WO2003099757A1 - Stabilisation of ethylenically unsaturated compounds comprising hydroxylamine derivatives - Google Patents

Abstract

The invention relates to the use of aldoximes, ketoximes which are not derived from quinones, hydroxime acid esters, and N-acyl-hydroxylamine derivatives for stabilising ethylenically unsaturated compounds containing oxygen and/or nitrogen, such as (meth)acrylic acid (esters). Co-stabilisers, such as transition metal salts, phenols, quinones, or hydroquinones, N-oxyls, aromatic amines or phenylenediamines, urea derivatives, compounds containing phosphorus, compounds containing sulphur, and sulfonamides, can be used with the above-mentioned substances. Preferably, a gas containing oxygen, such as air, is present.

Description

Stabilization of ethylenically unsaturated compounds with hydroxylamine derivatives

description

The present invention relates to the use of certain hydroxylactic derivatives for preventing undesired radical polymerization of oxygen- and / or nitrogen-containing ethylenically unsaturated compounds. It also relates to a mixture of substances which contains at least one oxygen- and / or nitrogen-containing ethylenically unsaturated compound and an effective amount of the hydroxylamine derivative. The invention also relates to a stabilizer composition.

Chemical compounds that have one or more ethylenically unsaturated groups have a pronounced tendency to undergo radical polymerization. Such compounds are used as monomers for the targeted production of polymers, eg. B. by free radical polymerization. At the same time, the pronounced tendency to radical polymerization is disadvantageous insofar as it is important both in storage and in chemical and / or physical processing, e.g. B. by distillation or rectification of the ethylenically unsaturated compounds, in particular under the influence of energy, for. B. heat and / or light, undesirable, spontaneous radical polymerization can occur. Such uncontrolled polymerizations can for the gradual formation of polymer coatings z. B. lead on heated surfaces or even run explosively.

It is therefore customary to add ethylenically unsaturated compounds or mixtures which contain such compounds, both during storage and during chemical and / or physical processing, to prevent or slow down spontaneous polymerization. They are generally referred to as inhibitors or retarders and are summarized under the generic term "stabilizers".

DE 10139767 and WO 03/016268 describe the use of amidoximes for stabilizing ethylenically unsaturated compounds against undesired polymerization. US-A 5,489,718 discloses compositions and methods for inhibiting the polymerization of vinyl aromatic compounds under oxygen-free conditions. The compositions contain an oxime compound and a hydroxylamine compound. Vinylaromatic compounds are generally less reactive than oxygen and / or nitrogen-containing ethylenically unsaturated compounds, such as acrylic acid or methacrylic acid. The person skilled in the art would not have readily expected the suitability of the oxime compounds for stabilizing (meth) acrylic acid and other ethylenically unsaturated compounds containing oxygen and / or nitrogen.

There is a constant need for polymerization inhibitors to stabilize (meth) acrylic acid and other oxygen and /

"or nitrogen-containing ethylenically unsaturated compounds which effectively inhibit undesired polymerization even in the presence of molecular oxygen and / or in the absence of mechanical movement and / or in the vapor space over a liquid mixture containing such unsaturated compounds.

20

It has now been found that certain hydroxylamine derivatives, namely aldoximes, etoximes, which are not derived from quinones, hydroximic acid esters and N-acylhydroxylamine derivatives are capable of radical polymerization of oxygen and / or

^2! * Inhibit or delay nitrogenous ethylenically unsaturated compounds. These hydroxylamine derivatives are effective in the presence of molecular oxygen and in the absence of mechanical motion, e.g. B. in non-stirred containers or plant parts. They are also able to polymerize

30 inhibition also in the vapor space over a liquid phase containing oxygen and / or nitrogen-containing ethylenically unsaturated compounds. They are therefore particularly suitable for use as stabilizers during the rectification of oxygen- and / or nitrogen-containing ethylenically unsaturated compounds.

"bonds, since they effectively stabilize both the condensate on the column trays, which is subject to little or no circulation, and the vapors in contact with them.

Accordingly, the invention relates to a mixture of substances comprising at least one oxygen- and / or nitrogen-containing ethylenically unsaturated compound and an amount effective at least one among aldoximes to prevent undesired radical polymerization; Ketoximes that are not derived from quinones; hy

* ⁵ hydroxymic acid esters and N-acylhydroxylamine derivatives containing selected hydroxylamine derivatives. The invention also relates to a method for stabilizing materials comprising at least one oxygen- and / or nitrogen-containing ethylenically unsaturated compound against undesired free-radical polymerization by adding an effective amount of the hydroxylamine derivative defined above to the materials to be stabilized. The materials to be stabilized can consist exclusively of one or more ethylenically unsaturated compounds or contain them in a concentration at which a radical polymerization can take place with spontaneous initiation.

