RU2380347C2 - Sulphonated phenols with nitrophenols as polymerisation inhibitors - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of inhibiting premature polymerisation and growth of a polymer chain of ethylene unsaturated monomers. The method involves addition to the said monomers an effective amount of a combination of at least one inhibitor, which is sulphonated phenol of general formula

(I):

where (1) R₂ is selected from a group consisting of hydrogen and hydrocarbon; and (2) R₁ and R₃ are independently selected from a group consisting of hydrogen and SO₃H, under the condition that, at least one of R₁ and R₃ is selected as SO₃H of at least one inhibitor which is nitrophenol and, if desired, one inhibitor selected from a group consisting of nitroxyl compounds and nitrosoanilines, and amine.

EFFECT: increased efficiency of the process and its cost effectiveness.

20 cl, 7 ex

Description

BACKGROUND OF THE INVENTION

1. The technical field to which the invention relates.

The present invention relates to inhibiting the polymerization of ethylenically unsaturated monomers by adding combinations of sulfonated phenol and nitrophenol to them.

2. Description of the Related Art

Many ethylenically unsaturated monomers are prone to unwanted polymerization at various stages of their production, processing, handling, storage and use. Polymerization, such as thermal polymerization, during their purification leads to the loss of monomer, i.e. to lower yields, and an increase in the viscosity of any resin that can be obtained. Processing and handling of more viscous resins subsequently requires higher temperatures and greater work (energy costs) to remove residual monomer.

Polymerization can also lead to clogging of equipment, especially in the case of the production of acrylic monomers. Such polymerization leads to losses in production efficiency due to polymer deposition in or on the equipment used. These deposits should be removed from time to time, giving an additional loss in monomer production.

A large number of compounds have been proposed and used to inhibit the uncontrolled and undesired polymerization of ethylenically unsaturated monomers. However, many of them were not completely satisfied.

US Pat. No. 2,867,672 describes that the polymerization of non-inhibited styrene, condensing in the form of a liquid on surfaces covering the gas portion of the space above the liquid level of the main styrene part in the reactor, can be minimized by spraying a polymerization inhibitor on the surfaces surrounding the gas phase.

US patent No. 4086147 describes a distillation process for an easily polymerizable vinyl aromatic compound, including heating the vinyl aromatic compound in a distillation apparatus in the presence of a polymerization inhibitor containing m-nitro-p-cresol.

US Pat. No. 4,468,343 teaches a compound and its use to prevent polymerization during heating of vinyl aromatic compounds, such as, for example, styrene. The composition includes effective amounts of 2,6-dinitro-p-cresol and / or phenylenediamine or 4-tert-butylcatechol, respectively, to work as a polymerization co-inhibition system in the presence of oxygen.

US patent No. 4670131 provides a method for suppressing the formation of blockages in equipment used to process the flow of incoming organic material, including olefins, by processing in the presence of from ~ 20 ppm. up to less than 1,000 ppm a stable free radical such as nitroxide.

US Pat. No. 5,254,760 describes the inhibition of the polymerization of a vinyl aromatic compound, such as styrene, during distillation or purification in the presence of at least one stable nitroxyl compound together with at least one aromatic nitro compound.

US patent No. 5290888 proposes a process for stabilizing an ethylenically unsaturated monomer or oligomer from premature polymerization, according to which a stabilizing amount of an N-hydroxy substituted sterically loaded amine is added to said polymerizable monomer or oligomer. The ethylenically unsaturated monomer or oligomer includes vinyl monomers or oligomers having at least one polymerization-active part. It is indicated that an N-hydroxy substituted sterically loaded amine inhibits the premature polymerization in the liquid and / or gas phase.

US Pat. No. 5,442,220 provides a method for inhibiting the polymerization of vinyl aromatic monomers in systems with treatment in the absence of oxygen. These methods include adding from 1 to ~ 10,000 ppm. combinations of dinitrophenol, hydroxylamine and phenylenediamine compounds from the corresponding monomer. Preferably, 2-sec-butyl-4,6-dinitrophenol or 4,6-dinitro-o-cresol is used in combination with bis- (hydroxypropyl) hydroxylamine and N, N'-di-sec-butyl-p-phenylenediamine.

US Pat. No. 5,545,786 teaches that nitroxyl inhibitors, in combination with some oxygen, reduce the premature polymerization of vinyl aromatic monomers during the production of such monomers. It is also described that even small amounts of air used in combination with nitroxyl inhibitors prolong the inhibition time for these monomers.

US Pat. No. 5,932,735 teaches that selected 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine derivatives in the presence of water are effective as inhibitors to prevent premature polymerization of acrylic and methacrylic acids, their esters, their amides, vinyl acetate and acrylonitrile.

US patent No. 6143205 describes a mixture with inhibition of premature polymerization of monomers, including (A) vinyl-containing monomers and (B) an effective amount of the mixture: (i) from 0.05 to 4.5 wt.%, In relation to the entire mixture (B), at least one N-oxyl compound of a secondary amine containing no hydrogen atoms at α-carbon atoms and (ii) from 99.95 to 95.5 wt.%, with respect to the entire mixture (B) of at least one nitro compound.

