Patent Application
20070276113
The present invention relates to a grafted polymer comprising a polyorganosiloxane backbone and glycoside units. The invention also relates to a method for preparing the polymer, and to the use thereof. The invention also relates to an intermediate compound derived from a glycoside, which can be used to graft a polyorganosiloxane.
Glycosides are compounds which are of specific interest due to their physicochemical properties. They are, in addition, compounds of natural origin which have a certain chemical complexity and which can be readily accessible. This origin may make them particularly attractive from an environmental and/or toxicological and/or commercial point of view. Numerous products which derive from glycosides have therefore been studied. It is thus known practice to functionalize glycosides in order to modulate the properties thereof.
It has, for example, been proposed to functionalize glycosides in order to subsequently be able to graft them onto polyorganosiloxane, in order to obtain polyorganosiloxanes with modified properties.
Functionalizations of an alcohol on the anomeric carbon of a glycoside, in the presence of an acid, under homogeneous conditions, are thus known. This reaction is known as a “Fischer reaction”. These functionalizations do not make it possible to obtain highly pure products. There is in particular a parasitic reaction, the Maïer reaction, which creates unsaturations in the product obtained. Such parasitic unsaturations can pose problems when the functionalized glycoside is used as a reactant in other reactions, in particular during grafting on a polymer. The parasitic unsaturations can, for example, cause unwanted crosslinkings. These parasitic reactions can require purification steps which can prove to be expensive.
Methods for grafting polyorganosiloxane with glycosides functionalized on the anomeric carbon using compounds comprising an alcohol group and an allyl group are in particular known. Such methods are, for example, described in the following documents:
Such methods lead to compounds comprising organosiloxane units and grafted glycoside units, the organosiloxane units and the glycoside units being connected via a linking unit comprising an —O— group. These methods are, however, too complex to seriously envision an industrial exploitation thereof, and/or too expensive to seriously envision uses in which properties that they could provide would compensate for the cost thereof.
A method for functionalizing glycosides with allylamine is, moreover, known. Such a method is, for example, described in the following documents:
An object of the present invention is to provide a novel method for preparing grafted polymers comprising a polyorganosiloxane backbone and glycoside units. This method is in particular sufficiently simple to envision an industrial exploitation thereof, and/or to seriously envision uses in which properties that the grafted polymers could provide would compensate for the cost thereof. Thus, a subject of the invention is also novel polymers which can be obtained by means of the method. Finally, a subject of the invention is also an intermediate product which can be used to carry out the method.
The invention thus provides a grafted polymer having one of the following formulae:
in which:
The polymer can in particular be:
The invention also provides a method for preparing the grafted polymer, comprising the following steps:
a) preparing a graft compound of formula L′-G′, in which:
b) grafting the graft compound by means of a method comprising a hydrosilylation step, and
c) optionally, deprotecting the —OH groups.
The invention also provides a compound (graft compound) which can be used in the preparation of the grafted polymer, and which has the following formula:
G″-N(COCH3)—CH2—CH═CH2
in which G″ is a glycoside connected to the N atom via an anomeric carbon, the —OH groups of the glycosides being at least partially protected with acetyl groups —COCH3.
Definitions
Glycoside
In the present application, the term “glycoside” refers to any group comprising one or more glycoside units, and to the derivatives of these groups. When the glycoside comprises several glycoside units, the term “polyglycoside” is also used. The term “polyglycoside” is intended to mean a glycoside comprising at least two glycoside units.
The glycoside units, the glycosides, the polyglycosides, the derivatives thereof, and the structures and formulae thereof are known to those skilled in the art. With respect to the glycoside units, it is specified that they may in particular be aldoses, ketoses, or derivatives, with rings containing 5 atoms (pentoses) or 6 atoms (hexoses). It is also known to those skilled in the art that the glycosides, the polyglycosides and the derivatives thereof have an “anomeric carbon” at one end, the right according to written convention. It is also known that the glycoside units, the glycosides, the polyglycosides and the derivatives thereof have —OH groups (if the latter are not protected).
The glycosides include in particular:
By way of examples of monosaccharide glycosides, mention may be made of the following glycosides:
D-glucose, fructose, sorbose, mannose, galactose, talose, allose, gulose, idose, glucosamine, mannoamine, galactosamine, glucuronic acid, rhamnose, arabinose, galacturonic acid, fucose, xylose, lyxose, ribose and palatinose.
