Phenol model structure

Scheme 10.4 (a) Structural changes in the Re-CVD/HZSM-5 (19) catalyst during direct phenol synthesis from benzene and O2 and treatment with NH3 (b) proposed model structure of the N-interstitial Reio-cluster catalyst supported in the pore of HZSM-5 (calculated by DFT). 

Figure 2 shows a difference curve obtained from methylol kraft lignin when untreated lignin was used as reference. The difference curve has a distinct maximum at 590 m/z, characteristic of the phenol alcohol structures formed. By comparing the absorbance at 590 m/z with the molar absorbance (e) of models investigated, the amount of phenol alcohols in lignin can be estimated. The numerical values depend somewhat on the e value of the model chosen. In this study a value of e = 840 was used, the increase found at 590 m/z between the molar absorbances of the dimeric phenol alcohol and its parent phenol of model II. 

Schnitzer and Khan (1972) concluded that fulvic acids consist in part of phenolic and benzenecarboxylic acids, held together through hydrogen bonds to form a polymeric structure of considerable stability (Fig. 5). Buffle s (1977) model structure of fulvic acid (Fig. 6) contains aromatic and aliphatic components extensively substituted with oxygen-containing functional groups. Both structures show an abundance of COOH groups. 

A fulvic acid of number average molecular weight 1000 can yield as many as 30 different substituted mononuclear phenol-carboxylate structures in a mild oxidative degradation which accounts for 30% of the mass of the sample. Because only a small fraction of these structures would be needed to make a polymer of MW = 1000, it is clear that the fulvic acid is a complex mixture, yet the aliphatic components have not so far been considered. It may be asked if efforts should not concentrate on the resolution of the mixture, regardless of how difficult that task may be. However, the task in understanding natural system chemistry would then require modeling the interactions that occur in the mixture, which is, in my opinion, more difficult than studying them directly. 

The graphic that opened this chapter IS a molecular model of phenol that shows its planar structure and electro static potential... 

Kaprelyants, A., Suleimenov, M., Sorokina, A., Deborin, G., El-Registan, G., Stoyanovich, F., Lille, Yu., Ostrovsky, D. Structural-functional changes in bacterial and model membranes induced by phenolic lipids. Biological membranes, Vol.4, No.3, (March 1987), pp. 254-261, ISSN 0748-8653... 

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