DE19845298A1 - New N-oxyl radicals for use in the controlled polymerisation of unsaturated monomers, especially acrylate esters, comprise N-oxides of 5-morpholone derivatives with organic substituents at positions two and six - Google Patents

Abstract

N-oxyl radicals derived from 5-morpholone derivatives substituted at positions 2 and 6 with four organic groups, possibly combined with the linking carbons to form at least 3-membered spiro rings. N-oxyl radicals of formula (I): R<1>-R<4> = organic residues, which may be combined in pairs (R<1>/R<2> and/or R<3>/R<4>) together with the linking carbons to form rings with at least 3 atoms. Independent claims are also included for: (a) N-oxyl radical formers which produce (I) as a fragment by homolytic cleavage of a chemical bond; (b) a process for the radically initiated polymerisation of olefinically unsaturated monomers in presence of (I); (c) a composition containing unsaturated monomer(s) and (I) and/or radical formers as in (a); (d) a method for the stabilization of unsaturated monomer-containing compositions against unwanted polymerisation by the addition of (I).

Description

The present invention relates to N-oxyl radicals, N-oxyl-radi Kalbildner and their use in the radical polymerisa tion of ethylenically unsaturated monomers.

N-oxyl radicals and N-oxyl radical formers, which differ from a se derived secondary amine, which has no hydrogen atoms on the α-C atoms are known (cf. e.g. EP-A 135280, DE-A 196 51 307, US-A 5,322,912, US-A 5,412,047, US-A 4,581,429, DE-A 16 18 141, CN-A 1052847, US-A 4,670,131, US-A 5,322,960, DE-A 196 02 539, EP-A 765856, JP-A5 / 320217 and DE-A 197 35 223). she are or form extremely stable radicals and are usually can be represented as a pure substance (e.g. by oxidation of the corresponding secondary amines with hydrogen peroxide).

Among other things, such stable N-oxyl radicals are found as Inhibitors of unwanted radical polymerizations Use (see e.g. US-A 5,322,960). Another application such stable N-oxyl radicals is that they are present a certain control of radical-initiated polymerisation at least one ethylenically unsaturated group send compounds (monomers) (see e.g. EP-A 135280, US-A 5,412,047 and US-A 5,322,912).

Radically initiated polymerizations usually have Monomers namely the disadvantage that the molecular weight of the Polymer chains do not increase linearly with the polymerization conversion and that the polymer chains of the resulting polymer in the Usually have no uniform molecular weight. That is, the polymers obtainable by radical-initiated polymerization sat is usually with regard to the property "molecular weight" not monodisperse, but usually indicates one Chen polydispersity index PDI from ≧ 2 to (PDI = /, with = weight average molecular weight of the polymer and number average molecular weight of the polymer). Both before appearances mentioned are due to termination reactions irreversible combination of growing free radical poly merisate chain ends returned.

The controlling influence of stable N-oxyl radicals (the are usually unable to form a radical polymer triggering monomers) is presumably green  det that the stable N-oxyl radicals reactive radical ends not irreversibly terminate a growing polymer chain, but only temporarily block it. This results a decrease in steady-state concentration of growing free radical polymer chain ends, which is the possibility for an irreversible termination of chain growth by combination two growing polymer chain ends reduced. this leads to on average with the polymerization conversion (ideally linear) growing polymer chains. The latter requires a poly merization turnover (ideally linear) growing middle Molecular weight of the polymer formed with a lie at 1 polydispersity index. This opens up as described carried out controlled radical polymerization the Her provision of tailor-made (a certain molecular weight having) polymers with a corresponding measure tailored physical properties. It also opens the possibility of producing block copolymers.

The stable N-oxyl radicals can the polymerization stem as such and / or in the form of N-oxyl radical formers be added. In the former case, it usually takes in necessary way of adding classic radical buttocks polymerization initiators to control the controlled radical Trigger polymerization. In the second case, the polymer already by thermal decay N-oxyl radical generator is formed in addition to the stable N-oxyl radicals radicals X. are triggered.

Stable free N-oxyl radicals used to date include TEMPO [(1): 2,2,6,6-tetramethylpiperidine-1-oxyl] and 4-OH-TEMPO [(2): 4-hydroxy-2, 2,6,6-tetramethyl-piperidine-1-oxyl].

