Organic compounds -- part of the class 532-570 series – Organic compounds – Cyclopentanohydrophenanthrene ring system containing
Reexamination Certificate
1999-04-16
2002-10-08
Badio, Barbara P. (Department: 1616)
Organic compounds -- part of the class 532-570 series
Organic compounds
Cyclopentanohydrophenanthrene ring system containing
C203S071000, C203S081000
Reexamination Certificate
active
06462210
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fractionation process of the unsaponifiable material derived from black-liquor soaps of the cellulose industry. Through this procedure fractions that essentially contain free sterols, fatty alcohols, sterol esters and fatty alcohol esters respectively are separated. Fractions containing sterols or fatty alcohols can be used as such in the alimentary, cosmetic and pharmaceutical industries or they can be used as raw materials for transforming into other useful products.
2. Description of the Related Art
Black-liquor soaps are by-products of the Kraft pulping process of pine and other woods. Typically, during the Kraft process, wood chips are digested or cooked for two hours at 170° C. in an aqueous liquor containing sodium hydroxide and sodium sulfide. The digestion delignifies the wood chips and gives rise to a dark aqueous suspension called black liquor which along with lignin contains cellulose pulp, sodium soaps of rosin acids and fatty acids, a series of neutral organic compounds such as sterols, terpene, fatty alcohols, sterol esters, fatty alcohol esters and products of lignin degradation. Under these conditions, the cellulose is stable and remains in suspension in the black liquor. When the pulping process reaction is finished, the cellulose pulp is separated from the black liquor and is washed. The pulp can be used as such or exposed to further purification processes.
The black liquor must be recovered for both economics and environmental reasons. To this end, the black liquor is typically concentrated by evaporation to a solid content from 23 to 32% in weight of black liquor solids. This causes the separation of fatty acid soaps and rosin soaps and also other hydrophobic compounds solubilized in the soaps. The soaps float at the top of the vessel where they are removed or skimmed off, hence they are called “skimming”. Skimming is the term that we are going to use as a synonym of black liquor soaps. Other names used to denominate this fraction are “tall oil soap” or “CSS” (Crude Sulfate Soap).
The skimming contains ordinarily between 30 and 50% of water. The skimming solids are a complex mixture of sodium fatty soaps and rosin acids, and a series of hydrophobic substances essentially composed of sterols, stanols, fatty alcohols, diterpenoids, sterol esters and fatty alcohol esters with fatty acids. These hydrophobic compounds are known as the neutral unsaponifiable fraction or unsap. Sometimes these unsaps constitute up to 25% of the skimming solids.
The skimming may be used as fuel oil; its calorific value is lower than the half of the fuel oil calorific value. It may be upgraded by transforming into tall oil with sulfuric acid and separating the oil from the aqueous phase. This oil is known as crude tall oil (CTO). Then CTO is exposed to a series of vacuum distillations which produce: fatty acids, TOFA or Tall Oil Fatty Acids, (these are the most valuable product obtainable from CTO); rosin acids or TOR (Tall Oil Rosins); DTO or Distilled Tall Oil, which has many industrial uses and PITCH that is the bottom of the distillation, which is used as fuel or as an ingredient for the preparation of asphalt emulsions.
Until recently, improvement in CTO quality was the major reason for refining or separating the unsaponifiable fraction.
Nowadays, there has been a revaluation of unsaps as a source of important chemical products such as sterols, stanols, superior alcohols (notably docosanol and tetracosanol) and their respective esters. They are increasingly applied in the pharmaceutical, cosmetic and alimentary industry.
The refining processes of soaps and the extraction of neutral or unsaponifiable material are widely known in the state of the art and involve the extraction of unsaponifiable material with organic solvents, including supercritical solvents. However, fractionation procedures of these unsaps exhibit a series of technical and economic drawbacks.
Table I shows the average chemical composition of unsaps used in the present invention derived from skimmings of domestic cellulose industries.
