FR3060560A1 - 1,3-DIPOLAR COMPOUND HAVING A CONJUGATED CARBON-CARBON DOUBLE BOND - Google Patents

Abstract

The present invention relates to a 1,3-dipolar compound having a nitrile oxide dipole and a substituted or unsubstituted anthracenyl group. The grafting of such a compound allows the synthesis of diene polymer bearing pendant conjugated carbon-carbon double bonds.

Description

Holder (s): COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN Limited partnership with shares, MICHELIN RECHERCHE ET TECHNIQUE S.A. Limited company.

Extension request (s)

Agent (s): MANUFACTURE FRANÇAISE DES PNEUMATIQUES MICHELIN.

105 / 1,3-DIPOLAR COMPOUND CARRYING A DOUBLE CARBON-CARBON CONJUGATE LINK.

tbq) The present invention relates to a 1,3-dipolar compound comprising a nitrile oxide dipole and an anthracenyl group, substituted or not. The grafting of such a compound allows the synthesis of diene polymer carrying pendant conjugate carbon-carbon double bonds.

FR 3 060 560 - A1

i

The field of the present invention is that of compounds intended to react with a polymer containing at least one carbon-carbon double bond, such as a diene polymer, to graft anthracenyl groups, substituted or not, on the polymer chain.

To graft functions on a diene polymer, it is known to use compounds

1,3-dipoles carrying on the one hand a nitrile oxide dipole capable of reacting with the carbon-carbon double bonds of the polymer chain and on the other hand the function to be grafted onto the polymer chain. Examples of grafting are for example described in patent applications WO 2006/045088 and WO 2012/007441. The mechanism of the grafting reaction proceeds from a cycloaddition of the nitrile oxide dipole on a double bond, as described in the work “Nitrile Oxides, Nitrones and Nitronates in Organic Synthesis”, 2 ^nd Edition, Wiley-lntersience, 2008.

The compound (anthracen-9-ylmethylidyne) azane oxide of formula 1 which has the characteristic of being a 1,3-dipolar compound carrying a nitrile oxide dipole and an anthracenyl group is known, but its reaction with a polymer containing at least a carbon-carbon double bond is not described. The grafting of an anthracenyl group, substituted or not, on said polymer is not described either, nor is the synthesis of diene polymers carrying pendant anthracenyl groups, in particular distributed statistically.

Formula 1

The Applicants have discovered a new class of compounds which provides access to polymers bearing pendant anthracenyl groups, substituted or not, in particular distributed in a statistical manner, by grafting reaction of these compounds. It has been found that these compounds are grafted onto diene polymers with much better yields than the known compound of formula (I)

Thus, a first object of the invention is a 1,3-dipolar compound comprising a nitrile oxide dipole and an anthracenyl group, substituted or not, the anthracenyl group being connected to the dipole via a spacer.

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Another object of the invention is a process for modifying, by a grafting reaction, a polymer containing at least one carbon-carbon double bond, which process comprises reacting the 1,3-dipolar compound according to the invention with the polymer.

The invention also relates to a polymer carrying one or more pendant anthracenyl groups and isoxazoline rings, the anthracenyl groups being substituted or unsubstituted.

The invention also relates to a rubber composition based on a diene elastomer, a reinforcing filler, a crosslinking system and the 1,3-dipolar compound, as well as methods for the preparation thereof.

The invention also relates to a tire comprising the rubber composition according to the invention.

I. DETAILED DESCRIPTION OF THE INVENTION

In the present description, unless expressly indicated otherwise, all the percentages (%) indicated are% by mass. The abbreviation pce means parts by weight per hundred parts of elastomer (of the total elastomers if several elastomers are present).

On the other hand, any range of values designated by the expression between a and b represents the range of values greater than a and less than b (i.e. limits a and b excluded) while any range of values designated by the expression from a to b signifies the range of values ranging from a to b (that is to say including the strict limits a and b).

