Process for conjugating carbon-carbon double bonds in oils

Details Process for conjugating carbon-carbon double bonds in oils Process for conjugating carbon-carbon double bonds in oils

2002-08-15

2004-02-24

Carr, Deborah (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

Reexamination Certificate

active

06696581

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an improved process for conjugating organic compounds containing methylene interrupted carbon-carbon double bonds. This invention further relates to a process for conjugating methylene interrupted carbon-carbon double bonds found in drying and semi-drying oils.
Drying oils, which are liquid vegetable or fish oils, are triglycerides, i.e. triesters of glycerol and fatty acids, which have the ability to dry or polymerize and form a dried film. Examples of drying oils include, but are not limited to, linseed, fish, soybean, tall, tung and oiticia. Drying oils are composed of fatty acids, which have a preponderance of two or three double bonds. The drying ability of these oils is in part related to their Iodine Value (“IV”), which is a quantitative measure of the number of double bonds which they contain. Oils in the range of 195-170 IV are relatively fast-drying. Oils in the range of 140-120 IV are semi-drying, and oils with IV's under 120 are non-drying. Most of these oils have methylene interrupted double bonds. Oiticia and tung are conjugated oils and have only negligible amounts of methylene interrupted double bonds. Tall oil has a small amount of conjugated fatty acid content.
The terms “conjugated” or “conjugation” are used herein to describe compounds, e.g. triglycerides, which have carbon-carbon double bonds on adjacent carbon atoms. As used herein, “methylene interrupted” means compounds containing more than one carbon-carbon double bond wherein the double bonds are separated by a methylene group. For oils to be useful in industrial applications, including coatings, inks and the like, it is advantageous to have the carbon-carbon double bonds be conjugated, i.e. the methylene interrupt is shifted or relocated. A simplified example of the difference between methylene interrupted and conjugated is illustrated in the following examples showing only the carbon atoms:
—C═C—C—C═C—
Methylene interrupted double bonds
—C═C—C═C—C—
Conjugated double bonds
This conjugation facilitates polymerization and, thus, allows for faster drying. These oils can dry in 8-16 hours. Linseed oil and other oils in the range of 195 to 170 IV having substantial amount of methylene interrupted carbon-carbon double bonds are classified as drying oils, but they need to be made to polymerize rapidly to dry with the speed necessary for industrial uses such as coatings and inks. Conjugation of the methylene interrupted double bonds achieves this. When linseed oil is conjugated to about 70-75%, it will dry in about 8-16 hours, whereas natural, unconjugated linseed oil takes many days to weeks to dry.
The methylene interrupted oils are edible and are essential to life. These oils are used as cooking oils and components of foods. The conjugated oils are used for industrial purposes such as in ink formulations and coatings. Tung oil has been one oil of choice for fine woodwork coating for many years. These conjugated oils, i.e. tung and oiticia, are very expensive and their supply has been erratic. Thus, their use is limited by cost and availability. So, oils such as linseed, which are plentiful, provide a very stable reliable and economical source for industrial purposes provided they can be conjugated in a cost effective manner.
Previous research in the area over the years has resulted in many methods for conjugation. However only one method, U.S. Pat. No. 5,719,301 (Feb. 17, 1998), (“the '301 patent”), was economical enough to be put into commercial production. The product, Archer I, produced by Archer Daniels Midland Co., Decatur, Ill., has been commercially available since 1995. The '301 patent discusses prior art and numerous unsuccessful attempts to discover a commercially viable process for conjugation. Subsequent to that work, other research groups have studied methods of conjugation. None of these were successful in developing a commercially cost effective process.
