FR2767271A1 - Ozonisation catalysts comprising at least one halide and ruthenium - Google Patents

Abstract

Ozonisation catalyst containing at least one halide and ruthenium. The halide is preferably a bromide. The ratio halide/ruthenium is e.g. between 1 and 2000. The catalysts are especially useful for ozonisation of carbohydrates including monosaccharides, oligosaccharides, polysaccharides and derivatives of these, including low molecular weight carbohydrates such as xylose, arabinose, glucose, maltitol, starch hydrolysates, etc.; and polymeric carbohydrates such as starch, cellulose, dextrans, gums, polydextrose, etc. A claimed carbohydrate is maltodextrin.

Description

OZONATION CATALYST AND OZONATION METHOD
CARBON HYDRATES IMPLEMENTING
SUCH A CATALYST
The present invention relates to an ozonation catalyst.

 The invention also relates to a process for the ozonation of carbohydrates using such an ozonization catalyst. More particularly, the invention relates to a carbohydrate ozonation process which uses a catalyst comprising at least one halide and ruthenium.

 The subject of the invention is also acid derivatives of carbohydrates capable of being obtained by implementing the process according to the invention as well as their use in the formulation of detergent or detergent compositions.

 In the present invention, the term “carbohydrates” is understood to mean the monosaccharides, the oligosaccharides and the polysaccharides, as well as the compounds derived from these by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups into carboxylic acids. , or by replacing one or more hydroxy groups with a hydrogen atom, an amino group, a thiol group or a similar heteroatomic group. Carbohydrates, within the meaning of the invention, also include derivatives of these compounds.

Thus, the method according to the invention can be applied, without this list being limiting
- low molecular weight carbohydrates
such as xylose, arabinose, glucose,
fructose, mannitol, sorbitol, lactitol,
maltitol, trehalose, starch hydrolysates, ...;
- carbohydrates of a polymeric nature such as
that starch, cellulose, dextrans,
arabanes, xylans, arabinoxylans,
fructosans, inulin, gums,
hemicelluloses, mucilages, pectins or their
hydrolysates, or products derived therefrom
esterification, etherification, crosslinking, or
many more synthetic polymers obtained by
polymerization of various monosaccharides in the presence
acid and high temperature, such as
polydextrose which is a highly branched polymer of
glucose.

 One advantage of ozonating monosaccharides, and especially their polymers, lies in obtaining hydroxylated molecules which become carriers of carboxylic groups. We know that such molecules show interesting sequestering properties.

 These sequestering properties can be exploited in the field of cements, mortars and concretes where glucose syrups oxidized by bleach have already been proposed as setting retarders, for example in the British patent application GB-A-2,075. 502.

 They can also be used in the detergency field where glucose syrups, this time oxidized by a gas containing oxygen in the presence of a catalyst based on a noble metal, have been proposed for cleaning articles made of glass or rectal, or as additives for detergents as mentioned, for example, in European patent application EP-A-232.202.

 All of these oxidized polysaccharides of the prior art carry carboxylic functions and, like other carboxylic acids such as citric acid, gluconic acid or polyacrylic acids, have sequestering properties which allow these products to play the role of "builders" or "cobuiffiders" in detergent or detergent formulations.

However, none of them alone, and to a sufficient degree, all of the following qualities
high sequestering power,
- high dispersing power,
- high biodegradability,
- high stability in heat and in an alkaline environment,
- attractive prices, which are those that we lend to an ideal "builder" or "cobuilder".

 In addition, the tendency being for detergent or detergent compositions to become more and more concentrated in really active products: surfactants, enzymes, bleaching agents, there remains less and less room for the "build-cobuilder" system, of which after all, the essential role is reduced to correcting only the imperfections of the washing waters and in particular their content of alkaline earth salts.

 There was therefore a need to develop a product which can serve as a "builder" or "cobuilder" in modern detergent or detergent compositions and which simultaneously possesses all the qualities mentioned above.

And it is by working on this research topic that the Applicant has developed a new ozonation catalyst capable of catalyzing the action of ozone on at least one compound comprising chemical functions reacting with ozone. By continuing its research efforts, the
The Applicant has developed a process for the ozonation of carbohydrates using such a catalyst and making it possible to access oxidized products which simultaneously possess all the qualities mentioned above.

