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Wood Chemistry l Wood Chemistry l l Lecture 14 Fats/Waxes/Lignans PSE 406 Lecture 14 l l l Tall oil Waxes Lignans » Chemistry » Role in the tree » Commercialization 1 What are Fats and Oils? PSE 406 Lecture 14 Wood Chemistry Both you and I recognize fat when we see it. We also probably know that fat and oils are energy storage material. Fats and oils are similar chemically: the difference is that fats are solids at room temperature and oils are liquids. PSE 406 Lecture 14 Fats and Fatty Acids » Chemistry » Role in the tree PSE 406/Chem E 470 Wood Chemistry Agenda Wood Chemistry 2 Chemical Composition of Fat/Oils l Esters of long chain fatty acids l Trigylcerides, diglycerides, & monoglycerides Similar structures in all plants. What varies is the fatty acids attached to the glycerol and the percentage of tri, di, and monoglycerides » Most often with glycerol l H2C O CO R1 H2C O CO R1 H2 C O CO R2 H 2C O CO R2 H 2C O CO R1 H2C OH H 2C O C O R3 H2C OH H2 C OH Diglyceride Triglyceride Monoglyceride O H2C O C 3 PSE 406 Lecture 14 4 1 1 Wood Chemistry l Chemical Composition of Fatty Acids Wood Chemistry l Fatty acids are long chained carboxylic acids » Mostly even numbered chains – 20-22 less common » 80% unsaturated: 1, 2 or 3 double bonds Secondary Fatty Acids COOH l COOH Palmitic acid (C16) Oleic acid (C18) There are high levels of fats in seeds. » Corn and soybeans contain 10-20% oils. » Canola and sunflower contain up almost 50% oils. » Nuts 50-70% oils – 16-18 carbons most common Major Fatty Acids Fat (Oil) Content COOH In agricultural crops the majority of the oils are triglycerides. COOH Linolenic acid (C18) COOH Linoleic acid (C18) Eicosadienoic acid (C20) PSE 406 Lecture 14 Wood Chemistry l 5 Fats in Trees Wood Chemistry Free Fatty Acids Most fatty acids are linked as esters to other components (glycerol, sterols, etc) in the cells. l A small amount of free fatty acids are present in plants. (not according to Encyclopedia Britannica) Function l » Fats role in trees is the same as in your waist line: serves as a storage material. » The amount of fat in the tree is seasonally dependent. PSE 406 Lecture 14 6 l Fats are found in living cells - parenchyma » Very low content (1 -2%) in oleoresin. » More present in sapwood than heartwood. » High content in many nuts. l PSE 406 Lecture 14 Roles of free acids: » Disease resistance (messengers) » Other????????? 7 PSE 406 Lecture 14 8 2 2 Fats & Fatty Acids Composition in Wood Wood Chemistry Picea abies a % of wood 1 b Pinus Syv. Populus Tr. % of wood % of wood Fatty Acids 0.08 (29%) 0.17 (24%) 0.11 (9%) Fats - Trigylcerides 0.12 (45%) 0.53 (72%) 0.98 (78%) - Digylcerides c 0.02 (3%) 0.05 (4%) - Monoglycerides 0.03 (13%) 0.01 (2%) 0.11 (9%) - OH OH - HOCH2CHCH2OH O H2C O C R Glycerol (glycerine) OH H2O O H2C OH - O C R PSE 406 Lecture 14 9 Fats & Fatty Acids Pulp and Paper Issues Fats and fatty acids are not water soluble and are therefore involved in the formation of stickies . 10 Tall Oil Production Turpentine Pulp Recovery Furnace Washers Evaporators pulp Chips Digester liquor Intermediate Liquor Fatty acids are often recovered along with resin acids from kraft mills. This combination of chemicals is known as tall oil. PSE 406 Lecture 14 PSE 406 Lecture 14 Wood Chemistry » Remember that these chemicals are found in little parenchyma cells. Beating of pulp can release this material. l Treatment of fats with alkali converts them to fatty acids and glycerol through saponification. O H 2C O C a: Norway spruce b: Scotch pine c: European aspen 1: % of total fatty material l l R 0.03 (13%) Wood Chemistry Saponification of Fats Wood Chemistry 11 Crude Tall Oil Acidulation Unit PSE 406 Lecture 14 Soap Skimmer 12 3 3 Wood Chemistry Product TOR TOFA DTO Heads Pitch Tall Oil Fractionization Temp < 260°C Yields 32% 28% 8% 10% 18% Vacuum Crude Fatty Acids Fatty Acids Pitch Rosin Wood Chemistry 13 Waxes CH3 (CH 2) n O CO ( CH2 )m CH 3 C2 0H 41OH C24H 49 OH Arachidic Alcohol Lignoceric Alcohol PSE 406 Lecture 14 Wood Chemistry Other components found in waxes include n-alkanes, ketones, primary and secondary alcohols, aldehydes, dicarboxylic acids, and hydroxy acids. Minor wood component Physical Properties l l l » Soluble in organic solvents. Water