The expression “composition based on” should be understood in the present description to mean a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these basic constituents (for example the elastomer, the filler or other additive conventionally used in a rubber composition intended for the manufacture of tires) being capable of, or intended to react with each other, at least in part, during the various stages of manufacture of the composition intended for the manufacture of tires.

The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they can be, partially or totally, from biomass or obtained from renewable raw materials from biomass. Also affected are polymers, plasticizers, fillers, etc.

The term 1,3-dipolar compound is understood according to the definition given by IUPAC.

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The essential characteristic of the 1,3-dipolar compound is that it comprises a nitrile oxide dipole and an anthracenyl group, substituted or not, the anthracenyl group being connected to the dipole via a spacer. By spacer is meant an atom or a group of atoms. In the compound according to the invention, among the carbon atoms constituting the 3 fused benzene rings of the anthracenyl group, one constitutes the point of attachment with the spacer, the other carbon atoms being able to be substituted.

According to one embodiment of the invention, the carbon atom of the anthracenyl group linked to the spacer is one of the two carbon atoms of the central benzene nucleus of the anthracenyl group. The central benzene nucleus of the anthracenyl group is the benzene nucleus of which 4 of the carbon atoms are linked to the carbon atoms of the other two benzene nuclei of the anthracenyl group. By applying the numbering adopted by IUPAC to designate the carbon atoms constituting a molecule of anthracene, it is considered in the present application that one of the 2 atoms which belongs to the central benzene nucleus and which has no covalent bond with the carbon atoms of the other 2 rings of the anthracenyl group is the carbon atom numbered 9 of the anthracenyl group, whether or not the anthracenyl group is substituted elsewhere. The following representation of an anthracene molecule illustrates the position of the carbon 9 atom.

According to this particular embodiment and the convention adopted for the numbering of the atoms, the spacer is attached to the anthracenyl motif on the carbon atom numbered 9.

According to this particular embodiment of the invention, the second carbon atom belonging to the central benzene nucleus of the anthracenyl group can be substituted or not be substituted. This carbon atom, according to the convention adopted for numbering, is the carbon atom numbered 10.

The 1,3-dipolar compound according to the invention has for example as anthracenyl group the group of formula (I) in which the symbol * represents the direct attachment to the spacer.

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(D

According to any one of the embodiments of the invention, the spacer preferably contains a group, aliphatic or aromatic, containing carbon, hydrogen atoms and optionally one or more heteroatoms.

According to one embodiment of the invention, the spacer is a group containing a benzene ring in which one of the carbon atoms is substituted by the dipole. According to this embodiment, the spacer is preferably of formula (II)

in which :

four of the 6 symbols Ri to R ₆ , identical or different, represent an atom or a group of atoms the fifth symbol represents the direct attachment to the nitrile oxide dipole CeN ^ O the sixth symbol represents a direct or indirect attachment to the anthracenyl group, substituted or unsubstituted, knowing that at least one of the symbols representing an ortho substituent of the fifth symbol is different from a hydrogen atom.

Preferably, three of the four symbols which are neither the fifth symbol nor the sixth symbol each represent an alkyl group, in particular methyl or ethyl. Advantageously, they are identical. Better still, they are in a meta position relative to each other.

The fourth of the four symbols which are neither the fifth symbol nor the sixth symbol preferably represents a hydrogen atom.

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The sixth symbol preferably represents an attachment to the anthracenyl group via a group comprising a -CH ₂ O- unit, the oxygen atom being linked directly to the carbon of the benzene nucleus of the spacer.

According to a particular embodiment of the invention, the 1,3-dipolar compound corresponds to formula (III)

The 1,3-dipolar compound according to the invention is typically used to graft one or more anthracenyl groups on a polymer which contains at least one carbon-carbon double bond, in particular a diene polymer. The polymer can be an elastomer.