A disadvantage of the above N-oxyl radicals, however, is that their scope of application mainly on the polymerization of Systems is limited to styrenic monomers or a mixture styrenic and other monomers included. Non-styrenic  Monomers cannot be in the presence of TEMPO or 4-OH-TEMPO are practically meaningful homopolymerized.

US 4,528,370 relates to polysubstituted 2-morpholones. So far Nitroxyl compounds are addressed in this publication, is only the production of the nitroxyls of precursor compounds mentioned in the form of substituted hydroxyethylaminoacetates.

The object of the present invention was therefore to create new ones N-oxyl radicals or formers of new N-oxyl radicals are available to ask themselves to carry out controlled radika polymerizations of non-styrenic monomers, in particular those of esters of acrylic and / or methacrylic acid, are suitable.

According to the invention, this object is achieved by N-oxyl radicals of the general formula I

wherein
R ¹ , R ² , R ³ and R ⁴ independently of one another represent organic radicals or R ¹ and R ² and / or R ³ and R ⁴ together with the C atom carrying them represent a ring consisting of at least three atoms, where the free valences of the atoms forming the ring are saturated with hydrogen and / or organic residues.

The N-oxyl radicals of the general formula I are in a preferred embodiment by a spiro ring system, formed from R ¹ and R ² and / or R ³ and R ⁴ together with the carbon atom carrying them, particularly preferably from R. ¹ and R ² together with the C atom bearing them. Advantageously, the aforementioned ring consists of 3 to 8, preferably three, five, six or seven atoms, the free valences of the atoms forming the ring being saturated with hydrogen and / or organic radicals. The free valences of the organic radicals which form the ring-forming atoms include, among others, C ₁ to C ₂₀ alkyl groups, preferably C ₁ to C ₄ alkyl groups (e.g. the methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl and tert-butyl group) into consideration, these alkyl groups advantageously being unsubstituted. Of course, aryl groups can also be considered as such saturating radicals. Among them, the phenyl and naphthyl groups are preferred. However, those heteroaryl groups are also suitable whose aromatic ring is formed by five atoms, of which up to four are different from carbon. (e.g. N, O and / or S). The ring is normally a saturated ring and the ring-forming atoms are usually carbon atoms, but the ring-forming atoms can also comprise heteroatoms. In the normal case, the number of heteroatoms is one or two, with N, O and / or S being particularly suitable as such heteroatoms.

The invention relates in particular to N-oxyl radicals of the general formula I, in which R ¹ , R ² , R ³ and R ⁴ independently of one another are C ₁ - to C ₂₀ -alkyl, preferably C ₁ - to C ₄ -alkyl, for . As methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or tert-butyl, optionally substituted aryl, especially phenyl or naphthyl, heteroaryl, especially aromatic five-membered rings with up to 4 ring atoms different from carbon (z B. N, O and / or S),

stand in what
R ⁵ for optionally branched C ₁ to C ₂₀ alkylene;
R ^{6 in} each case independently for H, C ₁ to C ₂₀ alkyl, if appropriate C ₃ to C ₂₀ cycloalkyl or aryl interrupted by oxygen atoms;
R ⁷ each independently for C ₁ to C ₂₀ alkyl or aryl;
R ⁸ for a chemical bond or optionally branched C ₁ - to C ₂₀ alkylene; and
R ^{9 is} H, C ₁ to C ₂₀ alkyl, aryl or an alkali metal;
p for 0 or 1; and
n stands for an integer from 1 to 100,
or R ³ and R ⁴ together for an oxygen atom and / or R ¹ and R ² and / or R ³ and R ⁴ together with the C atom carrying them form a carbocyclic ring consisting of 3 to 8 atoms, in which 1 or 2 C atoms can be replaced by O, S or N.

If aryl radicals are substituted, the substituents include C ₁ to C ₆ alkyl, C ₁ to C ₆ alkoxy, -SO ₃ H, SO ₃ M (where M is an alkali metal, for example Na or K stands) or NO ₂ in consideration.

Particularly preferred N-oxyl radicals have the general formula II:

wherein
p represents an integer from 2 to 7 and
R ³ and R ⁴ independently of one another are C ₁ -C ₄ -alkyl, phenyl, naphthyl or an aromatic five-membered ring.

