Polymerization in the presence of a beta-substituted nitroxide radical

TECHNICAL AREA :

0001The<img file="EP0832902A2_D0001.tif" />The invention relates to a process for the polymerization or copolymerization of<img file="EP0832902A2_D0002.tif" />at least one radically polymerizable monomer in the presence of<img file="EP0832902A2_D0003.tif" />a stable free radical of the nitroxide family.

PRIOR ART:

0002The presence of<img file="EP0832902A2_D0004.tif" />a stable free radical in the polymerization or copolymerization of monomers provides control of the polymerization and leads to more polydispersity polymers.

0003The quality of<img file="EP0832902A2_D0005.tif" />a polymerization or copolymerization control can also be assessed by<img file="EP0832902A2_D0006.tif" />observation of the<img file="EP0832902A2_D0007.tif" />increasing the number-average molecular weight as a function of the percentage of monomer conversion to polymer or copolymer. When the control is good, the number average molecular weight is linearly proportional to the conversion percentage. More we<img file="EP0832902A2_D0008.tif" />away from linearity, the less control is good.

0004US Pat. Nos. 5,322,912 and 5,401,804 illustrate the<img file="EP0832902A2_D0009.tif" />stable free radical action on the polymerization of styrene. US Patent 5,412,047 illustrates the<img file="EP0832902A2_D0010.tif" />action of free radicals stable on the polymerization of acrylates. US Patent 5,449,724 illustrates the<img file="EP0832902A2_D0011.tif" />stable free radicals action on the polymerization of l<img file="EP0832902A2_D0012.tif" />ethylene. Documents that come from<img file="EP0832902A2_D0013.tif" />cited as stable cyclic molecules which have β<img file="EP0832902A2_D0014.tif" />Atom<img file="EP0832902A2_D0015.tif" />nitrogen of the nitroxide group a group of low molecular weight, said molecules having in particular the<img file="EP0832902A2_D0016.tif" />disadvantage of considerably slowing down the rate of polymerization or copolymerization, so that<img file="EP0832902A2_D0017.tif" />it is sometimes difficult or impossible to conduct this polymerization or copolymerization at a sufficiently low temperature so that the polydispersity of the final polymer is sufficiently tightened.

0005Indeed, the higher the temperature of the medium, the less the control of the polymerization or copolymerization is good, so that the final polymer or copolymer has a higher polydispersity.

SUMMARY OF THE INVENTION

0006The<img file="EP0832902A2_D0018.tif" />invention overcomes the disadvantages mentioned above. The stable free radicals involved in the context of the present invention provide an excellent control of the polydispersity while ensuring a better polymerization or copolymerization rate, when compared with the stable free radicals employed by the present invention.<img file="EP0832902A2_D0019.tif" />prior art.

0007Another advantage of the invention is to allow the preparation of block copolymers. Indeed, the polymerization of a first monomer in the presence of a stable free radical leads to a living polymer block. It is then possible to join to this first block a block of another polymer by placing the first block of living polymer in a polymerization medium of a second monomer. It is thus possible to produce block copolymers, for example, copolymers comprising one or more polystyrene blocks and one or more polybutadiene blocks. The preparation of such copolymers is usually very difficult by the radical routes of the prior art and, for their preparation, the anionic copolymerization methods are generally used.

0008The production of such copolymers by radical means requires good control of the polymerization of each of the blocks. Indeed, if a termination reaction stops the polymerization growth of a block, it will not be possible to attach a block of another monomer. Termination reactions should therefore be as frequent as possible. There are fewer termination reactions when during the polymerization, the number average molecular weight is better linearly proportional to the conversion percentage. The existence of termination reactions results in a decrease in the rate of increase of the number average molecular weight as a function of the conversion percentage.

