Lignin and Lignans as Renewable Raw Materials

Francisco García Calvo-Flores, Associate Professor, Department of Organic Chemistry, University of Granada, Spain.José A. Dobado, Associate Professor, Department of Organic Chemistry, University of Granada, Spain.Joaquín Isac García, Associate Professor, Department of Organic Chemistry, University of Granada, Spain.Francisco J. Martin-Martinez, Post-doctoral Researcher, Free University of Brussels (VUB), Belgium.The authors form a multidisciplinary team in research areas spanning carbohydrate chemistry, green chemistry, chemical engineering, organic synthesis, and theoretical chemistry. They also have extensive experience in teaching subjects such as Green Chemistry, Environmental Chemistry, Organic Chemistry, Application of Spectroscopic Methods to Organic Compounds, Computational Organic Chemistry, both at the undergraduate and Masters level of Chemistry.

• Series Preface xvPreface xviiList of Acronyms xixList of Symbols xxiiiPart I Introduction 11. Background and Overview 31.1 Introduction 31.2 Lignin: Economical Aspects and Sustainability 41.3 Structure of the Book 5Part II What is Lignin? 92. Structure and Physicochemical Properties 112.1 Introduction 112.2 Monolignols, The Basis of a Complex Architecture 122.3 Chemical Classification of Lignins 162.4 Lignin Linkages 172.5 Structural Models of Native Lignin 202.6 Lignin–Carbohydrate Complex 342.7 Physical and Chemical Properties of Lignins 393. Detection and Determination 493.1 Introduction 493.2 The Detection of Lignin (Color-Forming Reactions) 493.3 Determination of Lignin 553.4 Direct Methods for the Determination of Lignin 553.5 Indirect Methods for the Determination of Lignin 603.6 Comparison of the Different Determination Methods 664. Biosynthesis of Lignin 754.1 Introduction 754.2 The Biological Function of Lignins 754.3 The Shikimic Acid Pathway 764.4 The Common Phenylpropanoid Pathway 784.5 The Biosynthesis of Lignin Precursors (the Monolignol-Specific Pathway) 804.6 The Dehydrogenation of the Precursors 854.7 Peroxidases and Laccases 864.8 The Radical Polymerization 874.9 The Lignin–Carbohydrate Connectivity 974.10 Location of Lignins (Cell Wall Lignification) 994.11 Differences Between Angiosperm and Gymnosperm Lignins 101Part III Sources and Characterization of Lignin 1135. Isolation of Lignins 1155.1 Introduction 1155.2 Methods for Lignin Isolation from Wood and Grass for Laboratory Purposes 1165.3 Commercial Lignins 1276. Functional and Spectroscopic Characterization of Lignins 1456.1 Introduction 1456.2 Elemental Analysis and Empirical Formula 1466.3 Determination of Molecular Weight 1476.4 Functional Group Analyses 1516.5 Frequencies of Functional Groups and Linkage Types in Lignins 1596.6 Characterization by Spectroscopic Methods 1646.7 Raman Spectroscopy 1667. Chemical Characterization and Modification of Lignins 1897.1 Introduction 1897.2 Characterization by Chemical Degradation Methods 1897.3 Other Chemical Modifications of Lignins 2167.4 Thermolysis (Pyrolysis) of Lignins 2277.5 Biochemical Transformations of Lignins 227Part IV Lignins Applications 2478. Applications of Modified and Unmodified Lignins 2498.1 Introduction 2498.2 Lignin as Fuel 2528.3 Lignin as a Binder 2538.4 Lignin as Chelating Agent 2548.5 Lignin in Biosciences and Medicine 2568.6 Lignin in Agriculture 2578.7 Polymers with Unmodified Lignin 2588.8 Other Applications of Unmodified Lignins 2678.9 New Polymeric Materials Derived from Modified Lignins and Related Biomass Derivatives 2718.10 Polymers Derived from Chemicals Obtainable from Lignin Decomposition 2788.11 Other Applications of Modified Lignins 2799. High-Value Chemical Products 2899.1 Introduction 2899.2 Gasification: Syngas from Lignin 2919.3 Thermolysis of Lignin 2919.4 Hydrodeoxygenation (Hydrogenolysis) 2949.5 Hydrothermal Hydrolysis 2959.6 Chemical Depolymerization 2959.7 Oxidative Transformation of Lignin 2999.8 High-Value Chemicals from Lignin 302Part V Lignans 31310. Structure and Chemical Properties of Lignans 31510.1 Introduction 31510.2 Structure and Classification of Lignans 31510.3 Nomenclature of Lignans 31910.4 Lignan Occurrence in Plants 32510.5 Methods of Determination and Isolation of Lignans from Plants 32810.6 Structure Determination of Lignans 33110.7 The Chemical Synthesis of Lignans 33211. Biological Properties of Lignans 36911.1 Introduction 36911.2 Biosynthesis of Lignans 37011.3 Metabolism of Lignans 37711.4 Plant Physiology and Plant Defense 38311.5 Podophyllotoxin 38611.6 Biological Activity of Different Lignan Structures 397Part VI Outcome and Challenges 45512. Summary, Conclusions, and Perspectives on Lignin Chemistry 45712.1 Sources of Lignin 45712.2 Structure of Lignin 45812.3 Biosynthesis and Biological Function 45912.4 Applications of Lignin 45912.5 Lignans 46112.6 Perspectives 462References 462Glossary 465Index 467