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Alkylation lignins

The use of dialkylsulfate, R SO, and base to alkylate lignin produces a product in which the aromatic and primary and secondary, aliphatic alcohols (109,110) are alkylated. Some tertiary aleohol groups may escape alkylation (111). These products are extensively hydrophobic since almost all of the acidic alcohol groups are now capped as ethers and all carboxylic acid groups have been converted to esters. Unless other ionic functional groups are present, these products dissolve only in nonpolar or organic solvents and have the physical properties of a thermoplastic. [Pg.92]

Substitution Reactions on Side Chains. Because the benzyl carbon is the most reactive site on the propanoid side chain, many substitution reactions occur at this position. Typically, substitution reactions occur by attack of a nucleophilic reagent on a benzyl carbon present in the form of a carbonium ion or a methine group in a quinonemethide stmeture. In a reversal of the ether cleavage reactions described, benzyl alcohols and ethers may be transformed to alkyl or aryl ethers by acid-catalyzed etherifications or transetherifications with alcohol or phenol. The conversion of a benzyl alcohol or ether to a sulfonic acid group is among the most important side chain modification reactions because it is essential to the solubilization of lignin in the sulfite pulping process (17). [Pg.139]

Manufacturing procedures for producing dye dispersions are generally not disclosed. The principal dispersants in use include long-chain alkyl sulfates, alkaryl sulfonates, fatty amine—ethylene oxide condensates, fatty alcohol—ethylene oxide condensates, naphthalene—formaldehyde—sulfuric acid condensates, and the lignin sulfonic acids. [Pg.450]

The method allowed the authors to characterise a pine pitch (viscous tar derived from the distillation of wood of pine trees). The main constituents detected by headspace SPME result from the pyrolysis of the lignin, guaiacol (11) and its p-w-alkyl derivatives [methyl... [Pg.265]

Dynaphen A process for converting mixed alkyl phenols (from coal liquids or lignin) to benzene, phenol, and fuel gas, by noncatalytic hydrogenation at high temperature. Developed and offered by Hydrocaibon Research. [Pg.94]

As to the origins of the major N compounds identified, it is possible that at least a portion of some of these compounds are pyrolysis products of amino acids, peptides, proteins, [18] and porphyrins (a component of chlorophyll), [19] or originate from the microbial decomposition of plant lignins and other phenolics in the presence of ammonia. [20] Of considerable interest are the identifications aromatic and aliphatic nitriles. Nitriles can be formed from amines with the loss of 2 H2, from amides with the loss of H20, and also by reacting n-alkanoic acid with NH3. [21] The detection of long-chain alkyl- and dialkyl-nitriles points to the presence in the soil or SOM of long-chain amines... [Pg.125]

Hie GOG-Dimer formed from the lignin dimer compound (GOG) by laccase III was also degraded by laccase HI, resulting in the formation of compounds (I), (VI), and biphenyl dimer of 2-methoxy-l,4-benzoquinone (DC). This indicates that GOG-Dimer also suffers the cleavage of -0-4 ether linkage via the alkyl-phenyl cleavage. [Pg.220]

Electrophiles other than protons were indeed shown to react with lignin model compounds at the 2- and 6-positions in acidic media Kratzl and Wagner investigated the reaction of paraphenolic benzyl alcohols in alkaline and acidic solutions (10). When 4-hydroxy-3-methoxybenzyl alcohol 4 was reacted with the 4-alkyl substituted phenol 5 under alkaline conditions, the expected ortho linked product (6) was isolated. However, under acidic conditions the methylene linkage formed meta to the phenolic hydroxy group (Fig. 2). [Pg.350]

Figure 5. Mechanisms responsible for the higher electron density on positions 2 and 6 on lignin phenylpropane units in acidic medium, (a) the induction effect of the alkyl group at position 1 (b) the resonance effects of the electron pairs on the methoxy oxygen. Figure 5. Mechanisms responsible for the higher electron density on positions 2 and 6 on lignin phenylpropane units in acidic medium, (a) the induction effect of the alkyl group at position 1 (b) the resonance effects of the electron pairs on the methoxy oxygen.

See other pages where Alkylation lignins is mentioned: [Pg.111]    [Pg.105]    [Pg.91]    [Pg.748]    [Pg.201]    [Pg.111]    [Pg.105]    [Pg.91]    [Pg.748]    [Pg.201]    [Pg.142]    [Pg.143]    [Pg.144]    [Pg.194]    [Pg.155]    [Pg.134]    [Pg.605]    [Pg.451]    [Pg.211]    [Pg.42]    [Pg.83]    [Pg.37]    [Pg.145]    [Pg.108]    [Pg.124]    [Pg.126]    [Pg.131]    [Pg.147]    [Pg.207]    [Pg.216]    [Pg.220]    [Pg.237]    [Pg.240]    [Pg.456]    [Pg.9]    [Pg.98]    [Pg.187]    [Pg.487]    [Pg.511]    [Pg.355]    [Pg.365]    [Pg.416]    [Pg.417]    [Pg.419]    [Pg.433]   
See also in sourсe #XX -- [ Pg.142 ]




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