5/20/2018 Wood Extractables

1/15

Extractive Components

of Wood

Barbara ColeUniversity of Maine

5/20/2018 Wood Extractables

2/15

CO2H

Major Components of Wood

5/20/2018 Wood Extractables

3/15

Wood Extractives

- Non-cell wall components

-Can be removed using solvents,

e.g. pet. ether, acetone, ethanol, water

- Relatively small molecules (< C40)

- Usually comprise 1-5% of the wood

- Under genetic control vary by species

5/20/2018 Wood Extractables

4/15

Lipid Extractive Components

I. Aliphatics

Fats (fatty acid esters of glycerol): 0.3-0.4%

Fatty acids:

5/20/2018 Wood Extractables

5/15

Suberin (polyester):

Fatty alcohols (C16-C28):

Waxes (esters of other alcohols):

CH3-(CH2)n-O-CO-(CH2)m-CH3

C20H41OH (Eicosanol)

[-O-(CH2)n-CO-] n= 18-28

Fatty acidAlcohol

5/20/2018 Wood Extractables

6/15

Lipid Extractive Components

II. Terpenoids: primarily in softwood species

Monoterpenes (C10)

a-Pinene b-Pinene Limonene

Uses: Turpentine, flavor and fragrance chemicals

5/20/2018 Wood Extractables

7/15

Lipid Extractive Components

II. Terpenoids: primarily in softwood species

Diterpenes (C20) (0.2-0.8% of wood)

CO2H

Abeitic Acid Pimaric Acid

CO2H

Uses: Rosin, sizing agents

5/20/2018 Wood Extractables

8/15

Lipid Extractive Components

II. Terpenoids:

Triterpenes (C30) (5-30% in birch bark)

HO

CH2OH

Betulin

5/20/2018 Wood Extractables

9/15

Phenolic Extractive Components

I. Simple Phenolics

CO2H

HO

OH

OH

Gallicacid

CHO

OH

OCH3

Vanillin

5/20/2018 Wood Extractables

10/15

Phenolic Extractive Components

II. Stilbenes

HO

HO

Pinosylvin

Stilbenes are generally very toxic!

Primarily in the heartwood of conifers.

5/20/2018 Wood Extractables

11/15

Phenolic Extractive Components

III. Flavonoids

HO

OH

OH

OH

OH

O Taxifolin

- Flavonoids are the most abundant phenolics.

-Coloration in foliage and flowers, astringent taste in unripe fruits.

-Condensed tannins: tanning agents, adhesives

5/20/2018 Wood Extractables

12/15

Phenolic Extractive Components

IV. Lignans

HC

HCO

CH2

CHH2C CH

O

OH

OCH3

OH

CH3O

Pinoresinol

Generally non-toxic and are very good antioxidants.

5/20/2018 Wood Extractables

13/15

Other Extractive Components

I. Alkanes

II. Proteins

III. Monosaccharides and derivatives

5/20/2018 Wood Extractables

14/15

Summary

- Extractive components are small molecules that can beextracted with a solvent from wood, bark, or foliage.

-Generally, extractives are present in small amounts.

-Extractives vary tremendously within species, between

species, and within trees.

-There are thousands of different extractives present in

wood.

5/20/2018 Wood Extractables

15/15

Softwoods:- Resin acids: 40-45% of extractives

- Fatty acids: 40-60%

- Monoterpenes (turpentine)- Phenolics

Hardwoods:- No resin acids or monoterpenes

- Fatty acids: 60-90%

- Phenolics

Softwoods vs. Hardwoods