RU2039757C1 - Method of inhibition of vinylaromatic monomer polymerization - Google Patents

Abstract

FIELD: petroleum and chemical industry. SUBSTANCE: method involves addition of inhibiting mixture for prevention of vinylaromatic compounds polymerization. Inhibiting mixture consists of hydroxylamine and dioxime-p-quinone derivatives at their mass ratio (10:90)-(90:10). Mixture shows synergistic effect. EFFECT: improved method of polymerization inhibition. 1 tbl

Description

 The invention relates to the petrochemical industry, in particular to processes for inhibiting the polymerization of vinyl aromatic compounds in the process of their preparation, storage and transportation.

It is known to use, as polymerization inhibitors of vinyl aromatic compounds, dioxim-p-quinone [1] a mixture of N, N-dialkylhydroxylamines with tertiary alkyl pyrocatechols [2]
The closest in technical essence to the proposed method is the use of mixtures of derivatives of N, N-diarylhydroxylamines with mono- or di-tert-alkylpyrocatechols and / or mono- or di-tert-alkylhydroquinones [3] taken in a mass ratio (10-90): (90-10) and in an amount of 0.5-1000 ppm per vinyl aromatic compound. The effectiveness is shown in mixtures of dibenzylhydroxylamine with 2,5-di-tert-butylhydroquinone and 4-tert-butylpyrocatechol, taken in a ratio of 50:50 wt. and a total concentration of 500 ppm based on styrene. To create more severe operating conditions for the inhibitor, sodium hydroxide and benzoyl peroxide are additionally introduced into styrene. The polymerization is carried out at 90 ^about C for 120 minutes When using 2,5-di-tert-butylhydroquinone as a co-component of dibenzylhydroxylamine, the amount of polymer formed was 0.01 wt. and when using 4-tert-butylpyrocatechol 0.08 wt.

 The invention consists in the use as an inhibitor of a mixture consisting of hydroxylamine derivatives (PHA) and dioxim-p-quinone (DOC) in a mass ratio (10-90) :( 90-10) in an amount of 0.5-1000 ppm in the calculation on the monomer.

N-OH где R¹ и R² водород, алкильные группы с нормальными или разветвленными углеродными цепями, имеющими от 2 до 10 (предпочтительно 2-6) атомов углерода, арильные или арилалкильные группы, имеющие структурную формулу

R³n где R³ алкиленовая группа с нормальной или разветвленной цепью, имеющая 1-10 атомов углерода;
R⁴ водород или алкильная группа с нормальной или разветвленной цепью, имеющая 1-6 атомов углерода;
n принимает значения 0 или 1;
R¹ и R² вместе с атомом азота могут образовать циклы такие, как N-гидроксиморфолин, N-гидроксипиперидин.As derivatives of PHA use compounds of the formula

N-OH where R ¹ and R ^{2 are} hydrogen, straight or branched chain alkyl groups having from 2 to 10 (preferably 2-6) carbon atoms, aryl or arylalkyl groups having the structural formula

R ³ n where R ^{3 is a} straight or branched chain alkylene group having 1-10 carbon atoms;
R ^{4 is} hydrogen or a straight or branched chain alkyl group having 1-6 carbon atoms;
n is 0 or 1;
R ¹ and R ² together with the nitrogen atom can form rings such as N-hydroxymorpholine, N-hydroxypiperidine.

Preferably R ¹ and R ² are alkyl, phenyl or aromatic radicals, R ³ has 1-6 carbon atoms, R ^{4 is} hydrogen. At n 0, the phenylene group is directly bonded to the nitrogen atom. Hydroxylamine derivatives can also be used with a large number of carbon atoms in hydrocarbon groups, but these results give quite satisfactory results.

 Hydroxylamine derivatives are, for example, N, N-diethylhydroxylamine, N, N-ethylbutylhydroxylamine, N, N-dibutylhydroxylamine, N, N-2-ethylbutylhydroxylamine, N, N-N-diphenylhydroxylamine, N, N-N-dibenylhydroxylamine - (3-phenylpropyl) hydroxylamine, N, N-bis- (3-phenylpropyl) hydroxylamine.