The polymer is preferably a diene polymer, more preferably a diene elastomer. The term “diene polymer” should be understood to mean a polymer comprising diene monomer units, in particular 1,3-diene monomer units. By diene elastomer (or indistinctly rubber) must be understood in known manner an elastomer consisting at least in part (ie, a homopolymer or a copolymer) of diene monomer units (monomers carrying two carbon-carbon double bonds, conjugated or not ). Preferably, the diene elastomer is an elastomer chosen from the group consisting of polybutadienes (BR), polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

The grafting proceeds from a [2 + 3] cycloaddition reaction of the dipole on a carbon-carbon double bond according to a well known mechanism.

The reaction of the 1,3-dipolar compound on the polymer can be carried out in bulk, for example in an internal mixer or an external mixer such as a cylinder mixer. The mixture comprising the 1,3-dipolar compound and the polymer is for example

2016PAT00584EN brought to a temperature of the external mixer or the internal mixer below 60 ° C, then put in a press or in an oven at temperatures ranging from 80 ° C to 200 ° C. Alternatively the mixture is brought to a temperature of the external mixer or of the internal mixer greater than 60 ° C. without subsequent heat treatment.

The addition reaction of the 1,3-dipolar compound on the polymer can also be carried out in solution. The temperature at which the reaction is carried out is easily adjusted by a person skilled in the art from his general knowledge, taking into account the concentration of the reaction medium, the reflux temperature of the solvent, the thermal stability of the polymer and of the compound. 1,3-dipole. For example, a temperature around 60 ° C may be suitable. The polymer thus modified can be separated from its solution by any type of means known to those skilled in the art and in particular by an operation of evaporation of the solvent under reduced pressure or by a stripping operation with steam. .

In the addition reaction of the 1,3-dipolar compound to the polymer, the 1,3-dipolar compound is reacted according to a preferred stoichiometry of between 0 and 3 molar equivalents, more preferably between 0 and 2 molar equivalents, even more preferably between 0 and 1 molar equivalent, of anthracenyl group, substituted or not, per 100 moles of monomer units constituting the polymer. For each of these preferred ranges, the lower limit is advantageously at least 0.1 molar equivalent of anthracenyl group. These preferred ranges can be applied to any of the embodiments of the invention.

Preferably, whether the reaction of the 1,3-dipolar compound with the polymer is carried out in solution or in bulk, the polymer is previously antioxidized to prevent possible degradation of the macrostructure of the polymer during the reaction.

The polymer, another object of the invention, which can be prepared by the process according to the invention, has the essential characteristic of carrying one or more, preferably several, pendant anthracenyl groups and isoxazoline rings, the anthracenyl groups being substituted or no.

The 1,3-dipole compound can also be used in a rubber composition to modify the properties of the rubber composition.

The rubber composition, another object of the invention, is typically based on a diene elastomer, a reinforcing filler and a crosslinking system and based on the 1,3-dipolar compound.

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The diene elastomer is typically an elastomer chosen from the group consisting of polybutadienes, polyisoprenes, butadiene copolymers, isoprene copolymers and their mixtures.

By reinforcing filler is meant any type of so-called reinforcing filler, known for its capacity to reinforce a rubber composition which can be used for the manufacture of tires, for example an organic filler such as carbon black, an reinforcing inorganic filler such as silica to which is associated in known manner a coupling agent, or a mixture of these two types of filler. Such a reinforcing filler typically consists of particles whose average size (by mass) is less than a micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm. As reinforcing filler, mention may be made of carbon blacks and silicas traditionally used in rubber compositions for tires.

The crosslinking system can be based on sulfur, sulfur donors, peroxides, bismaleimides or their mixtures.

The rubber composition can also contain other additives known for use in rubber compositions for tires, such as plasticizers, anti-ozonants, antioxidants.

The 1,3-dipolar compound is preferably introduced into the rubber composition at a rate of between 0 and 3 molar equivalents, preferably between 0 and 2 molar equivalents, more preferably between 0 and 1 molar equivalent, of anthracenyl unit per 100 moles of monomer units constituting the diene elastomer.