The preparation of compounds I is possible via various synthesis steps known per se. Basically, it takes place via a secondary amine, the
NH group is oxidatively converted into the corresponding N-oxyl group NO.

Peroxides such as H ₂ O ₂ , t-butylhydroxyperoxide, cumene hydroperoxide, peracids such as metachloroperbenzoic acid, a-chloroperbenzoic acid, peracetic acid, p-nitrobenzoic acid, perbenzoic acid or magnesium monoperoxyphthalate are suitable as oxidizing agents.

The oxidation can be carried out in an inert solvent such as CH ₂ Cl ₂ , petroleum ether, toluene, xylene or benzene.

The starting amine of Formula III

where R ¹ , R ² , R ³ and R ^{4 have} the meaning already given, z. B. can be obtained as follows:

A mono- or disubstituted 2-aminoethanol is used here a cyclic ketone and a haloform, e.g. B. chloroform or Bromoform, in the presence of an alkali metal hydroxide if substituted under phase transfer conditions Alkali metal hydroxyethylamino acetate implemented. This can be found under Acid catalysis can be cyclized. Regarding the reaction conditions Please refer to US-A-4,528,370.

Instead of directly amine in an N-oxyl-Ra according to the invention to convert dikal, it can also ver in a known manner various modifications are subjected to oxida tiv in a corresponding manner modified N-oxyl radicals hold (of course, the N-oxyl radical as such be modified).

The invention also relates to N-oxyl radical formers, which are characterized in that by homolytic cleavage, for. B. by thermolysis, a chemical bond as a fragment of an N-oxyl radical according to the invention. They have the general formula IV

wherein R ¹ , R ² , R ³ and R ^{4 have} the meaning already given and X for any radical, for. B. methyl, ethyl, cyclohexyl, octyl, C (CN) (CH ₃ ) ₂ , CHPhCH ₃ or CH (CH ₃ ) COOR.

Starting from N-oxyl radicals I, N-oxyl radical formers IV are in simple way z. B. available in that a small Amount of monomers using a radical polymerizationi initiators (e.g. peroxide, hydroperoxide and / or azo compound) in the In the presence of an N-oxyl radical I radically polymerized and attached finally cleaning the polymerization product by reprecipitation (see e.g. DE-A 197 35 225).

Furthermore, for the preparation of N-oxyl radical formers IV from N-oxyl radicals I, the procedures disclosed in EP-A 135280 for converting N-oxyl radicals into N-oxyl radical formers can be used. Particularly suitable combination partners X. for the preparation of N-oxyl radical formers IV are those of the general formula V

wherein R ¹⁵ , R ¹⁶ and R ^{17 are} hydrogen or an alkyl (preferably C ₁ - to C ₄ alkyl), phenyl, cyano or carboxylic acid group or substituted groups thereof.

As a further process for the preparation of N- Oxyl radical formers can be those described in US-A 5,021,481 be disclosed, applied analogously.

The use of the N-oxyl radicals according to the invention or the ent speaking N-oxyl radical generator can in a conventional manner respectively. In other words, it can be carried out as described in EP-A 135280, US-A 5,412,047, US-A 5,322,912, US-A 4,581,429, the WO 96/24620, DE-A 196 02 539, in TRIP Vol. 4, No 6, June 1996, P. 183 ff, in DE-A 197 35 225, DE-A 197 35 222 and in Macro molecules 1997, 30, pages 324-326 for other N-oxyl radicals  or N-oxyl radical generator is recommended. This also applies if the N-oxyl compounds according to the invention in the pre mentioned fonts did not always meet the required requirement profile speak. Accordingly, the N-oxyl radicals of the invention and N-oxyl radical formers to carry out controlled radicals lisch initiated solution, substance, suspension, emulsion, Mini-emulsion and micro-emulsion polymerizations (especially can also be used in an aqueous medium) of monomers. Yourself understandably they are also suitable for carrying out control ter inverse radical emulsion polymerizations. By To administration of organic acids such as camphorsulfonic acid or p-toluene sulfonic acid (US-A 5,322,912) or by adding dimethyl sulfoxide (US-A 5,412,047), 2-fluoropyridine-1-meta-p-toluenesulfo nat, 3-indolyl-butyric acid or indolylacetic acid to the polymer tion mixture, the rate of polymerization in the case be carried out control of the compounds of the invention radicalized polymerizations usually increased who the.