The group of components called “others” is mainly composed by terpenoids (mono and diterpenes and its by-products) and betulaprenols and an additional series of insufficiently characterized compounds.
Most identified components of unsaps in Table I are compounds of commercial interest. Sterols, either free or esterified, have many uses as raw material in the pharmaceutical, cosmetic and fermentation industries for transforming into steroids. Sterol esters have been revealed as important antitumor-like agents and their utilization for that purpose is described in U.S. Pat. No. 5,270,041. The reduced form sterols, or stanols, has an important application in the formulation of diets for the reduction of plasmatic cholesterol levels. The use of free stanols for that purpose appears in U.S. Pat. No. 5,244,887, and the utilization of ester stanols for the same purpose appears in U.S. Pat. No. 5,502,045.
There is an increasing interest about fatty alcohols, especially docosanol and tetracosanol, due to their notable pharmacological properties as both anti-inflammatory and antiviral agents. The use of these alcohols with pharmacological purposes appears in many US patents (U.S. Pat. Nos. 4,874,794; 3,031,376; 5,534,554; 5,071,879; and 5,166,219).
At present, the methods known for separating the valuable components of unsaps derived from black liquor soaps or skimming are, hardly without any exception, several variants to dissolution and recrystallization processes. One of the disadvantages of this technique is that it only allows recovering free sterols, remaining the valuable fatty alcohols and alcohol and sterol esters in the mother liquor and they can not be fractionated through liquor recrystallization. By this means, not only the valuable fatty alcohols are not used but also the sterol esters. As a cause of this, the sterol preparation obtained by the methods known in the state of the art is deprived of an important sterol that is mainly found in an esterified form in the unsaps (stigmasterol) and a significant quantity of stigmastanol and sitostanol. The latter is identified as one of the most active and important sterols in the reduction of plasmatic cholesterol levels as it is disclosed in the application PCT/CA95/00555 and U.S. Pat. No. 5,502,045.
TABLE I
Unsaps average composition
Compound
Weight %
3,5-sitostadiene-3-ona
0.6
4-stigmasten-3-ona
0.5
&agr;-Sitosterol
0.6
&bgr;-Sitostanol
7.5
&bgr;-Sitosterol
21.0
Campestanol
0.6
Campesterol
2.1
Cycloartenol
0.5
Docosanol
4.4
Eicosanol
3.6
Ergosterol
0.2
Escualene
1.6
Fatty alcohol esters
6.1
Sterol esters
13.7
Hexacosanol
0.2
Methylencycloartenol
0.4
Pimaral
0.7
Pimarol
2.1
Stigmasta-3-ona
0.3
Tetracosanol
2.5
Others
30.8
To illustrate what was mentioned above, Table II shows the sterol composition in the unsap fraction composed by esters. Through the procedure of this invention described below, these esters are separated from other unsaps components, then they are hydrolyzed and exposed to a chromatographic analysis, resulting the following results:
TABLE II
Relative composition of esterified sterols in the unsap
Sterol
% Relative
&bgr;-Sitostanol
41.6
Campestanol
6.6
Campesterol
1.6
Stigmasterol
36.6
Others
13.3
The separation of the ester fraction from unsaps and its further hydrolysis surprisingly discloses the presence of sterols in the unsaps like stigmasterol which is not normally detected.
There are many patents that disclose the different methods of the unsap fractionation technique.
U.S. Pat. No. 4,044,031 discloses a dissolution method of unsaps in a solvent mixture, which includes hexane-acetone-methanol, followed by a process of liquid-liquid extraction using a hexane-acetone-water mixture. The extract is concentrated and then is cooled down to obtain a sterol concentrate through crystallization.
U.S. Pat. No. 4,420,427 discloses a method by which the unsaps are exposed to a hot dissolution with methyl ethyl ketone or with a mixtu
Diaz Miguel Angel Fuenzalida
Markovits Rojas Alejandro
Badio Barbara P.
Baker & McKenzie
Harting, S.A.
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