The invention also relates to the use of a hydroxylamine derivative defined above for preventing undesired radical polymerizations of ethylenically unsaturated compounds, for. B. during manufacture, storage, transport or chemical and / or physical processing.

The invention also relates to a stabilizer composition which is suitable for stabilizing ethylenically unsaturated compounds against undesired free-radical polymerization and contains at least one hydroxylamine derivative defined above and at least one costabilizer. The stabilizer composition can be used as both a process and storage stabilizer, i.e. H. for stabilizing ethylenically unsaturated compounds during the process of their preparation and purification or for stabilizing the pure compounds.

All of the statements in the present description relating to the mixture of substances according to the invention apply accordingly to the method according to the invention, the stabilizer composition according to the invention and the use according to the invention and vice versa.

The hydroxylamine derivatives used according to the invention include: aldoximes [RHC = N-0R '] _r ketoximes [RRC = N-0R'], hydroximic acid esters [R (R0) C = N-0R '] and N-acylhydroxylamine derivatives, including hydroxamic acids and O-substituted derivatives thereof [RC0-N (R '') -0R '] and N-hydroxyimides and O-substituted derivatives thereof [(RCO) ₂ N-0R'] count [the characteristic structural element is given in brackets, where R stands for a radical bound via carbon, R 'stands for hydrogen or a radical bound via carbon and R''stands for hydrogen or a radical bound via carbon. Two radicals R or R and R ″ can be linked to form a cyclic structure.] The ketoximes which can be used according to the invention do not include those ketoximes derived from quinones, such as 1,4-benzoquinone dioxime.

The hydroxylamine derivatives used according to the invention are known compounds or can be prepared by customary processes. For example, aldoximes or ketoximes are obtained by reacting aldehydes or ketones with hydroxylamine.

The hydroxylamine derivatives used according to the invention preferably have a boiling point of less than 300 ° C. at normal pressure.

Suitable hydroxylamine derivatives have, for example, one of the general formulas I, II or III:

II

III

wherein

R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ and R ⁷ independently of one another for hydrogen, Ci-Cis-alkyl, which is optionally interrupted by one or more groups selected from 0, S and NR ^a , C ₇ -Ci ₈ aralkyl, C ₂ -C ₈ alkenyl, C _ß -C ₂ aryl, C ₅ -C ₂ cycloalkyl, in which one or more carbon atoms are optionally replaced by a group selected from 0, S and NR ^a , or Heterocyclyl, R ² , R ⁴ and R ⁵ can also independently of one another stand for OR ⁸ , COR ⁸ or C0 ₂ R ⁸ , where R ^{8 has} the meaning given for R ¹ ,

R ^{7 can} also stand for COR ⁸ , or R ⁶ and R ⁷ together with the carbon atom and the nitrogen atom to which they are attached also for a 5- to 12-membered, preferably 5- to 8-membered ring can stand

R ² together with the carbon atom to which it is attached and R ⁴ and optionally the repeating unit (s) [R ³ C (NO ¹ )] for a 5- to 12-membered, preferably 5- to 8- link ring can stand

R ^{3 represents} a chemical bond or Cχ-Cι ₂ alkylene, which is optionally interrupted by one or more groups selected from 0, S, NR ^a and optionally contains one or more carbon-carbon double bonds,

R ^{a is} hydrogen or -CC ₈ alkyl,

Q represents a k-valent organic radical bonded via carbon atoms,

n is an integer from 0 to 10, preferably 0 or 1, and

k represents an integer from 3 to 6,

where R ² and R ^{4 are} not simultaneously hydrogen or OR ⁶ if n is 0.

The alkyl, aralkyl, alkenyl, aryl, cycloalkyl and heterocyclyl radicals mentioned can in turn be substituted by halogen, hydroxy, alkoxy, amino, mono- and dialkylamino, cyano, nitro, alkoxycarbonyl, alkylcarbonyl, alkylcarbonyloxy or sulfonyloxy be the aryl and heterocyclyl residues also by alkyl.

The number of substituents in the stated radicals is not restricted. As a rule, in the case of radicals having one to three carbon atoms, it is up to three substituents, preferably up to two and particularly preferably up to one. In the case of radicals with four to six carbon atoms, it is generally up to four substituents, preferably up to three and particularly preferably up to one. In the case of radicals with more than seven carbon atoms, it is generally up to six substituents, preferably up to four and particularly preferably up to two.

Heterocyclyl is preferably an aromatic 5- or 6-membered heterocycle which has one to three heteroatoms selected from oxygen, nitrogen and / or sulfur and which is optionally benzanellated, such as furyl, thiophenyl, pyrryl, pyridyl, indolyl, benzoxazolyl, dioxolyl , Dioxyl, benzimidazolyl, benzthiazolyl.