Thus, after numerous tests, the Applicant has demonstrated that by using the catalyst according to the invention in a process for the ozonation of carbohydrates
- it was possible to manufacture, industrially and
at low cost, acid derivatives of hydrates of
carbon with excellent properties
sequestering allowing them to be used as
setting retarders in the field of cements,
mortars and concretes
- it was also possible to manufacture,
industrially and at low cost, derivatives
carbohydrate acids filling all
conditions required to play the role of "builder"
or "cobuilder" in laundry compositions
or detergents and this, from materials
inexpensive raw materials
- we obtained products whose powers
sequestering and dispersing were of such a level
that their use in detergents results in
redeposition rate and very incrustation rates
weak fabrics washed with these detergents
- we obtained easily biodegradable products
- the products thus obtained were sufficient
stable to withstand both stresses
related to the drying processes of
detergent compositions and constraints
chemicals related to the stability of molecules
organic in these detergent compositions
strongly alkaline.

 First of all, the present invention therefore relates to an ozonation catalyst comprising at least one halide and ruthenium.

 The catalyst according to the invention can be used on any compound comprising chemical functions capable of reacting with ozone. This is the case, for example, for primary alcohols with a hydrocarbon chain such as methanol, ethanol, propanol insofar as these are soluble in water at the temperatures of the ozonation reaction, as well as diols. This is also the case for carbohydrates.

To the knowledge of the Applicant, only RAKOVSKY,
SHELDON and RANTWIJK [Oxidation Communications 19, No 4, 482-498 (1996) 1 carried out investigations on the carbohydrate ozonation possibly catalyzed by ruthenium. In this document, these authors aimed to develop selective methods for the oxidation of sugars in the C2-C3 position by using ozone as the terminal oxidant (that is to say in stoichiometric quantity).

The direct action of ozone on sugars (the products studied are glucose and mannitol) is described as non-selective, giving rise to cuts in position
C2-C3 and C1-C4 in particular. Ruthenium salts (such as RuO4) are known to improve the selectivity of CC bond cleavage. These salts are obtained by oxidation of the ruthenium (III) salts with bleach. The authors therefore sought to replace the terminal oxidant with ozone. But the conclusion they draw from their work is that the transformation of Ru (III) into Ru (VIII) by ozone is too slow to make the catalytic system.

 The same authors then sought to prepare bleach by ozone oxidation of the halides (chloride, bromide) in a catalytic amount. But then again, the conclusion they reach is that the rate of generation of hypobromite or hypochlorite ions is too slow to make the catalytic system.

 Thus, according to the authors themselves, ozone cannot be used in these two cases.

 At no time did RAKOVSKY and its collaborators combine ruthenium, a halide and ozone to oxidize a carbohydrate.

 The Applicant has found, and it is above all what is at the basis of the invention, that the simultaneous presence of ruthenium, of at least one halide and of ozone makes it possible to oxidize (or to ozonate), catalytically, carbohydrates.

 Ruthenium can be in homogeneous form or in heterogeneous form. Thus, the ruthenium can be in the soluble form of ruthenium (III). In this case, chloride is advantageously preferred. Ruthenium can also be found, in the catalyst according to the invention, at higher degrees of oxidation (Ru (VIII) for example).

According to a particularly preferred embodiment of the invention, ruthenium is chosen from the group consisting of Ruz13, Ruz, -RuO, Ru / C, Ru-Silicalite,
Ru / zeolites and Ru / TiO2.

 The ruthenium is present in the catalyst according to the invention in an amount between 0.001 and 10 molar equivalents, preferably between 0.001 and 5 molar equivalents and more particularly between 0.001 and 1 molar equivalent relative to the substrate to be oxidized.

 The halide / ruthenium ratio in the catalyst according to the invention is between 1 and 2000.

 According to a particular embodiment of the invention, the halide is a bromide. It is advantageously constituted by sodium bromide.

 The halide is present in an amount between 0.01 and 1000 molar equivalents, preferably between 0.01 and 500 molar equivalents and more particularly between 0.01 and 100 molar equivalents relative to the substrate to be oxidized.

 The invention also relates to a process for the ozonation of carbohydrates, characterized in that an aqueous solution of at least one carbohydrate is brought into contact with a catalyst comprising at least one halide and ruthenium.

 According to the present invention, the carbohydrate is chosen from the group consisting of monosaccharides, oligosaccharides, polysaccharides as well as the compounds derived from these by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups in carboxylic acids, or by replacing one or more hydroxy groups with a hydrogen atom, an amino group, a thiol group or a similar heteroatomic group. Carbohydrates, within the meaning of the invention, also include derivatives of these compounds.

