RU2643006C2 - Water-soluble inhibitor of corrosion for protection of operating pipes and pipelines for natural gas and also method of its obtaining - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: component a) - a mixture of modified imidazoline derivatives is produced, the condensation reaction of diethylenetriamine with fatty acids and aliphatic dicarboxylic acids is carried out at a temperature of at least 140°C. A mixture of aminoamides with an acid number of <10 mg Koh/g is produced. At a temperature above 180°C, the condensation reaction is carried out. A mixture of compounds with an acid number of <1 mg KOH/g in an amount of 0, 1-50 wt % is produced. The mixture is neutralized at room temperature in the reaction medium containing the component e) - aliphatic alcohols in the amount of 15-99.7 wt %, aliphatic and/or aromatic monocarboxylic acid in an amount of 0.05-25 wt %. The final product is produced, and the next components: b) - oxyethylene fatty amines, c) an alkalinizing agent and f) - defoamer are added to the component a) in an amount of 0.15-75 wt % and the component e).

EFFECT: increasing the corrosion resistance of the corrosion inhibitor.

14 cl, 1 tbl, 13 ex

Description

FIELD OF TECHNOLOGY

The invention relates to a water-soluble corrosion inhibitor for the protection of production pipes and pipelines for natural gas, as well as to a method for its production.

BACKGROUND

Corrosion resulting from chemical or electrochemical reactions of metal elements with the environment is a serious problem in the production of natural gas.

In gas wells, there is more than one type of corrosion. Drilling fluids are most often aqueous salt solutions that play the role of an electrolyte. The produced water that is present in natural gas production also contains inorganic salts such as chlorides (sodium, potassium, magnesium), sulfates (sodium, potassium, magnesium) and carbonates. In aqueous systems containing salts, electrochemical corrosion easily occurs. It is due to the action of galvanic cells formed between a passivated metal surface and a surface that does not have a passivated layer. The result of electrochemical corrosion is mainly a corrosion ulcer on the surfaces of production pipes and pipelines, as well as on operational devices. The greatest damage to the surface of the pipes occurs in saline solutions with a concentration of 7-13%.

Significant corrosion damage is caused by the presence of carbon dioxide in the formation being drilled. A characteristic feature of corrosion caused by the presence of carbon dioxide in the extracted gas is the smooth edges of the shaft. Corrosion caused by the presence of carbon dioxide in gas wells is often referred to as “neutral” corrosion. Carbon dioxide, dissolving in water, forms carbonic acid Н ₂ СО ₃ , which reacts with iron to form iron carbonate FeCO ₃ , and hydrogen gas Н _{2 is} also formed. Carbon dioxide, dissolving in water, further reduces the pH of the water, which in turn increases the corrosion rate.

No less dangerous is the corrosion associated with the presence of hydrogen sulfide, called "acidic" corrosion. The content of hydrogen sulfide in the produced gas is on average from one to several percent, however, some gas reservoirs even contain up to several tens of percent hydrogen sulfide. Hydrogen sulfide causes more aggressive corrosion than carbon dioxide. Like carbon dioxide, hydrogen sulfide dissolves in water, lowering the pH. As a result of the reaction of hydrogen sulfide with iron, iron sulfide FeS and hydrogen gas H _{2 are formed} . Iron sulfide forms a coating on the surface of the metal and in the first phase inhibits “acidic” corrosion, however, even slight damage to this coating causes intense corrosion. "Acidic" corrosion leads to ulcers, often accompanied by cracks in metal coatings that occur due to the formation of hydrogen. Part of the hydrogen penetrates the steel and causes bloating, cracking and the so-called hydrogen embrittlement.

Corrosion processes in gas wells are intensified by sulfate-reducing bacteria of the genus Desulfovibrio Desulfuricans. These bacteria are most active under the surface of sediments formed as a result of sedimentation.

The rate of corrosion caused by carbon dioxide and hydrogen sulfide increases with increasing oxygen content in the system. Oxygen enters solutions when they pass through devices serving wells and reservoirs. The corrosion rate also depends on the temperature - the higher it is, the higher the corrosion rate, and reaches a maximum at a temperature of about 70 ° C. In wells not protected by corrosion inhibitors, it can even be several mm / year.