Patents SU 1027150; 1,139,722; and 1558888 describe reduced polymer formation under normal process conditions (without inhibitor), but do not protect the system in situations of emergency shutdown of the working material, i.e. there is no retardant effect.

The above patents are incorporated herein by reference.

SUMMARY OF THE INVENTION

In accordance with the present invention, it was found that inhibitory systems containing sulfonated phenols exhibit excellent inhibitors and retardants for the premature polymerization of ethylenically unsaturated monomers, especially vinyl aromatic compounds, when used together with nitrophenols, such as, for example, 2,4-dinitro-o S-butylphenol (DNBP). If desired, this inhibitory system can be used in combination with nitroxyl radical type compounds or nitrosoanilines and amines.

An advantage of the present invention is that sulfonated phenols can be obtained during the production of DNBP. Since DNBP is the preferred second component of the claimed inhibitory mixture, both components can be produced in the same process. Accordingly, production can be simplified by preparing both components in the same process in the same place. This provides an economic advantage, consisting in the fact that the material can be obtained in an existing process by small means, without additional investment. From the point of view of the buyer, the economic benefit is realized due to the low cost of funds for production (low cost) and because of the implementation of the optimal production scheme of the claimed mixture. Other features are the use of a small amount of inhibitor and significantly suppressed polymerization. Thus, it is an object of the present invention to provide a highly efficient and inexpensive system for inhibiting polymerization with extremely objective inhibitory and retardant capabilities.

This and other objectives are achieved by the present invention, which relates to a method of inhibiting premature polymerization and polymer chain growth of ethylenically unsaturated monomers and includes adding an effective amount of a combination of

(A) at least one sulfonated phenol inhibitor of the general formula:

Where

(1) R ₂ is selected from the group consisting of hydrogen and a hydrocarbon; and

(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R _{3 is} selected as SO ₃ H; and

(B) at least one nitrophenol inhibitor.

(C) at least one inhibitor selected from the group consisting of nitroxyl compounds and nitrosoanilines; and

(D) at least one amine.

On the other hand, the present invention relates to a composition comprising a combination of

(A) at least one sulfonated phenol inhibitor of the general formula:

Where

(1) R ₂ is selected from the group consisting of hydrogen and a hydrocarbon; and

(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R ₃ is selected as SO ₃ H;

(B) at least one nitrophenol inhibitor;

(C) at least one inhibitor selected from the group consisting of nitroxyl compounds and nitrosoanilines; and

(D) at least one amine.

Description of Preferred Embodiment

As indicated above, the present invention relates to an inhibitory system comprising a composition of

(A) at least one sulfonated phenol inhibitor of the general formula:

Where

(1) R ₂ is selected from the group consisting of hydrogen and a hydrocarbon; and

(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R _{3 is} selected as SO ₃ H;

(B) at least one nitrophenol inhibitor;

In a preferred embodiment, the inhibitory system also includes at least one amine and at least one additional inhibitor selected from the group consisting of nitroxyl compounds and nitrosoanilines.

If R ₂ is a hydrocarbon radical, it is preferably straight or branched chain alkyl or alkenyl containing from 1 to 50 carbon atoms, more preferably from 1 to 18 hydrocarbon atoms, including, but not limited to: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl-hexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, triecozyl, tetakeil, helekosyl, tetakeil, helekose, gene triacontyl, isomers of the above (such as, for example, isopropyl, sec-butyl, neopentyl, etc.) and the like; or cyclic alkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclododecyl.

Nitrophenols that can be used in the practice of the present invention include, but are not limited to: 2,6-dinitro-4-methylphenol, 2-nitro-4-methylphenol, 2,4-dinitro-1-naphthol, 2,4, 6-trinitrophenol (picric acid), 2,4-dinitro-6-methylphenol, 2,4-dinitrophenol, 2,4-dinitro-6-sec-butylphenol, 4-cyano-2-nitrophenol, 3-iodo-4- cyano-5-nitrophenol, m-nitro-p-cresol, 2,6-dinitro-p-cresol and the like. 2,4-dinitro-6-sec-butylphenol is preferred.

If the inhibitory system of the present invention further comprises an inhibitor which is a nitroxyl compound, then the nitroxyl compound is preferably a stable sterically-loaded nitroxyl component having the structural formula:

where R ₄ and R _{7 are} independently selected from the group consisting of hydrogen, alkyl, and heterosubstituted alkyl, and R ₅ and R _{6 are} independently selected from the group consisting of alkyl and heterosubstituted alkyl; and X ₁ and X ₂ (1) are independently selected from the group consisting of halogen, cyano, COOR ₇ , -S-COR ₇ , -OCOR ₇ , (where R _{7 is} alkyl or aryl), amido, -SC ₆ H ₅ , carbonyl, alkenyl or alkyl containing from 1 to 15 carbon atoms, or (2) both form a cyclic structure containing nitrogen.