Q stands for example for a radical of the formula

woπn

embedded image in which

R ^{3 has} the meaning already given, and p represents an integer from 1 to 3, preferably 1 or 2;

R ¹ is preferably hydrogen or Ci-Cs-alkyl, in particular hydrogen or methyl, particularly preferably hydrogen.

R ² is preferably Ci-Cβ alkyl, C-Cιg aralkyl, C _ß -Cι ₂ aryl, Ci-Cs-alkoxy, Ci-Cg-alkylcarbonyl, Cι-Cβ ₂ arylcarbonyl, Ci-Cs-Al kyloxycarbonyl, heterocyclyl; z. B. for methyl, ethyl, iso-Pro PY ^ - _r n-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, phenyl, benzyl, 1-hydroxy-l-phenylmethyl, methoxycarbonyl, 2nd -, 3- or 4-pyridyl, 2-, 3- or 4-hydroxyphenyl, benzoyl, acetyl, 2-, 3- or 4-methylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2- or 3-furyl. R ² preferably represents methyl, ethyl, phenyl. If n is different from 0, R ² preferably also represents hydrogen.

R ⁴ and R ⁵ are preferably hydrogen, Ci-Cs-alkyl, C ₇ -Ci ₈ aralkyl, Cζ — Cι ₂ aryl, Ci-C _ß alkyloxy; z. B. for hydrogen, methyl, ethyl, iso-propyl, n-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, phenyl, benzyl, methoxy, ethoxy, iso-propoxy, n-butoxy, tert -Butoxy, preferably for hydrogen, methyl, ethyl, Phenyl, methoxy, ethoxy, particularly preferably hydrogen, methyl, ethyl or phenyl.

R ⁶ preferably does not represent hydrogen, in particular Ci-Cs-alkyl, C-C ₈ aralkyl or C ₆ -C ₂ aryl. R ⁷ preferably represents hydrogen. R ⁶ and R ⁷ together with the carbon atom and the nitrogen atom to which they are attached preferably represent a 5- or 6-membered saturated or unsaturated ring.

R ³ preferably represents a chemical bond, methylene, ethylene or propylene, in particular a chemical bond or methylene, particularly preferably a chemical bond.

When n is 0, R ² and R ⁴ together with the carbon to which they are attached preferably also represent a saturated 5- to 12-membered carbocycle.

Preferred hydroxylamine derivatives are benzaldoxime, salicylic aldoxime, 2-pyridine doxime; Acetone oxime, methyl ethyl ketoxime, diethyl ketoxime, 4-heptanone oxime, 2,4-dimethyl-3-pentanone oxime, cyclohexanone oxime, 4-tert-butyl-cyclohexanone oxime, cyclododecanone oxime, 9-fluorenone oxime, phenyl-2-pyridyl ketoxime, benzil dioxime, 2,3- Butanedione dioxime, 2,3-butanedione monooxime, di-2-furanylethanedione dioxime and ethyl N-ethoxyacetimidate selected. Of these, methyl ethyl ketoxime, 2,3-butanedione dioxime, 2-pyridine doxime and salicylaldoxime are particularly preferred.

The person skilled in the art can easily determine the amount of hydroxylamine derivative required to prevent undesired radical polymerization by means of orienting experiments. It depends on various factors, including the reactivity of the ethylenically unsaturated compound to be stabilized, the temperature, the presence or absence of impurities which can act as a radical initiator, and the presence or absence of costabilizers. As a rule, 1 to 2000 ppm by weight, often 50 to 500 ppm by weight (based on the amount of ethylenically unsaturated compounds contained) of oxime is added to the material to be stabilized.

It was also found that the stabilizing effect of the hydroxylamine derivatives can be greatly increased by using costabilizers. These can be, for example, transition metal salts, phenols, quinones or hydroquinones, N-oxyls, aromatic amines or phenylenediamines, urea derivatives, phosphorus-containing compounds, sulfur-containing compounds and / or sulfonamides. Hy- droxylamines or derivatives which do not fall under the definition given above, such as N, N-diethylhydroxylamine.

For example, 2 to 2000 ppm by weight (based on the amount of ethylenically unsaturated compounds contained in the material to be stabilized) are used per costabilizer component, preferably 10 to 1000 ppm, particularly preferably 20 to 800 and very particularly preferably 30 to 700. In addition the oxime may be one or more of the co-stabilizer compo- ^■ * ^■ "components described above are co-used, preferably one or two co-stabilizer components.

Suitable transition metal salts include, for example, cerium, copper, manganese, nickel or chromium salts, of which cerium salts

- ^{15 are} preferred. Cerium (III) or cerium (IV) salts are preferred as cerium salts, particularly preferably cerium (III) salts. The counterions of the transition metal cations are not critical. Usually oxides, hydroxides, halides, sulfates, nitrates, carbonates or preferably carboxylates are used, especially how

20 For iate, acetate, propionate, hexanoate and 2-ethylhexanoate as well as oxalate, acetylacetonate, acrylate and methacrylate. The salts can be present as hydrates with varying amounts of water, which are equally suitable. Cerium (III) acetate, cerium (III) acetylacetonate, cerium (III) carbonate, cerium (III) chloride are particularly preferred,

²⁵ cerium (III) ethylhexanoate, cerium (III) nitrate, cerium (III) oxalate,

Cerium (III) sulfate or cerium (III) acrylate, which can be formed in situ, for example, when acrylic acid is stabilized.