 Both individual substances and mixtures based on them consisting of two or more components can be used as hydroxylamine derivatives.

 In the invention, the relative concentration of PHA and DOC varies between 10-90 wt. for PHA and in the range of 90-10 wt. for DOC calculated on the total weight of these compounds. The concentration of the inhibitory composition is 0.5-1000 ppm (preferably 5-500 ppm) based on the monomer to be inhibited.

Inhibitory mixture effective to inhibit polymerization of vinyl aromatic monomers during their isolation by distillation at temperatures up to 150 ^{° C} and above. It can be used in the presence of other additives, for example, corrosion inhibitors. The inhibitory mixture is fed in any way. It is most convenient to apply in a solvent compatible with the monomer, for example, kerosene, lower alkanes (hexane), aromatic solvents (toluene, benzene), alcohols, ketones, etc. Dissolution of inhibitors in the monomer is possible to prevent additional impurities from entering it. The mass concentration of the inhibitor in a solution of 1-30%, preferably 5-20%, based on the solvent.

 Since DOC is poorly soluble in aliphatic and aromatic hydrocarbons, it can be previously dissolved in liquid PHAs, for example, in N, N-diethylhydroxylamine, the solubility of which is about 20 wt.

 When inhibiting the polymerization of vinyl aromatic compounds, this mixture exhibits a synergistic effect, as confirmed by the above examples. In the examples, styrene is used as the vinyl aromatic monomer, and ethylbenzene hydroperoxide is added to create more stringent conditions for checking the effectiveness of the inhibitory composition, since its ability to accelerate the polymerization of vinyl aromatic monomers is known.

PRI me R 1. In a glass dilatometer, previously washed with ethyl alcohol and dried with nitrogen, styrene is added, not charged with a stabilizer, 200 ppm ethylbenzene hydroperoxide are added in the form of 25 wt. solution in ethylene benzene. Dilatometer thermostated at ¹²⁰ ° C in a silicone bath for 180 minutes. The amount of polymer in solution with a content of up to 3 wt. determined by the nephelometric method. At a higher polymer content determination by weight produced by a method based on maintaining a polymer sample solution under an infrared lamp at a temperature of 180-200 ^o C to constant weight. The percentage of polymer (X) is calculated by the formula
X (mm ₁ ) / (m ₂ m ₁ ) 100% where m is the mass of the box with the polymer after drying, g;
m ₁ weight of box, g;
m ₂ weight of weighing box, g.

 The amount of polymer is 40.5 wt.

 Example 2. Under the conditions of Example 1, a mixture of dibenzylhydroxylamine (BDHA) with 2,5-di-tert-butylhydroquinone (TBH) taken in a weight ratio of 1: 1 was introduced per 500 ppm monomer. The amount of polymer is 11.2 wt.

 EXAMPLES 3, 4. Under the conditions of Example 1, 250 and 500 ppm of N, N-diethylhydroxylamine (DEGA) per monomer are introduced. The amount of polymer is respectively 19.2 and 8.3 wt.

 Example 5. Under the conditions of Example 1, 500 ppm of dibenzylhydroxylamine per monomer is introduced. The amount of polymer is 15.8 wt.

 PRI me R s 6-8. Under the conditions of Example 1, 150, 250 and 500 ppm of dioxim-p-quinone (DOC) are calculated per monomer. The amount of polymer is respectively 12; 11.4 and 2.2 wt.

 PRI me R s 9-12. Under the conditions of Example 1, a DEGA / DOC mixture taken in a weight ratio of 1: 1 is introduced based on the monomer 200, 300, 400 and 500 ppm. The amount of polymer is 7.8, respectively; 2.04; 0.73 and 0.6 wt.

 PRI me R s 13-14. Under the conditions of example 1, a DEG / DOC mixture, taken in mass ratios of 23 and 3: 2, is introduced per 500 ppm monomer. The amount of polymer is respectively 0.46 and 0.61 wt.