The rubber composition according to the invention is produced in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working phase or thermomechanical kneading (so-called “nonproductive” phase) at high temperature. , up to a maximum temperature between 130 ° C and 200 ° C, followed by a second mechanical working phase (so-called "productive" phase) up to a lower temperature, typically below 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which the crosslinking system is incorporated.

The process for preparing the rubber composition according to the invention comprises the following steps:

- add, during a first step called non-productive to the diene elastomer, the 1,3-dipolar compound, the reinforcing filler by thermomechanically kneading until reaching a maximum temperature of between 130 and 200 ° C., the compound 1 , 3-dipole possibly being pre-grafted on the elastomer,

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- cool the assembly to a temperature below 100 ° C,

- then incorporate the crosslinking system,

- mix everything up to a maximum temperature below 120 ° C.

According to a particular embodiment of the invention, the 1,3-dipolar compound is pre-grafted onto the diene elastomer by the grafting process according to the invention implemented according to any one of its described embodiments. In this case, the diene elastomer and the 1,3-dipolar compound together form a component in the rubber composition, in this case a diene elastomer modified by the grafting reaction of the 1,3-dipolar compound.

Thus, a particular embodiment of the method comprises the following steps:

- add during a first so-called non-productive step to the diene elastomer, the 1,3-dipolar compound by thermomechanically kneading,

- then add the reinforcing filler by thermo-mechanical mixing until reaching a maximum temperature of between 130 and 200 ° C,

- cool the assembly to a temperature below 100 ° C,

- then incorporate the crosslinking system,

- mix everything up to a maximum temperature below 120 ° C.

The contact time between the diene elastomer and the 1,3-dipolar compound which are thermomechanically kneaded is adjusted as a function of the conditions of the thermomechanical kneading, in particular as a function of the temperature. The higher the mixing temperature, the shorter this contact time. Typically it is 1 to 5 minutes for a temperature of 100 to 130 ° C.

After the incorporation of all the ingredients of the rubber composition, the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for characterization in the laboratory, or even extruded, for forming, for example, a rubber profile used as a rubbery component for making up the tire, in particular a tread for a tire.

Thus, according to a particular embodiment of the invention, the rubber composition according to the invention, which can either be in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), is used in a tire.

The aforementioned characteristics of the present invention, as well as others, will be better understood on reading the following description of several exemplary embodiments of the invention, given by way of illustration and not limitation.

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II. EXAMPLES OF EMBODIMENT OF THE INVENTION

II. 1 NMR analysis:

The structural analysis as well as the determination of the molar purities of the synthesis molecules are carried out by an NMR analysis. The spectra are acquired on an Avance 3 400 MHz BRUKER spectrometer equipped with a 5 mm BBFO-zgrad broadband probe. The quantitative ¹ H NMR experiment uses a 30 ° single pulse sequence and a repetition delay of 3 seconds between each of the 64 acquisitions. The samples are dissolved in a deuterated solvent, chloroform or acetone, unless otherwise indicated. This solvent is also used for the lock signal, unless otherwise indicated.

The ¹ H NMR spectrum coupled to the 2D experiments HSQC ¹ H / 13C and HMBC ¹ H / ¹³ C allow the structural determination of the molecules (see attribution tables). The molar quantifications are carried out from the quantitative NMR ID ¹ H spectrum.

II. 2 Synthesis of the compounds of formula (1) and of formula (III):

Formula 1

II. 2-1 Synthesis of the compound of formula 1, anthracene-9-carbonitrile oxide:

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Step 1: Synthesis of anthracene-9-carbaldehyde oxime

A suspension of 9-anthracenecarboxaldehyde (10.40 g, 0.050 mol, [642-31-91], Aldrich) and hydroxylamine (16.60 g, 0.250 mol, 50% in water) in ethanol ( 175 ml) is stirred and brought to the boil for 3 hours. After returning to room temperature, water (800 ml) is added and the yellow solid is filtered and washed with water (IL). The product is dried under atmospheric pressure at room temperature.