 Preferably, the carbohydrates used in the process according to the invention have an average degree of polymerization greater than or equal to 3.

 Even more preferably, the carbohydrates used in the process of the invention have an average degree of polymerization of between 3 and 90, preferably between 20 and 70.

 This is explained by the fact that carbohydrates having the preferred average degrees of polymerization develop the highest sequestering powers when they are oxidized by the process according to the invention.

 In particular, excellent results have been obtained, in terms of sequestering power, by using in the process according to the invention, dextrins obtained by dry roasting of starch in the presence of acid, maltodextrins obtained by α-amylase hydrolysis of starch, pregelatinized starches.

 To carry out the process of the invention, the carbohydrate is dissolved in water to obtain an aqueous solution having a dry matter of between 1 and 60%, preferably between 1 and 30% and in particular between 1 and 15 t.

Carbohydrates can therefore be ozonated with relatively high concentrations. The
The Applicant has discovered that, in fact, it is mainly solubility or viscosity problems which limit the concentrations at which ozonations can be carried out according to the process of the invention.

 It is possible, for example, to ozonate substances of low molecular weight such as xylose, arabinose, glucose, fructose, mannitol, sorbitol, lactose, lactitol, maltitol, trehalose, hydrolysates. starch, ... at concentrations well above 100 g / 1.

 Insofar as it is desired to oxidize carbohydrates of a polymeric nature such as starch, inulin, cellulose, pectins, gums or their hydrolysates or the products derived therefrom by esterification, etherification, crosslinking. ., the concentration limit of the solutions to be ozonated will be those of the constraints imposed by the viscosity of the solutions.

 However, this limit will be higher the higher the temperature of the reaction medium. And this is another advantage of the process according to the invention since the latter is not subject to temperature constraints such that it would make it impossible to ozonate certain carbohydrates because of their viscosities in aqueous solution. .

 Thus, the method according to the invention is characterized in that it is implemented at a temperature between 0 and 1000C, preferably between 0 and 50 "C and in particular between 0 and 30" C.

 The possibility of working with high concentrations of carbohydrates results in considerable savings with regard to the volume of reactors necessary for implementing the process according to the invention.

 The pH for carrying out the ozonation reaction in accordance with the process of the invention is between 1 and 12, preferably between 3 and 10 and in particular between 4 and 7.

As an indication, in the case of an implementation of the process of the invention from a maltodextrin, the Applicant has found that the optimal pH, from the point of view of weight yield and purity of the product obtained (absence of products degradation), is approximately 5 to 6.

 The appearance of acidic functions as the ozonation reaction progresses obliges, of course, to introduce an alkali continuously into the reaction medium in order to maintain this pH.

 Once the carbohydrate has dissolved in the volume of water necessary to obtain the desired dry matter, the ozonization catalyst according to the invention is added, comprising at least one halide and ruthenium in a halide / ruthenium ratio of between 1 and 2000. Of course, the more the catalyst concentration is increased, the more the reaction time decreases. The reverse is also true.

 Preferably the halide is a bromide and, in particular, sodium bromide.

 Ruthenium can be in homogeneous form or in heterogeneous form. Thus, the ruthenium can be in the soluble form of ruthenium (III). In this case, chloride is advantageously preferred. Ruthenium at higher degrees of oxidation (Ru (VIII) for example) can also be used.

According to a particularly preferred embodiment of the invention, the ruthenium is chosen from the group consisting of RuC13, RuO4, RuO, Ru / C, Ru-Silicalite,
Ru / zeolites and Ru / TiO2.

 The catalyst according to the invention, consisting of ruthenium and at least one halide, can be added to water, either before or after the addition of the carbohydrate but, in any case, before the introduction of ozone into the reaction medium.

 Then finely divided ozone, prepared in an ozonizer from oxygen or air, is introduced at a concentration generally between 0.1 to 10%. This upper limit can be exceeded but is preferable taking into account security requirements.

 The time required for ozonation depends on both the temperature, the pH, the percentage of catalyst, and the carbohydrate concentration of the reaction medium. Generally, the desired ozonation rates are obtained in several hours.

 In the process according to the invention, it is preferred to proceed with the gradual addition of alkali to the reaction medium so as to keep the pH of this medium constant.

 The carbohydrate and the ozonation catalyst can be introduced continuously into the reactor, but it is preferred to dissolve and / or completely suspend them in water from the start of the reaction.

