10.14 Plant Waxes

Plant waxes are the protective cover between the plant cells and their environment, by which they regulate their water loss, and protect themselves from the environment.

When we speak of plant waxes, it is usually as if it were a single compound, but a deeper look reveals that it is a mixture of simple Alkanes, Alcohols, Aldehydes, and Fatty Acids, ranging from 20 carbon chains, to about 34. 

To put them into perspective, the well known Carnauba (C30 H62 O)  and Candelilla (C31 H64 O) plant waxes are C-30 and C-31 molecules respectively.  About the same consistency as bees wax, and denser than (C16 H34 O) ear wax.

WAXES

Wax

Alcohol

Fatty Acid

Carnauba

CH3(CH2)28CH2-OH

CH3(CH2)24COOH

Beeswax

CH3(CH2)28CH2-OH

CH3(CH2)14COOH

Spermacetic (ear wax)

CH3(CH2)14CH2-OH

CH3(CH2)14COOH

     

I've not found an analysis of cannabis plant waxes, but looking at plant waxes in general, here is a breakdown of what is in the waxes from the leaves of the xxxx plant, giving perspective as to the mixture:

% of Fraction in Plant Waxes from:

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3040.2000.00581.x/full

Carbon

Alkanes

Alcohols

Aldehydes

Fatty Acids

20

-

-

-

1

21

-

-

-

tr

22

-

tr

-

2

23

-

tr

-

1

24

-

1

2

7

25

tr

tr

-

2

26

Tr

3

3

5

27

5

1

4

4

28

3

13

24

19

29

47

4

8

8

30

4

33

31

31

31

38

4

-

-

32

2

28

28

21

33

2

3

-

-

34

-

7

-

-

Total

72

9

1

2

Tr = Traces less than 0.5% undetectable

 

Notice that it is no longer an issue of non polar plant waxes, as only the Alkane molecules are non polar.

Molecular weights also become an issue, when you are talking about processes like SCFE CO2, where molecular weights above about 400 g/mol are mostly insoluble.

Looking at C-30 Carnauba wax for instance as  CH3(CH2)28CH2OH or simplified as  C30H62O, it has a molecular weight of about  438.8127 g/mol.  http://www.webqc.org/molecular-weight-of-CH3%28CH2%2928CH2OH.html

Symbol

Element

Atomic Wt

Atoms

Total

C

Carbon

12.0107

30

360.321

H

Hydrogen

1.00794

62

62.49228

O

Oxygen

15.9994

1

15.9994

Molecular Weight

     

438.81268 g/mol

 

That suggests of course that those molecules smaller than about C-27 will have a molecular weight below 400 g/mol, so are readily extracted by SCFE CO2 as well.

Here are some interesting reads on plant waxes:

Biology of the plant cuticle:

https://books.google.com/books?id=qaJVSVYZhVQC&pg=PA119&lpg=PA119&dq=cannabis+plant+wax+chemical+properties&source=bl&ots=UUTo76r1TW&sig=HHQ6RLAXHETfeB5SIHLx8Wnh4b4&hl=en&sa=X&ved=0ahUKEwjbv5uOk7nXAhVDylQKHcBTCLEQ6AEIcjAO#v=onepage&q=cannabis%20plant%20wax%20chemical%20properties&f=false

Leaf cuticular waxes are arranged in chemically and mechanically distinct layers: evidence from Prunus laurocerasus L.

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3040.2000.00581.x/full

 

 


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