A white solid (10.57 g, yield 95%) of melting point 162 ° C is obtained.

The molar purity is greater than 96% (1 H NMR).

NMR characterization:

W 6 ^l H (ppm) S ^U C ..... (ppm) ....................................... .......... I i 9.16 149.0 I 2 / 123.7 3 / 130.2 4 S. 37 125.0 5/6 7.40-7.54 C _s = 126.8 C ₆ = 125.4 7 7.97 128.9 8 / 131.3 9 8.43 129.4 (

Solvent CDCI3

Step 2: Synthesis of ranthracene-9-carbonitrile oxide, according to the procedure described by Xiaochun Han, Nicholas R. Natale, J. Heterocyclic Chem., 38, 2001, 415.

To a solution of oxime of 9-anthracenecarboxaldehyde (10.20 g, 0.046 mol) and triethylamine (9.30 g, 0.092 mol) in dimethylformamide (DMF, 125 ml) is added dropwise a solution of N-chlorosuccinimide (12.31 g, 0.092 mol) with vigorous stirring at a temperature between 0 and +4 ° C. The mixture is stirred for 1 hour, then water (150 ml) is added. The mixture is stirred for 1 hour between 0 and + 4 ° C. The yellow solid is filtered and dried at room temperature.

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After crystallization from ethyl acetate, a yellow solid (5.54 g) is obtained with a yield of 55% and a melting point of 121 ° C.

The molar purity is greater than 97% (1 H NMR).

NMR characterization

O

M * δ ^X H (ppm) 6 ^U C (ppm) J 1 / / 2 / 107 d 3 / 133.8 4 S, 23 125.2 5 7.62 126.5 6 7.51 126.3 7 / 129.1 S & 131 9 8.51 130.7d

Solvent 'Chloroform

II. 2-2 Synthesis of the compound of formula (III), 3- (anthracen-9-ylmethoxy) -2,4,6 trimethylbenzonitrile oxide:

The compound of formula (III) is synthesized according to the following procedure:

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toluene

ANTR

Br-

ANTR

K ₂ CO ₃ / DMF

ANTR nh ₂ oh

the ANTR symbol representing the anthracenyl motif as shown below:

Step 1: Synthesis of 3-hydroxy-2,4,6-trimethylbenzaldehyde

+ MeOCHCl ₂

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The compound is synthesized according to the procedure described by Yakubov, A. P .; Tsyganov, D. V .; Belen'kii, L. I .; Krayushkin, Μ. M .; Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation); flight. 40; nb. 7.2; (1991); p. 1427 - 1432.

Step 2: _Synthesis of 9- (bromomethyl) anthracene (CAS [2417-77-8])

The compound is synthesized according to the procedure described by Shah, Jitesh R .; Mosier, Philip D .; Kellogg, Glen E .; Westkaemper, Richard B .; Roth, Bryan L. Bioorganic and Medicinal Chemistry, 2009, vol. 17, # 18 p. 6496 - 6504.

Step 3: Synthesis of 3- (anthracen-9-ylmethoxy) -2,4,6-trimethylbenzaldehyde

To a solution of 3-hydroxy-2,4,6-trimethylbenzaldehyde (7.76 g, 0.047 mol) in DMF (300 ml), potassium carbonate (6.52 g, 0.047 mol) is added. The reaction medium is stirred for 15-20 min. Then a solution of 9-bromomethylanthracene (12.81 g, 0.047 mol) in DMF (100 ml) is added dropwise. The temperature of the reaction medium is maintained at 100-110 ° C for 8 hours. After returning to room temperature, the mixture is diluted with water (2 L) and the pale yellow solid is filtered and washed with water (2 L). The product obtained is dried under atmospheric pressure at room temperature.

A solid (15.80 g, 95% yield), melting point 147-148 ° C is obtained.

The molar purity is greater than 97% (1 H NMR).