Suitable phenols include alkylphenols, for example

30 phenol, o-, - or p-cresol (methylphenol), 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl -4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2, 4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol , or 2,2 '-methylene-bis- (6-tert-bu-

35 tyl-4-methylphenol), 4,4'-oxydiphenyl, 3,4-methylenedioxydiphenol (sesame oil), 3,4-dimethylphenol, hydroquinone, pyrocatechol (1,2-dihydroxybenzene), 2- (1'-methylcyclohex-1 '-yl) -4, 6-dimethylphenol, 2- or 4- (l'-phenyl-eth-l'-yl) phenol, 2-tert-butyl-6-methylphenol, 2,4, 6-tris-tert-butylphenol, 2, 6-di-tert-bu-

40 tylphenol, 2,4-di-tert-butylphenol, 4-tert-butylphenol, nonylphenol [11066-49-2], octylphenol [140-66-9], 2,6-dimethylphenol, bisphenol A, bisphenol F , Bisphenol B, bisphenol C, bisphenol S, 2,6-di-tert-butyl-p-cresol, Koresin® from BASF AG, 3, 5-di-tert-butyl-4-hydroxybenzoic acid methyl ester, 4-tert- butylpyrocatechol,

45 2-hydroxybenzyl alcohol, 2-methoxy-4-methylphenol, 2,3,6-trimethylphenol, 2,4,5-trimethylphenol, 2,4,6-trimethylphenol, 2-isopropylphenol, 4-isopropylphenol, 6 -Isopropyl-m-cresol, n-octade- cyl-β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (3,5-di-tert-butyl -4-hydroxybenzyl) isocyanurate, 1,3,5, -Tris- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl isocyanurate, 1, 3, 5-tris- (2, 6 -dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate or pentaerythritol tetra-kis [ß- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,6-di- tert-butyl-4-dimethylaminomethylphenol, 6-sec-butyl-2, 4-dinitrophenol, Irganox® 565, 1141, 1192, 1222, 1425, 1076 and 1010 from Ciba Specialty Chemicals, 3- (3 ', 5' -Di-tert-butyl- '-hydroxyphenyl) propionic acid octadecyl ester, 3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionic acid hexadecyl ester, 3- (3 ', 5' -di-tert -butyl-4'-hydroxyphenyl) propionic acid octyl ester, 3-thia-l, 5-pentanediol-bis- [(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], 4.8- Dioxa-l, ll-undec andiol-bis- [(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], 4, 8-dioxa-l, ll-undecanediol-bis- [(3 '-tert-butyl -4'-hydroxy-5'-methylphenyl) propionate], 1, 9-nonanediol-bis- [(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], 1,7-hep- tandiamine-bis [3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionic acid amide], 1,1-methanediamine-bis [3- (3 ', 5' -di-tert- butyl-4'-hydroxyphenyl) propionic acid amide], 3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionic acid hydrazide, 3- (3 ', 5'-di-methyl-4'-hydroxyphenyl) propionic acid hydrazide, bis (3-tert-butyl-5-ethyl-2-hydroxyphen-l-yl) methane, bis (3,5-di-tert-butyl-4-hydroxyphen-l-yl) methane, Bis [3- (1'-methylcyclohex-l'-yl) -5-methyl-2-hydroxyphen-1-yl] methane, bis (3-tert-butyl-2-hydroxy-5-methylphen- 1-yl) methane, 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphen-1-yl) ethane, bis (5-tert-butyl-4-hydroxy-2-methyl- phen-1-yl) sulfide, bis (3-tert-butyl-2-hydroxy-5-methylphen-1-yl) sulfide, 1,1-bis (3,4-dimethyl-2-hydroxyphen-l- yl) -2-methylpropane, 1, 1-bis (5-tert-butyl-3-methyl-2-hydroxyphen-1-yl) butane, 1,3,5-tris [l '- (3'',5''-di-tert-butyl-4''-hydroxyphen-1''-yl)-meth-1' -yl] -2, 4, 6-trimethylbenzene, 1,1, 4-tris (5'-tert-Butyl-4'-hydroxy-2'-methylphen-1'-yl) butane, aminophenols, such as e.g. B. para-aminophenol, nitrosophenols, such as. B. para-nitrosophenol, p-nitroso-o-cresol, alkoxyphenols, for example 2-methoxyphenol (guaiacol, pyrocatechol monomethyl ether), 2-ethoxyphenol, 2-isopropoxyphenol, 4-methoxyphenol (hydroquinone monomethyl ether), mono- or di- tert-butyl-4-methoxyphenol, 3,5-di-tert-butyl-4-hydroxyanisole, 3-hydroxy-4-methoxybenzyl alcohol, 2,5-dimethoxy-4-hydroxybenzyl alcohol (syringa alcohol), 4-hydroxy -3-methoxybenzaldehyde (vanillin), 4-hydroxy-3-ethoxybenzaldehyde (ethylvanillin), 3-hydroxy-4-methoxybenzaldehyde (isovanillin), l- (4-hydroxy-3-methoxyphenyl) ethanone (acetovanillon ), Eugenol, dihydroeugenol, isoeugenol, or tocopherols, such as. B. ^α_ . ß ~. - δ- and ε-tocopherol, tocol or tocopherol hydrochloric non, and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran (2,2-dimethyl-7-hydroxycoumaran), Trolox®, gallic acid, ferulic acid, cinnamic acid and their derivatives.