In a particular preferred embodiment, the stable sterically-loaded nitroxyl component has the structural formula:

where R ₄ and R _{7 are} independently selected from the group consisting of hydrogen, alkyl, and heterosubstituted alkyl, and R ₅ and R _{6 are} independently selected from the group consisting of alkyl and heterosubstituted alkyl, and

the part (shown above) represents atoms connected in a five-, six- or seven-membered heterocycle.

Accordingly, one of several classes of cyclic nitroxides that can be used in the practice of the present invention can be represented by the following structural formula:

where Z ₁ , Z ₂ and Z _{3 are} independently selected from the group consisting of oxygen, sulfur, secondary amines, tertiary amines, phosphorus in various oxidation states and substituted or unsubstituted carbon atoms such as> CH ₂ ,> CHCH ₃ ,> C = O,> C (CH ₃ ) ₂ ,>CHBr,>CHCl,>CHI,>CHF,>CHOH,>CHCN,> C (OH) CN,>CHCOOH,> CHCOOCH ₃ ,> CHCOOC ₂ H ₅ ,> C (OH) COOC ₂ H ₅ ,> C (OH) COOCH ₃ ,> C (OH) CHOHC ₂ H ₅ ,> CR ₈ OR ₉ ,> CHNR ₈ R ₉ ,> CCONR ₈ R ₉ ,> C = NOH, > C = CH-C ₆ H ₅ ,> CF ₂ ,> CCl ₂ ,> CBr ₂ ,> CI ₂ ,> CR ₈ PR ₁₃ R ₁₄ R ₁₅ and the like, where R ₈ and R _{9 are} independently selected from the group consisting of of hydrogen, alkyl, aryl and acyl, and R ₁₃ , R ₁₄ and R _{15 are} independently selected from the group consisting of lone electron pair, alkyl, aryl, = O, OR ₁₆ and NR ₁₇ R ₁₈ , where R ₁₆ , R ₁₇ and R _{18 are} independently selected from the group consisting of hydrogen, alkyl and aryl. If R ₈ and / or R ₉ are alkyl, it is preferred that they are lower alkyls (i.e., containing from one to five carbon atoms, for example methyl, ethyl, propyl, butyl, pentyl and their isomers). If R ₈ and / or R _{9 are} aryls, then it is preferable that they are aryls containing from 6 to 10 carbon atoms, for example phenyl or naphthyl, which can also be substituted by groups having a low steric effect, for example lower alkyls, halogens and the like.

If R ₈ and / or R ₉ are acyl, it is preferred that they are acyl of the following structure:

where R _{19 is} alkyl, aryl, OR ₂₀ or NR ₂₀ R ₂₁ , and where R ₂₀ and R ₂₁ are alkyl, aryl, or

where R ₂₂ is alkyl or aryl. If R ₁₉ , R ₂₀ , R ₂₁ or R _{22 are} alkyl, then preferably alkyls containing from 1 to 15 carbon atoms, more preferably lower alkyls containing from 1 to 5 carbon atoms, as described above. If R ₁₉ , R ₂₀ , R ₂₁ or R _{22 are} aryls, then preferably aryls containing from 6 to 10 carbon atoms, as described above.

Another of the remaining classes of cyclic nitroxides, which can be used in the implementation of the present invention, can be represented by the following structural formula:

where Z ₁ and Z ₂ are the same or different groups: nitrogen or substituted or unsubstituted carbon atoms, such as = C (H) -, = C (CH ₃ ) -, = C (COOH) -, = C (COOCH ₃ ) -, = C (COOC ₂ H ₅ ) -, = C (OH) -, = C (CN) -, = C (NR ₈ R ₉ ) -, = C (CONR ₈ R ₉ ) - and the like, and where Z ₃ , R ₈ and R ₉ , as described above.

The cyclic nitroxides used in the practice of the present invention may also be five-membered cyclic derivatives. These compounds with the structural formula:

where Z ₂ and Z ₃ are the same or different groups: sulfur, oxygen, secondary amines, tertiary amines, phosphorus in different oxidation states or substituted or unsubstituted carbon atoms, such as> CH ₂ ,> CHCH ₃ ,> C = O,> C (CH ₃ ) ₂ ,>CHBr,>CHCl,>CHI,>CHF,>CHOH,>CHCN,> C (OH) CN,>CHCOOH,> CHCOOCH ₃ ,> CHCOOC ₂ H ₅ ,> C (OH) COOC ₂ H ₅ ,> C (OH) COOCH ₃ ,> C (OH) CHOHC ₂ H ₅ ,> CR ₈ OR ₉ ,> CHNR ₈ R ₉ >,> CCONR ₈ R ₉ ,> C = NOH,> C = CH-C ₆ H ₅ , CF ₂ , CCl ₂ , CBr ₂ , CI ₂ ,> CR ₈ PR ₁₃ R ₁₄ R ₁₅ and the like, where different R, as described above.

The cyclic nitroxides used in the practice of the present invention may also have the structure:

where Z ₄ and Z ₅ are the same or different groups, which may be nitrogen or a substituted or unsubstituted carbon atom, such as = C (H) -, = C (CH ₃ ) -, = C (COOH) -, = C ( COOCH ₃ )>, = C (COOC ₂ H ₅ ) -, = C (OH) -, = C (CN) -, = C (NR ₈ R ₉ ) -, = C (CONR ₈ R ₉ ) - and the like where R ₈ and R ₉ as described above.