NMR characterization

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9—2 //

0—8 3—4 / W

Z

- ² 123 25, 12. > I4

15, 20. ^ 18 21 19

N ^J δ ^l H fpprr.) δ ^U C {ppmJ 1 10.43 193.5 2 " 1215 ................................................. .................................................. ........................ 3 - 136, ⁷ 4 .................................................. ............................. 1 ~~ .................. .................................................. ........ .................................................. ...............AT 12.................................. ............................. 5 6 39 132.5 vs - 131.5 7 .................................................. ............................................. 122 .... .................................................. .................................. .................................................. ............................................. 11.5 .... .................................................. ................................... 3 156.2 9 - i54.5 .................. 10 2.34 13 he 5 92 6 '9 22 - 125.3 Lî'25 - 131.6 14'24 ................................ 5 ..... 37 ........... ................................ 1254 15 ^; 2î ', 43 S' 33 127.1 16.21 122.7 IL 21 S 06 129.6 IC, '20 - 132.2 19 3.56 125.5

· »3Tl

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Step 4: Synthesis of 3- (anthracen-9-ylmethoxy) -2,4,6-trimethylbenzaldehyde oxime

A mixture of aldehyde 3- (anthracen-9-ylmethoxy) -2,4,6-trimethylbenzaldehyde (15.48 g, 0.044 mol) and hydroxylamine (14.50 g, 0.22 mol, 50% solution in water) in ethanol (600 ml) is stirred for 8 hours at reflux. After cooling to -18 ° C, the white precipitate is filtered and washed with cooled ethanol (100 ml). The product obtained is dried under atmospheric pressure at room temperature.

A solid (13.80 g, yield 85%) of melting point 178-179 ° C is obtained.

The molar purity is greater than 96% (1 H NMR).

NMR characterization

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Z- <

^z Q /

12.

'25 ¹⁴ \

13 '^ 15 /

M>

?

\ /

^ 20 ^ 18 ^ 16 21 19 17

M * δ ^l H (ppm) δ ° C (ppm) 1 8.25 148.8 2 - 130.2 3 - 133 4 2.24 20.7 5 6.32 131.4 i - 131.9 7 2.05 .................................................. .................................................. ...................... ÎV S - 156 9 - 131 10 2.15 14.6 11 5.88 67, S 12 - 129.8 13/25 131.5 14/24 S, 39 125.2 15/23 7.42 to 7.53 126.8 16/22 125.8 17/21 S, 05 129.6 13/20 - 132.3 13 5.53 129.2 OH 10.15 -

Solvent: Acetone

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Step 5: Synthesis of 3- (anthracen-9-ylmethoxy) -2,4,6-trimethylbenzonitrile oxide

To a solution of 3- (anthracen-9-ylmethoxy) -2,4,6-trimethylbenzaldehyde oxime (13.69 g, 0.037 mol) and triethylamine (7.50 g, 0.074 mol) in DMF (200 ml) a solution of N-bromosuccinimide (13.17 g, 0.074 mol) is added dropwise at 0 ° C. The mixture is stirred for 2 hours then diluted with water at 5 ° C (2 L) and stirred for 1 hour at +4 ° C. The yellow solid is filtered and washed with water (2 L). The product obtained is dried under atmospheric pressure at room temperature. The solid obtained is taken up in a mixture of ethyl acetate / isopropanol (EtOAc-iPrOH: 1 -1, 600 ml) for 15-20 min then filtered and dried under reduced pressure.

A yellow solid is obtained (11.19 g, 82% yield), melting point 156 ° C. is obtained. The molar purity is greater than 98% (1 H NMR).

