Coniferyl alcohol

According to a widely accepted concept, lignin [8068-00-6] may be defined as an amorphous, polyphenoHc material arising from enzymatic dehydrogenative polymerization of three phenylpropanoid monomers, namely, coniferyl alcohol [485-35-5] (2), sinapyl alcohol [537-35-7] (3), and /)-coumaryl alcohol (1). 

It has also been proposed that under the acidic conditions found ia whiskeys, ethanol reacts with lignin (qv) to reduce an alcohol-soluble form of lignin (ethanol lignin). This can be converted into coniferyl alcohol, which can be oxidized to coniferaldehyde. The partial oxidation of ethanol lignin can produce siaapic and coniferyl alcohols that can be converted to syfingaldehyde and vanillin, respectively (8). 

Conditioning chamber la 87,129,131 y-Coniceine 15188 Coniferyl alcohol 15 401 Coniine 15 188... 

As described above, the enzymatic polymerization of phenols was often carried out in a mixture of a water-miscible organic solvent and a buffer. By adding 2,6-di-0-methyl-(3-cyclodextrin (DM-(3-CD), the enzymatic polymerization of water-insoluble m-substituted phenols proceeded in buffer. The water-soluble complex of the monomer and DM-(3-CD was formed and was polymerized by HRP to give a soluble polymer. In the case of phenol, the polymerization took place in the presence of 2,6-di-O-methyl-a-cyclodextrin (DM-a-CD) in a buffer. Only a catalytic amount of DM-a-CD was necessary to induce the polymerization efficiently. Coniferyl alcohol was oxidatively polymerized in the presence of a-CD in an aqueous solution. ... 

Savidge, R. A. Forster, H. Coniferyl alcohol metabolism in conifers—II. Coniferyl alcohol and dihydroconiferyl alcohol biosynthesis. Phytochemistry 2001, 57, 1095-1103. 

Foumand, D. Cathala, B. Lapierre, C. Initial steps of the peroxidase-catalyzed polymerization of coniferyl alcohol and/or sinapyl aldehyde capillary zone electrophoresis study of pH effect. Phytochemistry 2003, 62, 139-146. 

Cho, N.S., Rogalski, J., Jaszek, M., Luterek, J., Wojtas-Wasilewska, M., Malarczyk, E., Fink-Boots, M., and Leonowicz, A., Effect of coniferyl alcohol addition on removal of chlorophenols from water effluent by fungal laccase, J. Wood Sci., 45, 174-178, 1999. 

Recent work by Atalla(H) supports the idea that lignin is at least a semi-ordered substance in wood with the plane of the aromatic ring parallel to the cell wall surface. Woody plants synthesize lignin from trans-coniferyl alcohol (pines), trans-sinapyl alcohol 2 (deciduous), and trans-4-coumaryl alcohol 3 by free radical crosslinking initiated by enzymatic dehydrogenation(l2). Structures of these alcohols are given in Figure 1. 

Benzoe resin (also known as benzoin) comes from Styrax spp. (Styraceae family). In the Sty rax genus the only species that occurs in the Mediterranean is Styrax officinalis, so this was probably the source of the resin in ancient times in that area. Benzoe mainly contains free cinnamic and benzoic acids, and their corresponding esters with cinnamyl, p-coumaryl and coniferyl alcohols. The amounts of these compounds are quite variable and depend on which species the resin was obtained from [129]. 

The synthesis of tetrahydrofuran derivatives from unsaturated alcohols via hydroformylation intermediates was developed many years ago. Moderate yields are obtained from but-2-en-l,4-diol (Scheme 54)94 but hydroformylation is not the major pathway when coniferyl alcohol is subjected to the oxo process (Scheme 55).9S A more complicated reaction is involved... 

Silica gel successfully catalyzed the stereoselective synthesis of several glucoside terpenoids. Treatment of 49a with propan-2-ol, geraniol, the tetrahydropyranyl (THP) ether of coniferyl alcohol, and (—)-perillyl alcohol gave glucosides 52a-d in good yields (Scheme 12). The acid-labile THP group was retained under these reaction... 

However, in the light of the results presented herein, this cannot be stated unequivocally, otherwise it would follow that only guaiacyl type compounds would be obtained as softwood lignin degradation products. It has been found that the native lignin from the softwood white Scots pine also yields p-hydroxybenzaldehyde upon oxidation. Thus, it seems that either coniferyl alcohol is not the only lignin progenitor in woody tissues, or that this coniferyl compound is preceded in the process of... 

The data presented in a recent communication by Freudenberg et al. (32) show that the methoxyl content of the dehydrogenation polymers of coniferyl alcohol do not change with condensation time. However, their reference to p-hydroxycinnamyl alcohols seems to indicate their appreciation of the significance of a p-hydroxyphenylpropane unit in the mechanism of lignin formation. 

The contribution of each of these three monomers to the lignin macromolecule differs depending on the source of the lignin. Gym-nosperm (softwood) lignin is based only on coniferyl alcohol,... 

Since the oxidative polymerization of phenols is the industrial process used to produce poly(phenyleneoxide)s (Scheme 4), the application of polymer catalysts may well be of interest. Furthermore, enzymic, oxidative polymerization of phenols is an important pathway in biosynthesis. For example, black pigment of animal kingdom "melanin" is the polymeric product of 2,6-dihydroxyindole which is the oxidative product of tyrosine, catalyzed by copper enzyme "tyrosinase". In plants "lignin" is the natural polymer of phenols, such as coniferyl alcohol 2 and sinapyl alcohol 3. Tyrosinase contains four Cu ions in cataly-tically active site which are considered to act cooperatively. These Cu ions are presumed to be surrounded by the non-polar apoprotein, and their reactivities in substitution and redox reactions are controlled by the environmental protein. 

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