RU2168500C1 - 2-(n-methyl-alpha-phenyl(n-butyl)amino)-4-pyridine as inhibitor of acid corrosion of steel - Google Patents

Abstract

FIELD: corrosion protection. SUBSTANCE: invention provides novel compound 2-(N-methyl-alpha-phenyl(n-butyl)amino)-4-pyridine that can be used as steel corrosion inhibitor in acid treatment of wells or at petroleum refineries. EFFECT: enlarged choice of corrosion inhibitors. 1 tbl, 2 ex

Description

 The invention relates to new chemical compounds, in particular, 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine of the general formula (1), which can be used as an acid corrosion inhibitor of steel.

Коррозия стального оборудования промышленных объектов при их контакте с водными растворами минеральных кислот приносит значительный ущерб народному хозяйству. На сегодняшний день наиболее эффективным способом защиты стального оборудования промышленных объектов является применение ингибиторов кислотной коррозии стали.

Corrosion of the steel equipment of industrial facilities in contact with aqueous solutions of mineral acids causes significant damage to the national economy. To date, the most effective way to protect steel equipment of industrial facilities is the use of acid corrosion inhibitors of steel.

Known acid corrosion inhibitor of steel - catapine B-300 / [1], The catalog "Corrosion inhibitors", M .: 1975, S. 61 /, which at a concentration of 0.5 wt.% In a 20% HCl solution at 20 ^o C protects steel against corrosion by 97%. The main disadvantage of the known inhibitor is the relatively large (0.5 wt.%) Consumption, which makes it disadvantageous for widespread use in industry.

A well-known acid corrosion inhibitor is pyridine / [2], A. Altsibeeva, S. Levin. Metal corrosion inhibitors. Ed. "Chemistry", L., 1968, p. 20 / protects steel from corrosion in a 10% solution of hydrochloric acid at 20 ^o C for 71.4% (at a pyridine concentration of 0.4%).

The disadvantages of the known inhibitor are:
relatively low degree of corrosion protection of steel (~ 71%);
relatively high consumption of inhibitor;
high toxicity and volatility of pyridine, hindering its large-scale use.

 The aim of the invention is the identification of new pyridine derivatives, allowing, when used as an acid corrosion inhibitor, to give steel an increased protective effect.

 This goal is achieved by the synthesis of 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine of the formula (1).

The proposed compound is obtained by mixing in an inert gas atmosphere equimolar amounts of benzalmethylamine (PhCH = NCH ₃ ) with n-propyl magnesium bromide (n-C ₃ H ₇ MgBr) in tetrahydrofuran (THF), followed by stirring at a temperature of ~ 40 ^o C for 2 hours. Next a catalytic amount (2-5 mol.% with respect to benzalmethylamine) of palladium catalyst (Pd [PPh ₃ ] ₄ ) and an equimolar amount with respect to benzalmethylamine of 2-bromo-4-methylpyridine are added to the reaction mass at 0 ^° C, stirred at a temperature 30-50 ^o C for 6-10 hours. The obtained 2- (N-methylene -α-phenyl (n-butyl) amino) -4-methylpyridine in a yield of 77-95% of the scheme shown at the end of the description.

The protective effect of 2- (N-methyl-α-phenyl (n-butyl) -4-methylpyridine as an inhibitor of carbon steel corrosion in acidic environments was tested under laboratory conditions. 15% HCl solution and 20% were used as working media solution of H ₂ SO ₄ .

Samples of steel ST pretreated for corrosion testing. 3 GOST 380-71 placed in the working environment for a certain time (τ) at 20 ^o C. After the exposure time, the samples are subjected to appropriate processing, weighed to the nearest 0.0001 g. Corrosion rate (ρ), degree of protection of steel (Z) metal corrosion inhibitor is determined in accordance with formulas (2) and (3).

где Δ m - изменение массы, г;
S - площадь образца, м²;
τ - время испытания, ч;

где ρ₁ - скорость коррозии в среде без ингибитора;
ρ₂ - скорость коррозии в ингибированной среде.

where Δ m is the change in mass, g;
S is the area of the sample, m ² ;
τ is the test time, h;

where ρ ₁ is the corrosion rate in a medium without an inhibitor;
ρ ₂ - corrosion rate in an inhibited medium.

 As the test results show, the proposed inhibitor exhibits a high inhibitory effect of 95.6-98.0% at an inhibitor concentration of 0.05-0.1 wt.%, While pyridine at a concentration of 0.4 wt.% Protects steel from corrosion by only 71.4% at a flow rate of 5-10 times (0.5 wt.%).

 Thus, 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine exhibits inhibitory properties (95.6-98.0%) at a low reagent consumption (0.05-0.1 wt.%).

 The proposed acid corrosion inhibitor of steel suggests the possibility of its use in industries where contact of metals with aqueous solutions of mineral acids takes place, in particular, in acid treatment of wells or in oil refineries.

 The synthesis of 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine is illustrated by example.

Example. To 10 mmol of nC ₃ H ₇ MgBr in a THF solution under argon atmosphere, 10 mmol of benzalmethylamine are added and stirred for 2 hours at a temperature of ~ 40 ^o C. 0.3 mmol of Pd (PPh ₃ ) ₄ and 10 mmol of 2 are added at a temperature of ~ 0 ^o C -bromo-4-methylpyridine, stirred at a temperature of ~ 40 ^o C for 8 hours (total time 10 hours). The reaction mass is cooled to ~ 20 ^o C, add a saturated solution of NH ₄ Cl, the organic layer is extracted with ether, dried MgSO ₄ . 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine is obtained in 88% yield. Rf 0.69 (silica gel L, 40/100, hexane / ethyl acetate = 7: 3), n _D ²⁰ 1.5872, IR spectrum (V, cm ^-1 ): 3060, 2960, 2870, 1600, 755, 700 . PMR spectrum (δ, ppm): 0.94 t (3H, CH ₃ , J = 7 Hz), 1.61 - 2.32 m (5H, CH, CH ₂ ), 2.24 s ( 3H, CH ₃ ), 2.68 s (3H, CH ₃ N), 5.92-8.64 m (3H, pyridine), 7.25 s (5H, Ph). M ⁺ 254.

 Data illustrating the protective properties of 2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine are given in table. 1.

Claims (1)

2- (N-methyl-α-phenyl (n-butyl) amine) -4-methylpyridine of the formula

as an inhibitor of acid corrosion of steel.

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