^ Suitable quinones or hydroquinones include hydroquinone or hydroquinone monomethyl ether, 2,5-di-tert-butylhydroquinone, 2-methyl-p-hydroquinone, 2, 3-dimethylhydroquinone, trimethylhydroquinone, 4-methylpyrocatechol, tert-butylhydroquinone, 3-methyl- catechol, benzoquinone, 2-methyl-p-hydroquinone, 2,3-dimethyl

^• '- ⁰ hydroquinone, trimethylhydroquinone, 3-methylcatechol, 4-methylcatechol, tert-butylhydroquinone, 4-ethoxyphenol, 4-butoxyphenol, hydroquinone monobenzyl ether, p-phenoxyphenol, 2-methylhydroquinone, 2,5-di- tert-butylhydroquinone, tetramethyl-p-benzoquinone, diethyl-l, 4-cyclohexanedione-2,5-dicarboxylate, phenyl-

^• ^ p-benzoquinone, 2,5-dimethyl-3-benzyl-p-benzoquinone, 2-isopropyl-5-methyl-p-benzoquinone (thymoquinone), 2, 6-diisopropyl-p-benzoquinone, 2 , 5-Dimethyl-3-hydroxy-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, embelin, tetrahydroxy-p-benzoquinone, 2,5-dimethoxy-l, 4-benzoquinone, 2-amino-5 -methyl-p-benzoquinone, 2,5-bisp-

2 henylamino-l, 4-benzoquinone, 5, 8-dihydroxy-l, 4-naphthoquinone, 2-anilino-l, 4, naphthoquinone, anthraquinone, N, N-dimethylindoaniline, N, N-diphenyl-p-benzoquinone diimine , 1,4-benzoquinone dioxime, Coerulignon, 3,3 '-di-tert-butyl-5, 5'-dimethyldiphenoquinone, p-ro-sol acid (aurine), 2, 6-di-tert-butyl-4-benzylidene benzoquinone or

²⁵ 2,5-di-tert-amyl hydroquinone.

Suitable N-oxylenes include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2, 2,6, 6-tetramethyl-piperidine-N-oxyl,

4-acetoxy-2, 2,6, 6-tetramethyl-piperidine-N-oxyl, 2,2,6, 6-tetrame-

30 thyl-piperidine-N-oxyl, 4,4 ', 4' 'tris (2, 2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2, 2.5 , 5-tetramethyl-pyrrolidine-N-oxyl, l-oxyl-2,2,6, 6-tetramethyl-4-methoxypiperidine, l-oxyl-2, 2,6, 6-tetramethyl-4-trimethylsilyloxypiperidine, l-0xyl -2, 2,6, 6-tetramethylpiperidin-4-yl-2-ethylhexanoate,

35 l-0xyl-2,2,6,6-tetramethylpiperidin-4-yl stearate, l-0xyl-2, 2,6,6-tetramethylpiperidin-4-yl-benzoate, l-0xyl-2, 2,6 , 6-tetramethylpiperidin-4-yl- (4-tert-butyl) benzoate,

Bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) succinate,

Bis (l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate, 1,10-decane

40 disaure bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) ester,

Bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) -n-butylmalonate,

Bis (l-oxyl-2, 2,6, 6-tetramethylpiperidin-4-yl) phthalate,

Bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) isophthalate,

Bis (l-oxyl-2, 2,6, 6-tetramethylpiperidin-4-yl) terephthalate,

45

Bis (l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate, N, N 'bis (l-0xyl-2,2,6,6-tetramethylpiperidin-4-yl) -adipina-mid, N- (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) -caprolactam, N- (l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) -dodecylsuccinimide, 2,4,6-tris [N-butyl-N- (l-oxyl-2, 2,6, 6-tetramethylpiperid-4-yl] triazine, N, N'-bis (l-oxyl-2,2, 6,6-tetramethylpiperid-4-yl) -N, N'-bis-formyl-l , 6-diaminohexane or 4,4'-ethylene-5 bis (l-oxyl-2,2,6,6-tetramethylpiperazin-3-one).

