Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-03-17
1999-04-27
Robinson, Douglas W.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 185, C07G 300, C07H 100, C07H 1504
Patent
active
058980709
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production of alkyl and/or alkenyl oligoglycosides in which a combination of a stirred tank reactor and a falling-film evaporator is used.
2. State of Related Art
Alkyl oligoglycosides, more particularly alkyl oligoglucosides, are nonionic surfactants which are acquiring increasing significance by virtue of their excellent detergent properties and their high ecotoxicological compatibility. The production and use of these compounds have been described just recently in a number of synoptic articles, of which the articles by H. Hensen in Skin Care Forum, 1, (October 1992), D. Balzer and N. Ripke in Seifen-ole-Fette-Wachse 118, 894 (1992) and B. Brancq in Seifen-ole-Fette-Wachse 118, 905 (1992) are cited as representative.
They are normally produced by acetalization of glucose with fatty alcohols in the presence of acidic catalysts. The catalyst is then neutralized, excess fatty alcohol is removed and, if desired, the product is bleached.
There are numerous known processes for their production which are characterized by the use of certain units. For example, DE-A1 4 231 833 (Huls) describes an acetalization reaction which is carried out as a liquid/liquid reaction in a thin-layer evaporator. Another process for the production of alkyl glucosides, in which the acetalization reaction is carried out in an evaporator at an acid value of 1 to 10, is known from EP-A1 0 501 032 (Huls). Finally, a process in which aqueous starch sirup is introduced into the reaction solution through an in-line mixer is known from WO 93/11143 (Henkel).
The discontinuous acetalization reaction is normally carried out in stirred reactors which are equipped with a distillation head for removing the water of condensation. Under laboratory conditions, substantially complete conversions can be obtained in short times, in addition to which the reaction products are distinguished by a low polysugar content. However, scaling-up for industrial application involves difficulties. More particularly, it has been found that much longer reaction times are required for complete reaction of the glucose, resulting in an unwanted increase in secondary products, more particularly the polysugar content, quite apart from longer reactor possession times.
Accordingly, the problem addressed by the present invention was to provide an improved process for the production of alkyl glucosides which would be free from the disadvantages mentioned above.
DESCRIPTION OF THE INVENTION
The present invention relates to a process for the production of alkyl and/or alkenyl oligoglycosides corresponding to formula (I): carbon atoms, G is a sugar unit containing 5 or 6 carbon atoms and p is a number of 1 to 10, by acid-catalyzed acetalization of primary alcohols with monomeric carbohydrates, in which the reaction is carried out in a stirred tank reactor surmounted by a vacuum falling-film evaporator through which the mixture is pumped under reaction conditions.
It has surprisingly been found that, by comparison with conventional processes, pumping of the reaction mixture through a falling-film evaporator enables equally high conversions of glucose to be obtained in shorter times and the polyglucose content to be reduced to levels which, normally, are only achieved in laboratory processes. The process according to the invention may be carried out discontinuously although it is preferably carried out continuously.
Alkyl and alkenyl oligoglycosides are known materials which may be obtained by the relevant methods of preparative organic chemistry. EP-A1 0 301 298 and WO 90/03977 are cited as representative of the extensive literature available on the subject.
The alkyl and/or alkenyl oligoglycosides may be derived from aldoses or ketoses containing 5 or 6 carbon atoms, preferably glucose. Accordingly, the preferred alkyl and/or alkenyl oligoglycosides are alkyl and/or alkenyl oligoglucosides. Powder forms of glucose, for example dextrose monohydrate, are preferably used as startin
REFERENCES:
patent: 4939245 (1990-07-01), Rasche et al.
patent: 5206357 (1993-04-01), Schmidt
patent: 5212292 (1993-05-01), Ripke
patent: 5374716 (1994-12-01), Biermann et al.
Skin Care Forum,. (Oct. 1992) p. 1.
Seifen-Ole-Fette-Wachse 118,(1992) p. 894.
Seifen-Ole-Fette-Wachse 118,(1992) p. 905.
Eskuchen Rainer
Nitsche Michael
Schulz, deceased Paul
Henkel Corporation
Jaeschke Wayne C.
Millson Jr. Henry E.
Robinson Douglas W.
Szoke Ernest G.
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