Palladium-Catalyzed Functionalization of Kraft Lignin: Ether Linkages through the Telomerization Reaction

Abstract

Kraft lignin was efficiently functionalized with octadienyl ether linkages through the palladium-catalyzed telomerization of 1,3-butadiene. Comparison with molecular model substrates assessed the grafting of phenols and alcohols and an optimization study led to up to 69 % conversion of the total number of hydroxyl groups present in lignin. This catalytic study evidenced the partial oxidation of triphenylphosphine into triphenylphosphine oxide and triphenylphosphine sulfide by contaminants present in the industrial grade kraft lignin. The telomerised lignin is a malleable material and a preliminary study of the thermal properties showed a decrease in the glass transition in comparison with the starting material.

The Telomerization of 1,3‐Dienes – A Reaction Grows Up

“…A rather unusual approach to the valorization of renewable alcohols is the telomerization of phenols that resemble lignin‐type phenols with a subsequent Claisen rearrangement . Sauthier et al were recently able to demonstrate that the telomerization of lignin with 1,3‐butadiene can lead to a modified bio‐polymer, which still offers terminal unsaturated double bonds for further functionalization …”

“…Acid treatment after the first step still leads to a 22% yield . This reaction can also be carried out using more complex alcohols, for example lignin‐type phenols or even Kraft‐Lignin . The resulting structures of this reaction are nonadienyl carboxylic esters with aryl and aliphatic substituents.…”

Correlations among Miscibility, Structure, and Properties in Thermoplastic Polymer/Lignin Blends

“…10,12 The functional groups offer possibilities to use lignin for various purposes or to modify them by chemical reactions. [12][13][14][15][16][17] Many attempts were made to use lignin as stabilizer in polymers utilizing the hydrogen scavenging ability of its phenolic hydroxyl groups. Lignin stabilized the polymers in smaller and larger extent indeed, but its industrial utilization is difficult because of its limited efficiency compared to commercial phenolic antioxidants, strong smell and intensive color.…”

The Palladium‐Catalyzed Carbonylative Telomerization Reaction with Phenols, Polyphenols and Kraft Lignin

“…This indicates that the reaction is tolerant to the presence of aldehyde, alkene and acetal This also emphasizes the efficiency of the proposed approach as at ool for upgrading bioresources. [19] Particular focus was put on Kraft lignin [20] which is industrially produced on av ery large scale and essentially valorized for the production of energy.T he materialc ontains al argen umber of phenolic (hydroxyl) and aliphatic alcohols both of which act as nucleophiles during carbonylative transformations. The O-functionalization of lignin can be targeted to chemically modify such materials and introduce new functionalities.…”

“…In our approach we targeted lignins as phenolic-type reactants to catalytically functionalize agromaterial. [19] Particular focus was put on Kraft lignin [20] which is industrially produced on av ery large scale and essentially valorized for the production of energy.T he materialc ontains al argen umber of phenolic (hydroxyl) and aliphatic alcohols both of which act as nucleophiles during carbonylative transformations. Before attempting direct transformation of lignin,w ei nvestigated the transformation of methoxy-substituted "lignin-type" phenolsw hich have been previously exploredf or telomerization reaction.…”