Suitable aromatic amines or phenylenediamines include N, N-diphenylamine, N-nitrosodiphenylamine, nitrosodiethylaniline, N, N'-dialkyl-para-phenylenediamine, where the alkyl radicals "can be the same or different and each independently from 1 to 4 Carbon atoms exist and can be straight-chain or branched, for example N, N'-di-iso-butyl-p-phenylenediamine, N, N'-di-iso-propyl-p-phenylenediamine, Irganox 5057 from Ciba Specialty Chemicals, N, N '-Di-iso-butyl-p-phe- ^5- nylene diamine, N, N'-di-iso-propyl-p-phenylene diamine, p-phenylene diamine, N-phenyl-p-phenylene diamine, N, N'-diphenyl -p-phenylene-diamine, N-isopropyl-N-phenyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine (Kerobit® BPD), N-phenyl-N'-isopropyl-p- phenylenediamine (Vulkanox® 4010 from Bayer AG), N- (1,3-dimethyl-butyl) -N'-phenyl-p-phenylenediamine, N-phenyl-2-naphthylamine, i-nodibenzyl, N, N'- Diphenylbenzidine, N-phenyltetraaniline, acridone, 3-hydroxydiphenylamine or 4-hydroxydiphen ylamine.

Suitable urea derivatives include urea or thiourea.

Suitable phosphorus-containing compounds include triphenylphosphine, triphenylphosphite, hypophosphorous acid or triethylphosphite, and those P (III) compounds whose peroxide-decomposing effect is known to the person skilled in the art.

Suitable sulfur-containing compounds include dimethyl sulfide, diphenyl sulfide, ovothiols, other sulfur-containing natural substances such as cysteine or phenothiazine. Phenothiazine is particularly preferred.

Sulfonamides which act as stabilizers are described, for example, in the older German patent application with the file number 10204280.2 0.

Transition metal salts, phenols, quinones and hydroquinones, phosphorus-containing compounds and sulfur-containing compounds are preferred as costabilizers. Of these, transition metal salts, phenols, quinones and hydroquinones and sulfur-containing compounds are particularly preferred. Particularly preferred as costabilizers are cerium (III) salts, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2, 4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2- tert-butylphenol, 4-tert-butylphenol, 4-tert-butylcatechol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2, 6- dimethylphenol, 2-tert-buty1-6-methylphenol, 2, 4,6-tris-tert-butylphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, bisphenol A or F, 3 -Diethylaminophenol, 2,4-dinitro-6-isobutylphenol, hydroquinone, hydroquinone monomethyl ether, tert-butylhydroquinone, N, N'-di-sec-butyl-p-phenylenediamine, hypophosphorous acid and phenothiazine.

The hydroxylamine derivative used according to the invention and, if also used, the costabilizers can be added to the material to be stabilized one after the other, simultaneously or even premixed. The hydroxylamine derivative and, if used, the costabilizers are advantageously as a dispersion, for. B. suspension, or solution in any suitable solvent.

Such solvents are for example water, (meth) acrylic acid (ester), acetone, acetylacetone, acetoacetic ester, lower alcohols, such as. B. methanol, ethanol, iso-propanol, n-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n- butyl ether, diethylene glycol, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, lower carboxylic acids, such as, for. B. formic acid, acetic acid or propionic acid, THF, dioxane, sulfuric acid, toluene, xylene, paraffins, naphtha, mineral oil, petroleum ether fractions, biphenyls, diphenyl ether, dimethyl phthalate.

The solvent is expediently material streams from the production and / or workup of the materials to be stabilized, eg. B. (meth) acrylic acid (ester). This can be the pure products, e.g. H. the (meth) acrylic acid (ester), e.g. B. in a purity of generally 95% or more, preferably 99% or more, or the starting materials used for the production of the (meth) acrylic acid (ester), or such material flows, the starting materials and / or products and / or Intermediates and / or by-products included.

When stabilizing (meth) acrylic acid esters, preferred solvents are water, the (meth) acrylic acid used, the (meth) acrylic acid ester itself, the alcohol corresponding to the (meth) acrylic acid ester to be stabilized, such as methanol, Ethanol, n-butanol, 2-ethylhexyl alcohol, and streams from the working up and / or production of the (meth) acrylic acid (ester), particularly preferred are water and (meth) acrylic acid (ester).