Another class of cyclic nitroxides that can be used in the practice of the present invention is represented by the structural formula:

where Z ₂ and Z _{3 are the} same or different groups: sulfur, oxygen, secondary amines, tertiary amines or substituted or unsubstituted carbon atoms, such as> CH ₂ ,> CHCH ₃ ,> C = O,> C (CH ₃ ) ₂ , >CHBr,>CHCl,>CHI,>CHF,>CHOH,>CHCN,> C (OH) CN,>CHCOOH,> CHCOOCH ₃ ,> CHCOOC ₂ H ₅ ,> C (OH) COOC ₂ H ₅ ,> C (OH) COOCH ₃ ,> C (OH) CHOHC ₂ H ₅ ,> CHNR ₈ R ₉ ,> CONR ₈ R ₉ ,> R ₈ OR ₉ ,> C = NOH,> C = CH-C ₆ H ₅ , CF ₂ , CCl ₂ , CBr ₂ , CI ₂ ,> CR ₈ PR ₁₃ R ₁₄ R ₁₅ and the like, where different R groups are as described above.

Also, two or more nitroxyl groups can be represented in the same molecule, for example, by linking through one or more Z parts via a linking group E, as described in US patent No. 5254760, which is incorporated herein by reference.

As indicated above, for all of the above nitroxyl structures, R ₄ and R _{7 are} independently selected from the group consisting of hydrogen, alkyl, and heterosubstituted alkyl, and R ₅ and R _{6 are} independently selected from the group consisting of alkyl and heterosubstituted alkyl. Such alkyl (or heterosubstituted alkyl) groups from R ₄ to R ₇ may be the same or different and preferably contain from 1 to 15 carbon atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl and the like, and their isomers, for example tert-butyl, 2-ethylhexyl and the like. More preferably, the radicals R ₄ to R _{7 are} independently selected from lower alkyls (or heterosubstituted lower alkyls) containing from one to 5 carbon atoms (e.g. methyl, ethyl, propyl, butyl, pentyl and their isomers). If hetero substituents are present, they may, for example, include halogen, oxygen, sulfur, nitrogen and the like. Most preferably, all R ₄ to R ₇ radicals are methyl.

Examples of suitable nitroxide free radicals that can be used in combination with hydrogen donors or electron withdrawers in the practice of the present invention include, but are not limited to:

N, N-di-tert-butyl nitroxide;

N, N-di-tert-amyl nitroxide;

N-tert-butyl-2-methyl-1-phenyl-propyl nitroxide;

N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide;

2,2,6,6-tetramethylpiperidinyloxy;

4-amino-2,2,6,6-tetramethylpiperidinyloxy;

4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy;

4-oxo-2,2,6,6-tetramethylpiperidinyloxy;

4-dimethylamino-2,2,6,6-tetramethylpiperidinyloxy;

4-ethanoyloxy-2,2,6,6-tetramethylpiperidinyloxy;

2,2,5,5-tetramethylpyrrolidinyloxy;

3-amino-2,2,5,5-tetramethylpyrrolidinyloxy;

2,2,4,4-tetramethyl-1-oxa-3-azacyclopentenyl-3-hydroxy;

2,2,4,4-tetramethyl-1-oxa-3-pyrroinyl-1-hydroxy-3-carboxylic acid;

2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxi;

4-bro-2,2,6,6-tetramethylpiperidinyloxy;

4-chloro-2,2,6,6-tetramethylpiperidinyloxy;

4-iodo-2,2,6,6-tetramethylpiperidinyloxy;

4-fluoro-2,2,6,6-tetramethylpiperidinyloxy;

4-cyano-2,2,6,6-tetramethylpiperidinyloxy;

4-carboxy-2,2,6,6-tetramethylpiperidinyloxy;

4-carbomethoxy-2,2,6,6-tetramethylpiperidinyloxy;

4-carboethoxy-2,2,6,6-tetramethylpiperidinyloxy;

4-cyano-4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy;

4-methyl-2,2,6,6-tetramethylpiperidinyloxy;

4-carboethoxy-4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy;

4-hydroxy-4- (1-hydroxypropyl) -2,2,6,6-tetramethylpiperidinyloxy;

4-methyl-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

4-carboxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

4-carbomethoxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

4-carboethoxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

4-amino-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

4-amido-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridin-1-oxyl;

3,4-diketo-2,2,5,5-tetramethylpyrrolidinyloxy;

3-keto-4-hydroxyimino-2,2,5,5-tetramethylpyrrolidinyl-oxy;

3-keto-4-benzylidene-2,2,5,5-tetramethylpyrrolidinyl-oxy;

3-keto-4,4-dibromo-2,2,5,5-tetramethylpyrrolidinyl-oxy;

2,2,3,3,5,5-hexamethylpyrrolidinyloxy;