As a result of prolonged contact of natural gas with formation water in the formation, the gas is saturated with water vapor. The amount of steam in the gas depends on the temperature, pressure and salt content in the water. The amount of water vapor in the gas increases during the life of the formation, and the older it is, the higher the amount of water vapor in the gas. In gas pipelines, as a result of pressure reduction, water is released, the presence of which accelerates corrosion.

As a result of corrosion processes, the wall thickness of production pipes and pipelines decreases, deep ulcers occur, which can lead to leaking pipes and a strong decrease in their strength properties.

In order to prevent corrosion in gas wells, corrosion inhibitors are used to reduce the corrosive effects of produced natural gas on steel elements of production equipment and pipelines. As corrosion inhibitors, liquid corrosion inhibitors of a different chemical nature are used: most often quaternary ammonium salts, imidazoline derivatives, salts of fatty acids and gas phase protection inhibitors, ordinary amines. To be effective, the corrosion inhibitor used must be soluble in water in order to neutralize the corrosive effects of water-soluble salts and acid gases.

A water-soluble corrosion inhibitor to protect production pipes and pipelines for natural gas provides corrosion protection against agents such as hydrogen sulfide and carbon dioxide contained in the produced gas, chlorides contained in produced water and drilling fluids, as well as oxygen contained in water.

US Pat. No. 3,629,104 and US Pat. No. 3,758,493 disclose water-soluble corrosion inhibitors containing a carboxylic acid salt of an imidazoline derivative obtained by condensation of dimerized fatty acids with diethylene triamine.

US Pat. No. 5,759,485 describes a method for producing a corrosion inhibitor by neutralizing C ₂₂ tricarboxylic acids, followed by the addition of imidazoline or amidoamine.

Patent application WO 2003/054251 describes the good anticorrosion properties of oxyethylenated fatty alkyl amines, in particular oxyethylenated alkyl ether amines.

Patent descriptions PL 61535 and PL 85729 disclose a method for preparing imidazoline inhibitors in the condensation reaction of diethylenetriamine with fatty acids or naphthenic acids.

Patent descriptions PL 135655 and PL 175452 disclose a method for producing an inhibitor of increased activity by condensation of diethylenetriamine with fatty acids, followed by modification using urotropine introduced in the final phase of the condensation reaction.

According to patent PL 182943, a water-soluble corrosion inhibitor contains a salt of an imidazoline derivative, which is a condensation product of fatty acids with diethylene triamine and urotropine or formaldehyde and low molecular weight carboxylic acids.

Patent application US 2004/0087448 recommends the use of a condensation product of dimers of unsaturated C ₁₈ fatty acids (containing 1 and 2 double bonds) and diethylene triamine as a corrosion inhibitor.

US 6,695,897 describes a process for the preparation of amidoamine as a condensation product of N-ethylethylenediamine and a fatty acid. After solubilization with acetic acid, the reaction product may act as a water-soluble corrosion inhibitor.

US Pat. No. 7,057,050 describes a process for preparing a water-soluble corrosion inhibitor. The reaction product is N-propyl-2-heptadecynyl-imidazoline. The resulting product is solubilized to a water-soluble form using acrylic acid.

Patent application WO 2006/078723 describes a method for producing a microemulsion containing imidazoline derivatives and amido amines prepared with the participation of oleic acid. The microemulsion also contains hydroxyethylenated nonylphenols and acetic acid.

The patent literature describes the condensation of diethylene triamine with fatty acids containing from 12 to 24 carbon atoms in the molecule, while the molar ratio of diethylene triamine to fatty acids is 1: 0.5-1.0. Examples of such condensation are known, in particular, from the descriptions of US patents US 2267965, US 2355837 and Polish patent PL 61535.

US Pat. No. 5,326,630 describes an imidazoline corrosion inhibitor resulting from the reaction of unsaturated monocarboxylic acids with fatty amines, amino amides or fatty imidazole amines.

In the description of patent RU 2394941 a mixture of imidazoline derivatives modified with aldimines or Schiff bases is described. According to this patent, an imidazoline derivative is a reaction product of polyamines with oleic acid or monocarboxylic acids. The imidazoline derivative is then cyanethylated with nitriles, acrylic acid or hydroxyalkylated.