The stabilizers are preferably used at those points where the ethylenically unsaturated compounds are exposed to the risk of polymerization, for example due to the high residence time and / or high temperature. 0

This can be, for example, a reactor for the production of the ethylenically unsaturated compounds, absorption units which, for example, with water or a high-boiling solvent, such as. B. mixtures of diphenyl ether, biphenyl and optionally phthalic acid esters, are operated as absorbents, 5 desorption units, rectification units, for example distillation or stripping apparatus or rectification columns, condensation columns, evaporators, for example natural or forced circulation evaporators, condensers or vacuum units. 0

For example, a mixture of hydroxylamine derivative and costabilizer (s), optionally dissolved or dispersed in a solvent, can be metered directly into the compound to be stabilized, for example together with one of the starting materials or separately from them, or at one Distillation or rectification are metered in, e.g. B. in the head of the rectification unit or on the separating internals such. B. bottoms, packs or fillings, sprayed or sprayed or metered together with the return into a condenser, z. B. sprayed so that the condenser head and / or the cooling surfaces are wetted, or it can in a vacuum unit, as described in EP-A 1 057 804 or as a barrier liquid in a liquid ring pump, as in the older German patent application with the file number 101 43 565.7 can be used.

It was also found that the stabilizing effect of the hydroxylamine derivative, in particular when costabilizers are also used, is further increased in the presence of an oxygen-containing gas. In preferred embodiments, an oxygen-containing gas is therefore used to stabilize ethylenically unsaturated compounds according to the invention, i. H. the mixture of substances additionally contains an oxygen-containing gas and / or is in contact with an oxygen-containing gas. 5

Air or a mixture of oxygen or air and one under the conditions of use can preferably be used as the oxygen-containing gas inert gas can be used. Nitrogen, helium, argon, carbon monoxide, carbon dioxide, water vapor, lower hydrocarbons or mixtures thereof can be used as the inert gas. The oxygen content of the oxygen-containing gas can be, for example, 0.5 to 30% by volume, preferably 2 to 21% by volume. The oxygen-containing gas is preferably essentially free of nitrogen oxides, such as NO, N0 ₂ , N ₂ 0 ₄ , N ₂ 0 ₃ . Air or air-nitrogen mixtures are preferred.

The oxygen-containing gas can be added via any device at any point in the manufacturing, processing or storage process of the ethylenically unsaturated compound. The oxygen-containing gas and the oxime and, if appropriate, the costabilizers can be metered in at different points.

For example, an atmosphere of the oxygen-containing gas can be provided above the liquid level of the compound to be stabilized. However, preference is given to bringing the compound to be stabilized into intimate contact with the oxygen-containing gas, for example by feeding the gas into the compound to be stabilized via a submerged tube or the gas of the compound to be stabilized, e.g. B. counteracts in a rectification column. The amount of the oxygen-containing gas fed in is advantageously from 0.0001 to 100 times the mixture to be separated which is fed into the column (in each case based on the weight), preferably from 0.0001 to 10 times, particularly preferably from 0.001 to 1 times.

In a preferred embodiment, the oxygen-containing

Gas is at least partially metered into the upper part of a rectification or condensation column, the upper part of the column being the upper 75% of the column, based on the theoretical plates which are effective in separating, preferably the upper 50% and particularly preferably the upper 40%. The introduction up to 4 theoretical plates above and below a side draw is particularly preferred, from which the purified unsaturated compound is drawn off.

The oxygen-containing gas is metered into a column by means of suitable devices, for example by means of pipes provided with openings, which are connected to an external feed line. The material from which the metering devices are made should be corrosion-stable under the conditions prevailing in the column relative to the mixture to be separated in the column. They are preferably made of stainless steel or copper fer or made of copper-plated material. The openings can be holes, slots, valves or nozzles, for example.

"In addition to metering in the oxygen-containing gas in the upper part of the column, an oxygen-containing gas can be metered in the remaining part of the column, preferably into the bottom and particularly preferably into the bottom circulation. The amount of oxygen-containing gas fed in can also be between the bottom and the top columns be fed in split.

The ethylenically unsaturated compounds which are stabilized according to the invention are very oxygen- and / or nitrogen-containing ethylenically unsaturated compounds. 5

These include, in particular, 3 to 6 carbon atoms having α, β-mono-ethylenically unsaturated mono- and dicarboxylic acids, such as, in particular, acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, the esters of the aforementioned carboxylic acids with, for. B. 1 to * 20, often 1 to 8 and often 1 to 4 alkanols, such as in particular acrylic acid and methacrylic acid methyl, ethyl, n-butyl, isobutyl, tert -butyl and -2-ethylhexyl esters, dimethyl maleate or di-n-butyl maleate, are suitable. According to the invention the Vorlauferaldehyde, Ni ⁵ Trile and amides of the aforementioned mono- and dicarboxylic acids such. As acrolein, methacrolein, acrylonitrile, methacrylonitrile, acrylonamide and methacrylamide, are stabilized. The stabilization according to the invention is also applicable to monomers such as esters of vinyl alcohol and monocarboxylic acids containing 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate or vinyl sulfonic acid and N-vinyl lactams such as N- vinylpyrrolidone.