NMR characterization

2016PAT00584FR: z z / 1; - j b

É M · ',. 'Z

Z; Z Z

-

........... "........ δ ^U C (ppm) 2 ' NOT 2 - 223 4 3 25 ~, S 4 2.5 2C 5 .................................................. .................................................. ............... "...... 23.10 6 23? 4 7 236 27.1 S - -55S 5 - 235.3 10 2.23 253 12 .................................................. ....................... 5J4 .......................... .............................................. 67.5 x: NOT 13 - 151.3 14, / 24 S 35 224, S 15/23 7.42 a ~ ES 226.9 16/22 -25.7 17/22 S 35 225.6 18/20 232,, 1 19 S.6 225.4

Solvent: acetone

II. 3 Modification of diene polymers:

The diene polymers to be modified are respectively a copolymer of butadiene and styrene (SBR) and a synthetic polyisoprene (IR). The SBR, synthesized by anionic polymerization, contains 26% of styrene and 24% of unit 1,2 of the butadiene part. The IR, synthesized by Ziegler Natta polymerization, is Natsyn 2200 with 97% of 1,4-cis motif.

The 1,3-dipole compounds used to modify the polymers are respectively the compounds of formula 1 and of formula (III).

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The polymers were modified according to the following procedure:

At 20 g of an SBR polymer at 26% styrene and 24% of unit 1,2 of the butadiene part, the 1,3-dipolar compound (1.51 mmol, or 0.5 mol% of elastomer) is incorporated on cylinder tool (external mixer at 30 ° C). The targeted grafting rate is 0.5% by mole. The mixture is homogenized in 15 portfolio passes. This mixing phase is followed by a heat treatment at 120 ° C for 10 minutes in a press at 10 bar pressure.

At 15 g of IR2200 Natsyn polymer at 97% of 1,4-cis unit, the 1.3 dipole compound 0.66 mmol, or 0.3% by mole of elastomer, is incorporated on a cylinder tool (external mixer at 30 ° C.) . The mixture is homogenized in 15 portfolio passes. This mixing phase is followed by a heat treatment at 120 ° C for 10 minutes in a press at 10 bar pressure.

The grafting reaction is demonstrated by ¹ H NMR analysis carried out on samples dissolved in carbon disulfide, in the presence of deuterated C ₆ D ₆ cyclohexane for the lock signal. The grafting yields, defined as being the ratio of the amount of 1,3-dipolar compound grafted on the elastomer to the amount of 1,3-dipolar compound introduced initially, and determined from the ¹ H NMR analysis are shown in the following table according to the polymer and the 1,3-dipolar compound.

1,3-dipole compound Formula 1 Formula (III) SBR 57% 84% IR 73% 84%

Unexpectedly, the 1,3-dipolar compound of formula (III) leads to grafting yields much higher than those of the 1,3-dipolar compound of formula 1. It is also surprising that the grafting on an SBR and on a IR lead to the same grafting yield with the 1,3-dipolar compound of formula (III), whereas this is not the case with the 1,3-dipolar compound of formula 1. The improvement of the efficiency of the grafting is assumed to result from the presence of a spacer between the anthracenyl group and the nitrile oxide dipole.

In summary, the use of 1,3-dipolar compounds in accordance with the invention make it possible to significantly improve the grafting yields. Their use also makes it possible to obtain high grafting yields for a wide range of diene polymers, even differentiating themselves by their microstructure and their mode of synthesis.

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Claims (21)

