Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2002-08-07
2004-04-20
Carr, Deborah (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S163000, C554S169000
Reexamination Certificate
active
06723863
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of the filing date of U.S. Provisional Application No. 60/370,728, filed Apr. 9, 2002, and U.S. Provisional Application No. 60/310,844, filed Aug. 9, 2001, which are incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a novel process for producing a monoester mixture which possesses a desirable composition and color.
2. Background Art
In general, the preparation of propylene glycol fatty acid esters is possible from a number of routes. For example, propylene glycol and triglycerides can be reacted together to give a reaction product comprising monoesters of propylene glycol, propylene glycol diesters, monoglycerides, diglycerides, and triglycerides, after removal of the excess propylene glycol and glycerol. A second route is through the reaction of propylene glycol with fatty acids or fatty acid esters, such as methyl or ethyl esters of fatty acids. The product from this reaction will generally be a mixture comprising primarily mono- and diesters of propylene glycol after the removal of water or the low-boiling alcohol (ethanol, methanol, etc.), by-products and any excess starting reactants. A third route is to react propylene oxide with fatty acid, leading to a mixture of monoester isomers. A fourth route is to react propylene glycol with an acid chloride of a fatty acid.
Commercially, propylene glycol monoesters can be prepared by either directly esterifying propylene glycol with fatty acid or by interesterifying triglyceride with propylene glycol. Direct esterification under practical conditions can be accomplished by reacting propylene glycol with a fatty acid to yield approximately 55 to 60 percent of a propylene glycol monoester product; the balance is a reaction by-product comprising diester and unreacted starting material. Because of the high cost of fatty acids relative to triglycerides, the direct esterification process is not commonly utilized. The most commonly utilized process of making propylene glycol monoesters is by interesterifying triglycerides with propylene glycol. This interesterification reaction proceeds at temperatures ranging from 350° to 450° F. with the use of a catalyst such as sodium hydroxide. The resulting crude product contains propylene glycol mono- and diesters, monoglycerides and diglycerides, as well as numerous by-products. The final product composition of these processes can be described in terms of the ratio of mono- to diesters comprising the product. The composition of the end product can be controlled by varying the amounts of polyol with respect to oil, and through manipulating the reaction conditions. A higher concentration of monoesters is usually obtained through a molecular distillation process.
In many instances, it is preferable to utilize a monoester mixture which possesses a high ratio of monoester to diester. A typical commercial operation utilizes a high ratio of propylene glycol to fat to yield a product possessing a high monoester content usually 65% to 75% mono-ester. However, the crude monoester mixtures are typically purified for at least partial isolation of the monoesters from the diesters. Distillation or extraction of the crude monoester mixture produces purified monoester compositions (U.S. Pat. Nos. 3,669,848 and 6,153,773). In general, a distillation process is the most widely used technique for such purification. Typically the crude monoester mixture is distilled under vacuum, in a short path distillation process. The distillate generally comprises greater than 90% (by weight) monoesters. The remaining material generally comprises mainly diesters.
Monoglycerides are mono-fatty acid ester derivatives of the polyol, glycerol. In general, crude monoglyceride mixtures are made from reacting naturally occurring triglycerides, often obtained from oil seed processing, with glycerol. The process is known as glycerolysis. Such reactions generate a mixture of monoglycerides, diglycerides and triglycerides. Limitation on monoglyceride production, via this approach, is generally controlled by: (1) solubility of the glycerol in the reaction mixture; (2) the overall equilibria statistics; and, (3) time. Typical commercially available crude monoglyceride mixtures made using this approach include ratios of monoglyceride:diglyceride:triglyceride (by weight) of about 45:45:10; or about 60:35:5, depending on processing conditions used.
In many instances, it is preferred to utilize more purified monoglycerides. That is, crude monoglyceride compositions or mixtures are purified for at least partial isolation of the monoglycerides from the diglycerides and triglycerides. In general, monoglyceride distillation has been the most widely utilized technique for such purifications. Typically the crude monoglyceride mixture is distilled under vacuum, in a short path distillation process. The distillate generally comprises greater than 90% (by weight) monoglycerides. The remainder generally comprises diglycerides and triglycerides. During the process, the monoglycerides are generally heated to at least 200° C. Sometimes processes which involve distillation of monoesters, such as monoglycerides or propylene glycol monoesters, are associated with the generation of “off tastes” and/or “off aromas” in the final product. The specific source of these off flavors or off aromas is not presently known. However, it seems to be associated with the conduct of distillation processes, i.e., processes that concern heating mixtures containing the monoglyceride (or propylene glycol monoester) of interest until they vaporize under the distillation conditions, typically 240° C.
Typically, the esterification of polyols to produce monoester mixtures is catalyzed by strong base. For example, the most commonly used catalyst is NaOH (Hui Y. H., “Manufacturing Processes for Emulsifiers” in
Bailey's Industrial Oil and Fat Products,
John Wiley & Sons, Inc.(1996), 5
th
Ed., Vol. 4, pp. 569-601). However, there are reports of monoglyceride production in the absence of catalyst (U.S. Pat. Nos. 3,083,216; 2,197,339 and 2,197,340). These processes either required a distillation or did not produce a high monoester content of about 90%. Alternatively, an acid such as para-toluene sulfonic acid catalyzes the esterification of palmitic acid and propylene glycol (U.S. Pat. No. 3,669,848).
It is also desirable to prepare a monoester mixture of acceptable color. A dark-colored monoester mixture is not suitable for incorporation into products such as paint or food. A Lovibond tintometer is an instrument for evaluating colors on the Lovibond scale, which is a standard scale in the industry. The color of the monoester mixture can be determined by comparing the monoester mixture product to standard reference samples.
It would be useful to develop a process for producing monoesters from polyols and oils in which the product of said process contains a high amount (approximately 90%) of monoester and desirable characteristics such as light color without the need for purification through a distillation or extraction process. It has been found that the novel process disclosed herein yields a monoester mixture composed of about 90% monoester possessing acceptable color as measured by the Lovibond scale. Acceptable color is typically lower than 2 Red on the Lovibond scale.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a process of producing a high monoester mixture from a polyol and a triglyceride oil wherein said process eliminates the use of organic solvents, multiple water washings and/or molecular distillation. It has been found that in the presence of a catalyst, described herein, at a temperature range from about 180° C. to about 280° C. under an inert atmosphere or under the vapor pressure of the polyol with a pressure up to about 500 psig at reaction temperature, a polyol, described herein, interesterifies with an oil, described herein, to yield a monoester mixture possessing a desirable m
Lee Inmok
Poppe George
Archer-Daniels-Midland Company
Carr Deborah
Sterne Kessler Goldstein & Fox PLLC
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