3-carboxyimido-2,2,5,5-tetramethylpyrrolidinyl-oxy;

3-hydroxyimino-2,2,5,5-tetramethylpyrrolidinyloxy;

3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

3-cyano-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

3-carbomethoxy-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyl-oxy;

3-carboethoxy-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyl-oxy;

2,2,5,5-tetramethyl-3-carboxamido-2,5-dihydroxypyrrole-1-oxyl; 2,2,5,5-tetramethyl-3-amino-2,5-dihydropyrrole-1-oxyl;

2,2,5,5-tetramethyl-3-carboethoxy-2,5-dihydropyrrole-1-oxyl;

2,2,5,5-tetramethyl-3-cyano-2,5-dihydropyrrole-1-oxyl;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate,

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacinate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butyl malonate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;

bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;

N, N'-bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;

N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) caprolactam;

N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecylsuccinamide;

2,4,6-tris- [N-butyl-N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)] c-triazine;

4,4'-ethylene-bis (1-oxyl-2,2,6,6-tetramethylpiperazin-3-one);

and the like.

The abbreviation TEMPO as used herein means 2,2,6,6-tetramethyl-1-piperidinyloxy. Thus, 4-amino-TEMPO means 4-amino-2,2,6,6-tetramethyl-1-piperidinyloxy; 4-hydroxy-TEMPO is 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (also known in science / technology as HTEMPO); 4-oxo-TEMPO means 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy; etc. Preferably, when one member of the combination used in the practice of the present invention is 4-amino-TEMPO, 4-oxo-TEMPO, 4-hydroxy-TEMPO or TEMPO.

Combinations of two or more of the above, for example 4-amino-TEMPO and 4-oxo-TEMPO, can also be used.

Such stable nitroxide free radicals can be obtained by known methods. (See, for example, US Pat. Nos. 3163677; 3334103; 3372182; 3422144; 3494930; 3502692; 3873564; 3966711 and 4665185, which are incorporated herein by reference.) They are suitable for use in wide temperature ranges, while distillation temperatures used for ethylenically unsaturated monomers, which are stabilized by treatment in accordance with the present invention, typically lie from 60 ° C to ~ 180 ° C, preferably from ~ 70 ° C to ~ 165 ° C and, more preferably, from ~ 80 ° C to ~ 150 ° C. Such distillations, for the most part, are carried out at an absolute pressure of from ~ 10 to ~ 1,200 mm Hg.

When the inhibitory system of the present invention further comprises an inhibitor, nitrosoaniline, it may be N-nitrosoaniline or C-nitrosoaniline. Preferably, the nitrosoaniline component is C-nitrosoaniline.

C-nitrosoanilines can be prepared by C-nitrosation of the corresponding anilines in any standard embodiment used for C-nitrosation of aromatic amines. For example, the reaction of an amine with cold nitric acid leads to an N-nitroso compound, which rearranges into p-nitrosoaniline under the influence of an excess of hydrochloric acid.

In some cases, it is more efficient to carry out nitrosation and rearrangement in one stage, carrying out the reaction in methanol in the presence of an excess of hydrogen chloride under anhydrous conditions. This method is described in US patent No. 2046356. In accordance with the experience of modern science / technology, it is known that nitrosoaniline derivatives are capable of tautamerizing into quinoneiminoxim derivatives, i.e.

See, for example, Sidgwick, NV, The Organic Chemistry of Nitrogen, Third Edition, Clarendon Press, Oxford, 1966. Both forms can be present, mainly in solution at elevated temperatures, and a contribution to the inhibitory activity of both of these can be expected. forms.

The nitrosoanilines that can be used in the practice of the present invention preferably have the structure:

Where

R ₂₁ and R _{22 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, nitroso and sulfonyl, or R ₂₁ and R ₂₂ may form an aryl, cycloalkyl, polyaryl or heterocycle ring; radicals from R ₂₃ to R _{27 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, acyloxy, NR ₂₈ (R ₂₉ ), nitro, nitroso, halogen and sulfonyl, or any two adjacent R's can form the cycle is aryl, cycloalkyl, polyaryl or heterocycle, provided that at least one of the radicals from R ₂₃ to R ₂₇ must be a nitroso group; and

R ₂₈ and R _{29 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, and nitroso. Preferably, R ₂₈ is hydrogen and R ₂₉ is alkyl.

If the inhibitory system of the present invention includes an additional inhibitor, an amine, then the amine may be primary, secondary, or tertiary and may contain alkyl groups, aryl groups, or combinations thereof. Such amines include, but are not limited to: α-naphthylamine, thiodarylamines, p-phenylenediamine, o-phenylenediamine, 2,4-diaminodiphenylamine, cyclohexylnaphthylamine, polybutylamines, methylaniline, diphenyl-p-phenylenediamine, phenylene-β-naphthyl-amidylamine, isopropyl -α-naphthylamine, symmetric di-β-naphthyl-p-phenylenediamine, trimethyldihydroquinoline, ditolylamines, phenyl-α-naphthylamine, phenyl-β-naphthylamine, diaminophenol, 4-cyclohexylaminophenol, p-aminophenol, o-aminophenol 2-hydroxytoluene and the like.

