Bond cleavage of lignin model compounds into aromatic monomers using supported metal catalysts in supercritical water

More efficient use of lignin carbon is necessary for carbon-efficient utilization of lignocellulosic biomass. Conversion of lignin into valuable aromatic compounds requires the cleavage of C–O ether bonds and C–C bonds between lignin monomer units. The catalytic cleavage of C–O bonds is still challenging, and cleavage of C–C bonds is even more difficult. Here, we report cleavage of the aromatic C–O bonds in lignin model compounds using supported metal catalysts in supercritical water without adding hydrogen gas and without causing hydrogenation of the aromatic rings. The cleavage of the C–C bond in bibenzyl was also achieved with Rh/C as a catalyst. Use of this technique may greatly facilitate the conversion of lignin into valuable aromatic compounds.journal articl

5 肝内異所性膵を併発した肝内胆管粘膜癌の一例(I. 一般演題)(第 2 回新潟胆膵研究会)

departmental bulletin pape

Construction of Sequence-Regulated Vinyl Copolymers via Iterative Single Vinyl Monomer Additions and Subsequent Metal-Catalyzed Step-Growth Radical Polymerization

A series of sequence-regulated vinyl copolymers with high-order and long vinyl monomer sequences were constructed via a combination of iterative single vinyl monomer additions, which were mediated by radical and cationic intermediates, and subsequent metal-catalyzed step-growth radical polymerization. The construction of vinyl monomer sequences was attained by iterative single monomer radical and cationic additions between a dichloride, having a similar substituent to that of vinyl monomers, and vinyl monomers such as styrenes, acrylates, and acrylonitrile. The resulting products were converted into sequence-regulated ab-type monomers that have embedded vinyl monomer sequences between an unconjugated C═C bond and reactive C–Cl bond via selective allylation of one of the two C–Cl bonds at their terminals. The synthesized sequence-regulated ab-type monomers were polymerized via metal-catalyzed step-growth radical polymerization, which resulted in vinyl chloride units via repetitive intermolecular addition reactions between the C═C and C–Cl terminals. Alternatively, aa- and bb-type sequence-regulated monomers, which have two unconjugated C═C and two reactive C–Cl bonds, respectively, were prepared by similar iterative single monomer additions and were subsequently polymerized via metal-catalyzed step-growth radical polymerization. The repeating vinyl monomer sequence codes in the resulting polymers, such as ABCC, ABCD, ABBAC, ABDBAC, and ABDBACAEEAC, varied from 4 to 11 monomer units in which the embedded vinyl monomer units were styrenes, acrylates, acrylamides, acrylonitrile, vinyl chloride, vinylidene chloride, and ethylene.journal articl