A study of the chemical and physical properties of epoxidized and hydrated conjugated linoleic acid
A STUDY OF THE CHEMICAL AND PHYSICAL
PROPERTIES OF EPOXIDIZED AND HYDRATED
CONJUGATED LINOLEIC ACID
for the degree of Master of Philosophy
at The University of Hong Kong
in December 2002
A study was carried out on a synthetic sample of conjugated linoleic acid
[18:2(9Z,llE)] (CLA), which was prepared from ricinoleic acid (isolated from the
castor-oil plant, Ricinus cummunis). The synthesis of CLA involved the substitution
of the hydroxyl group in ricinoleic acid by bromide followed by dehydrobromination
to give the requisite CLA isomer after purification.
CBr4/ CH2CI2/ PPh3 0-5?
i) KOH / EtOH (95 %)
Br Z reflux
R1~R2 ii) BF3-MeOH / MeOH reflux
E Z ~~R2 R1""'----
The synthetic 18:2(9Z,11E) was epoxidized usmg either m-
chloroperoxybenzoic acid, methyltrioxorhenium/hydrogen peroxide, dimethyl
dioxirane or Novozyme 43S?hydrogen peroxide to give the corresponding
monoepoxy lYiz. methyl 11,12-E-epoxy-9Z-octadecenoate ~) and methyl 9,1O-Z-
epoxy-llE-octadecenoate (4)] and diepoxy [viz. methyl 9,1O-Z;1l,12-E-
diepoxystearate (5)] CI8 derivatives.
E Z R1~R'1
+ R1~R'1 + R~R'1
(i) m-chloroperoxybenzoic acid;
(ii) methyltrioxorhenium, hydrogen peroxide; (iii) dimethyl dioxirane;
(iv) Novozyme 435? hydrogen peroxide.
Ring opening reactions of the resulting monoepoxy (3 and 4) and diepoxy (5)
derivatives in the presence of boron trifluoride etherate were conducted. Compound
3 and 4 gave a mixture of a,~-unsaturated ketones (7a!7b and 8a!8b, respectively).
The monoepoxy ~ and 4) and diepoxy (5) derivatives were treated with sodium
iodide and iodomethane in N,N-dimethylformamide to give a furanoid derivative (9),
~,y-unsaturated ketone (6 and 10) and a,~-unsaturated ketone (7a and 8a) fatty esters.
o Z 1\~2
R1 ~ + ~R2
R1 E ~ II + 1 _ E II + n
9 R2 R ~R2 R1~O?...R2
(6) (8a) (9)
Extending the study to a propargylic epoxy CI8 acetylenic fatty ester [methyl
11,12-E-epoxy-9-octadecynoate (11)], which derived from the epoxidation of methyl
IIE-octadecen-9-ynoate (Santalum album seed oil) with m-chloroperoxybenzoic acid,
was treated with boron trifluoride etherate and tetrabutylammonium
dihydrogentrifluoride led to the production of mixtures of keto-allene (l2a), keto-
acetylene (12b) and fluorohydrins (13, 14a and 14b).
+ ~O R
+ R1~ y
OH R2 F R2
R1~ ..?,# + R1~ ? \,#
(14a, erythro) (14b, erythro)
The reaction of propargylic epoxy CI8 acetylenic Btty ester (11) with sodium
iodide and iodomethane in N,N-dimethylformamide gave mixtures of keto-allene
(12a), keto-acetylene (12b) and dihydroxy acetylene fatty esters (15).
o /R + 0 R2
II _ ?.p' IT #"
Hydration of 18:2 (9Z,IIE) furnished methyl 9,12-epoxy-1O-octadecenoate
(16), a mixture of methyl 9,12-epoxy-1O-hydroxystearate (l7a) and methyl 9,12-
epoxy-ll-hydroxystearate (17b) and methyl 9,1 O-dihydroxy-llE-octadecenoate (18).
OH R1~R2 OH
The threo fluorohydrin fatty ester (13) obtained above was subjected to
chromic acid oxidation, which gave methyl ll-fluoro-12-oxo-9-octadecynoate (19).
Cyclization of compound 19 catalyzed by bis(benzonitrile )palladium(II) chloride
gave methyl 8-(4-fluoro-5-hexyl-furan-2-yl)-octanoate (20).
R1- Y F
propylene oxide DMF
All the derivatives were rigorously characterized by a combination of
spectroscopic and spectrometric techniques. In conclusion, CLA can be readily
epoxidized and hydrated.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Date of Publication:01/01/2003