-catalyzed gelation of our R:F mixtures is exothermic and molds warm up somewhat. But, because of the small size of our samples, no runaway conditions were ever encountered, as has been oftentimes reported during synthesis of novolak resins by the acid-catalyzed reaction of phenol with formaldehyde …”

Section: Discussionmentioning

confidence: 83%

“…But, because of the small size of our samples, no runaway conditions were ever encountered, as has been oftentimes reported during synthesis of novolak resins by the acid-catalyzed reaction of phenol with formaldehyde. 29 According to the nanomorphology observed in SEM, it seems that polymerization leads to particle formation, followed by phase separation and gelation. SEM results and particle size calculations based on BET surface areas and skeletal densities (Table 1) are internally consistent.…”

Section: Discussionmentioning

confidence: 99%

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Time-Efficient Acid-Catalyzed Synthesis of Resorcinol−Formaldehyde Aerogels

2007

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Resorcinol (R)-formaldehyde (F) aerogels are pursued as precursors of carbon aerogels, which are electrically conducting. They are usually prepared via a week-long base-catalyzed gelation process from an aqueous sol. For this work, we reasoned that because both the reaction of R with F and the condensation of the resulting hydroxymethyl resorcinol with R are electrophilic aromatic substitutions, they should proceed easily by acid catalysis in one pot. Thereby, we have developed and reported an HCl-catalyzed gelation process in CH 3 CN, which is completed in about 2 h at room temperature or in 10 min at 80°C. The final aerogels are chemically indistinguishable (by IR and 13 C CPMAS NMR) from typical basecatalyzed samples. In analogy to phenol-formaldehyde resin formation, the mechanism may involve o-quinone methide intermediates (hence the red color prevailing throughout the process). The effect of aging is discussed in terms of shrinkage and is attributed to further reaction and incorporation of more formaldehyde into wet gels, followed by syneresis (reaction with one another of dangling oligomeric appendices on the skeletal framework).

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Time-Efficient Acid-Catalyzed Synthesis of Resorcinol−Formaldehyde Aerogels

2007

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“…In the case of other phenolic compounds, acid-catalyzed condensation reactions have also been proposed. [39,40] Further studies will be needed to investigate the condensation mechanism and concomitant aerosol formation.…”

mentioning

confidence: 99%

Understanding the Fast Pyrolysis of Lignin

2011

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In the present study, pyrolysis of corn stover lignin was investigated by using a micro-pyrolyzer coupled with a GC-MS/FID (FID=flame ionization detector). The system has pyrolysis-vapor residence times of 15-20 ms, thus providing a regime of minimal secondary reactions. The primary pyrolysis product distribution obtained from lignin is reported. Over 84 % mass balance and almost complete closure on carbon balance is achieved. In another set of experiments, the pyrolysis vapors emerging from the micro-pyrolyzer are condensed to obtain lignin-derived bio-oil. The chemical composition of the bio-oil is analyzed by using GC-MS and gel permeation chromatography techniques. The comparison between results of two sets of experiments indicates that monomeric compounds are the primary pyrolysis products of lignin, which recombine after primary pyrolysis to produce oligomeric compounds. Further, the effect of minerals (NaCl, KCl, MgCl(2), and CaCl(2)) and temperature on the primary pyrolysis product distribution is investigated. The study provides insights into the fundamental mechanisms of lignin pyrolysis and a basis for developing more descriptive models of biomass pyrolysis.

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“…1). A dehydrated intermediate, namely, phenolic formaldehyde condensate (PF), was prepared using phenol and formaldehyde as raw materials according to literature [11]. In brief, 94.1 g phenol (1 mol) and 20.0 g sulfuric acid solution (20 wt%, 0.04 mol sulfuric acid) were added into a four-neck flask equipped with a thermometer, a mechanical stirrer, and a flush condenser.…”

Section: Preparation Of Pfss With Different Dssmentioning

confidence: 99%

A deeper exploration of the relation between sulfonation degree and retanning performance of aromatic syntans

et al. 2021

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It is well-known that the sulfonation degree (DS) of aromatic syntan is an important factor affecting its retanning performances. But the quantitative relation between DS and syntan property and the influencing mechanism of DS on syntan property are not clarified. In this work, five phenolic formaldehyde syntans (PFSs) with the same polymerization degree but varying DS were prepared to investigate the effect of DS on the properties of syntan and crust leather. It was found that the absolute value of zeta potential and the particle size of PFS decreased with increasing DS in aqueous solution. Molecular dynamic simulation results proved that the DS of PFS was a major contributor to electrostatic interaction and hydrogen bonding in the PFS–water system and greatly affected the aggregation and dispersion of PFS in aqueous solution. The PFS with a low DS was prone to aggregate to large particles in aqueous solution because of low intermolecular electrostatic repulsion and less hydrogen bonds and therefore can be used to increase the thickness and tightness of leather. The PFS with a high DS presented a small particle size with more anionic groups in aqueous solution, thereby sharply decreasing the positive charge of leather surface and facilitating the penetration of the post-tanning agents into the leather. These results might be scientifically valid for rational molecular design of syntans and more productive use of syntans in leather making. Graphical Abstract

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The Acid-Catalyzed Phenol–Formaldehyde Reaction

Cited by 21 publications

References 11 publications

Time-Efficient Acid-Catalyzed Synthesis of Resorcinol−Formaldehyde Aerogels

Time-Efficient Acid-Catalyzed Synthesis of Resorcinol−Formaldehyde Aerogels

Understanding the Fast Pyrolysis of Lignin

A deeper exploration of the relation between sulfonation degree and retanning performance of aromatic syntans

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