0009The<img file="EP0832902A2_D0020.tif" />The invention relates to the polymerization or copolymerization of<img file="EP0832902A2_D0021.tif" />at least one polymerizable monomer in the presence of<img file="EP0832902A2_D0022.tif" />a stable free radical of the family of nitroxides comprising a sequence of formula:<chemistry id="chem0001" num="0001"><img file="EP0832902A2_D0023.tif" /></chemistry> in which the radical R_The has a molar mass greater than 15. The radical R_The, monovalent, is said in position β with respect to<img file="EP0832902A2_D0024.tif" />Atom<img file="EP0832902A2_D0025.tif" />nitrogen of the nitroxide radical. The remaining valences of the<img file="EP0832902A2_D0026.tif" />carbon atom and l<img file="EP0832902A2_D0027.tif" />Atom<img file="EP0832902A2_D0028.tif" />nitrogen in the formula (1) can be linked to various radicals such as<img file="EP0832902A2_D0029.tif" />an atom of<img file="EP0832902A2_D0030.tif" />hydrogen, a hydrocarbon radical such as an alkyl, aryl or aralkyl radical, comprising from 1 to 10 carbon atoms. It does not<img file="EP0832902A2_D0031.tif" />is not excluded that the<img file="EP0832902A2_D0032.tif" />carbon atom and l<img file="EP0832902A2_D0033.tif" />Atom<img file="EP0832902A2_D0034.tif" />nitrogen in formula (1) are connected to one another by<img file="EP0832902A2_D0035.tif" />intermediary<img file="EP0832902A2_D0036.tif" />a divalent radical, so as to form a ring. Preferably, however, the remaining valences of the<img file="EP0832902A2_D0037.tif" />carbon atom and l<img file="EP0832902A2_D0038.tif" />Atom<img file="EP0832902A2_D0039.tif" />Nitrogen of formula (1) are linked to monovalent radicals. Preferably, the radical R_The has a molar mass greater than 30. The radical R_The can for example have a molar mass of between 40 and 450. As a<img file="EP0832902A2_D0040.tif" />example, the radical R_The may be a radical comprising a phosphoryl group, said radical R_The which can be represented by the formula:<chemistry id="chem0002" num="0002"><img file="EP0832902A2_D0041.tif" /></chemistry> in which R¹ and R² , which may be identical or different, may be chosen from alkyl, cycloalkyl, alkoxyl, aryloxyl, aryl, aralkyloxyl, perfluoroalkyl and aralkyl radicals, and may comprise from 1 to 20 carbon atoms. R¹ and / or R² may also be a halogen atom such as a chlorine or bromine atom or fluorine or iodine. Radical R_The may also comprise at least one aromatic ring as for the phenyl radical or the naphthyl radical, the latter may be substituted, for example by an alkyl radical comprising from one to four carbon atoms.

0010As a<img file="EP0832902A2_D0042.tif" />for example, the stable free radical can be chosen from the following list:<ul id="ul0001" list-style="none" compact="compact"><li>N-tert-butyl-1-phenyl-2-methylpropyl nitroxide,</li><li>N-tert-butyl-1- (2-naphthyl) -2-methylpropyl nitroxide,</li><li>N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide,</li><li>N-tert-butyl-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide,</li><li>N-phenyl-1-diethyl phosphono-2,2-dimethylpropyl nitroxide,</li><li>N-phenyl-1-diethylphosphono-1-methylethyl nitroxide,</li><li>N- (1-phenyl-2-methylpropyl) -1-diethylphosphono-1-methylethyl nitroxide.</li></ul>

0011The stable free radical can be introduced into the polymerization or copolymerization medium at a rate of 0.005% to 5% by weight of the sum of the mass of polymerizable monomer and stable free radical.

0012In the context of the present invention, any monomer having a carbon-carbon double bond capable of radical polymerizing or copolymerizing can be used.

0013At least one monomer present in the polymerization or copolymerization medium may be a vinylaromatic monomer or an olefin or a diene or an acrylic or methacrylic monomer. The monomer may also be vinylidene difluoride or vinyl chloride.

0014By vinylaromatic monomer is meant styrene, styrene substituted on the vinyl group by an alkyl group such as<img file="EP0832902A2_D0043.tif" />alpha-methylstyrene or<img file="EP0832902A2_D0044.tif" />ortho-vinyltoluene, para-vinyltoluene, l<img file="EP0832902A2_D0045.tif" />ortho-ethylstyrene, 2,4-dimethylstyrene, styrene substituted on the ring by a halogen such as 2,4-dichlorostyrene and vinylanthracene.

0015By diene is meant in particular a conjugated diene comprising from 4 to 8 carbon atoms, such as 1,3-butadiene,<img file="EP0832902A2_D0046.tif" />isoprene, 2,3-dimethyl-1,3-butadiene, piperylene.