A water-soluble corrosion inhibitor obtained by neutralizing tricarboxylic acid with aminethylethanolamine, and then with an imidazoline derivative, amidoamine, or a mixture thereof, is disclosed in US Pat. No. 5,759,485.

GB 2340505 discloses a method for preparing imidazoline derivatives in the process of condensation of tall oil fatty acids with amine-ethyl-ethanol-amine. The inhibitor is characterized by good anti-corrosion properties, and also, forming a complex with mercaptans, removes the smell of sulfur compounds.

US patent 5723061 and application US 2007/0152191 describe compositions which include salts formed by the reaction of dicarboxylic acids With ₁₀ -C ₁₂ with polyamines.

Corrosion inhibitors, which include bis-amides, are described in US patents. Bis amide as a reaction product of polyamines with fatty acid dimers is described in US Pat. No. 4,614,600, and a reaction product of polyamines with dicarboxylic acids is described in US Pat. No. 4,344,461.

Patent application WO 2003/054251 discloses good anticorrosive properties of oxyethylenated fatty alkyl amines, in particular oxyethylenated alkyl ether amines.

Patent application US 2009/181678 recommends the use of a condensation product of dimers of unsaturated fatty acids C18 (containing 1 and 2 double bonds) and diethylene triamine as a corrosion inhibitor.

US 2007/0261842 describes a process for inhibiting the corrosion of oil / gas pipelines by using at least one amine with a boiling point of 105-130 ° C or at least one amine selected from mono-, di- and trialkyl pyridine, 3-methoxypropylamine (MOPA), ethyldiisopropylamine (EDIPA); the inhibitor composition may also contain at least one imidazoline or its derivative, and / or phosphoric esters and / or thioacids.

Many available corrosion inhibitors to protect production pipes and pipelines for natural gas are not effective enough and require a high dosing level to provide corrosion protection. It is accepted that the level of corrosion protection at a dosage of 100 mg of corrosion inhibitor per 1 kg of corrosive medium should be higher than 80% according to ASTM NACE 1D182.

Most of the proposed corrosion inhibitors for use in natural gas wells are based on quaternary ammonium salts. Compounds of this type are completely soluble in water, and therefore are often used by manufacturers. The best corrosion inhibitors are those that dissolve very well in water, while leaving a layer of corrosion inhibitor on the metal surface. The corrosion inhibitor must protect the piping / installation for at least 24 hours from an emergency stop of the metering pump. The disadvantage of corrosion inhibitors based on quaternary ammonium salts is much lower anticorrosion properties than inhibitors with imidazoline derivatives, since they do not adequately protect against corrosion ulcers.

Many of the available corrosion inhibitors to protect boreholes and pipelines for natural gas are not effective enough and require a high dosage level to provide corrosion protection. Many of them, after mixing with produced water, form a heterogeneous liquid, releasing deposits and precipitating part of the inhibitor. This leads to inadequate corrosion protection and can cause dangerous corrosion ulcers.

An additional disadvantage of the available inhibitors is their tendency to form an emulsion with formation water, other inhibitors have a high tendency to foam, and the presence of foam leads to interference in the operation of devices serving gas wells.

The objective of the invention was the creation of a water-soluble corrosion inhibitor to protect production pipes and pipelines for natural gas, which would provide much better anti-corrosion properties than the corrosion inhibitors currently used.

SUMMARY OF THE INVENTION

This invention relates to a water-soluble corrosion inhibitor for the protection of production pipes and pipelines for natural gas and to a method for its production.

One aspect of the invention is the provision of a water-soluble corrosion inhibitor for protecting production pipes and pipelines for natural gas.