1. A 1,3-dipolar compound comprising a nitrile oxide dipole and an anthracenyl group, substituted or not, the anthracenyl group being linked to the dipole via a spacer. 2. 1,3-dipolar compound according to claim 1, in which the carbon atom of the anthracenyl group linked to the spacer is one of the two carbon atoms of the central benzene nucleus of the anthracenyl group, the central benzene nucleus being the benzene nucleus 4 of which carbon atoms are linked to the carbon atoms of the other two benzene rings of the anthracenyl group. 3. A 1,3-dipole compound according to claim 2 in which the second of the two carbon atoms of the central benzene ring is substituted or unsubstituted. 4. 1,3-dipole compound according to any one of claims 1 to 3 in which the anthracenyl group linked to the dipole via the spacer is of formula (I) in which * represents the direct attachment to the spacer. 5. A 1,3-dipole compound according to any one of claims 1 to 4 in which the spacer is a group containing a benzene ring in which one of the carbon atoms is substituted by the dipole. 6. 1,3-dipole compound according to the spacer is of formula (II) any one of claims 1 to 5 wherein in which 2016PAT00584EN four of the 6 symbols Ri to R ₆ , identical or different, represent an atom or a group of atoms the fifth symbol represents the direct connection to the nitrile oxide dipole CeN ^ O the sixth symbol represents a direct or indirect connection to the anthracenyl group , knowing that at least one of the symbols representing an ortho substituent of the fifth symbol is different from a hydrogen atom. 7. A 1,3-dipolar compound according to claim 6 in which three of the four symbols which are neither the fifth symbol nor the sixth symbol each represent an alkyl group, in particular methyl or ethyl. 8. A 1,3-dipolar compound according to any one of claims 6 to 7 in which the sixth symbol represents a connection to the anthracenyl group via a group comprising a motif -CH ₂ O-, the atom d oxygen being directly linked to the carbon of the benzene nucleus of the spacer. 9. 1,3-dipolar compound according to any one of claims 1 to 8, which compound has the formula (III) (III) 10. A process for modifying a polymer containing at least one carbon-carbon double bond by a grafting reaction, which process comprises the reaction of a compound 1,3-dipole defined according to any one of claims 1 to 9 with the polymer. 11. The method of claim 10 wherein the polymer containing at least one carbon-carbon double bond is a diene polymer. 12. Method according to any one of claims 10 to 11 in which the polymer is an elastomer. 2016PAT00584FR 13. Method according to any one of claims 10 to 12 in which the 1,3-dipolar compound is reacted according to a stoichiometry between 0 and 3 molar equivalents, preferably between 0 and 2 molar equivalents, more preferably between 0 and 1 molar equivalent of anthracenyl group per 100 moles of monomer units constituting the polymer. 14. Method according to any one of claims 10 to 13 wherein the polymer is chosen from the group of diene elastomers constituted by polybutadienes, polyisoprenes, butadiene copolymers, isoprene copolymers and their mixtures. 15. Polymer capable of being obtained by the process defined according to any one of claims 10 to 14, which polymer carries one or more pendant anthracenyl groups and isoxazoline rings, the anthracenyl groups being substituted or unsubstituted. 16. A rubber composition based on at least one diene elastomer, a reinforcing filler, a crosslinking system and a 1,3-dipolar compound defined according to any one of claims 1 to 9. 17. The rubber composition as claimed in claim 16 in which the amount of 1,3-dipolar compound is between 0 and 3 molar equivalents, preferably between 0 and 2 molar equivalents, more preferably between 0 and 1 molar equivalent, of anthracenyl group for 100 moles of monomer units constituting the diene elastomer. 18. A rubber composition according to any one of claims 16 to 17 in which the 1,3-dipolar compound is pre-grafted onto the diene elastomer according to the process defined according to claim 12, 13 or 14. 19. A method for preparing a rubber composition defined according to any one of claims 16 to 18, which method comprises the following steps: - add during a first so-called non-productive step to the diene elastomer, the 1,3-dipolar compound, the reinforcing filler by thermomechanically kneading until reaching a maximum temperature of between 130 and 200 ° C., the compound 1,3-dipolar possibly being pre-grafted on the elastomer, - cool the assembly to a temperature below 100 ° C, - then incorporate the crosslinking system, - mix everything up to a maximum temperature below 120 ° C. 2016PAT00584FR 20. A method for preparing a rubber composition defined according to claim 16, 17 or 18, which method comprises the following steps - add during a first so-called non-productive step to the diene elastomer, the 1,3-dipolar compound by thermomechanically kneading, 5 - then add the reinforcing filler by thermomechanically kneading until a maximum temperature of between 130 and 200 ° C is reached, - cool the assembly to a temperature below 100 ° C, - then incorporate the crosslinking system, - mix everything up to a maximum temperature below 120 ° C. .0 21. A tire which comprises a rubber composition according to any one of claims 16 to 18. 2016PAT00584FR