As in combination with the stable N-oxyl according to the invention Radicals I within the framework of controlled radical initiated Free radical polymerization to be used for polymerizations In principle, initiators are all those who are able to trigger a radical polymerization. It can be peroxides (e.g. peroxodisulfuric acid or their alkali metal salts), hydroperoxides and azo trade connections. They can be both oil-soluble and what be soluble in water and become the chosen polymerization medium and the chosen polymerization temperature in a manner known per se Adapted way. Of course, redoxinita are also suitable door systems.

As in the presence of the N-oxyl radicals I according to the invention controlled radically initiated polymerizable monomers, all those are suitable which have at least one ethylenically unsaturated group. These monomers include olefins, such as. B. ethylene, vinyl aromatic monomers such as styrene, α-methyl styrene, o-chlorostyrene or vinyl toluenes, vinyl and vinylidene halides such as vinyl and vinylidene chloride, esters of vinyl alcohol and monocarboxylic acids containing 1 to 12 carbon atoms such as vinyl acetate, vinyl propionate, vinyl -n-butyrate, vinyl laurate and commercially available monomers VEOVA® 9-11 (VEOVA X is a trade name of Shell and stands for vinyl esters of carboxylic acids, which are also known as Versatic® X acids), esters from allyl alcohol and 1 monocarboxylic acids containing up to 12 carbon atoms, such as allyl acetate, allyl propionate, allyl n-butyrate and allyl laurate, esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids preferably having 3 to 6 carbon atoms, such as in particular acrylic acid, methacrylic acid, maleic acid, Fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as, in particular, acrylic acid and methacrylic acid emethyl-, -ethyl-, -n-butyl-, -iso-butyl, -tert.-butyl- and -2-ethylhexyl ester, maleic acid dimethyl ester or maleic acid n-butyl ester, nitriles α, β-monoethylenically unsaturated carboxylic acids such as acrylonitrile such as C _4-8 conjugated dienes such as 1,3-butadiene and isoprene. But also 3 to 6 carbon atoms α, β-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as. B. acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, N-methylacrylamide, N-ethyl acrylamide, N-isopro pylacrylamide and N, N'-dimethylacrylamide, also vinyl sulfonic acid and its water-soluble salts and N-vinylpyrrolidone are suitable. This also applies to those monomers which usually increase the internal strength of the resulting polymers and which normally have an epoxy, hydroxyl or N-methylol group. Examples of these are N-alkylolamides of α, β-monoethylenically unsaturated carboxylic acids having 3 to 10 carbon atoms and their ethers with alkanols having 1 to 4 carbon atoms, among which the N-methylolacrylamide and the N-methylolmethacrylamide are very particularly preferred .

Based on the molar amount of monomers to be polymerized by radicals, the amount of N-oxyl radicals or N-oxyl radical formers according to the invention to be used for a controlled radical polymerization is generally 10 ^-6 to 5 mol%, usually 10 ^{- 4} to 1 mol%. The molar ratio between N-oxyl radicals and radical polymerization initiator is generally chosen to be 0.5 to 5, often 0.8 to 4, for a controlled radical-initiated polymerization. The N-oxyl radicals and N-oxyl radical formers according to the invention are particularly suitable for carrying out radically initiated aqueous emulsion polymerizations.

The radicals according to the invention are also suitable as inhibitors to prevent an undesired radically initiated Polymerization of monomers, i.e. i.e., to stabilize mono mer (as stabilizers). The invention therefore also relates to the Use of the N-oxyl radicals according to the invention for stabilization tion of ethylenically unsaturated monomers against undesired radical initiated polymerization. The application concentrations are generally 0.001 to 0.1 mol%, based on the monomers.  

