RU2168509C1 - 2-(n-morpholyl)-4-methylpyridine as inhibitor of acid corrosion of steel - Google Patents

Abstract

FIELD: corrosion protection. SUBSTANCE: invention provides novel compound 2-(N-morpholyl)-4-methylpyridine 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

Description

 The present invention relates to new chemical compounds, specifically, 2- (N-morpholyl) -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], Catalog "Corrosion inhibitors", M .: 1975, s.61 /, which at a concentration of 0.5 weight. % in a 20% HCl solution at 20 ^o C protects steel from 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. Altsibeyeva, S. Levin. Metal corrosion inhibitors. Ed. "Chemistry", L., 1968, p. 20 / protects steel from corrosion in a 10% hydrochloric acid solution at 20 ^o C by 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-morpholyl) -4-methylpyridine of the formula (1).

c этилмагнийбромидом (EtMgBr) в тетрагидрофуране (ТГФ) с последующим перемешиванием при температуре ~ 40^oC в течение 2 ч. Реакция сопровождается выделением этана. Реакционную массу охлаждают до ~ 0^oC, добавляют каталитическое количество (2-5 мол.% по отношению к морфолину) палладиевого катализатора (Pd[PPh₃]₄) и эквимольное по отношению к морфолину количество 2-бром-4-метилпиридина, перемешивают при температуре 30-50^oC в течение 6-10 ч. Получают 2-(N-морфолил)-4-метилпиридин с выходом 75-94% по схеме:

Испытания защитного действия 2-(N-морфолил)-4-метилпиридина в качестве ингибитора коррозии углеродистых сталей в кислых средах проводились в лабораторных условиях. В качестве рабочих сред использовались 15% раствор HCl и 20% раствор H₂SO₄.The proposed compound is obtained by mixing in an inert atmosphere of equimolar amounts of mofoline

with ethylmagnesium bromide (EtMgBr) in tetrahydrofuran (THF), followed by stirring at a temperature of ~ 40 ^° C for 2 hours. The reaction is accompanied by the evolution of ethane. The reaction mass is cooled to ~ 0 ^o C, a catalytic amount (2-5 mol.% With respect to morpholine) of palladium catalyst (Pd [PPh ₃ ] ₄ ) and an equimolar amount with respect to morpholine of 2-bromo-4-methylpyridine are added, stirred at a temperature of 30-50 ^o C for 6-10 h. Receive 2- (N-morpholyl) -4-methylpyridine with a yield of 75-94% according to the scheme:

Tests of the protective effect of 2- (N-morpholyl) -4-methylpyridine as an inhibitor of carbon steel corrosion in acidic environments were carried out under laboratory conditions. As working media, 15% HCl solution and 20% H ₂ SO ₄ solution were used.

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).

(2)
где Δm - изменение массы, г;
S - площадь образца, м²;
τ - время испытания, ч;

(3)
где ρ₁ - скорость коррозии в среде без ингибитора;
ρ₂ - скорость коррозии в ингибированной среде.

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

(3)
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 93.1-95.6% at an inhibitor concentration of 0.05-0.1% by weight, while pyridine at a concentration of 0.4 wt.% Protects steel from corrosion by only 71.4%. To obtain an equal protection effect, it is necessary to expend 5-10 times more catapine B-300 (0.5 wt.%).

 Thus, 2- (N-morpholyl) -4-methylpyridine exhibits inhibitory properties (93.1-95.6%) at 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-morpholyl) -4-methylpyridine is illustrated by example.

Example. To 10 mmol of EtMgBr in a THF solution in an argon atmosphere, 10 mmol of morpholine is added and stirred for 2 hours at a temperature of ~ 40 ^° C. The reaction is accompanied by the evolution of ethane. Then, at a temperature of ~ 0 ^° C, 0.3 mmol of Pd (PPh ₃ ) ₄ and 10 mmol of 2-bromo-4-methylpyridine are added, stirred at a temperature of ~ 40 ^° 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 . Get 2- (N-morpholyl) -4-methylpyridine with a yield of 83%. T bale. 98-99 ^o C (2 mm Hg), n _D ²⁰ 1.5682, IR spectrum (V, cm ^-1 ): 1245, 1125, 780, 750. PMR spectrum (δ, ppm) : 2.29 s (3H, CH ₃ ), 3.58 - 3.66 m (4H, CH ₂ , N), 3.73 - 3.95 m (4H, CH ₂ O), 6.80 - 8.57 m (3H, pyridine) M ⁺ 178.

 Data illustrating the protective properties of 2- (N-morpholyl) -4-methylpyridine are shown in the table.

Claims (1)

2- (N-morpholyl) -4-methylpyridine of the formula

as an inhibitor of acid corrosion of steel.

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