It has been found that good anticorrosive properties sufficient to protect natural gas production devices and gas pipelines are exhibited by a composition comprising:

- component a) in an amount of from 0.15 to 75 wt. %, preferably from 1.5 to 35 wt. % obtained as a result of neutralization from 0.1 to 50 wt. %, preferably from 1 to 30 wt. % of a new mixture of modified derivatives of imidazoline, which is a condensation product of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms in a molecule and aliphatic dicarboxylic acids containing from 2 to 12 carbon atoms in a molecule, which is a mixture of compounds of general formulas (1) and (2 ),

Where

Where

with the possible addition of from 0.05 to 20 wt. % of a known product of the condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms in a molecule, obtained according to the known method at a temperature of from 180 ° C to 280 ° C, preferably from 220 ° C to 260 ° C, of the General formula (1 ')

Where

with aliphatic and / or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms in a molecule used in an amount of from 0.05 to 25 wt. %, while maintaining the mass ratio of the mixture of compounds of general formulas (1), (2) and possibly (1 ') to monocarboxylic acid 1: 0.15-0.70, to obtain the final product, which is a mixture of compounds of general formulas (5), (6) and possibly (5 ')

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

- component b), which is an oxyethylenated fatty amine containing from 14 to 22 carbon atoms in the molecule and from 2 to 20, preferably from 3 to 15 ethoxyl groups in the molecule, in an amount of from 0.01 to 10 wt. %;

- component c), which is an alkalizing agent in an amount of from 0.06 to 25 wt. %, preferably from 1 to 20 wt. %;

- possibly component d), which is an aliphatic polyol in an amount of from 0.04 to 50 wt. %;

- component e), which is aliphatic alcohols containing from 1 to 6 carbon atoms in the molecule, possibly with the addition of water, in an amount of from 15 to 99.7 wt. %

and

- component f), which is an antifoam agent in an amount of from 0.01 to 2 wt. %

Another aspect of the invention is to provide a method for producing a water-soluble corrosion inhibitor for protecting production pipes and pipelines for natural gas, comprising the following steps:

I) the preparation of component a) is carried out at room temperature in a reaction medium containing component e), which is aliphatic alcohols containing from 1 to 6 carbon atoms in the molecule, possibly with the addition of water, in an amount of from 15 to 99.7 wt. %, neutralization of a new mixture of modified imidazoline derivatives, which is a condensation product of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing from 2 to 12 carbon atoms in the molecule, and which is a mixture of compounds of general formulas (1 ) and 2),

Where

Where

used in an amount of from 0.1 to 50 wt. %, preferably from 1 to 30 wt. %, with the possible addition of from 0.05 to 20 wt. % of a known condensation product of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms in a molecule obtained in a known manner at a temperature of 180 ° C-280 ° C, preferably 220 ° C-260 ° C, of the general formula (1 '),

Where

with aliphatic and / or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms in a molecule used in an amount of from 0.05 to 25 wt. %, while the mass ratio of the mixture of compounds of general formulas (1), (2) and possibly (1 ') to monocarboxylic acid is 1: 0.15-0.70, to obtain the final product, which is a mixture of compounds of general formulas (5) , (6) and possibly (5 '),

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

Where

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₆ )

II) the introduction of component a) in an amount of from 0.15 to 75 wt. %, preferably from 1.5 to 35 wt. %, and in the mentioned component e) of the subsequent components of the inhibitor:

component b), which is an oxyethylenated fatty amine containing from 14 to 22 carbon atoms and from 2 to 20, preferably from 3 to 15 ethoxyl groups in the molecule, in an amount of from 0.01 to 10 wt. %;

component c), which is an alkalizing agent in an amount of from 0.06 to 25%, preferably from 1 to 20%;

and possibly component d), which is an aliphatic polyol in an amount of from 0.04 to 50 wt. %

and at the end of component f), which is an anti-foaming agent in an amount of from 0.01 to 2 wt. %

PREFERRED EMBODIMENTS

It was unexpectedly found that the use of a new mixture of modified imidazoline derivatives with higher anticorrosion properties with the possible addition of the known condensation product of diethylenetriamine with fatty acids, neutralized aliphatic and / or aromatic monocarboxylic acid to a salt state, as well as a surfactant from the group of hydroxyethylenated, hydrogenated tall dual function amines: corrosion inhibitor and dispersant, in combination with volatile amine, anti-foaming agent and possibly aliphatic polyols dissolved in an alcohol solvent with the possible addition of water, led to a corrosion inhibitor with improved anticorrosion properties compared to corrosion inhibitors containing conventional imidazoline derivatives.