The invention is illustrated by the following examples clear.

example 1

Preparation of 2,2-dimethyl-1-oxyl-4-oxa-1-spiro [5.5] undecan-5-one

To 17.7 g of 3,3-pentamethylene-5,5-dimethyl-2-morpholone in 500 ml of methylene chloride, 34.2 g of 3-chloroperoxybenzoic acid are added in portions at 0 ° C. in the course of 2 hours. The mixture is then stirred for 12 hours, increasing the temperature to 23 ° C. Then 250 ml of saturated NaHCO ₃ solution are added. The organic phase is separated off, extracted with 200 ml of 20% Na ₂ SO ₃ solution and extracted three times with 200 ml of water each time. The organic phase is dried with MgSO ₄ , filtered and concentrated in vacuo. Yield: 18.2 g.

Example 2

Preparation of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

To 100.4 g of 3,3-tetramethylene-5,5-dimethyl-2-morpholone in 1.5 l Methylene chloride are 172.5 g of 3-chloroperoxybenzoic acid at 0 ° C added in portions within 2 hours. It's going on then stirred for 12 hours, bringing the temperature to 23 ° C elevated.

Then saturated NaHCO ₃ solution is added until the gas evolution ceases. The organic phase is separated off, extracted with 200 ml of 20% Na ₂ SO ₃ solution and extracted three times with 200 ml of water each time. The organic phase is dried with MgSO ₄ , filtered and concentrated in vacuo. Yield: 92.4 g of red crystalline solid.

Further N-oxyl radicals of the formula I can be prepared in a similar manner be produced.

Example 3

The following examples illustrate emulsion and miniemul sion polymerizations in the presence of the Radi kale. In the case of the miniemulsion polymerizations, the specified template using an ultrasound device (Dr. Hiel shear; UP 400 S model) for 5 minutes at 25% setting and then another 20 minutes at the 100% emul setting yaws. The monomer mixture was used for emulsion polymerizations emulsified by stirring the template components. The procedure in Following the filling of the template emulsion in the reaction piston is given below. The degassing was done by pressurizing the reaction flask with nitrogen to 50 bar filled and evacuated. This was done five times repeated.

The sales reported in the examples below were calculated by gravimetry. It is therefore weight based % sales based on the reaction sales of Relate monomer to polymer at the time of sampling and not based on the total amount of the monomer in the reaction are.

Mini emulsion polymerization of styrene and n-butyl acrylate in Ge presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

The contents of the reaction flask were degassed, heated to 110 ° C and kept at this temperature for 1 hour. Subsequently feed 1 was added over 3 hours and reaction 3 was left Progress for hours. Then feed 2 was added and held the reaction flask to 110 ° C for another 4 hours before changing to Um temperature was cooled.

template

Inlet 1

Inlet 2

The conversion of monomer to polymer immediately before the addition of feed 2 (ie after 7 hours) at 110 ° C. was 13% and at the end of the polymerization 12%. The molecular weight distribution (MWD) after 7 hours of polymerization had a poly dispersity of 1.7 with a number average molecular weight of 5.30 × 10 ³ g.mol ^-1 . The MWD of the polymer at the end of the polymerization had a polydispersity of 1.8 with a number average molecular weight of 7.09 × 10 ³ g.mol ^-1 . The polymer obtained had a diblock character, according to the GPC investigation.

Example 4 Mini emulsion polymerization of styrene and n-butyl acrylate in Ge presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

The contents of the reaction flask were degassed, heated to 130 ° C and kept at this temperature for 1 hour. Subsequently feed 1 was added over 2 hours and the reaction was left 1.5 Progress for hours. Then the feed 2 was given over 2 hours and held the reaction flask at 130 ° C for a further 2 hours, before it has cooled to ambient temperature.

template

Inlet 1

Inlet 2

The conversion of monomer to polymer immediately before the addition of feed 2 at 130 ° C. was 30% and 37% at the end of the polymerization. The molecular weight distribution (MWD) after 4 hours of polymerization showed, according to the measurement, a polydispersity of 1.4 with a number average molecular weight of 6.16 × 10 ³ g.mol ^-1 . The MWD of the polymer at the end of the polymerization had a poly dispersity of 1.4 with a number average molecular weight of 1.60 × 10 ⁴ g.mol ^-1 . Two glass transition temperatures were found (39 ° C and 71 ° C). The polymer obtained had a diblock character according to GPC analysis.