 The ozonation reaction is stopped when the quantity of alkali added corresponds to the desired rate of progress. The rate of progress is defined as the number of moles of alkali poured relative to the number of moles of primary alcohols to be oxidized.

 Depending on its destinations or its uses, the raw reaction medium thus obtained can undergo various types of treatment or purification.

 Depending on the applications considered, it may be necessary to remove the catalyst. If the catalyst is in homogeneous form, this can be done for example by carrying out a purification using a membrane technique (reverse osmosis, nanofiltration, etc.) or using selective resins capable of complexing heavy metals .

If the catalyst is in heterogeneous form, this can be done by simple filtration.

 If necessary, these reaction media thus purified can be concentrated and dried. They can also be subjected to crystallization in order to isolate pure products thereof when pure carbohydrates have been subjected to ozonation.

 However, such purifications are not necessary when it is desired to use the products obtained by implementing the process according to the invention in applications such as detergent formulations, detergency or modifiers of fluidity or setting time. for concrete, mortar and cement.

 Other characteristics and advantages of the present invention will appear on reading the examples which follow, and which are intended to illustrate by way of indication the best embodiments of the invention.

EXAMPLE
In a stirred and thermostatically controlled reactor fitted with a pH measurement probe, 2.5 g of GLUCIDEXR 2 (maltodextrin marketed by the Applicant and which is obtained by hydrolysis with α-amylase) are dissolved in 40 ml of water. starch), 1.14 g of sodium bromide and 6.2 mg of ruthenium (III) chloride trihydrate.

 The solution thus obtained is stirred (500 to 1000 rpm) and the pH is adjusted to 5.5.

 Ozone (2% solution in oxygen, flow rate: 1.6 l / min) is introduced into the solution via a submersible disperser at the bottom of the reactor, while maintaining the temperature of the mixture between 15 and 20 "C and the pH constant at 5.5 by addition of dilute sodium hydroxide (10 &).

 The consumption of sodium hydroxide indicates the progress of the ozonization reaction and the stopping of the latter takes place at the desired value. The average duration of ozonation is 30 to 40 hours. After stopping the introduction of ozone, the pH of the reaction medium is brought back to 8.5 in order to neutralize all the acid functions formed.

 The solution is then concentrated to bring its volume to 35 ml. 140 ml of ethanol are then added to this concentrated solution with stirring in order to precipitate the oxidized product and to remove the bromides. The solid is filtered and then washed with an ethanol-water solution (- / 1 v / v). The weight yield is 110%. The product is contaminated with a little sodium oxalate (2%).

Dose of total carboxylic functions
1 g of GLUCIDEXR 2, oxidized by the method described above, is dissolved in 40 ml of distilled water. This solution is passed over a cationic resin (PUROLITER C150 type). The acidified solution is assayed with 0.5 M sodium hydroxide solution. The assay result is 9.0 mmol of carboxylic functions per gram of oxidized product.

Determination of oxidized primary alcohol functions
The determination of the oxidized primary alcohol functions is carried out by quantification of the 3 C NMR spectrum of a sample of 100 to 200 mg of the oxidized product dissolved in 0.5 ml of D2O.

 The accumulation lasts between 15 and 24 hours depending on the concentration of the NMR tube.

The acetal carbons leave around 100 ppm and the primary alcohols around 62 ppm and are well distinct from the other carbons. We can therefore determine the quantity of non-oxidized primary alcohol functions. And the percentage of oxidized primary alcohol functions is determined by applying the following formula 100 - (IR63-61 / IR102-99) x (I? 102-90 / I263-61) in which IP and IR are respectively the surfaces of the peaks of the reagent and oxidized product. For a GLUCIDEX 2: IR63-61 - IR101-99
By applying this formula, it is found that the percentage of oxidized primary alcohol functions is greater than 96%.

Measurement of complexing power SC)
The sequestration tests are carried out on the oxidized products at 60 "C in accordance with the following method
100 ml of a 10-3 mol / l solution of calcium in the form of CaCl 2 are prepared. This solution is brought to 60 ° C. and the pH is maintained throughout the assay at 10.5 by addition of 0.5 M sodium hydroxide. The assay is carried out with a sequestrant solution at 10 g / l added per fraction. selective calcium electrode allows monitoring the measurement of the concentration of free calcium in solution during the assay.

