Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-03-04
2001-02-13
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S884000
Reexamination Certificate
active
06187974
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing unsaturated fatty alcohols from lauric oils.
2. The Prior Art
As compared to saturated fatty alcohols, unsaturated fatty alcohols are only produced in comparatively small quantities. However, unsaturated fatty alcohols, because of their special properties, are important intermediates for oleochemical derivatives or tensides. They are also directly employed in fields such as the cosmetic and pharmaceutical industries. Derivatives of unsaturated fatty alcohols are also employed in the cosmetic and pharmaceutical fields. They are predominantly employed in the technical sector, for example as auxiliary agents or as components of lubricants, or also in detergents. They are technically produced exclusively from native raw materials by heterogeneously catalytic processes. Here the raw material is specifically selected for defined unsaturated final products, so that important components of the chain length spectrum are already present in the raw material. For example, tallow and lard as well as technical oleins produced from the latter by various concentration methods have been the raw materials for producing unsaturated fatty alcohols. Other raw materials are various vegetable oils with higher iodine numbers such as rapeseed oil, sunflower oil, palm kernel oil, and cottonseed oil.
Vegetable raw materials such as oils with low iodine numbers, the so-called laurics, have been employed for the production of unsaturated fatty alcohols. As compared to animal raw materials, these oils have superior sensorial properties such as odor and color. Their shelf life is much longer due to a lower component of N-containing by-products; and they have fewer color-imparting impurities in the purified raw substances. With lauric oils, the unsaturated components are almost exclusively present in the C
18
-chain length range, which makes their concentration possible.
In industrial practice, a distinction has previously been made between substantially three procedures for producing unsaturated fatty alcohols. In light of the availability of different raw materials or intermediates, these three procedures have each become relatively important:
(1) Direct hydrogenation of triglycerides will produce unsaturated fatty alcohols and a few decomposition products of the glycerin, primarily 1,2-propane-diol. This process has the significant drawback that the glycerin is destroyed and that the decomposition products formed in the process have to be removed by washing or extraction. Furthermore, hydrocarbons are formed in greater amounts and have to be separated in complicated fractionating operations.
(2) Splitting of the oils or fats will produce fatty acids and glycerin. Following separation of the glycerin, esterification of the fatty acids takes place with lower alcohols such as methanol or butanol to obtain the respective esters. Hydrogenation of the esters will produce unsaturated fatty alcohols with the release of the alcohol used for the esterification. This alcohol can be recycled. This procedure is relatively costly in light of the multitude of required stages, as well as due to the requirements in these stages with respect to distillatory purification. The overall process is complicated by the stages both in technical and economical respects.
(3) Ester interchange of the oils and fats with methanol according to various methods can be used to obtain methyl esters, using homogeneous or heterogeneous catalysts. Hydrogenation of these methyl esters can be used to obtain unsaturated fatty alcohols, with recovery and recycling of the methanol.
According to procedure variation (1), unsaturated fatty alcohols are obtained with a composition which is predetermined by the fatty acid spectrum of the oil. Also, the composition can be slightly influenced by selection, partial hydrogenation or crystallization. Where more extensive alterations are possible only in the stage of the alcohols, it is possible in connection with procedure variations (2) and (3) to effect targeted changes in the raw material. These changes can occur both in the preliminary stages of the split fatty acids, distilled fatty acids, or methyl esters, as well as also in the alcohol stage.
The use of lauric oils for producing unsaturated fatty alcohols is known, for example from German Patent Numbers DE 43 35 781 A1 and DE 44 25 180 A1. The lauric oils have a focal point of their C-chain distribution in the C
12
to C
14
range. The unsaturated components are almost exclusively present in the C
18
chain length range, which makes their concentration possible.
DE 43 35 781 A1 describes a process for producing unsaturated fatty alcohols with an iodine number of 20 to 110 from lauric oils. Here the triglycerides contained in the raw materials are split by pressure splitting into the fatty acids, and esterified with methanol, if need be, or converted by ester interchange into fatty acid methyl esters. The fatty acids or fatty acid methyl esters are subsequently hydrogenated to the fatty alcohol. The fatty acid, the fatty acid methyl esters and/or the hydrogenation product are finally fractionated. Prior to fractionation, the iodine number of the product to be fractionated is determined. A defined quantity of the first runnings is withdrawn in the course of fractionation depending on the determined iodine number and the desired one, which raises the iodine number of the fatty alcohol. The drawback of this procedure is mainly that costly fractionating operations are required, and that different coupled fractions are collected, for which only limited possibilities for utilization are available. Furthermore, in the Cle-range it is not possible to separate the C
18
:0 and the C
18
:1 components by distilling, so that only a certain iodine number can be obtained. This process is very costly and consequently uneconomical.
In the process described in DE 44 25 180 A1, the lauric oils are split into fatty acids and glycerin. The separated fatty acids so obtained are subjected to fractionated crystallization. The fraction of unsaturated fatty acids is subsequently esterified to methyl esters, if need be, or finally hydrogenated to unsaturated fatty alcohols with an iodine number of 85 to 100. Such fatty alcohols have very good color and odor properties and are characterized by a particularly advantageous cold behavior. The step of separating saturated and unsaturated fatty acids required in connection with this procedure is preferably feasible by means of a so-called “rewetting” separation. This is known from the separation of tallow fatty acid into stearin and olein. In the separation of the tallow fatty acid by rewetting, the technical fatty acid mixture is cooled to low temperatures, whereby crystallization of the palmitic/stearic acid takes place in the oleic acid with formation of a dispersion. For washing off the oleic acid from the crystals, it is necessary to add to the dispersion an aqueous wetting agent solution, such as a tenside.
By finally centrifuging the emulsion/dispersion in a separator, the latter is separated into an oleic acid phase and a water/saturated fatty acid dispersion. The fatty acid dispersion, the palmitic/stearic acid water dispersion, subsequently has to be heated to about 50° to 80° C. in order to separate the molten palmitic/stearic acid from the aqueous wetting agent solution, which is recycled.
The process stage of separation by rewetting for fractionated crystallization of the split fatty acids obtained according to process step (a) is very time-consuming and requires additional expenditure in terms of equipment. This leads to substantial costs for the final product. Furthermore, when separating split fatty acids by rewetting from lauric oil, it is necessary due to the composition of the lauric oils to separate in a number of process stages a large amount of excess saturated fatty acids with differentiated solidification ranges.
The high content of 80% to 90% saturated C
12
-C
18
-fatty acids can be separated also, i
Konetzke Gerhard
Seifert Ekkehard
Wieczorek Frank
Collard & Roe P.C.
DHW Deutsche Hydrierwerke GmbH Rodleben
Shippen Michael L.
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