The ethylenically unsaturated monomer, premature polymerization and polymer chain growth, which is the object of the present invention, can be any such monomer for which random polymerisation and / or polymer chain growth during production, storage and / or distribution is a problem. Among the monomers for which the use of the present invention will be useful: styrene, α-methylstyrene, styrenesulfonic acid, vinyltoluene, divinylbenzenes, polyvinylbenzenes, alkyl styrene, 2-vinylpyridine, acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, ethyl methacrylate, methyl methacrylate, methyl methacrylate , butadiene, chloroprene, isoprene and the like.

Ethylenically unsaturated monomers need not be constantly stabilized by the presence of inhibitor (s) specifically when the monomers are heated, as, for example, during distillation, but the possibility of their stabilization is considered when the presence of inhibitor (s) A in the static system significantly increases the time during which monomers can be heated before polymerization and / or polymer chain growth, B) in a dynamic system, the amount of polymer formed at a constant temperature remains constant over time, and / or C) ck The growth rate of the polymer polymer chain is much lower than in the absence of a polymerization inhibiting system.

From the experience of modern science / technology, it is understood that, if desired, free radical traps can be included in embodiments of the present invention. For example, air or O ₂ may be added, as described in US Pat. Nos. 5,545,782 and 5,545,786, aromatic nitro compounds as described in US Pat. No. 5,254,760, diheter-substituted benzenes having at least one mobile hydrogen atom, for example quinone derivatives, such such as hydroquinone monomethyl ether described in EP 0765856 A1, iron compounds described in WO 98/25872, and other inhibitors, for example phenolic and some inorganic salts, well known in modern science / technology.

Polymerization inhibitors can be introduced into the monomer for protection by any effective procedures. They can, for example, be added in the form of a concentrated solution in a suitable solvent or other possible methods.

Individual inhibitory components can also be introduced separately into the distillation system together with the feed material and / or via separate and different points of entry, provided that an effective distribution of the inhibitory composition is realized. Since inhibitors are gradually consumed during the distillation process, it is important to maintain appropriate amounts of inhibitors in the distillation apparatus by adding them during the distillation process. The addition of inhibitors can be carried out either continuously or from time to time, in order to maintain the concentration of the inhibitor above the minimum acceptable level.

As a rule, the total concentration of inhibitors lies in the range from ~ 1 to ~ 2000 ppm. in relation to the inhibited monomer; preferably from ~ 5 to ~ 1000 ppm, depending on the conditions used.

The ratio of the amount of the first component (A) to the second (B), taken in relation to the sum of these two components, is from ~ 1 to ~ 100 wt.% A: from ~ 99 to ~ 0 wt.% B; preferably about 25-75 wt.% A: about 75-25 wt.% B; more preferably, about 50-75 wt.% A: about 50-25 wt.% B. The advantages and important features of the present invention will be better apparent from the following examples.

EXAMPLES

Example 1

Concentrated H ₂ SO ₄ (280 g, 2.8 mol) was placed in a one-liter flask equipped with a mechanical stirrer, thermocouple, heating jacket, refrigerator and a plastic tube. The acid was preheated to 40 ° C and 300 g of o-sec-butylphenol (OSBP) (2 mol) was quickly charged through a plastic tube so that the system was heated to 82 ° C. 40 minutes after the initial temperature of 40 ° C reached 82 ° C, the reaction mixture was heated to maintain a temperature of 82 ° C. This was additionally maintained for 1 h 45 min. The product, sulfonated OSBP (SOSBP), was used together with DNBP to conduct inhibitor test experiments.

Example 2

The inhibitory and retardant properties of this material with respect to styrene were measured during the Continuous Dynamic Reboiler Test, registering the formation of the polymer using UV spectrometry. According to this experiment, the inhibitor is added to styrene (monomer) previously purified from tert-butylcatechol (TBC) by distillation. Styrene (180 g) is placed in a flask immersed in an oil bath. Styrene temperature is usually 116 ° C. During the experiment, fresh material is fed into the flask at a speed of 3 g / min, and at the same time, material is taken from the flask at the same speed. The constant mode continues until equilibrium is reached. For the mode with the material supply stop - the supply and withdrawal are interrupted. In a constant mode, samples are taken every hour, in a regime with a cut-off, every 5-10 minutes.

After 5 hours of continuous operation with concentrations of 50 ppm / 100 ppm SOSBP / DNBP recorded 0.0007% of the polymer, while at 1.5 hours of operation with the cessation of material supply, 0.024% of the polymer.

Example 3

During the Continuous Dynamic Reboiler Test SOSBP / NMP / DNBP at concentrations of 250 ppm / 285 ppm / 250 ppm respectively 0.0039 of the polymer is detected under continuous operation and 0.25% of the polymer two hours after the cessation of material supply. NMP (1-methyl-2-pyrrolidinone) was added to neutralize acidic SOSBP.