The invention uses a new mixture of modified imidazoline derivatives of the general formulas (1) and (2),

Where

Where

which can be obtained as follows: diethylenetriamine is condensed with fatty acids containing 12-22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing 2-12 carbon atoms in the molecule, while the molar ratio of diethylene triamine to fatty acids and aliphatic dicarboxylic acids is 1: 0.5-0.99: 0.01-0.5, at a temperature of at least 140 ° C, preferably 150 ° C, to obtain a mixture of aminoamides of the general formulas (3) and (4),

Where

Where

with an acid number <10 mg KOH / g,

and then the temperature rises to more than 180 ° C, preferably to 220 ° C and the condensation reaction is carried out to obtain a mixture of compounds of General formulas (1) and (2)

Where

Where

with an acid number <1 mg KOH / g.

The aforementioned new mixture of modified imidazoline derivatives creates a very strong layer on the metal surface that protects against corrosion. The use of a volatile amine as an inhibitor complements its anticorrosive effect in the gas phase.

Many available corrosion inhibitors for protecting boreholes and pipelines for natural gas contain dispersants that are nonylphenol derivatives. Phenolic groups are especially harmful to the environment due to their very low biodegradability. The use in the composition of the corrosion inhibitor according to the invention of a surfactant from the group of oxyethylenated, hydrogenated tall amines with a high degree of biological decomposition has a positive effect on the biocompatibility of the corrosion inhibitor according to the invention.

There may be many variations of the invention depending on its components and ways of combining them. Preferred modifications of the invention regarding components a), e), d), c) and f) are presented below.

In a preferred embodiment, the corrosion inhibitor according to the invention as component a) contains a product obtained by neutralizing with acetic acid and / or benzoic acid the following imidazoline derivatives:

i) a mixture of modified derivatives of imidazoline, which is a condensation product of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing from 6 to 10 carbon atoms in the molecule, while the molar ratio of diethylenetriamine to fatty acids and aliphatic dicarboxylic acids is 1: 0.5-0.99: 0.01-0.5, at a temperature of at least 140 ° C, preferably 150 ° C, to obtain a mixture of aminoamides of the general formulas (3) and (4),

Where

Where

with an acid number <10 mg KOH / g,

and then after increasing the temperature to more than 180 ° C, preferably to 220 ° C, a condensation reaction is carried out to obtain a mixture of compounds of General formulas (1) and (2)

Where

Where

with an acid number <1 mg KOH / g,

ii) a possibly added known condensation product of diethylenetriamine with fatty acids.

In a preferred embodiment, the corrosion inhibitor according to the invention contains methanol, isopropanol, ethanol or mixtures thereof as component e).

In a preferred embodiment, the corrosion inhibitor according to the invention contains, as component d), ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol or mixtures thereof.

In a preferred embodiment, the corrosion inhibitor according to the invention contains, as component c), 3-methoxypropylamine, 2-aminoethanol (monoethanolamine), diethylamine or mixtures thereof.

In a preferred embodiment, the corrosion inhibitor according to the invention contains, as component f), a siloxane derivative, preferably branched siloxane polymers.

The percentage composition of the corrosion inhibitor according to the invention is given in mass percent, calculated in relation to the total weight of the inhibitor.

In a preferred embodiment of the invention relating to a method for producing a water-soluble corrosion inhibitor for protecting production pipes and pipelines for natural gas, neutralization with glacial acetic acid is carried out in relation to the following imidazoline derivatives:

i) a mixture of modified imidazoline derivatives, which is a condensation product of diethylenetriamine with fatty acids containing 12 to 22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing 6 to 10 carbon atoms in the molecule, when the molar ratio of diethylene triamine to fatty acids and aliphatic is condensed dicarboxylic acids is 1: 0.5-0.99: 0.01-0.5, at a temperature of at least 140 ° C, preferably 150 ° C, to obtain a mixture of aminoamides of the general formulas (3) and (4),

Where

Where

with an acid number <10 mg KOH / g,

and then after increasing the temperature to more than 180 ° C, preferably to 220 ° C, a condensation reaction is carried out to obtain a mixture of compounds of General formulas (1) and (2)

Where

Where

with an acid number <1 mg KOH / g,

ii) a possibly added known condensation product of diethylenetriamine with fatty acids.

The percentage of components used to obtain a corrosion inhibitor by the method according to the invention is indicated in mass percent calculated in relation to the total weight of the inhibitor.

