Wood Chemistry PSE 406

1
Wood ChemistryPSE 406

• Lecture 12
• Wood Extractives

2
Agenda

• General Extractives Information
• Classes
• Chemistry
• Occurrence
• Uses

3
Tree Extractives (1)

• Besides the big three wood compounds, trees
  contain other compounds that serve a variety of
  functions including
• Protection (from insects, animals, and rot).
• Attractants (flowers, fruits)
• Food storage
• The amount of extractives in wood can range from
  1-20 (species, position in the tree, season,
  geographical location)
• More in heartwood

4
Tree Extractives (2)

• Extractives add significant properties to wood
• Color
• Odor
• Density
• These compounds are typically present in very
  limited amounts but still affect the wood
  properties greatly.

5
Protection Chemicals

• Here is a list of the classes of extractives that
  can serve to protect the tree.
• Terpenes
• Resin Acids
• Flavonoids
• Lignans
• Stilbenes
• Tannins
• Phenolics

6
Other Extractives

• These extractives are in the tree typically for
  reasons other than protection.
• Fats and fatty acids
• Proteins
• Flavonoids
• Sterols

7
The Fragrance of a Tree

• Each tree has a unique fragrance.
• Some have strong fragrances than others like
  Cedar.
• Some have only light odor.
• The aroma is due to volatile compounds produced
  by the tree (the odor chemicals become gases
  easily).
• These chemicals can be isolated and sold.

8
General info

• End use
• Pine pitch and resins (waterproof boats, in
  torches and binders).
• Medicine, etc.
• Monomers, dimers, polymers.
• Softwood have higher extractive content than
  hardwood.
• Might be poplar (water) or non-polar solvent
  (toluene, ethanol, or ether) soluble.
• More extractives in bark compared to whitewood.

9
Pitch Chemicals

• When you grab a softwood tree and your hand
  sticks to the tree, you have discovered pitch.
• Pitch consists of about 50/50 terpenes and resin
  acids. Resin acids are glassy like chemicals
  also made of isoprene units.

10
Pitch as a Bandage

• When a softwood tree is wounded, it releases
  pitch to seal the wound.
• Terpenes serve as the antiseptic and then
  evaporate.
• Resin acids serve as the bandage (and also as an
  antiseptic).

11
Sterols Role in Nature

• Sterols are found in plants as both free sterols,
  as sterol esters (of fatty acids) and as sterol
  glycosides
• Serve as components of membranes
• Work with phospolipids to create membranes which
  are only permeable to certain chemicals
• Sterol esters
• Believed to serve as transport agent to get
  sterols from site of biosynthesis to membrane

12
What are Fats and Oils?

• 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.

13
Chemical Composition of Fat/Oils

• Esters of long chain fatty acids
• Most often with glycerol
• 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

H
H
H
14
Chemical Composition of Fatty Acids

• Fatty acids are long chained carboxylic acids
• Mostly even numbered chains
• 16-18 carbons most common
• 20-22 less common
• 80 unsaturated 1, 2 or 3 double bonds

15
Fat (Oil) Content

• 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
• In agricultural crops the majority of the oils
  are triglycerides.

16
Fats in Trees

• 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.
• Function
• 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.

17
Waxes

• 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.

18
Flavonoids

• Serve many roles in plants
• Protection
• Coloration
• Other unique roles.

19
FlavonoidsLocation in Tree

• Found in the heartwood of most tress
• Often responsible for coloration
• Found in lesser amounts in the sapwood
• Are found in large amounts in bark and roots
• Leaves green tea can contain up to 30
  flavonoids
• Flowers color is often due to flavonoids

20
FlavonoidsMedicinal Uses

• Higher flavonoid content in diet reduces chance
  of
• Heart Disease
• Strengthen capillaries
• Dilates blood vessels
• Stroke
• Cancer all types reduced
• Finnish study ½ rate of cancer

21
Condensed TanninsBiological Significance

• Western hemlock
• Bark 18 tannins, wood 2 tannins
• Chestnut and oak
• Protection of plants against insects/animals
• Bad Taste (bitter taste)
• Toxic to bacteria
• Uses of condensed tannins
• Leather tanning 10,000 year old industry
• Adhesives

22
Alkaloids

• These nitrogen containing compounds are found in
  a variety of different plants.
• Located in the leaves, fruits, and bark.
• You are all aware of the alkaloids shown on this
  page you probably have never seen their
  structures. These are typically found in small
  amounts in plants but are worth large sums of
  cash.

Caffeine
Nicotine
Cocaine