By way of examples of disaccharide or oligosaccharide glycosides, mention may be made of the following glycosides:
By way of examples of glycosides, mention may also be made of:
The polyglycosides, comprising several glycoside units, can be described as chains of glycosides (mono- and/or polyglycosides). In the present application, a glycoside chain is described by the formula Ga-Gb-, in which Ga is a glycoside or a polyglycoside, and Gb is a glycoside or a polyglycoside. When Ga or Gb is a polyglycoside, the latter can also be described by a formula Ga′-Gb′-, in which Ga′ is a glycoside or a polyglycoside, and Gb′ is a glycoside or a polyglycoside, and so on. Glycosides or polyglycosides that can constitute Ga, Gb, Ga′, Gb′, etc., groups have been mentioned above.
Protected Glycoside
The term “protected glycoside” is intended to mean a glycoside in which at least some of the —OH groups have been modified to groups of formula —OP, where P is a protective group, for example a trimethylsilyl (TMS, —Si(CH3)3), or an acetyl group —COCH3.
The protective group can have the function of preventing unwanted side reactions on the —OH groups of the glycoside, for example reactions leading to crosslinkings during the reaction with the backbone compound.
The protective group can also help to modulate the solubility of the glycoside.
The protection is said to be complete if all the —OH groups of a glycoside are substituted with the —OP group.
The protection is said to be partial if only some of the —OH groups of a glycoside are substituted with the —OP group.
Details of the method according to the invention are given below.
Preparation of the Graft Compound
In a first step a) of the method, a graft compound of formula L′-G′ is prepared, in which formula:
The group L′ preferably has one of the following formulae:
—NR4—(CH2)q′—CH═CH2
—NR4—(CH2)q′—C≡CH
in which:
The L′ group is thus preferably an allylamine-derived group, with preferably an acetyl protective group connected to the nitrogen atom.
Thus, the graft compound can be a compound of formula G′-N(COCH3)—CH2—CH═CH2, in which G′ is an optionally protected glycoside. The protective groups can be chosen from trimethylsilyl (-TMS, —Si(CH3)3) or acetyl (—COCH3) groups.
According to an advantageous embodiment, G′ has the formula Ga-Gb- in which Ga is a glycoside (monoglycoside or polyglycoside) and Gb is linker glycoside connected to the N atom via an anomeric carbon. G′ may, for example, be a cellobiose group, or a Ga-Gb-group in which Gb is a cellobiose group.
The graft compound can be prepared by reaction of the anomeric carbon of a glycoside G″ with a functionalization reactant comprising an amine group, preferably a primary amine group, and a group comprising an unsaturation (for example, alkene or alkyne type). The glycoside G″ comprises free —OH groups. The functionalization reactant is preferably allylamine.
The reaction can be carried out in the absence of solvent, at ambient temperature, but other reaction methods are not excluded.
Thus, step a) for preparing a graft compound can comprise the following steps:
a1) reaction of the anomeric carbon of a glycoside G″ comprising free —OH groups with excess allylamine,
a2) elimination of the excess allylamine,
a3) reaction with acetic anhydride, so as to protect the nitrogen atom, and optionally primary —OH groups of the glycoside, and
a4) optionally, protection of the other —OH groups of the glycoside.
An example of preparation of a graft compound in which the glycoside G″ is cellobiose, by reaction with an allylamine functionalization compound, is given below. The example below comprises steps a1) to a3), in which —P represents an acetyl group:
According to a particularly advantageous embodiment of the invention, step a3) consisting of reaction with acetic anhydride is carried out under conditions such that at least some of the —OH groups of the glycoside are acetylated, in addition to the nitrogen atom. The acetylation is, for example, carried out at ambient temperature in the presence of acetic anhydride for several hours. The hydroxyl functions in the C6-position are optionally modified if there is an excess of reactant. In this embodiment, the primary —OH groups are acetylated as a priority. It is not impossible for all the —OH groups to be acetylated. This embodiment can make it possible in particular to avoid using a specific protection step. It is advantageous with regard to the simplicity of the method, and with regard to the control of the solubility of the graft compound.
Thus, according to an advantageous embodiment, the graft compound is a group of formula:
G″-N(COCH3)—CH2—CH═CH2
in which G″ is a glycoside connected to the N atom via an anomeric carbon, the —OH groups of the glycosides being at least partially protected with acetyl groups —COCH3. According to an advantageous embodiment, G″ is a cellobiose group, or a Ga-Gb-group in which Gb is a cellobiose group, and Ga is a glycoside.