The corrosion inhibitor obtained on the basis of a mixture of modified imidazoline derivatives is characterized by the best anticorrosive and hydrophilic properties with respect to inhibitors containing known imidazoline derivatives.

The inhibitor according to the invention creates homogeneous liquids with produced water containing up to 30% salt, and even at a temperature of 80 ° C, the inhibitor is not precipitated from them. The exceptional compatibility of the inhibitor according to the invention with formation waters of varying degrees of salinity leads to an increase in its anticorrosion properties in both the aqueous and gas phases.

In the case where high transparency of the inhibitor according to the invention is required during prolonged storage in winter at temperatures below -30 ° C, the introduction of the known imidazoline derivative into the inhibitor provides advantages, the small addition of which leads to the fact that the inhibitor according to the invention at very low temperatures is completely transparent.

In the case where high transparency of the inhibitor according to the invention is required during prolonged storage in winter at temperatures below -40 ° C, aliphatic polyols, preferably ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol or mixtures thereof in an amount of from 0.5 up to 50 wt. %, possibly aliphatic alcohols containing from 1 to 6 carbon atoms in the molecule, except for methanol, isopropanol and ethanol.

The corrosion inhibitor obtained by the method according to the invention creates a strong protective layer on the metal surface, protects against corrosion in the gas phase, preventing corrosion even in very aggressive environments containing carbon dioxide, hydrogen sulfide and chlorides. The corrosion inhibitor according to the invention is resistant to high temperatures occurring in the formation, is not prone to release from formation water and precipitation. A corrosion inhibitor is effective at a low dosage continuously from 10 to 80 ppm of natural gas and produced water. Its high anticorrosive efficiency allows to protect operational equipment not only from uniform corrosion, but, above all, from corrosion ulcers. It protects metal surfaces well from corrosion, even in the event of a temporary accident in the dosing system. An additional advantage of the inhibitor according to the invention is the lack of a tendency to foam in the formation water-inhibitor system.

The corrosion inhibitor according to the invention in one of many production options contains benzoic acid, which has a bactericidal effect. In practice, a water-soluble corrosion inhibitor for protecting production pipes and pipelines for natural gas according to the invention is continuously added to the gas-water mixture. Typically, the corrosion inhibitor according to the invention is added to the liquid in an amount of from about 0.01 to 5000 ppm, preferably from 1 to 500 ppm, most preferably from 10 to 100 ppm.

The following examples illustrate the invention without limiting its scope.

Examples 1 to 5 relate to the preparation of a new mixture of modified imidazoline derivatives, and examples 6 to 11 relate to the preparation of a corrosion inhibitor according to the invention.

Example 1

103.16 kg (1 mol) of diethylene triamine, 141.23 kg (0.5 mol) of distilled olein, in which the main component is oleic acid C ₁₈ H ₃₄ O ₂ , and 45.02 kg (0.5 mol) were introduced into the reactor ) oxalic acid. The contents were heated with constant stirring with a mechanical stirrer and nitrogen sparging was additionally applied in order to remove water that arose during the reaction. After reaching a temperature of 150 ° C, the reaction was held for 3 hours until an acid number of 3.51 mg KOH / g was obtained, then it was further heated until a temperature of 220 ° C was reached. The reaction was carried out for 4 hours while maintaining the temperature at a constant level of 220 ° C while simultaneously sparging with nitrogen in order to remove water from the reaction. Received 226 kg of product with an acid value of 0.25 mg KOH / g

Example 2

103.16 kg (1 mol) of diethylene triamine, 279.64 kg (0.99 mol) of oleic acid and 1.88 kg (0.01 mol) of azelaic acid were introduced into the reactor. The contents were heated with constant stirring with a mechanical stirrer and nitrogen sparging was additionally applied in order to remove water that arose during the reaction. After reaching a temperature of 150 ° C, the reaction was held for 3 hours (acid number - LK = 4.32 mg KOH / g), after which it was further heated until a temperature of 220 ° C was reached. The reaction was carried out for 5 hours while maintaining the temperature at a constant level of 220 ° C while simultaneously sparging with nitrogen in order to remove water from the reaction. Received 317 kg of product (mixture of modified derivatives of imidazoline) with an acid number = 0.38 mg KOH / g