0016The process according to<img file="EP0832902A2_D0047.tif" />The invention is more particularly effective in the case of vinylaromatic monomers and dienes.

0017The polymerization or copolymerization is carried out under the usual known conditions of the invention.<img file="EP0832902A2_D0048.tif" />skilled in the art considering the monomer or monomers considered, as long as this polymerization or copolymerization occurs by a radical mechanism, and with the difference that<img file="EP0832902A2_D0049.tif" />the β-substituted stable free radical is added to the medium in accordance with<img file="EP0832902A2_D0050.tif" />invention. Depending on the nature of the monomer or monomers that it is desired to polymerize, it may be necessary to introduce into the polymerization or copolymerization medium a free radical initiator. The person skilled in the art knows the monomers which require the presence of such an initiator for this monomer to polymerize or copolymerize. For example, the polymerization or copolymerization of a diene requires the presence of a free radical initiator.

0018The free radical initiator may be introduced into the polymerization or copolymerization medium at 50 to 50,000 ppm based on the polymerizable or copolymerizable monomer mass.

0019The<img file="EP0832902A2_D0051.tif" />Free radical initiator may for example be selected from those of peroxide type or azo type. we can mention<img file="EP0832902A2_D0052.tif" />example the following initiators: benzoyl peroxide, lauroyl peroxide, tert-butyl peracetate, tylenyl perpivalate, butyl per-2-ethylhexanoate, tert-butyl perpivalate, tert-butyl perneodecanoate, tert-butyl perisononanoate, tert-amyl perneodecanoate, tert-butyl perbenzoate, di-2-ethylhexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, cumyl perneodecanoate, tert-butyl permaleate, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethyl-valeronitrile), 2,2'-azobis (cyclohexanenitrile), 2,2'-azobis- (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile).

0020In the case where the medium comprises a vinylaromatic monomer and it is desired to have excellent control of the growth of the polymer or copolymer so that the latter is of particularly narrow polydispersity, it is preferable to carry out the polymerization or copolymerization at a desired temperature. temperature at which no polymerization or copolymerization<img file="EP0832902A2_D0053.tif" />is observed in l<img file="EP0832902A2_D0054.tif" />absence of<img file="EP0832902A2_D0055.tif" />initiator of free radicals, and<img file="EP0832902A2_D0056.tif" />add a free radical initiator in the middle. For example, in the case of the polymerization or copolymerization of<img file="EP0832902A2_D0057.tif" />at least one vinylaromatic monomer, it is in this situation when the temperature is below about 120 ° C. However, appreciable speeds of polymerization or copolymerization are obtained when the temperature is between 90 and 120 ° C., and a free radical initiator has been added to the medium.

0021Nevertheless, if<img file="EP0832902A2_D0058.tif" />we accept a higher polydispersity, it does not<img file="EP0832902A2_D0059.tif" />It is not excluded to heat the environment at higher temperatures.

0022Thus, in the case where the medium comprises a vinylaromatic monomer, the polymerization or copolymerization can be initiated thermally and without initiator of free radicals, in which case it is generally conducted between 120 and 200 ° C and preferably between 120 and 160 ° C. If a free radical initiator has been introduced, it is possible to carry out the polymerization or copolymerization at 25.degree. To 120.degree. C., but it is also possible, depending on the nature of the<img file="EP0832902A2_D0060.tif" />initiator and in particular its half-life temperature, heat up<img file="EP0832902A2_D0061.tif" />at 200 ° C, if<img file="EP0832902A2_D0062.tif" />a higher rate of polymerization is preferred over polydispersity.

0023In the case where the medium comprises a vinylaromatic monomer, the polymerization or copolymerization can be carried out in bulk, in suspension or in solution.

0024In the case of<img file="EP0832902A2_D0063.tif" />a diene, the polymerization or copolymerization is generally carried out in solution or suspension. The polymerization or copolymerization medium may be intended to lead to an impact vinyl aromatic polymer, in which case it generally comprises at least one vinylaromatic monomer and a rubber, the latter being generally a conjugated polydiene such as<img file="EP0832902A2_D0064.tif" />one or more polybutadienes.

0025The invention also relates to the preparation of copolymers. For example, when at least one vinylaromatic monomer is present in the medium, this monomer can be copolymerized with, for example, at least one monomer chosen from acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, a alkyl ester whose alkyl group contains from 1 to 4 carbon atoms, an N-alkylamelimide whose alkyl group contains from 1 to 4 carbon atoms, N-phenylmaleimide.

