Method for producing low molecular weight aromatic lignin-derived compounds

A method for producing at least one low molecular weight aromatic lignin-derived compound, the method comprising the steps of

• (A) providing optionally chopped lignocellulosic material;
• (B) subjecting the lignocellulosic material to a pulping process;
• (C) separating cellulose obtained in step (B) in a pulp separating step from the process stream obtainable from step (B), to provide a substantially cellulose-free process stream, wherein the process stream comprises modified lignin-derived components, hemicellulose and/or fragments thereof;
• wherein the process stream is provided as one single process stream or as at least two partial process streams;
• (D) isolating a fraction of modified lignin-derived components being comprised
• (D.1) in the process stream of step (C) or,
• (D.2) in at least one of the at least two partial process streams in step (C)
• from either of these process streams;
• (E) subjecting the fraction of modified lignin-derived components of step (D) to a chemical decomposition step, wherein the chemical decomposition step comprises
• (E.1) oxidative cracking (cracking and oxidizing) of the modified lignin components in the presence of a heterogenous or homogeneous catalyst comprising a metal ion or a metalloid component;
• (E.2) reductive cracking (cracking and reducing) of the modified lignin components in the presence of a heterogeneous or homogeneous catalyst comprising a metal ion or metalloid component;
• or
• (E.3) subjecting the modified lignin components to electro-oxidation in alkaline or acidic solution;
• (F) subjecting resulting modified lignin-derived products obtained in step (E) to an isolation and optionally purification step, wherein low molecular weight aromatic lignin-derived compounds are isolated from higher molecular weight aromatic lignin-derived components and/or other non-lignin-derived residual components and optionally purified, and
• wherein the at least one low molecular weight aromatic lignin-derived compound provided by step (F) comprises one aromatic ring and is further processed in a step (G), wherein said low molecular weight aromatic lignin-derived compound comprising one aromatic ring is subjected to an annulation reaction, wherein the annulation reaction product is a low molecular weight aromatic bi- or tricyclic annulated aromatic lignin-derived compound, wherein said compound is characterized by Formula (II), (III) or (IV)
• wherein
• each of R2, R3, R5-R8 of Formula (II) is independently selected from the group consisting of hydrogen, hydroxy, carboxy, linear or branched, optionally substituted, C1-6 alkyl, linear or branched, optionally substituted, C1-6 alkenyl, linear or branched, optionally substituted, C1-6 alcohol, linear or branched, optionally substituted, C1-6 aminoalkyl, linear or branched, optionally substituted, C1-6 carboxyalkyl, linear or branched, optionally substituted, C1-6 alkoxy, linear or branched, optionally substituted, C1-6 aldehyde, ester, oxo and carbonyl;
• and optionally at least one of R2, R3, R5-R8 is hydroxy or C1-3 alkoxy,
• R1 and R4 of Formula (II) is/are selected from the group consisting of hydrogen, hydroxy, linear or branched, optionally substituted, C1-6 carboxyl, linear or branched, optionally substituted, C1-6 aldehyde, and linear or branched, optionally substituted, C1-6 alcohol,
• each of R1-R10 of Formula (III) is independently selected from the group consisting of hydrogen, hydroxy, carboxy, linear or branched, optionally substituted, C1-6 alkyl, linear or branched, optionally substituted, C1-6 alkenyl, linear or branched, optionally substituted, C1-6 alcohol, linear or branched, optionally substituted, C1-6 aminoalkyl, linear or branched, optionally substituted, C1-6 carboxyalkyl, linear or branched, optionally substituted, C1-6 alkoxy, linear or branched, optionally substituted, C1-6 aldehyde, ester, oxo and carbonyl;
• and optionally at least one of R2, R4, R5, R6 and R8 is hydroxy or C1-3 alkoxy,
• each of R2, R3 and R7-R10 of Formula (IV) is independently selected from the group consisting of hydrogen, hydroxy, carboxy, linear or branched, optionally substituted, C1-6 alkyl, linear or branched, optionally substituted, C1-6 alkenyl, linear or branched, optionally substituted, C1-6 alcohol, linear or branched, optionally substituted, C1-6 aminoalkyl, linear or branched, optionally substituted, C1-6 carboxyalkyl, linear or branched, optionally substituted, C1-6 alkoxy, linear or branched, optionally substituted, C1-6 aldehyde, ester, oxo and carbonyl;
• and optionally at least one of R2, R3 and R7-R10 is hydroxy or C1-3 alkoxy, and
• R1, R4, R5 and R6 of Formula (IV) is selected from the group consisting of hydrogen, hydroxy, linear or branched, optionally substituted C1-6 carboxyl, linear or branched, optionally substituted, C1-6 aldehyde, and linear or branched, optionally substituted, C1-6 alcohol.