Example 3

103.16 kg (1 mol) of diethylene triamine, 264.10 kg (0.95 mol) of tall oil fatty acids and 10.11 kg (0.05 mol) of sebacic acid were introduced into the reactor. The contents were heated with constant stirring with a mechanical stirrer and nitrogen sparging was additionally used to remove water that arose during the reaction. After reaching a temperature of 150 ° C, the reaction was held for 3 hours (acid number — LK = 5.1 mg KOH / g), after which it was further heated until a temperature of 220 ° C was reached. The reaction was carried out for 5 hours while maintaining the temperature at a constant level of 220 ° C while simultaneously sparging with nitrogen in order to remove water from the reaction. Received 308 kg of product (a mixture of modified derivatives of imidazoline) with an acid number of 0.7 mg KOH / g

Example 4

103.16 kg (1 mol) kg of diethylene triamine, 268.34 kg (0.95 mol) of distilled olein, in which the main component is oleic acid C ₁₈ H ₃₄ O ₂ , and 5.90 kg (0.05) were introduced into the reactor mol) succinic acid. The contents were heated with constant stirring with a mechanical stirrer and nitrogen sparging was additionally applied in order to remove water that arose during the reaction. After reaching a temperature of 150 ° C, the reaction was held for 3 hours (an acid value of LK = 3.94 mg KOH / g was obtained), after which it was further heated until a temperature of 210 ° C was reached. The reaction was carried out for 5 hours while maintaining the temperature at a constant level of 210 ° C while simultaneously sparging with nitrogen to remove water from the reaction. Received 312 kg of product (a mixture of modified imidazoline derivatives) with an acid value of 0.24 mg KOH / g.

Example 5

103.16 kg (1 mol) of diethylene triamine, 268.34 kg (0.95 mol) of distilled olein, in which the main component is oleic acid C ₁₈ H ₃₄ O ₂ , and 7.67 kg (0.05 mol) were introduced into the reactor. ) adipic acid. The contents were heated with constant stirring with a mechanical stirrer, while evacuation of 100 mm Hg was simultaneously turned on to remove water from the reaction. After reaching a temperature of 150 ° C, the reaction was held for 3 hours (acid value — LK = 4.72 mg KOH / g), after which it was further heated until a temperature of 220 ° C was reached. The reaction was carried out for 5 hours while maintaining the temperature at a constant level of 220 ° C with the simultaneous application of evacuation of 100 mm Hg in order to remove water from the reaction. Received 299 kg of product (a mixture of modified imidazoline derivatives) with an acid value of 0.33 mg KOH / g.

Example 6

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), представляющий собой светлую жидкость низкой вязкости с температурой застывания ниже -60°C и кинематической вязкостью 2,7 мм²/с при температуре 20°C.440.9 kg (44.09 wt%) of methyl alcohol, 400 kg (40 wt%) of isopropyl alcohol, and then 66 kg (6.6 wt%) of the condensation product of diethylene triamine with distilled olein and sebacic acid were introduced into the reactor , with an acid number of 0.7 mg KOH / g, obtained by the method according to example 3, but in the condensation process, instead of tall oil fatty acids, distilled olein was used in an amount of 0.95 mol per 1 mol of diethylene triamine and 0.05 mol of sebacic acid. After complete dissolution, 33 kg (3.3 wt.%) Of glacial acetic acid was added. After the complete reaction at room temperature to a neutral pH, 10 kg (1% by weight) of oxyethylenated hydrogenated tall amine containing 5 ethoxy groups in the molecule and 20 kg (2% by weight) of glycerol were introduced. After complete dissolution, 30 kg (3 wt.%) Of 3-methoxypropylamine and 0.1 kg (0.01 wt.%) Of a siloxane derivative under the trade name Foam Ban НР732 of the company

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100 wt.%) Was obtained, which is a light liquid of low viscosity with a pour point below -60 ° C and a kinematic viscosity of 2.7 mm ² / s at a temperature of 20 ° C.