0026Of course, depending on the polymerization or copolymerization conditions, and in particular the duration, the temperature, the degree of monomer to polymer or copolymer conversion, it is possible to produce products of very different molecular mass.

0027The<img file="EP0832902A2_D0065.tif" />The invention relates to the preparation of oligomers, polymers or copolymers having a weight average molecular weight of less than 10,000, and to polymers or copolymers having a weight average molecular weight greater than 10,000, such as high molecular weight polymers. average in weight generally ranging from 100,000 to 400,000.

0028The<img file="EP0832902A2_D0066.tif" />The invention relates to both polymerization or copolymerization processes whose monomer to polymer or copolymer conversion rate is less than 50% than those whose conversion of monomer to polymer or copolymer is greater than 50%.

0029The process for preparing the<img file="EP0832902A2_D0067.tif" />secondary amine comprises a reaction step between:<ul id="ul0002" list-style="dash" compact="compact"><li>a compound C comprising a carbonyl group,</li><li>a primary amine,</li><li>a phosphorus derivative comprising a phosphoryl group.</li></ul>

0030Compound C may for example be represented by the formula<chemistry id="chem0003" num="0003"><img file="EP0832902A2_D0068.tif" /></chemistry> in which R³ and R⁴ , may be identical or different, may represent various radicals such as<img file="EP0832902A2_D0069.tif" />an atom of<img file="EP0832902A2_D0070.tif" />hydrogen or an alkyl, aryl or aralkyl radical comprising, for example, from 1 to 10 carbon atoms. Radicals R³ and R⁴ can also be linked together to form a cycle including the<img file="EP0832902A2_D0071.tif" />carbon atom of the carbonyl group. Compound C may be chosen from aldehydes or ketones.

0031As a<img file="EP0832902A2_D0072.tif" />for example, the compound C can be:<ul id="ul0003" list-style="dash" compact="compact"><li>trimethylacetaldehyde,</li><li>isobutyraldehyde,</li><li>diethylketone,</li><li>dibutylketone,</li><li>methyl ethyl ketone</li><li>cyclohexanone,</li><li>4-tert-butylcyclohexanone,</li><li>the tetralone.</li></ul>

0032The<img file="EP0832902A2_D0073.tif" />primary amine can be represented by the formula R⁵-NH₂ in which R⁵ can represent for example a linear or branched hydrocarbon radical, saturated or unsaturated, which may comprise at least one ring, said radical comprising from 1 to 30 carbon atoms, such as<img file="EP0832902A2_D0074.tif" />an alkyl, aryl or aralkyl radical. As a<img file="EP0832902A2_D0075.tif" />example, the radical R⁵ may be chosen from the following radicals: methyl, ethyl, propyl, isopropyl, tert-butyl, diphenylmethyl, triphenylmetyl, phenyl, naphthyl, benzyl, phenyl-1-ethyl.

0033The phosphorus derivative can be represented by the formula HP (O) (R)⁶) (R⁷) in which R⁶ and R⁷ , which may be identical or different, may be chosen from alkyl, cycloalkyl, alkoxyl, aryloxyl, aryl, aralkyloxyl, perfluoroalkyl and aralkyl radicals, and may comprise from 1 to 20 carbon atoms. R⁶ and / or R⁷ may also be a halogen atom such as a chlorine or bromine atom or fluorine or iodine. As a<img file="EP0832902A2_D0076.tif" />example, radicals R⁶ and R⁷ may be chosen from the following radicals: methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-butyl, phenyl, benzyl, benzyl, methoxyl, ethoxyl, trifluoromethyl, benzyloxyl.

0034As a<img file="EP0832902A2_D0077.tif" />for example, the phosphorus derivative may be: diethyl phosphite, dibenzyl phophite, diisopropyl phosphite, di-n-dodecyl phosphite, diphenylphosphine oxide, dibenzylphosphine oxide.

0035For the reaction, we preferably put everything in<img file="EP0832902A2_D0078.tif" />firstly in contact with the compound C and the<img file="EP0832902A2_D0079.tif" />primary amine, then in a second step, the phosphorus derivative is added.