insoluble » mp/bp: think candles l PSE 406 Lecture 14 Waxes Distilled Tall Oil » 0.08-0.09% » Much higher percentage in foliage, fruits and some barks. l Wax is the water resistant protective coatings of leaves, fruits, and trees (bark). Wax is a mixture of a variety of different chemicals. » Waxes consist mainly of very long chained (C12-38) fatty acid esters of long chained alcohols. PSE 406 Lecture 14 l l Heads Depitched Crude Tall Oil Waxes No Air Heads Tall Oil l Wood Chemistry 15 14 Lignans Another class of extractive produced by the plant for protection.There are large numbers of different lignans. Lignans are found in the bark, fruit, heartwood, leaves, and roots of plants. Isolation is accomplished though solvent extraction. Yields of 0-30% are obtained. PSE 406 Lecture 14 O CH3O O HO OCH3 OH α-Conidendrin Example lignan found In heartwood of softwoods 16 4 4 Lignans Wood Chemistry l Structural Information » Comes through same biosynthetic pathway as lignins » C9 units linked through enzymatic free radical coupling » Protein found which acts as template to force β-β orientation l γ C Two phenylpropane units (C9) linked β−β l β C 1 6 2 3 » Ring substitution (3, 4, 5) » Nature of linked side chain » Nature of additional bonds between rings 5 4 l OCH3 In trees, lignans are laid down at the sapwood/heartwood boundary. » They are laid down when the tree is depositing chemicals to protect itself. OH PSE 406 Lecture 14 Wood Chemistry Many lignans have fungicidal, insecticidal, and antioxidant properties. » Hydroxymatairesinol actually consumed by fungi accelerating degradation. α C Lignans differ in: Lignans: Role in the Plant Wood Chemistry 17 PSE 406 Lecture 14 18 Lignans Lignans: Location in Tree Typical Softwood Species Wood Chemistry O l O Widely distributed in softwoods and hardwoods H2 C HC CH2 » Typically amount: < 1% of heartwood » Can be as high as 30% of heartwood l Found in Heartwood CH3O CO CH CH2 HO OH » Nearly non existent in sapwood » In Tsuga, lignans were found lining the tracheid walls as surface coatings and encrusting bordered pits » Lignans deposited during heartwood formation » Greatly responsible for coloration of heartwood OH OCH3 OH OH α -Conidendrin Matairesinol CH2 CH2 CH OH OCH3 CH3 O H2C CH CH O Hinokiresinol OH OCH 3 H2COH HC HC H2C H2COH CH CH2 O HC HC CH CH O CH OCH3 CH3 O OH OH CH 3O OH Pinoresinol Isolariciresinol PSE 406 Lecture 14 19 PSE 406 Lecture 14 20 5 5 Lignans Wood Chemistry l Lignans Medicinal uses Wood Chemistry l Large amount of research devoted to investigating medicinal properties of lignans. l – Example 1999 reference: 35 lignans isolated from the twigs of Tazus mairei (a shrub) for possible use as drugs. l l Lignans are phytoestrogens » These are compounds produced by plants which are similar in structure to oestrogen and ehibit oestogenicity. PSE 406 Lecture 14 Also found in mayapple: common American weed l 21 l l Sold by Bristol-Myer Squibb as VePesid Treatment for testicular cancer and small lung cancers and others. Glycoside (sugar containing) of Podophyllotoxin O CH3 Wood Chemistry OCH3 OCH3 22 Nordihydroguaiaretic Acid l Isolated from the leaves of Larrea divaricata l NDGA is a proven antioxidant » 12% yield O O OH O l O O HO HO » Used in fats and oils in food. O CH3O CH3O PSE 406 Lecture 14 O HO O Lignans Example Uses: Etoposide H l O O Functions as cell poison: affects cells undergoing mitosis. Inhibits enzyme needed for cancer cell reproduction. Starting material for the manufacture of other cancer drugs. Lignans Wood Chemistry OH O » Extracted from leaves Studies have found certain medicinal properties: » Antiviral, antitumor , antioxidant l Extract of Phodophyllum emodi » Asian plant » Material in root (rhyzomes ) » Particularly from tropical hardwoods and grasses. l Example Uses: Podophyllotoxin Produced synthetically from petroleum based starting material. OH OH OCH3 OCH3 PSE 406 Lecture 14 23 PSE 406 Lecture 14 24 6 6 Wood Chemistry l Lignans: Industrial Problems Lignans found in water discharge from mechanical pulping operations » Toxic to fish but not as much as other extractive compounds » Are readily handled through biological treatment systems l Plicatic acid has been found to be the number one cause of respiratory problems in cedar saw mills PSE 406 Lecture 14 25 7 7