Example 5 Emulsion polymerization of styrene and n-butyl acrylate in counter were from 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

The contents of the reaction flask were degassed, heated to 130 ° C and kept at this temperature for 1 hour. In connection feed 1 was added over 3 hours and reaction 1 was left Expire for an hour. Then the inlet 2 was added over 1 hour and held the reaction flask at 130 ° C for a further 2 hours, before it has cooled to ambient temperature.

template

Inlet 1

Inlet 2

The conversion of monomer to polymer immediately before addition of feed 2 (ie after 5 hours) at 130 ° C. was 10% and at the end of the polymerization 35%. The MWD of the polymer at the end of the polymerization had a polydispersity of 1.7 with a number average molecular weight of 3.27 × 10 ⁴ g.mol ^-1 .

Example 6 Mini emulsion polymerization of n-butyl acrylate in the presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

Feed 1 was added to the reaction flask and the contents were degassed of the reaction flask. The reaction flask was then raised to 100 ° C warmed and held at this temperature for 16 hours. Then the temperature was raised to 120 ° C and ge for a further 6 hours hold. The temperature was then raised to 130 ° C and held for 6 hours.

template

Inlet 1

The conversion from monomer to polymer after 6 hours at 120 ° C was 12% and after a further 2 hours at 120 ° C 22%. After 6 hours at 130 ° C the conversion was 39%. The MWD of the end product had a polydispersity of 2.9 with a number average molecular weight of 6.72 × 10 ³ g.mol ^-1 .

Example 7 Mini emulsion polymerization of styrene and n-butyl acrylate in Ge presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

Feed 1 was added to the contents of the reaction flask and degassed ste. The flask was heated to 130 ° C and opened for 5 hours kept at this temperature. Then feed 2 was added and the Reaction flask kept at 130 ° C for another 6 hours before was cooled to ambient temperature.

template

Inlet 1

Inlet 2

The conversion of monomer to polymer immediately before the addition of feed 2 (ie after 5 hours) at 130 ° C. was 19% and at the end of the polymerization 41%. The MWD after 5 hours of polymerization had a polydispersity of 2.8 with a number average molecular weight of 1.08 × 10 ⁴ g.mol ^-1 . The MWD of the polymer at the end of the polymerization had a polydispersity of 2.7 with a number average molecular weight of 1.39 × 10 ⁴ g.mol ^-1 . The polymer obtained showed diblock character after GPC examination.

Example 8 Mini emulsion polymerization of styrene and butadiene in the presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

Feed 1 was added to the contents of the reaction flask and degassed ste. The flask was heated to 130 ° C and opened for 5 hours kept at this temperature. Then feed 2 was closed over 1 hour given and the reaction flask ge for a further 6 hours at 130 ° C. hold before it has cooled to ambient temperature.

template

Inlet 1

Inlet 2

The conversion from monomer to polymer was 10% after 4 hours and 21% at the end of the polymerization. The MWD after 4 hours of polymerization showed a polydispersity of 1.8 with a number average molecular weight of 2.49 × 10 ³ g.mol ^-1 according to the measurement. The MWD of the polymer at the end of the polymerization had a polydispersity of 2.2 with a number-average molecular weight of 1.90 × 10 ⁴ g.mol ^-1 .

Example 9 Mini emulsion polymerization of n-butyl acrylate in the presence of 2,2-dimethyl-1-oxyl-4-oxa-1-aza-spiro [5.6] dodeca-15-one

Feed 1 was introduced into the reaction flask and its Content then degassed. The flask was heated to 130 ° C and held at this temperature for 7 hours before turning on Ambient temperature was cooled.

template

Inlet 1

The conversion of the monomer to the polymer was 14% after 4 hours and 31% at the end of the polymerization. The MWD of the polymer after 4 hours of polymerization had a polydispersity of 1.5 with a number average molecular weight of 9.47 × 10 ³ g.mol ^-1 . The MWD of the polymer at the end of the polymerization had a polydispersity of 1.4 with a number average molecular weight of 2.28 × 10 ⁴ g.mol-1.

Example 10 Mini emulsion polymerization of styrene in the presence of 7,7-dime thyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

Feed 1 was introduced into the reaction flask and its 1 content then degassed. The flask was heated to 130 ° C and held at this temperature for 16 hours and 45 minutes before it has cooled to ambient temperature.

template

Inlet 1

The conversion of the monomer to the polymer was 52% after 2 hours, 64% after 4 hours and 84% at the end of the polymerization. The MWD of the polymer at the end of the polymerization had a polydispersity of 1.5 with a number average molecular weight of 3.26 × 10 ⁴ g.mol ^-1 .

