Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Reexamination Certificate
1999-12-09
2001-03-13
Prats, Francisco (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
C435S198000
Reexamination Certificate
active
06200784
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention belongs to the alimentary, pharmaceutical, cosmetic and chemical sectors. The products obtained are excellent biodegradable and biocompatible non-ionic tensioactive agents which are used as additives for their emulsifying, oily, thickening and moisturising properties.
DESCRIPTION OF PRIOR ART
The employment of enzymes in organic media is an attractive alternative to classical organic synthesis. The main drawbacks of conventional chemical techniques are their high energy consumption (high temperatures and pressures), the low selectivity of the processes and/or the employment of inorganic catalysts which produce coloured impurities of variable toxicity. In contrast, enzymatic catalysts can achieve selective synthesis of a given product under less extreme pressures and temperatures and are less environmentally toxic.
Lipases are the hydrolytic enzymes most effective at catalytic processes involving long chain fatty acids. These form covalent bonds with alcohols in media with a low degree of hydration. Because of their versatility and wide availability these make very valuable industrial biocatalysts. Besides, lipases are biodegradable. When several hydroxyl groups are present in the same molecule, because of their extreme selectivity lipases can replace long synthetic pathways (with phases of protection/exposure) with one enzymatic step. This increases yields and reduces the cost of the process itself and also that associated with treatment of the waste products [Biocatalysts for industry (1991) Plenum Press, N.Y. Ed. J. Dordick] compared to alternative chemical processes. Moreover, the chemo- and enantioselectivity of lipases can give rise to highly competitive synthetic processes.
More than 80% of the world market of tensioactive agents are molecules formed by condensation between polyols or monosaccharides and long chain fatty acids (glycerides, spans, tweens etc.). Esterified sorbitan derivatives with long chain fatty acids are biocompatible glycolipid surfactants commonly used in a variety of industries. The commercial name for esterified sorbitan derivatives is Spans. These are highly lipophilic and are precursors of Tweens. At present, Tweens™ and Spans™ are prepared industrially by non-enzymatic procedures at 180-150° C. Gluco and glycolipidic surfactants are additives used in cosmetic and pharmaceutical products for their different properties (moisturizing and lubricative capacities etc.). The employment of many of these emulsifiers, which are themselves biocompatible, for certain applications (e.g. in the alimentary sector) is often problematic. These problems are related with the conventional chemical method used in their preparation. The presence of certain synthetic agents in the chemical processes used to manufacture or purify the additive constitute one of the main drawbacks of the preparation methods used. Selective obtainment of emulsifiers by enzymes can solve this problem. European and American legislation consider substances produced or modified by enzymes as natural products.
The enzymatic production of glucolipidic tensioagents derived from monosaccharides and polyols has been studied in the literature although only low yields were obtained [Khaled, N., Montet, D. Pina, M. and Graille, J. Biotech. Let., 13, 167-172 (1991) and Schlotterbeck, A. Lang, S., Wray, V. and Wagner, F. Biotechnol. Lett. 15, 61-64 (1993)] and/or these require preliminary non-enzymatic steps [Fregapane, G., Sarney, D. B. and Vulfson, E. N. Enz. Microb. Technol.13, 796-800 (1991) and Bjorklong, F., Godtfredsen, S. E. and Kirk, O. J. Am. Soc. chem. Commun. 934-935 (1989)]. One enzymatic method based on an aqueous mixture of reagents at 20-60° C. [DE-B-3430944 (SEINO)] and the later improved version of the process using high pressure water evaporation [JP-A-62195-292] have been disclosed. In both cases the yields obtained are relatively low due to displacement of the thermodynamic equilibrium of the aqueous process towards hydrolysis. The sugars recommended in these patents are glucose, saccharose, raffinose, dextrin, mannan, cellulose, sorbitol and xylitol. Yields have been increased using almost anhydrous organic media and increasing the solubility of the starting sugar in the medium by previous chemical modification. This was also the aim of a number of international patents. A further esterification process, JP-A-63-112993, published on the of May 18, 1988 includes a preliminary step that consists of acetylating the sugar, whereas according EP-A-0334498 the glucoside is alkylated before carrying out the enzymatic acylation. The processes described in the aforecited prior art literature all include a previous non-enzymatic step to decrease the polarity of the substrate followed by enzymatic processes with high yields. However, the tensioactive molecules obtained are more complex than those obtained with the previous methods.
EP-A-0506159 and EP-A-0274798 disclose processes for esterification of carboxylic acids with alcohols in the presence of lipases. Due to that the alcohols are immediately miscible with the acids, or made immediately miscible by dissolving them in a suitable solvent, the alcohols immediately contact the lipase and the carboxylic acids, whereby not only primary but also secondary hydoxyls of the alcohols are esterified whereby rather heterogeneous reaction products are obtained. The disadvantage of said processes is that no selective esterification is possible.
BRIEF DESCRIPTION OF THE INVENTION
This invention as claimed consists of an enzymatic procedure of selective synthesis of partially acylated polyol and monosaccharide esters with fatty acids in almost anhydrous media. Quantitative or almost quantitative yields are obtained in only one step.
DETAILED DESCRIPTION OF THE INVENTION
The invention refers to the highly selective enzymatic production of monosaccharides and polyols being mono and/or disubstituted with fatty acids. The procedure is based on a simple mixture of polyol or monosaccharide with the fatty acid, the addition of solvent and the use of lipases that permit the highly selective obtainment of these products without catalysts or toxic agents. The water produced during the process must be continually removed throughout the process.
The tensioactive agents synthesized present a higher biodegradability than ethoxylated alkyl phenols commonly used in washing powders etc.
Moreover, these enzymatic reactions permit the recovery and reassessment of the waste products. Lipases can act with pure fatty acids and also with mixtures of these derived from natural oils and fats (olive, coconut or palm oil etc.) The European Union produces large surpluses of oils and fats. Minimization of the waste products and the recovery of by-products (oils and fats) and their industrial reassessment and recycling is one of the priority objectives in Europe and elsewhere.
The chemical procedures currently used for the industrial preparation of these products involve high energy consumption and the corresponding installations for conditions of high pressure and temperature. Because of the low selectivity of these chemical procedures [U.S. Pat. No. 2,759,922], unlike enzymatic processes these chemical procedures can not obtain products with a specific and constant structure. Previously patented enzymatic procedures [DE-B-3439944 (SEINO) and JP-A-62195292] which use aqueous medium, achieve very low yields, limiting their industrial use. The present enzymatic process can achieve almost quantitative yields by direct esterification of the polyol and/or monosaccharide in an almost anhydrous organic medium. Our invention can directly use the polyol or sugar without the prior chemical modification described in JP-A-63-112993 and EP-A-0334498 which obtain different final products than those obtained here. In both these procedures the previous non-enzymatic step and also the possible use of solvents with a high boiling point make the patented processes more expensive than
Arcos Jiménez José Antonio
Otero Hernández Cristina
Coe Susan D.
Consejo Superior de Investigaciones Cientificas
Klauber & Jackson
Prats Francisco
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