Optional Protections
The preparation of the graft compound can include a protection. According to one embodiment, the protection can be carried out during a specific protection step a4). The specific protection step can be a partial or complete protection of the G′ group with acetyl groups, for example using acetic anhydride, in a solvent such as pyridine, or using acetic acid in the presence of strong acid of the H2SO4 type. The specific protection step can be a partial or complete protection of the G′ group with trimethylsilyl groups, for example using trimethylchlorosilane, in a medium of imidazole/toluene type, or preferably in pyridine medium.
An example of protection step a4) with acetyl groups is given below:
An example of protection step a4) with TMS groups is given below:
Grafting
The grafting is carried out during a step b) by means of a method comprising a hydrosilylation step.
According to a first embodiment, step b) is grafting onto a backbone compound, by means of a simple hydrosilylation reaction.
According to a second embodiment, step b) comprises a reaction consisting of grafting onto a backbone compound by means of hydrosilylation, and a redistribution reaction. The redistribution reactions are known to those skilled in the art.
According to a third embodiment, step b) comprises hydrosilylation of the graft compound with a backbone silane having the formula H—Si(OR5)3-aR5a, in which R5, which may be identical or different, is a hydrocarbon group, and a is equal to 1 or 2, the backbone silane preferably having the formula H—Si(—O—CH2—CH3)2CH3, and then redistribution in the presence of a polyorganosiloxane. Such functionalized silane redistributions are known to those skilled in the art.
Thus, step b) can be described in the following way:
grafting the graft compound by means of a method comprising a hydrosilylation step, said method comprising:
in which:
The backbone compound can in particular be:
Hydrosilylation Reaction
During this phase, the graft compound is reacted with a backbone compound.
The backbone compound is a polyhydrogenosiloxane or a hydrogenosilane. Such compounds comprise a variable number of hydrogen atoms, at the ends of the macromolecular chains, and/or within the macromolecular chains, or a hydrogen atom connected to the silicon atom of a silane.
Such hydrogenated compounds are known to those skilled in the art and are commercially available. In the present application, in addition to the formulae mentioned above, reference may also be made to the terminology known to those skilled in the art for M, D, T and Q groups and corresponding M′ and D′ groups, comprising a hydrogen atom connected to a silicon atom, or a graft.
The hydrosilylation reaction is also known to those skilled in the art. Many works exist on this subject. It consists in reacting a hydrogen atom connected to a silicon atom, with a group comprising an unsaturation. The hydrosilylation reaction is generally carried out using a catalyst, for example a platinum-based catalyst, such as the Karstedt catalyst described in patent U.S. Pat. No. 3,775,452.
The hydrosilylation process is preferably carried out:
The hydrosilylation process is carried out in the presence of a hydrosilylation catalyst; the latter is in particular chosen from those which are based on platinum (0) or on a derivative of platinum (0), such as the platinum complexes described in U.S. Pat. No. 3,159,601, U.S. Pat. No. 3,159,662, U.S. Pat. No. 3,715,334, U.S. Pat. No. 3,814,730, etc. A preferred catalyst is the KARSTEDT catalyst, used, for example, at a rate of 1 to 300 parts, preferably of 5 to 100 parts by mass of platinum per million parts by mass of reactants (SiH) and (Vi) used.
The hydrosilylation process is preferably carried out under atmospheric pressure.
The introduction of the reactants (backbone compound and graft compound) is preferably carried out by simultaneously running the two reactants continuously into the reaction mass comprising the solvent and the catalyst.
The solvent (S) and the reactants which have not reacted can subsequently be eliminated. The elimination thereof can be carried out by distillation under vacuum or reduced pressure (for example, of the order of 1.013 Pa to 101 300 Pa).
This distillation process can optionally be followed by a hydrogenation process.
According to one embodiment, the medium derived from the hydrosilylation process is subjected to a hydrogenation process according to the conditions described above (in order to reduce the amount or eliminate the presence of unsaturated compounds resulting from the hydrosilylation reaction), and is then optionally subjected to a process consisting in eliminating the products other than the desired compounds. This elimination process can be carried out by distillation under vacuum or reduced pressure, for example of the order of 1.013 Pa to 101 300 Pa.
Solvent
The hydrosilylation reaction is carried out in a solvent which solubilizes or swells the graft and the backbone.
The solvent may, for example, be chosen from the following solvents:
According to an advantageous embodiment, the solvent is IPA and the groups are protected with acetyl groups —COCH3 in step a).