0036The<img file="EP0832902A2_D0080.tif" />reaction step may be carried out for example between 0 and 100 ° C, and preferably between 20 and 60 ° C.

0037Preferably, the molar ratio of the phosphorus derivative to the compound C is greater than 1.

0038Preferably, the molar ratio of the compound C on the<img file="EP0832902A2_D0081.tif" />primary amine ranges from 0.8 to 1.5.

0039Following the<img file="EP0832902A2_D0082.tif" />reaction step, the medium contains a secondary amine, also object of the present invention. This secondary amine can, if necessary, be isolated in any suitable way.

0040In particular, the medium can be acidified with an aqueous solution of<img file="EP0832902A2_D0083.tif" />hydrochloric acid to form a hydrochloride of<img file="EP0832902A2_D0084.tif" />secondary amine, then add to the medium an organic solvent such as<img file="EP0832902A2_D0085.tif" />an ether to solubilize the species to be removed, then isolate the aqueous phase, then add in this aqueous phase sodium carbonate to release the<img file="EP0832902A2_D0086.tif" />secondary amine. The latter is then extracted with an organic solvent such as<img file="EP0832902A2_D0087.tif" />an ether to be isolated after evaporation of the solvent.

0041The<img file="EP0832902A2_D0088.tif" />secondary amine can be represented by the formula:<chemistry id="chem0004" num="0004"><img file="EP0832902A2_D0089.tif" /></chemistry> in which the R radicals³, R⁴, R⁵, R⁶ and R⁷ retain the previously given meanings.

0042The<img file="EP0832902A2_D0090.tif" />secondary amine can be used for the preparation of<img file="EP0832902A2_D0091.tif" />a nitroxide.

0043The process for preparing this nitroxide comprises, after forming the<img file="EP0832902A2_D0092.tif" />secondary amine, a step of<img file="EP0832902A2_D0093.tif" />oxidation of this secondary amine, capable of replacing its group> NH with a grouping> NO_• . Listed below, in a non-exhaustive way are some appropriate techniques:<ul id="ul0004" list-style="dash" compact="compact"><li>reaction of the<img file="EP0832902A2_D0094.tif" />secondary amine with l<img file="EP0832902A2_D0095.tif" />hydrogen peroxide, the principle of which is taught by patent application EP 0 488 403;</li><li>reaction of the<img file="EP0832902A2_D0096.tif" />secondary amine with dimethyldioxirane according to the principle taught in RW Murray and M. Sirgh, Tetrahedron Letters, 1988, 29 (37), 4677-4680 (or US 5,087,752);</li><li>reaction of the<img file="EP0832902A2_D0097.tif" />secondary amine with l<img file="EP0832902A2_D0098.tif" />metachloroperbenzoic acid (MCPBA), according to the principle taught in J. Am. Chem. Soc., 1967, 89 (12), 3055-3056.</li></ul>

0044The techniques described in patent applications EP 0 157 738 and GB 1 199 351 can also be used.

0045With regard to the method of<img file="EP0832902A2_D0099.tif" />oxidation with MCPBA, it is preferred to carry out the<img file="EP0832902A2_D0100.tif" />oxidation under the following conditions:<ul id="ul0005" list-style="dash" compact="compact"><li>molar ratio of l<img file="EP0832902A2_D0101.tif" />secondary amine on the MCPBA of between 0.5 and 1 and more preferably between 0.8 and 1;</li><li>temperature between -10 and 10 ° C,</li><li>use of<img file="EP0832902A2_D0102.tif" />an inert solvent so that it can better control the<img file="EP0832902A2_D0103.tif" />exothermicity of the reaction. This solvent may for example be chosen from the family of chlorinated solvents such as dichloromethane or chloroform.</li></ul>

0046The nitroxide can be represented by the formula:<chemistry id="chem0005" num="0005"><img file="EP0832902A2_D0104.tif" /></chemistry> in which the R radicals³, R⁴, R⁵, R⁶ and R⁷ retain the previously given meanings. Following this step of<img file="EP0832902A2_D0105.tif" />oxidation with MCPBA, the nitroxide can be purified, for example by elution on a silica column, and then isolated after evaporation of the solvents that may be necessary.