Example 4

During the Continuous Dynamic Reboiler Test SOSBP / DNBP at concentrations of 250 ppm / 250 ppm respectively 0.0004% of the polymer is detected after 5 hours at a constant mode and 0.025% of the polymer two hours after the cessation of material supply.

Example 5

In the Continuous Dynamic Reboiler Test N, N-diethyl-4-nitrosoaniline / SOSBP / NMP / DNBP process at concentrations of 100 ppm / 250 ppm / 170 ppm / 250 ppm, respectively 0.0038% of the polymer is detected after 5 hours at a constant mode and 0.315% of the polymer after two hours after the cessation of material supply.

Example 6

In the process of Continuous Dynamic Reboiler Test 4-oxo-TEMPO / SOSBP / NMP / DNBP at concentrations respectively 100 ppm / 250 ppm / 187 ppm / 250 ppm 0.0004% of the polymer is detected after 5 hours under continuous operation and 0.016% of the polymer two hours after the cessation of material supply.

Example 7

During the Continuous Dynamic Reboiler Test of one DNBP at a concentration of 500 ppm 0.11% of the polymer is detected under continuous operation and 1.18% of the polymer is detected two hours after the supply of material is stopped.

In view of the many changes and modifications that can be made without departing from the principles underlying the present invention, in order to understand the scope of protection that is realized by the invention, emphasis should be placed on the attached claims.

Claims (20)

1. A method of inhibiting premature polymerization and polymer chain growth of ethylenically unsaturated monomers, comprising adding to said monomers an effective amount of a combination of (A) at least one inhibitor, which is a sulfonated phenol of the general formula

where (1) R ₂ selected from the group consisting of hydrogen and hydrocarbon, and
(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R _{3 is} selected as SO ₃ H, and
(B) at least one nitrophenol inhibitor. 2. The method according to claim 1, in which R ₂ is alkyl or alkenyl of a straight or branched chain containing from 1 to 50 carbon atoms. 3. The method according to claim 2, in which R ₂ is selected from the group consisting of: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl-hexyl, nonyl, decyl, undecyl, dodecyl, tridecyl , tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, geneukosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, isomers of the aforementioned: cyclopentyl, cyclohelocylocyloxy, 4. The method according to claim 2, in which R ₂ is sec-butyl. 5. The method according to claim 1, in which the nitrophenol is selected from the group consisting of: 2,6-dinitro-4-methylphenol, 2-nitro-4-methylphenol, 2,4-dinitro-1-naphthol, 2,4, 6-trinitrophenol (picric acid), 2,4-dinitro-6-methylphenol, 2,4-dinitrophenol, 2,4-dinitro-6-sec-butylphenol, 4-cyano-2-nitrophenol, 3-iodo-4- cyano-5-nitrophenol, m-nitro-p-cresol and 2,6-dinitro-p-cresol. 6. A method of inhibiting premature polymerization and polymer chain growth of ethylenically unsaturated monomers, comprising adding to said monomers an effective amount of a combination of (A) at least one inhibitor, which is a sulfonated phenol of the general formula

where (1) R ₂ is selected from the group consisting of hydrogen and a hydrocarbon, and
(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R _{3 is} selected as SO ₃ H,
(B) at least one nitrophenol inhibitor;
(C) at least one inhibitor selected from the group consisting of nitroxyl compounds and nitrosoanilines, and
(D) at least one amine. 7. The method according to claim 6, in which R ₂ is a straight or branched chain alkyl or alkenyl containing from 1 to 50 carbon atoms. 8. The method according to claim 7, in which R ₂ is selected from the group consisting of: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl-hexyl, nonyl, decyl, undecyl, dodecyl, tridecyl , tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, geneukosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, isomers of the aforementioned: cyclopentyl, cyclohelocylocyloxy, 9. The method according to claim 7, in which R ₂ is sec-butyl. 10. The method according to claim 6, in which nitrophenol is selected from the group consisting of: 2,6-dinitro-4-methylphenol, 2-nitro-4-methylphenol, 2,4-dinitro-1-naphthol, 2,4, 6-trinitrophenol (picric acid), 2,4-dinitro-6-methylphenol, 2,4-dinitrophenol, 2,4-dinitro-6-sec-butylphenol, 4-cyano-2-nitrophenol, 3-iodo-4- cyano-5-nitrophenol, m-nitro-p-cresol and 2,6-dinitro-p-cresol. 11. The method according to claim 6, in which (C) is a stable sterically-loaded nitroxyl component having the structural formula

where R ₄ and R _{7 are} independently selected from the group consisting of hydrogen, alkyl, and heterosubstituted alkyl, and R ₅ and R _{6 are} independently selected from the group consisting of alkyl and heterosubstituted alkyl, and X ₁ and X ₂ (1) are independently selected from a group consisting of halogen, cyano, COOR ₇ , -S-COR ₇ , -OCOR ₇ , where R ₇ is alkyl or aryl, amido, -S-C ₆ H ₅ , carbonyl, alkenyl or alkyl, containing from 1 to 15 carbon atoms, or (2) both form a cyclic structure containing nitrogen. 12. The method according to claim 6, in which (C) is nitrosoaniline with the General formula