Examples of reaction schemes for grafting, onto a backbone compound, a graft compound comprising cellobiose, protected with TMS, are given below.
According to the first embodiment, mentioned above, step b) can be a simple reaction consisting in grafting the graft compound onto the backbone compound, by hydrosilylation.
According to the second embodiment, a hydrosilylation reaction of the type such as that mentioned above can be carried out, and then a redistribution can be carried out. This method consists in preparing, firstly, a polyorganosiloxane oligomer containing glycoside groups by hydrosilylation according to the route described above and in subsequently carrying out a redistribution. The redistribution thus makes it possible to adjust the length of the chains. It can be carried out by reaction of polyorganosiloxane containing glycoside groups with octamethylcyclotetrasiloxane (D4) in the presence of an acid catalyst, for example Tonsil (diatomaceous earth). The reaction is carried out in the presence or absence of solvent, preferably at a temperature of between 50 and 100° C. Advantageously, a backbone compound of M′DnM′ type with n between 0 and 20 is used as backbone compound, in order to obtain the polyorganosiloxane containing glycoside groups.
According to the third embodiment, a grafting onto an alkoxysilane or dialkoxysilane can be carried out by means of a hydrosilylation reaction, followed by a redistribution reaction in the presence of a polyorganosiloxane. In this approach, an organosilane can be used without modification or after prior hydrolysis. It is preferable to use a dialkoxysilane of the type G-L-Si(OR2)(R2) where R2, which may be identical or different, is an alkyl group, preferably a dialkoxysilane of formula G-L-Si(OC2H5)(CH3). In a first procedure, the silane can be introduced into a silicone oil and the redistribution is carried out at a temperature (70-110° C.) in the presence of a redistribution catalyst such as potassium silanolate. This catalyst is advantageously neutralized at the end of the reaction. Similarly, it is sometimes necessary to eliminate the cyclic compounds formed during the redistribution reaction. The chain ends are of the alkoxy or methyl type.
In a second procedure, the hydrolysis of the silane is carried out in the presence of water and the alcohol is eliminated. The redistribution is then carried out at temperature and in the presence of a basic catalyst.
Optional Deprotection
If the graft compound used for the reaction comprises —OP groups, i.e. protected —OH groups, the method can comprise a deprotection step. Such a step consists in carrying out a reaction which converts the —OP groups to —OH groups.
For example, trimethylsilyl groups (TMS, —Si(CH3)3) can be deprotected by reacting the grafted polymer at ambient temperature using a treatment consisting of methanolysis, possibly in the presence of an acidic resin, of the amberlite type.
Acetyl groups can be deprotected by reacting the grafted polymer using a treatment in methanol medium containing sodium methoxide, at ambient temperature, or else still in methanol medium in the presence of gaseous ammonia.
Details of the polymer according to the invention are given below.
The polymer according to the invention, which can be prepared by means of the method described above, has one of the formulae mentioned above. In these formulae:
The L group is preferably a divalent group having one of the following formulae:
—NR4—(CH2)q—CH2—CH2—
—NR4—(CH2)q—CH(CH3)—
—NR4—(CH2)q—CH═CH—
—NR—(CH2)q—C(CH3)═CH—
in which
R3 is advantageously a group of formula G-NH—CH2—CH2—CH2—, in which G has the formula Ga-Gb-, in which Ga is a glycoside (monoglycoside or polyglycoside), and Gb is a linker glycoside connected to the L group via an anomeric carbon. G can, for example, be cellobiose, or a group of formula Ga-Gb- in which Ga- is a glycoside (monoglycoside or polyglycoside), and Gb is cellobiose.
G is advantageously a glycoside chosen from:
Form or Presentation of the Grafted Polymer
The grafted polymer according to the invention can in particular be in the form of an oil. It can also be in a form dispersed or solubilized in a vector, for example at a concentration of 10 to 90% by weight. The vector can advantageously be a solvent for the polymer, for example an optionally volatile silicone compound, for example a linear or cyclic polydimethylorganosiloxane such as cyclopentasiloxane, disiloxane, linear dimethicones, or a trimethylsiloxyphenyl dimethicone, or a mixture.
Uses
The grafted polymer according to the invention can in particular be used as an emulsifier or coemulsifier for preparing or stabilizing emulsions. It can, for example, be used in emulsions in which one phase is a silicone oil. When in the form of a solution in polyorganosiloxane, for example in cyclopentasiloxane, it can be used as an emulsifier for water-in-oil or oil-in-silicone emulsions. It can also be used to render several compounds compatible within a formulation. It can also be used as an agent for aiding the deposition of another compound, or as an agent for initiating the deposition of another compound. It can be of use for delivering a silicone compound onto a surface. It can also be used as a dispersant or codispersant for preparing or stabilizing dispersions of particles, for example pigments.
