Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1986-04-18
1988-04-19
Griffin, Ronald W.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 184, 536 84, 536111, C07H 1504, C07H 15207, C07H 1510
Patent
active
047390433
DESCRIPTION:
BRIEF SUMMARY
The subject of the invention is the provision of an improved method for the synthesis of alkyl, cycloalkyl or alcenyl aldosides or polyaldosides.
Alkyl aldosides and polyaldosides are well-known industrial products which can be used for a great variety of purposes and in particular as intermediates for obtaining surfactants or in the manufacture of polyurethane foams, for example.
STATE OF THE ART
It is known that alkyl aldosides or polyaldosides can be synthesized by reacting a hydroxylated compound with starch in the presence of an acid catalyst:
U.S. Pat. No. 2,276,621 describes the preparation of methyl-D-glucopyranosides by alcoholysis of starch in the presence of an acid catalyst such as sulfuric acid. In that case, the reaction is carried out at 100.degree. C. for 2 hours in the presence of excess methanol in order to increase the yield of methyl glucosides.
U.S. Pat. No. 3,346,558 relates to the preparation of glucosides of polyols according to a continuous method. Thus ethylene glycol, glycerol, sorbitol glucosides are obtained by passing a mixture of starch, a polyalcohol and an acid catalyst such as paratoluene sulfonic acid or a Lewis acid like the etherate of boron trifluoride into an extruder heated to a temperature above 170.degree. C.
U.S. Pat. No. 3,375,243 describes the preparation of alkyl glucosides and more particularly methyl-D-glucopyranosides from glucose or starch in the presence of excess methanol (3 moles per monosaccharide equivalent) and an acid catalyst such as paratoluene sulfonic acid (0.0025 to 0.1 mole per monosaccharide equivalent). The reaction is carried out in a reactor in a few minutes at a temperature between 100.degree. and 250.degree. C. under a maximum pressure of 15 to 20 bars. Under these conditions the methyl glucosides conversion rate is about 85 to 90%.
In U.S. Pat. No. 4,223,129, alkyl glucosides are prepared from starch and polyosides by a continuous method. The starch is suspended in alcohol in the presence of an acid inorganic or organic catalyst and passesd under pressure into a coil having a well-delimited heating zone in which the reaction takes place. This apparatus is based on U.S. Pat. Nos. 2,735,792 and 3,617,383. In particular, in the preparation of methyl-D-pyranosides, the reaction temperature is of the order of 160.degree. to 180.degree. C., and the pressure adjusted in accordance with the desired contact time in the heating zone (8 to 20 minutes). The methanol/starch ratio may vary between 15:1 and 6.5:1 whereas the catalyst content is of the order of 0.005 per monosaccharide equivalent. Under these conditions, the methyl glucosides yield varies between 65 and 90%, mixed essentially with reversion di- and tri-saccharides. The authors indicate that this method is applicable to the preparation of C.sub.2 to C.sub.18 alcohol glucosides. Supplementing this method, U.S. Pat. No. 4,329,449 describes a method of crystallizing methyl-alpha-D-pyranoside, with recycling of the mother waters.
In the same field, U.S. Pat. No. 3,839,318 claims the preparation of alkyl glucoside by direct reaction under reduced pressure between glucose and an alcohol with heating in the presence of sulfuric acid under reduced pressure. The yields of alkyl glucosides vary under these conditions between 25 and 60%, the rest consisting of reversion alkyl oligosaccharides.
Another continuous method is described in Patent Application EP No. 96917. Alkyl glucosides (C.sub.8 to C.sub.15) are prepared by reacting an aldose, aldoside or polyaldoside with a 50% excess of alcohol in the presence of an acid catalyst, in particular toluene sulfonic acid, at a temperature between 80.degree. and 150.degree. C. Under these conditions, glucose is fed continuously, the water resulting from the reaction being removed as it is formed.
Other methods propose the utilization of ion-exchange resins.
Thus U.S. Pat. No. 2,606,186 describes the preparation of methyl glucoside by reacting glucose with methanol in the presence of an acid sulfonic resin. The reaction time is 1 to 48 h at a temperatur
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patent: 2390507 (1945-12-01), Cantor
patent: 2606186 (1952-08-01), Dean et al.
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patent: 3928318 (1975-12-01), Panusch et al.
patent: 4329449 (1982-05-01), Roth et al.
Chemical Abstracts, vol. 9, No. 21, May 21, 1979, abstract 90:168854k.
Chemical Abstracts, vol. 85, No. 6, Aug. 9, 1976, abstract 85:34931z.
Carbohydrate Research, tome 110, 1982, Elsevier Scientific Publishing Company, (Amsterdam, NL), J. Defaye et al.: "The Behaviour of Cellulose, Amylose, and Beta-D-Nylon Towards Anhydrous Hydrogen Fluoride", pp. 217-227, especially pp. 217-219.
Bouchu Alain
Chedin Jean
Defaye Jacques
Pedersen Christian
Wong Emile
Beghin-Say S.A.
Breiner A. W.
Griffin Ronald W.
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