where R ₂₁ and R _{22 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, nitroso and sulfonyl, or R ₂₁ and R ₂₂ can form an aryl, cycloalkyl, polyaryl or heterocycle ring, radicals from R ₂₃ to R _{27 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, acyloxy, NR ₂₈ (R ₂₉ ), nitro, nitroso, halogen and sulfonyl, or any two adjacent R's form a ring - aryl, cycloalkyl , polyaryl or heterocycle, provided that at least one of the radicals from R ₂₃ to R ₂₇ must be a nitroso group, and R ₂₈ and R _{29 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, and nitroso. 13. The method according to claim 6, in which (D) is selected from the group consisting of: α-naphthylamine, thiodarylamines, p-phenylenediamine, o-phenylenediamine, 2,4-diaminodiphenylamine, cyclohexylnaphthylamine, polybutylamines, methylaniline, diphenyl-p- phenylenediamine, phenyl-β-naphthylamine, izopropoksidifenilamin, aldol-α-naphthylamine, symmetrical di-β-naphthyl-p-phenylenediamine, trimetildigidrohinolin, ditolilaminy, phenyl-α-naphthylamine, phenyl-β-naphthylamine, diaminophenol, 4-tsiklogeksilaminofenol n -aminophenol, o-aminophenol and 5-amino-2-hydroxytoluene. 14. A composition for inhibiting premature polymerization and polymer chain growth of ethylenically unsaturated monomers, comprising a combination of:
(A) at least one sulfonated phenol inhibitor of the general formula

where (1) R ₂ is selected from the group consisting of hydrogen and a hydrocarbon, and
(2) R ₁ and R _{3 are} independently selected from the group consisting of hydrogen and SO ₃ H, provided that at least one of R ₁ and R _{3 is} selected as SO ₃ H,
(B) at least one nitrophenol inhibitor,
(C) an inhibitor selected from the group consisting of nitroxyl compounds and nitrosoanilines, and
(D) amine. 15. The composition of claim 14, wherein R ₂ is straight or branched chain alkyl or alkenyl containing from 1 to 50 carbon atoms. 16. The composition of claim 15, wherein R ₂ is selected from the group consisting of: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl-hexyl, nonyl, decyl, undecyl, dodecyl, tridecyl , tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, geneukosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, isomers of the above, cyclopentyl, cyclohecylocylocyloxy, 17. The composition of claim 14, wherein the nitrophenol is selected from the group consisting of: 2,6-dinitro-4-methylphenol, 2-nitro-4-methylphenol, 2,4-dinitro-1-naphthol, 2,4, 6-trinitrophenol (picric acid), 2,4-dinitro-6-methylphenol, 2,4-dinitrophenol, 2,4-dinitro-6-sec-butylphenol, 4-cyano-2-nitrophenol, 3-iodo-4- cyano-5-nitrophenol, m-nitro-p-cresol and 2,6-dinitro-p-cresol. 18. The composition according to 14, in which (C) is a stable sterically-loaded nitroxyl component having the structural formula

where R ₄ and R _{7 are} independently selected from the group consisting of hydrogen, alkyl, and heterosubstituted alkyl, and R ₅ and R _{6 are} independently selected from the group consisting of alkyl and heterosubstituted alkyl, and X ₁ and X ₂ (1) are independently selected from a group consisting of halogen, cyano, COCR ₇ , -S-COR ₇ , -OCOR ₇ , (where R ₇ is alkyl or aryl), amido, -S-C ₆ H ₅ , carbonyl, alkenyl or alkyl, containing from 1 up to 15 carbon atoms, or (2) both form a cyclic structure containing nitrogen. 19. The composition of claim 14, wherein (C) is nitrosoaniline with the general formula

where R ₂₁ and R _{22 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, nitroso and sulfonyl, or R ₂₁ and R ₂₂ form a ring - aryl, cycloalkyl, polyaryl or heterocycle, radicals from R ₂₃ to R _{27 are} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, hydroxyl, alkoxy, acyloxy, NR ₂₈ (R ₂₉ ), nitro, nitroso, halogen and sulfonyl, or any two adjacent R's forming a ring - aryl, cycloalkyl , polyaryl or heterocycle, provided that at least one of the radicals from R ₂₃ to R ₂₇ must be a nitroso group, and R ₂₈ and R _{29 is} independently selected from the group consisting of hydrogen, alkyl, aryl, acyl, and nitroso. 20. The composition of claim 14, wherein (D) is selected from the group consisting of: α-naphthylamine, thiodarylamines, p-phenylenediamine, o-phenylenediamine, 2,4-diaminodiphenylamine, cyclohexylnaphthylamine, polybutylamines, methylaniline, diphenyl-p-phenylenediamine , phenylene-β-naphthylamine, isopropoxydiphenylamine, aldol-α-naphthylamine, symmetric di-β-naphthyl-p-phenylenediamine, trimethyldihydroquinoline, ditolylamines, phenyl-α-naphthylamine, phenyl-β-naphthyl-amyl-4-diamino aminophenol, o-aminophenol and 5-amino-2-hydroxytoluene.