Example 11 Mini emulsion polymerization of butyl acrylate in the presence of 7,7-dimethyl-6-oxyl-9-oxa-6-aza-spiro [4.5] decan-10-one

Feed 1 was introduced into the reaction flask and its Content then degassed. The flask was heated to 130 ° C and held at this temperature for 10 hours before turning on Ambient temperature was cooled.  

template

Inlet 1

The conversion of monomer to polymer is shown below under different time periods:

The MWD of the polymer at the end of the polymerization had a polydispersity of 1.9 with a number-average molecular weight of 1.51 × 10 ⁴ g.mol ^-1 .

Example 12 Bulk polymerizations

The following reactions in bulk were carried out in test tubes. The total mass of each sample was approximately 10 g. Each sample was degassed by passing nitrogen through it, then sealed from the atmosphere and immersed in a thermostated oil bath at the desired temperature for 7 hours. The experiments were carried out using either styrene or n-butyl acrylate as the monomer, benzoyl peroxide as the initiator and in each case a regulator. TEMPO was included for comparison. The tables show the amounts used, the conversion achieved, the number average molecular weight (<M _n <) and the polydispersity of the polymer MWD (γ).

Polymerization of styrene at 110 ° C

At 110 ° C in the presence of TEMPO there was no significant conversion receive.

Polymerization of styrene at 130 ° C

Polymerization of n-butyl acrylate at 130 ° C

In the presence of TEMPO, no significant implementation was carried out takes care.

Claims (8)

1. N-oxyl radicals of the general formula I
wherein
R ¹ , R ² , R ³ and R ⁴ independently of one another represent organic radicals or R ¹ and R ² and / or R ³ and R ⁴ together with the carbon atom carrying them represent a ring consisting of at least three atoms. 2. N-oxyl radicals according to claim 1, characterized in that R ¹ , R ² , R ³ and R ⁴ independently of one another for C ₁ - to C ₂₀ -alkyl, optionally substituted aryl, heteroaryl,
stand in what
R ⁵ for optionally branched C ₁ to C ₂₀ alkylene;
R ^{6 in} each case independently for H, C ₁ to C ₂₀ alkyl, if appropriate C ₃ to C ₂₀ cycloalkyl or aryl interrupted by oxygen atoms;
R ⁷ each independently for C ₁ to C ₂₀ alkyl or aryl;
R ⁸ for a chemical bond or optionally branched C ₁ - to C ₂₀ alkylene; and
R ^{9 is} H, C ₁ to C ₂₀ alkyl, aryl or an alkali metal;
p for 0 or 1; and
n stands for an integer from 1 to 100,
or R ³ and R ⁴ together for an oxygen atom and / or R ¹ and R ² and / or R ³ and R ⁴ together with the C atom carrying them form a carbocyclic ring consisting of 3 to 8 atoms, in which 1 or 2 C atoms can be replaced by O, S or N. 3. N-oxyl radicals according to claim 2, the general formula II
wherein
R ³ and R ⁴ independently of one another are C ₁ - to C ₄ -alkyl, phenyl, naphthyl or an aromatic five-membered ring and
p represents an integer from 2 to 7. 4. N-oxyl radical generator, characterized in that by ho molytic cleavage of a chemical bond as a fragment an N-oxyl radical according to any one of claims 1 to 3 ent stands. 5. Process of radical initiated polymerization of ethylenically unsaturated monomers, characterized in that the polymerization in the presence of N-oxyl radicals ge according to one of claims 1 to 3. 6. Composition containing one or more ethylenically un saturated monomers and at least one N-oxyl radical according to one of claims 1 to 3 and / or at least one N-oxyl Radical generator according to claim 4. 7. Use of N-oxyl radicals according to one of claims 1 to 3 to stabilize ethylenically unsaturated mono against undesired radically initiated polymers station. 8. Method of stabilizing compositions that ethy contain lenically unsaturated monomers against unwanted radical-initiated polymerization by going to the Zu composition according to an effective amount of N-oxyl radicals one of claims 1 to 3.