MANNER OF REALIZING THE INVENTION:

0047The following is the meaning of some abbreviations used in the examples:<dl id="dl0001" compact="compact"><dt>Per. Benz.</dt><dd>: Benzoyl Peroxide</dd><dt>AIBN</dt><dd>2,2'-azobis (isobutyronitrile)</dd><dt>Tempo</dt><dd>2,2,6,6-tetramethyl-1-piperidinyloxy</dd><dt>DTBn</dt><dd>: di-tertiobutylnitroxide</dd></dl>

Example 1

at)

Synthesis of diethyl 2,2-dimethyl-1- (1,1-dimethylethylamino) propyl phosphonate

0048It is mixed at room temperature under an atmosphere of<img file="EP0832902A2_D0106.tif" />nitrogen, in a two-ton 250 ml flask equipped with<img file="EP0832902A2_D0107.tif" />magnetic stirring and<img file="EP0832902A2_D0108.tif" />an addition funnel 6.68 g (0.077 mol) pivalaldehyde and 5.62 g (0.077 mol) tert-butyl amine. The mixture is then heated at 30 ° C for one hour. After cooling to room temperature, 26.23 g (0.19 mol) of diethyl phosphite are added dropwise at room temperature. The mixture is then stirred at 40 ° C for 24 hours.

0049After returning to ambient temperature, 20 ml of<img file="EP0832902A2_D0109.tif" />diethyl ether and<img file="EP0832902A2_D0110.tif" />cooled to 10 ° C. The medium is then acidified with an aqueous solution at 5% by volume of water.<img file="EP0832902A2_D0111.tif" />hydrochloric acid, up to<img file="EP0832902A2_D0112.tif" />at l<img file="EP0832902A2_D0113.tif" />obtaining<img file="EP0832902A2_D0114.tif" />a pH of 3 in the aqueous phase. 120 ml of<img file="EP0832902A2_D0115.tif" />diethyl ether. 10 g of pure sodium hydrogencarbonate are then added, until<img file="EP0832902A2_D0116.tif" />at l<img file="EP0832902A2_D0117.tif" />obtaining<img file="EP0832902A2_D0118.tif" />a pH of 8 in the aqueous phase. Then extract<img file="EP0832902A2_D0119.tif" />amine by four successive extractions of 60 ml of<img file="EP0832902A2_D0120.tif" />diethyl ether each, and then the organic phase thus obtained is dried with approximately 5 g of anhydrous sodium sulphate. After filtration, the solvent is evaporated at room temperature.<img file="EP0832902A2_D0121.tif" />rotary evaporator at 40 ° C under 1 mbar, then at<img file="EP0832902A2_D0122.tif" />help<img file="EP0832902A2_D0123.tif" />a vacuum ramp at room temperature under 0.2 mbar. There was thus obtained 19.36 g of diethyl 2,2-dimethyl-1- (1,1-dimethylethylamine) propyl phosphonate. The NMR characteristics of this product are as follows:<ul id="ul0006" list-style="none" compact="compact"><li><u>NMR</u>^<u>1</u><u>H in CDCl</u>_<u>3</u> :    0.99 ppm (s, 9H, tBu);    1.06 ppm (s, 9H, tBu);    1.28 ppm (t; 6H; J_HH = 7.1Hz: CH₃);    2.69 ppm (d; 1H; J;_HP = 17.9 Hz; H to P);    4.06 ppm (solid; 4H; J)_HH = 7.1Hz; CH₂).</li><li><u>NMR</u>^<u>13</u><u>C in CDCl</u>_<u>3</u> :    16.49 ppm (d; J;_CP = 5.5 Hz; C₁₃-C₁₁);    27.90 ppm (d; J;_CP = 6.1Hz; C₅-C₄-C₃);    30.74 ppm (s; C₇-C₈-C₉);    35.24 ppm (d; J;_CP = 9.6HZ; C₂);    50.93 ppm (s; C₆);    59.42 ppm (d;_CP = 132.9Hz; C₁);    61.39 ppm (d; J;_CP = 7.1HZ; <u>C</u>H₂).</li><li><u>NMR</u>^<u>31</u><u>P in CDCl</u>_<u>3</u> :    29.84 ppm.</li></ul>

b)