 Example 15. Under the conditions of Example 1, a DBHA / DOC mixture taken in a weight ratio of 1: 1 is introduced based on the monomer 500 ppm. The amount of polymer is 0.54 wt.

 PRI me R 16. In the conditions of example 1 are introduced calculated on the basis of the monomer 500 ppm of the mixture DEGA / DOC taken in a mass ratio of 9: 1. The amount of polymer is 2.7 wt.

 Example 17. Under the conditions of Example 1, a DEGA / DOC mixture taken in a weight ratio of 1: 9 was added per 750 ppm monomer. The amount of polymer is 0.7 wt.

PRI me R 18. In a round-bottomed glass flask with a volume of 250 ml, pre-washed with ethanol, dried with nitrogen and equipped with a reflux condenser, 100 ml of the product of industrial dehydrogenation of ethylbenzene of the following composition, wt. styrene 50.83; ethylbenzene 44.16; x methylstyrene 0.17; paraffins 0.21; benzene 1.11; toluene 3.39; heavy residue 0.13. Additionally, based on the monomer 500 ppm, a DEGA / DOC mixture taken in a mass ratio of 1: 1 is introduced. The flask was placed in an oil bath thermostated at ¹²⁰ ° C for 180 min. The conditions for the determination of the polymer are given in example 1 of the description. The amount of polymer is 0.13 wt.

 PRI me R 19. Under the conditions of example 18, the product of industrial dehydration of methylphenylcarbinol of the following composition, wt. styrene 76.11; ethylbenzene 0.58; x-methylstyrene 0.02; benzaldehyde 0.22; acetophenone 20.69; methylphenylcarbinol 1.35; light hydrocarbons 0.83; heavy residue 0.2. The amount of polymer is 0.66 wt.

 The results are presented in the table.

 PRI me R 20. In a flat-bottomed glass flask with a volume of 250 ml, pre-washed with ethyl alcohol and dried with nitrogen, 150 ml of marketable styrene, not charged with a stabilizer, are introduced, 0.5 ppm of a mixture of N- (p-hexylphenyl) -N- ethylhydroxylamine (GPEGA) with dioxim-p-quinone (DOC), taken in the ratio 1: 1, is tightly closed with a stopper and stored under normal conditions for 2 months. The polymer defined in the conditions of example 1 is missing.

 PRI me R 21. In the conditions of example 20 add 0.5 ppm HFEGA. The amount of polymer after 2 months of storage is 0.016 wt.

 PRI me R 22. In the conditions of example 20 add 0.5 ppm DOC. The amount of polymer is 0.001 wt.

 Example 23. Under the conditions of Example 1, N- (10-phenyldecyl) -N-decylhydroxylamine (FDGA) is introduced per 800 ppm monomer. The amount of polymer is 16.4 wt.

 PRI me R 24. In the conditions of example 1 is introduced per monomer 200 ppm DOC. The amount of polymer is 11.8 wt.

 Example 25. Under the conditions of Example 1, an FDDGA / DOC mixture taken in a weight ratio of 4: 1 was introduced based on the monomer 1000 ppm. The amount of polymer is 10.2 wt.

 Example 26. Under the conditions of Example 1, a mixture of N-phenylhydroxylamine (PHA) / DOC, taken in a weight ratio of 1: 7, was introduced per 200 ppm monomer. The amount of polymer is 8.4 wt.

Claims (1)

METHOD FOR INHIBITING POLYMERIZATION OF VINYLAROMATIC MONOMERS by introducing 0.5 to 1000 ppm by weight of the monomer of a mixture of inhibitors containing hydroxylamine derivatives and dioxim-p-quinone in a mass ratio of (10 90) (90 10), characterized in that compounds are used as hydroxylamine derivatives general formula

,
where R ¹ , R ² H, C ₂ H ₅ C _{1 0} - H _{2 1} , aryl or arylakyl groups of the general formula

where R ³ CH ₂ C _{1 0} H _{2 0} ;
R ⁴ H, CH ₃ C ₆ H _{1 3} ;
n 0, 1.

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