It can in particular be used or included in a cosmetic formulation, possibly intended to be rinsed off, for skin care and/or hair care and/or lip care, for example in skincare creams, milks or oils, suncreams, milks or oils, shampoos, conditioners, shower gels, make-up compositions, lipsticks, deodorants. In particular, the polymer according to the invention has the advantages, in these applications, of being relatively non-irritant, of being partially biodegradable, of providing a pleasant feel, and/or of providing advantageous spreading.
Other details or advantages of the invention will emerge more clearly in view of the example given below by way of indication.
Functionalization of Cellobiose:
3.26 g of cellobiose (9.51 mmol) and 15.22 g of allylamine (266.55 mmol) are introduced at ambient temperature into a 250 ml three-necked glass reactor equipped with a stirrer and a condenser. After dissolution of the cellobiose, the mixture is left stirring and under a layer of argon at ambient temperature for 72 hours.
The excess allylamine is then eliminated under vacuum by heating at 50° C. under vacuum. After elimination of most of the allylamine, 20 ml of toluene are introduced in order to carry out a codistillation under vacuum so as to completely eliminate the allylamine. After this treatment, 220 ml of a methanol/acetic anhydride mixture (10/1 v/v) are introduced into the reactor and this reaction medium is left under argon at ambient temperature for 16 hours. The reaction medium is then optionally filtered and then distilled under vacuum at 50° C. in order to eliminate the acetic anhydride. The product obtained, referred to as A, is an orangey solid, the 1H NMR analysis of which confirms the expected structure and shows that the primary hydroxyl functions are partially acetylated.
The product is soluble in water, in DMSO or alternatively in isopropyl alcohol (IPA)
Silylation of Cellobiose Comprising an Allyl Group:
1 g of the product A prepared above, 20 ml of pyridine containing no water and then 2.33 g (21.5 mmol) of trimethylchlorosilane are introduced into a glass reactor. The reaction medium is maintained at ambient temperature for 16 hours. After this period of time, the pyridine is eliminated by distillation under vacuum after having added toluene. The product obtained, referred to as B, is analyzed by NMR. The presence of the Si—CH3 peaks is clearly observed around 0 ppm and the signals of the allyl protons are clearly observed between 6 and 4 ppm.
Hydrosilylations:
1/Hydrosilylation on a per-O-silylated Product B:
1 g of per-O-silylated N-acetyl allylcellobiose (1.08 mmol) is dissolved in 20 ml of toluene in a three-necked reactor equipped with stirring and an argon inlet. 100 ppm of platinum (relative to the reactants) in the form of Karstedt platinum, are added and the medium is brought to 70° C. with stirring. 0.45 g of an α,ω-dihydrogen polyorganosiloxane oil of molar mass 1000-620H2 oil (i.e. 0.9 mmol of SiH) is then loaded into the reactor. The reaction is followed by measuring the SiH function content. After reaction for 4 hours, the degree of conversion is greater than 90%. 2.3 grams of carbon black are then added to the reaction medium in order to eliminate the catalyst. After filtration, the toluene is eliminated by distillation under vacuum. The product obtained (reference C) is in the form of a viscous oil, the 1H NMR analysis of which shows the disappearance of the allyl proton signals and the appearance of propyl group signals at 0.5 and 1.5 ppm. The disappearance of Si—H groups is confirmed by 29Si NMR.
2/Hydrosilylation on Nonprotected Product A
0.5 g of N-acetyl allylcellobiose and 1.5 ml of isopropyl alcohol are introduced into a 50 ml three-necked reactor. The medium is heated to 70° C. in order to solubilize the cellobiose derivative and then 25 mg of ADAMS platinum catalyst are introduced. After the introduction of 0.745 g of 620H2 oil, the reaction medium is left at 70° C. for 4 hours and then treated as previously.
The NMR analysis confirms the expected structure with, however, the presence of DOR bonds characteristic of Si—O—C bonds.
Deprotection
The deprotection of the product C can be carried out at ambient temperature in a 50/50 methanol/THF medium in the presence of an acidic resin of the Amberlist type.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0402497 | Mar 2004 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR05/00577 | 3/10/2005 | WO | 6/25/2007 |