Synthesis of N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide

00502.28 g (0.0082 mol) of the<img file="EP0832902A2_D0124.tif" />amine prepared in a) in 5 ml of dichloromethane at room temperature, and then the solution thus obtained is introduced into a flask cooled to 0 ° C. and provided with<img file="EP0832902A2_D0125.tif" />magnetic stirring. A solution of 1.29 g (0.0075 mol) dichloromethane is added dropwise.<img file="EP0832902A2_D0126.tif" />metachloroperbenzoic acid (MCPBA) in 5 ml of dichloromethane. After 6 hours<img file="EP0832902A2_D0127.tif" />stirring at room temperature, a saturated aqueous solution of NaHCO 3 is added to the mixture.₃ up<img file="EP0832902A2_D0128.tif" />at the disappearance of the release of CO₂about 30 ml of this solution. We recover the organic phase that the<img file="EP0832902A2_D0129.tif" />it is dried with approximately 5 g of sodium sulphate. The solvent is then removed at<img file="EP0832902A2_D0130.tif" />rotary evaporator at 40 ° C under 1 mbar then at<img file="EP0832902A2_D0131.tif" />help<img file="EP0832902A2_D0132.tif" />a vacuum ramp at room temperature under 0.2 mbar. We thus obtain 1.39 gd<img file="EP0832902A2_D0133.tif" />an orange oil. This oil is purified on a column of diameter 4 cm and 30 cm in height containing 100 g of silica (silica gel 60, particle size 0.040-0.063 mm) by proceeding as follows: A suspension is prepared comprising 100 g of silica mixed with 200 g of silica. ml of an eluent consisting of<img file="EP0832902A2_D0134.tif" />a mixture CH₂Cl₂/ THF / pentane in the volume proportions of 1/1/2. The column is filled with this suspension and left for one hour, then 1.39 g of orange oil in the form of an 80% by volume solution in the eluent are deposited at the top of the column. At least 200 ml of eluent are needed to purify the product. The liquid at the bottom of the column is recovered in fractions of 15 ml. We then proceed to<img file="EP0832902A2_D0135.tif" />elimination of volatile species, all<img file="EP0832902A2_D0136.tif" />first to<img file="EP0832902A2_D0137.tif" />rotary evaporator at 40 ° C until<img file="EP0832902A2_D0138.tif" />at a residual pressure of 1 mbar then at<img file="EP0832902A2_D0139.tif" />help<img file="EP0832902A2_D0140.tif" />a vacuum ramp at room temperature under 0.2 mbar. 1.06 g of N-tert-butyl-1-diethyl-phosphono-2,2-dimethylpropyl nitroxide are finally collected and the structural formula of which is:<chemistry id="chem0006" num="0006"><img file="EP0832902A2_D0141.tif" /></chemistry>

0051The<img file="EP0832902A2_D0142.tif" />elemental analysis of the final product is consistent with the calculated values. The RPE data for this product is as follows:<ul id="ul0007" list-style="none" compact="compact"><li>at_P = 45.26 G</li><li>at_NOT = 14.27G</li><li>g = 2.0061 (Landé factor)</li></ul>

0052This radical is stable insofar as its EPR spectrum shows no significant change after storage for two months at 25 ° C.

0053For the sake of simplicity, this product is called β-P.

Example 2

at)

Synthesis of the magnesian (CH

<u>3</u>

)

<u>2</u>

CH-MgBr

0054In a 250 ml bicolour flask equipped with<img file="EP0832902A2_D0143.tif" />magnetic stirring and<img file="EP0832902A2_D0144.tif" />a refrigerant comprising a CaCl trap₂1 g (0.041 mol) of magnesium chips coated with 10 ml of<img file="EP0832902A2_D0145.tif" />diethyl ether, then a crystal (about 5 mg) of<img file="EP0832902A2_D0146.tif" />iodine, the latter having the function of<img file="EP0832902A2_D0147.tif" />activate the magnesium and start the reaction.

