Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-10-20
1998-10-06
Kunz, Gary L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 185, 536124, C07H 100, C07H 300, C07H 7027
Patent
active
058177809
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/FR95/01598 filed Dec. 5, 1995."
The present invention relates to an improved process for the alkaline oxidative degradation of oses or uloses and their polymers.
The expression oses, uloses and their polymers is understood to refer to any reducing sugar or carbohydrate of he polyhydroxyaldehyde or polyhydroxyketone type (or any compound derived therefrom, such as ketoaldonic acids, uronic acids, acetyl, amino, alkyl, carboxymethyl, etc. derivatives) or polymers or polysaccharides which are capable of liberating these same compounds by hydrolysis.
As novel industrial products, the invention also relates to dextrins or hydrolysates of native or modified starch which have been thus degraded, as well as the products obtained by alkaline oxidative degradation of polysaccharide or polyholoside hydrolysates such as hydrolysates of cellulose, of dextrans, of arabans, of xylans, of arabinoxylans, of fructans or of inulin or hydrolysates of heteropolyholosides such as gums, hemicelluloses, mucilages or pectins, or alternatively synthetic polymers obtained by polymerization of various monomeric oses in the presence of acid and at high temperature, such as polydextrose, which is a highly branched glucose polymer.
One advantage of oxidatively degrading oses, and especially their polymers, in a kaline medium lies in the production of hydroxylated molecules which become carriers of carboxyl groups. It is known that such molecules show advantageous sequestering properties.
These sequestering properties may be exploited in the field of cements, mortars and concretes in which glucose syrups oxidized by bleach have already been proposed as setting retardants, for example in British patent application GB 2,075,502.
They may also be exploited in the field of detergency, in which glucose syrups, this time oxidized with a gas containing oxygen in the presence of a catalyst based on a noble metal, have been proposed for cleaning glass or metal articles, or as additives for detergents, as is dealt with, for example, in European patent application EP 232,202.
The alkaline oxidation processes described in these two patent applications have in common the fact that they use weakly alkaline media with a pH of between 7.5 and 11, and that oxidation of the reducing functions is carried out with virtually no loss of carbon and thus without degradation, that is to say that under the conditions described, the oxidation of the reducing function of an ose essentially gives the aldonic acid of the same order, which thus has the same number of carbon atoms. The oxidized glucose syrups thus obtained are therefore composed essentially of gluconate originating from the oxidation of glucose, of maltobionate originating from the oxidation of maltose, and, more generally, of dextrin-gluconates originating from the oxidation of polysaccharides with a higher degree of polymerization.
However, neither of these two processes allows the total conversion of the reducing functions into carboxylic acid functions, and the products thus obtained always have a non-negligible residual reducing power. In the case of oxidation with bleach, even overoxidation phenomena occur, leading to the creation of reductive ketone functions from the secondary alcohol groups of the oses. In the case of oxidation with oxygen, catalysed by a noble metal, these overoxidation phenomena are not observed, but, although this oxidation reaction takes place at a relatively low pH, the appearance of ketone functions cannot be avoided, these functions forming by alkaline isomerization of the hemiacetal functions and not being oxidizable by the process used.
Thus, in the case of a 33 DE glucose syrup oxidized with bleach according to patent application GB 2,075,502, it can hardly be envisaged to go down to residual reducing sugar levels, expressed as glucose and measured by the Bertrand method, of less than 4.5%, and in the case of European patent application EP 232,202, this content can hardly be lowered to values below 1.7%.
Although the products obtained
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Duflot Pierrick
Fleche Guy
Freres Roquette
Kunz Gary L.
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