The (meth) acrylic acid esters which can be stabilized according to the invention include, for. B. (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid n-butyl ester, (meth) acrylic acid n-propyl ester, (eth) acrylic acid iso-propyl ester, (meth) acrylic acid 2-ethylhexyl ester, trimethylolpropane triacrylate, Butanediol diacrylate, hydroxyethyl (meth) acrylate or dimethylaminoethyl (meth) acrylate and (meth) acrylic esters of alkoxylated, for example mono- to 20-fold ethoxylated and / or propoxylated polyols, such as. B. trimethylolpropane, trimethylolethane, neopentyl glycol, hydroxypivalic acid neopentyl glycol ester, pentaerythritol, 2-ethyl-l, 3-propanediol, 2-methyl-l, 3-propanediol, 5 2-ethyl-l, 3-hexanediol, glycerol, ditriethylolpropane, Dipentaerythritol, 2,2-bis (4-hydroxycyclohexyl) propane, 1,1-, 1,2-, 1,3- and 1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexanediol.

(Meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid n-butyl ester, (meth) acrylic acid 2-ethylhexyl ester and (meth) acrylic acid are particularly preferred.

Acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate are very particularly preferred. Acrylic acid is particularly preferred.

The following examples are intended to illustrate the invention in more detail.

Examples

Aliquots of double distilled, stabilizer-free acrylic acid were mixed with 10 ppm phenothiazine and 25 ppm of the test substances listed in the table below and stored in an air atmosphere in an oven at 120 ° C. rotating or standing. The point in time until the visually visible start of polymerization was determined. The table shows the factor by which the inhibition phase compared to a measured

Reference was extended with only 10 ppm phenothiazine.

n. b. = nicht bestimmt

nb = not determined

It can be seen that the presence of the investigated compounds causes a significant delay in the polymerization in the unmoved tube.

Claims

claims 1. Mixture of substances containing at least one oxygen- and / or nitrogen-containing ethylenically unsaturated compound and an effective amount to prevent undesired radical polymerization of at least one among aldoximes; Ketoximes that are not derived from quinones; Hydroximic acid esters and N-acyl-hydroxylamine derivatives selected hydroxylamine derivatives. 2. A mixture according to claim 1, wherein the hydroxylamine derivative among benzaldoxime, salicylaldoxime, 2-pyridine doxime; Acetone oxime, methyl ethyl ketoxime, diethyl ketoxime, 4-heptanone oxime, 2,4-dimethyl-3-pentanone oxime, cyclohexanone oxime, 4-tert-butyl cyclohexanone oxime, cyclododecanone oxime, 9-fluorenone oxime, phenyl-2-pyridyl ketoxime, benzil dioxime, 2 3-butanedione dioxime, 2,3-butanedione monooxime, di-2-furanylethanedione dioxime and ethyl N-ethoxyacetimidate is selected. 3. A mixture of substances according to claim 1 or 2, additionally containing at least one costabilizer. 4. A mixture of substances according to claim 3, wherein the costabilizer is selected from transition metal salts, phenols, quinones or hydroquinones, N-oxylene, aromatic amines or phenylenediamines, urea derivatives, phosphorus-containing compounds, sulfur-containing compounds and sulfonamides. 5. Mixture of substances according to one of the preceding claims, which additionally contains an oxygen-containing gas and / or is in contact with an oxygen-containing gas. 6. Mixture of substances according to one of the preceding claims, wherein the ethylenically unsaturated compound is selected from acrylic acid, methacrylic acid, acrolein, methacrolein, acrylic acid esters, methacrylic acid esters, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide or mixtures thereof. 7. A method for stabilizing materials comprising at least one oxygen- and / or nitrogen-containing ethylenically unsaturated compound against undesired free-radical polymerization by adding to the materials to be stabilized an effective amount of one among aldoximes; Ketoximes that are not derived from quinones; Hydroximic acid esters and N-acyl-hydroxylamine derivatives selected hydroxylamine derivatives. 8. Use of an aldoxime; Ketoximes that are not derived from quinones; Hydroximic acid esters and N-acyl-hydroxylamine derivatives selected hydroxylamine derivatives to prevent undesired radical polymerization of oxygen and / or nitrogen-containing ethylenically unsaturated compounds. 9. stabilizer composition containing at least one of aldoximes; Ketoximes that are not derived from quinones; Hydroxy acid esters and N-acyl-hydroxylamine derivatives selected hydroxylamine derivative and at least one costabilizer. 10. Stabilizer composition according to claim 9, wherein the costabilizer is selected from transition metal salts, phenols, quinones or hydroquinones, N-oxylene, aromatic amines or phenylenediamines, urea derivatives, phosphorus-containing compounds, sulfur-containing compounds and sulfonaides.