0055It is then added drop by drop and by<img file="EP0832902A2_D0148.tif" />intermediary<img file="EP0832902A2_D0149.tif" />an addition funnel 5.04 g bromide d<img file="EP0832902A2_D0150.tif" />isopropyl (0.041 mol) diluted in 10 ml of<img file="EP0832902A2_D0151.tif" />diethyl ether. The medium is stirred at room temperature for 3 hours.

b)

Preparation of N-tert-butyl-1-phenyl-2-methylpropyl nitroxide

0056In a 100 ml two-necked flask equipped with<img file="EP0832902A2_D0152.tif" />magnetic stirring and<img file="EP0832902A2_D0153.tif" />a refrigerant, purged at<img file="EP0832902A2_D0154.tif" />nitrogen, 0.3 g of phenyl-N-tert-butyl nitrone (PBN), ie 0.0017 mol, dissolved in 5 ml of<img file="EP0832902A2_D0155.tif" />diethyl ether. The magnesium solution prepared in a) is then added dropwise. 10 ml of<img file="EP0832902A2_D0156.tif" />distilled water, and the mixture is stirred at room temperature for 2 hours. The extraction is then carried out twice with 20 ml of<img file="EP0832902A2_D0157.tif" />diethyl ether, then the organic phase is dried with 5 g of sodium sulfate. After filtration, the volatile species are removed from the organic solution at room temperature.<img file="EP0832902A2_D0158.tif" />help<img file="EP0832902A2_D0159.tif" />a rotary evaporator at 40 ° C until<img file="EP0832902A2_D0160.tif" />at 1 mbar, then at<img file="EP0832902A2_D0161.tif" />help<img file="EP0832902A2_D0162.tif" />a vacuum ramp at room temperature under 0.2 mbar. 0.42 gd is thus obtained<img file="EP0832902A2_D0163.tif" />a yellow-orange liquid. A purification is then carried out on silica identical to that described in<img file="EP0832902A2_D0164.tif" />example 1b) except that<img file="EP0832902A2_D0165.tif" />eluent is a pentane / acetone mixture in a volume ratio of 90/10. After evaporation of<img file="EP0832902A2_D0166.tif" />eluting in the same way that<img file="EP0832902A2_D0167.tif" />at l<img file="EP0832902A2_D0168.tif" />Example 1b), 0.1 g of N-tert-butyl-1-phenyl-2-methyl-propyl nitroxide are collected, the structural formula of which is:<chemistry id="chem0007" num="0007"><img file="EP0832902A2_D0169.tif" /></chemistry>

0057The<img file="EP0832902A2_D0170.tif" />elemental analysis of the final product is consistent with the calculated values. The RPE data for this product is as follows:<ul id="ul0008" list-style="none" compact="compact"><li>at_NOT = 15.21G</li><li>at_H = 3.01 G.</li></ul>

0058This radical is stable insofar as its EPR spectrum shows no significant change after storage for two months at 25 ° C. For the sake of simplification, this product is called β-φ.

Examples 3 to 16

0059In a 0.25 liter stainless steel reactor equipped with<img file="EP0832902A2_D0171.tif" />a ribbon stirrer and<img file="EP0832902A2_D0172.tif" />a temperature regulation is introduced at 20 ° C. and under an atmosphere of<img file="EP0832902A2_D0173.tif" />nitrogen, 150 g styrene, y millimoles d<img file="EP0832902A2_D0174.tif" />initiator and x millimoles of stable free radical. The<img file="EP0832902A2_D0175.tif" />together is brought to a temperature T (° C). The<img file="EP0832902A2_D0176.tif" />moment at which the mixture reaches the temperature T is defined as the<img file="EP0832902A2_D0177.tif" />starting moment of the<img file="EP0832902A2_D0178.tif" />trial.

0060Samples are then taken over time for analysis:<ul id="ul0009" list-style="dash" compact="compact"><li>of the conversion to polymer ("conv" in the tables), which corresponds to the weight percentage of solid obtained after evaporation under a vacuum of 25 mbar for 20 minutes at 200.degree.<img file="EP0832902A2_D0179.tif" />sample taken from its initial weight;</li><li>the weight average molecular weight (Mw) and number (Mn) and therefore the polydispersity P which is equal to Mw / Mn, these determinations being made by gel permeation chromatography.</li></ul>

0061Tables 1 and 2 summarize the results according to the nature and quantities x and y respectively of stable free radical and<img file="EP0832902A2_D0180.tif" />initiator introduced. Tables 1 and 2 give the<img file="EP0832902A2_D0181.tif" />evolution of Mn, conversion and polydispersity as a function of the polymerization time from 1<img file="EP0832902A2_D0182.tif" />initial moment. Examples 10 to 16 are comparative.<tables id="tabl0001" num="0001"><img file="EP0832902A2_D0183.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP0832902A2_D0184.tif" /></tables>