Other studies on isomerization using ruthenium catalysts have been published. “Isomerization of Vegetable Oils Catalyzed by Dichlorotris(Triphenylphosphine)ruthenium”, S. Krompiec, J. Suwinski, J. Majewski and J. Grobelny, Pol. J. Appl. Chem. XLI, z. 1-2, 35-46 (1997), (“Krompiec I”), disclosed the isomerization of rapeseed oil and soybean oil wherein the isomerization was conducted at a temperatures between 212° C. and 238° C., and 15-116 ppm ruthenium as the organometallic complex. In “Isomerization of Vegetable Oils Catalyzed by Ruthenium Complexes”, S. Krompiec, J. Jerzy, J. Majewski and J. Grobelny), Pol. J. Appl. Chem. 42: 43-48 (1998), (“Krompiec II”), the following ruthenium catalysts were used: RuHCl(CO)(PPh
3
)
3
, Ru(CO)
3
(PPh
3
)
2
, [RuCl
2
(1,5-COD)]
x
, Ru(acac)
3
, RuCl
2
(PPh
3
)
3
, RuH
2
(PPh
3
)
4
, RuCl
2
(AsPh)
3
, [RuCl
2
(NBD)]
x
, and RuCl
2
(SbPh
3
)
3
. Krompiec II ran isomeriztion reactions on rapeseed, soybean, linseed, and sunflower oils at 212° C. and 226° C. with two concentrations of ruthenium complexes of 58 and 116 ppm as ruthenium. Conjugation plus polymerization generally was greater than 90% for most reactions. Krompiec II disclosed that the best results were with RuHCl(CO)(PPh
3
)
3
. The reactions in Krompiec I and Krompiec II are of little commercial value because the catalyst cost is prohibitively expensive.
The paper “(n6-Naphthalene)(n4-cycloocta-1,5-diene)ruthenium(0) as Efficient Catalytic Precursor for the Isomerization of Methyl Linoleate Under Mild Conditions”, P. Pertici, V. Ballantini, S. Catalano, A. Giuntioli, C. Malanga and G. Vitulli, J. Mol. Catal. A: Chem. 144:7-13 (1999) disclosed the isomerization of methyl linoleate. This reaction was run at 60° C. in hexane or methanol as solvent. The hexane needed to be dried over sodium/potassium metal alloy under argon and anhydrous methanol was obtained by drying over CaH
2
and distilling. Isomerization of methyl linoleate is faster in methanol than in hexane, but the percent conjugation is substantially lower in methanol than in hexane under equivalent reaction conditions. The ruthenium catalyst concentration used was 0.06 mmoles to 6.0 mmoles of methyl linoleate. Here again the catalyst fabrication cost is prohibitive and the solvent and reaction conditions are unrealistic for a viable commercial process.
The paper “Preparation of Conjugated Soybean Oil and Other Natural Oils and Fatty Acids by Homogeneous Transition Metal Catalysis”, Richard Larock, et al. of Iowa State University, Journal of the American Oil Chemists Society 78, 5, 447-453 (2001). The Larock et al. paper included a few reactions with ruthenium catalyst RuHCl(CO)(PPh
3
)
3
. Most reactions studied used various homogenous organo-complexes of precious metal (rhodium and platinum) catalysts: RhCl(PPh
3
)
3
, Rh[(C
2
H
4
)
2
Cl]
2
, RhCl
3
.2H
2
O, [RhCl(C
8
H
14
)
2
]
2
, and PtCl
2
(PPh
3
)
2
. All of these reactions with the Rh and Pt catalysts were run with a SnCl
2
.2H2O promoter. In addition to the added cost of the SnCl
2
promoter, the cost of rhodium is generally ten times the cost of ruthenium. Platinum generally exhibits a factor of two to five times the cost of ruthenium. These costs are on a raw metal basis and do not include the additional cost of catalyst fabrication to make the organometallics. Thus the use of these Rh and Pt catalysts is practically only useful for research laboratory study. The set of experiments on isomerization of soybean oil using RuHCl(CO)(PPH
3
)
3
as catalyst were run without the SnCl
2
promoter. These were run at 60° C. in the presence of a solvent, i.e. benzene or ethanol, or in the absence of a solvent. One of the Ru catalyzed reactions was run in benzene using 0.10 mole percent ruthenium and gave a conjugation of 42%. The rest of the reactions used 0.25 mole percent ruthenium or greater. The 0.10 mole percent reaction described in the Larock et al. paper is equivalent to 100 ppm ruthenium or ten times the catalyst required in the present invention (10 ppm ruthenium reaction=approximately 0.01 mo

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