The sequestering power (SC) is determined when a concentration of 10-d mol / l of free calcium is reached. It is expressed in mg of calcium which can be complexed per gram of product
SC = 1000 x mass of initial free Ca (mg) / mass of added sequestrant (mg)
The SC values at 60 ° C. of the oxidized GLUCIDEXR 2 are deduced therefrom at different degrees of progress of the reaction. These values are grouped in the following table, for degrees of progress respectively of 140, 162 and 178%. The reference is sodium tripolyphosphate (TPPNa).

The degree of advancement is defined as the number of moles of alkali added relative to the number of moles of primary alcohols to be oxidized (ozone)

<tb> Progress rate <SEP><SEP> SC <SEP> to <SEP> 600C <SEP>
<tb><SEP> 140% <SEP> 64 <SEP> - <SEP> 66
<tb><SEP> 162% <SEP> 78 <SEP> - <SEP> 80
<tb><SEP> 17896 <SEP> 109 <SEP> - <SEP> 111
<tb><SEP> TPPNa <SEP> 122 <SEP> - <SEP> 124
<tb>
The single figure illustrates the curves of the concentration of free calcium as a function of the mass of sequestrant (oxidized GLUCIDEXR 2) at different degrees of progress of the reaction, sodium tripolyphosphate being the reference.

EXAMPLE 2
In the same reactor, 1 g of GLUCIDEXR 6 (maltodextrin sold by the
Applicant and which is obtained by hydrolysis with a-amylase of starch), 1.14 g of sodium bromide and 6.2 mg of ruthenium (III) chloride trihydrate.

 The solution thus obtained is stirred (500 to 1000 rpm) and the pH is adjusted to 5.5.

 Ozone (2% solution in oxygen, flow rate: 1.6 l / min) is introduced into the solution via a submersible disperser at the bottom of the reactor, while maintaining the temperature of the mixture between 15 and 200C and the pH constant at 5.5 by addition of dilute sodium hydroxide (10%).

 The sodium hydroxide consumption indicates the progress of the ozonization reaction and the stopping of the latter takes place at the desired value. The average duration of ozonation is 30 to 40 hours. After stopping the introduction of ozone, the pH of the reaction medium is brought back to 8.5 in order to neutralize all the acid functions formed.

 The solution is then concentrated to bring its volume to 35 ml. 140 ml of ethanol are then added to this concentrated solution with stirring in order to precipitate the oxidized product and to remove the bromides. The solid is filtered and then washed with an ethanol-water solution (4/1 v / v). The weight yield stands at i10%. The product is contaminated with a little sodium oxalate (6%).

 The thus oxidized GLUCIDEXR 6 has 6.3 mmol of carboxyl functions per gram of oxidized product, 86% of oxidized primary alcohol functions and a SC of 40 to 42 to 60 ° C., for a rate of advancement of 110%.

Claims (13)

 1. Ozonation catalyst comprising at least one halide and ruthenium.  2. Ozonation catalyst according to claim 1, characterized in that the halide is a bromide.  3. Ozonation catalyst according to either of claims 1 and 2, characterized in that the halide / ruthenium ratio is between 1 and 2000.  4. Carbohydrate ozonation process, characterized in that an aqueous solution of at least one carbohydrate is brought into contact with a catalyst comprising at least one halide and ruthenium.  5. Ozonation method according to claim 4, characterized in that the aqueous solution has a dry matter of between 1 and 60%, preferably between 1 and 30%.  6. Ozonation method according to either of claims 4 and 5, characterized in that the halide / ruthenium ratio is between 1 and 2000.  7. Ozonation method according to any one of claims 4 to 6, characterized in that the halide is a bromide.  8. Ozonation method according to any one of claims 4 to 7, characterized in that the ozone is used at a concentration between 0.1 and 10%.  9. Ozonation method according to any one of claims 4 to 8, characterized in that one works at a temperature between 0 and 100 "C, preferably between 0 and 50" C and in particular between 0 and 30 "C.  10. Ozonation method according to any one of claims 4 to 9, characterized in that one works at a pH between 1 and 12, preferably between 3 and 10 and in particular between 4 and 7.  11. Ozonation method according to any one of claims 4 to 10, characterized in that the carbohydrate is a maltodextrin.  12. Acid derivatives of carbohydrates capable of being obtained by the implementation of the process according to any one of claims 4 to 11.  13. Use of an ozonated carbohydrate obtained by the implementation of the process according to any one of claims 4 to 11, in the formulation of detergent or detergent compositions.