Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Reexamination Certificate
1999-08-23
2001-08-14
Prats, Francisco (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
C435S072000, C536S004100, C536S018600
Reexamination Certificate
active
06274349
ABSTRACT:
The present invention relates to a process for the preparation of long-chain alkyl glycosides.
More particularly, the present invention relates to an enzymatic process for the preparation of long-chain alkyl glycosides.
As described, e.g., as background in U.S. Pat. No. 5,191,071, which is directed to monoesters of glycosides, surface active compounds constitute an exceedingly important class of industrial organic chemicals finding a wide variety of uses, e.g., as detergents for washing purposes, as emulsifiers in food and feed products, or even as functional ingredients in many personal care products, such as shampoos, moisturizing creams, etc.
Basically, on the molecular level, surfactants are characterised by and owe their properties to the presence of hydrophobic and hydrophilic regions within the individual surfactant molecules. This particular constellation can be established in numerous fashions, e.g., by combining sulphonic acid residue, a quartenised ammonium entity or a glycerol moiety with an alkyl chain, as is the case in the linear alkyl sulfonates, the quarternised alkyl amines, and the monoglycosides, respectively. In the actual design of such surfactant molecules, major consideration is given to the detailed molecular architecture of the compounds, important issues being the precise balance between the hydrophilic and hydrophobic domains of the surfactant molecules and the actual special arrangements of these parts of the molecules. Besides, consideration is obviously given to the possibilities of actually producing the surfactants in high yielding processes and on the basis of raw materials available at reasonable costs. The environmental issues related to the eventual loading of the surfactant into the environment are finally a matter of major concern.
Due to the above considerations, over the years there has been a keen interest in preparing surfactant molecules on the basis of sugars and fatty acids or fatty alcohols, e.g., as sugar esters or ethers. Such conjugates were expected to exhibit surface active properties due to the presence of the hydrophilic sugar regions and the hydrophobic fatty acid or fatty alcohol residues. The balance, and thus the precise properties of the conjugates, might be varied through changes of the nature of the sugar and the fatty acid or fatty alcohol residues; the materials would be produceable from exceedingly cheap raw materials; and the surfactants, being composed of, and degradable into, natural constituents, would not be harmful to the environment.
As described and discussed by D. Balzer in
Tenside Surf. Det.,
Vol. 28, p. 6 (1991), alkyl polyglycosides were described for the first time about 100 years ago. However, it was not until 1934 that their potential as surface active substances was appreciated in a patent to H. Th. Boehme AG of Chemnitz. They then fell into obscurity for a long time, probably because not only were they difficult to manufacture, especially as regards the control of the colour quality, but also because of the many surfactants already in production. It was not until about 10 years ago that this old class of surfactants was unearthed again, against a background of increasing environmental concerns, but also because of the spectre of a raw material, i.e., crude oil, shortage.
Alkyl polyglycosides are non-ionic surfactants prepared on the basis of renewable raw materials, namely, starch and fat, or their derivatives glucose and fatty alcohols. By utilising D-glucose, probably the most common natural organic monomer unit, as a surfactant base, the range of raw materials for surfactants is advantageously expanded. This statement is underlined by the excellent application properties and favourable eco-tox data of the alkyl polyglycosides.
Thus, in recent years, several companies have begun to market alkyl polyglycoside surfactants.
In the 1980's, it was reported that Horizon Chemical, a newly-formed division of A. E. Staley Manufacturing Co., was commercializing a new generation of alkyl polyglycoside surfactants, superior in quality to surfactants offered, and suitable for use in a wide range of surfactant applications, including household laundry, dishwashing and general purpose cleaners.
The alkyl polyglycosides were described as being non-ionic in nature, but with properties much different from ethoxylated fatty alcohols or alkyl phenols.
As described in said press release, the alkyl polyglycoside surfactants can be used as primary surfactants, or in combination with other surfactants. Synergistic performance has been observed when alkyl polyglycosides are combined with both linear alkylbenzene sulfonate (LAS) and linear alcohol ethoxylate (LAE).
These surfactants are more soluble than other surfactants and are stable under a wide range of conditions. They are milder to the skin than LAS and LAE, and are non-toxic and readily biodegradable. Their foam characteristics in combination with anionic surfactants, combined with their mildness and solubility allows for, the formulation of a mild, high performance hand dishwashing product with non-ionic grease-cutting ability, but requiring less hydrotrope and no foam booster.
The solubility of the alkyl polyglycoside surfactants in concentrated electrolyte solutions allows the formulation of a stable, concentrated surfactant solution, containing 20-30% of a conventional inorganic builder. In addition, the solubility and solvent properties of these surfactants allow the formulation of a hard surface cleaner which requires no rinsing and less solvent than current products. The solubility, self-hydrotroping and electrolyte compatibility of alkyl polyglycoside surfactants enable slurry concentrations to be increased, thereby allowing processing rates to be raised and cost to be reduced.
The development of copious amounts of stable foam is a primary criteria for a premium dishwashing liquid. Other important factors include mildness and grease emulsification. Alkyl polyglycoside surfactants, unlike ethoxylated fatty alcohols, bring non-ionic grease-cutting strength and mildness to hand dishwashing. These properties make them an ideal surfactant for this end use.
In a press release issued Jan. 5, 1993, it is reported that Henkel Cospha Dusseldorf launched what it describes as a new generation of surfactants, specially developed for the cosmetics industry and sold under the product name Plantaren. Plantaren is an alkyl polyglycoside from renewable raw materials: glucose derived from corn, and fatty alcohols from coconut and palm kernel oils. It is also biodegradable under aerobic and anaerobic conditions. These non-ionic surfactants are said to provide a broad spectrum of possibilities for formulation in the cosmetics sector. Plantaren surfactants are described as being suitable for a variety of personal care applications, such as shampoos, hair conditioners, facial cleansers and bath products, and are found to have very good foaming and cleaning performance, with extraordinary mildness to skin and eyes.
It will thus be realized that alkyl glycosides are now becoming major surfactants of interest and use.
Several patents have issued which propose various processes for the production of alkyl glycosides, e.g., European Patents 0096917 and 0132043 and U.S. Pat. Nos. 3,839,318; 4,393,203; 5,206,357 and 5,212,292. All of the processes described in said patents, however, are carried out by reacting a carbohydrate and an alkanol in the presence of an acidic catalys and at a temperature range of about 80-150° C. and mostly in a preferred range above 100° C., which presents serious drawbacks in that, at said temperatures, there is both undesirable isomerization and caramelization of sugars, resulting in discoloration and a consequent need for complicated and/or expensive purification steps.
Thus, it will be realized that at the relatively high temperatures and in the presence of an acidic catalyst, many undesirable reactions take place, resulting in difficulties in controlling production in terms of the isomer formed and in the number of glucose groups in the product
Eyal Aharon Meir
Reuveni Tal
Vitner Asher
Prats Francisco
Williams Morgan & Amerson P.C.
Yissum Research Development Company of the Hebrew University of
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