Example 7

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), представляющий собой светлую жидкость низкой вязкости с температурой застывания - 60°C и кинематической вязкостью 7,6 мм²/с при температуре 20°C.405.0 kg (40.5 wt.%) Of methyl alcohol, 302 kg (30.2 wt.%) Of isopropyl alcohol, and then 150 kg (15 wt.%) Of the condensation product of diethylene triamine with tall oil fatty acids and azelaic acid, with an acid number of 0.4 mg KOH / g obtained by the method according to example 2, but instead of oleic acid, tall oil fatty acids were used in the amount of 0.99 mol per 1 mol of diethylene triamine and 0.01 mol of azelaic acid. After complete dissolution, 90 kg (9 wt.%) Of benzoic acid was added. After the complete reaction at room temperature to a neutral pH, 7 kg (0.7 wt.%) Of oxyethylenated hydrogenated tall amine containing 6 ethoxy groups in the molecule and 5 kg (0.5 wt.%) Of ethylene glycol were added. After complete dissolution, 40 kg (4 wt.%) Of 3-methoxypropylamine was introduced, followed by 1 kg (0.1 wt.%) Of a siloxane derivative under the trade name Foam Ban НР732 of the company

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100 wt.%) Was obtained, which is a light liquid of low viscosity with a pour point of 60 ° C and a kinematic viscosity of 7.6 mm ² / s at a temperature of 20 ° C.

Example 8

. После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), представляющий собой светлую жидкость с температурой застывания -30°C и кинематической вязкостью 37 мм²/с при температуре 20°С.79 kg (7.9 wt.%) Of water, 150 kg (15 wt.%) Of isopropanol, 100 kg (10 wt.%) Of ethanol and 200 kg (20 wt.%) Of the condensation product of diethylene triamine, tall fatty acids were introduced into the reactor oil and adipic acid, with an acid number of 0.3 mg KOH / g, obtained by the method according to example 5, but instead of distilled olein, tall oil fatty acids in the amount of 0.95 mol per 1 mol of diethylene triamine and 0.05 mol were used in the condensation process adipic acid. After complete dissolution, 110 kg (11 wt.%) Of glacial acetic acid was added. After the complete reaction at room temperature to a neutral pH, 100 kg (10 wt.%) Of an oxyethylenated hydrogenated tall amine containing 5 ethoxyl groups in the molecule was introduced. After complete dissolution, 50 kg (5 wt.%) Of 3-methoxypropylamine, 100 kg (10 wt.%) Of monoethanolamine, 100 kg (10 wt.%) Of diethylamine, 10 kg (1 wt.%) Of dipropylene glycol monomethyl ether were added, and then 1 kg (0.1 wt.%) Siloxane derivative under the trade name Foam Ban НР732 of the company

. After complete dissolution at room temperature, a corrosion inhibitor was obtained in an amount of 1000 kg (100 wt.%), Which is a clear liquid with a pour point of -30 ° C and a kinematic viscosity of 37 mm ² / s at a temperature of 20 ° C.

Example 9

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), представляющий собой светлую жидкость низкой вязкости с температурой застывания ниже - 60°C, кинематической вязкостью 4,5 мм²/с при температуре 20°C и высокой прозрачностью во время хранения при температуре -40°C в течение 1 года.770 kg (77 wt.%) Of methyl alcohol, 80 kg (8 wt.%) Of the condensation product of diethylene triamine, distilled olein, in which the main component is oleic acid C ₁₈ H ₃₄ O ₂ , and succinic acid, with an acid number, are introduced into the reactor 0.25 mg KOH / g, obtained by the method according to example 4, and 20 kg (2 wt.%) Of the known condensation product of diethylene triamine and oleic acid. After complete dissolution, 40 kg (4 wt.%) Of glacial acetic acid was added. After the complete reaction at room temperature to a neutral pH, 10 kg (1% by weight) of an oxyethylenated hydrogenated tall amine containing 5 ethoxy groups in a molecule was introduced, and after lowering to room temperature 40 kg (4 wt.%) 3-methoxypropylamine and 30 kg (3 wt.%) Diethylamine, and then 10 kg (1 wt.%) Siloxane derivative under the trade name Foam Ban НР732 of the company

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100 wt.%) Was obtained, which is a light liquid of low viscosity with a pour point below - 60 ° C, kinematic viscosity of 4.5 mm ² / s at a temperature of 20 ° C and high transparency during storage at -40 ° C for 1 year.

Example 10

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), представляющий собой светлую жидкость с температурой застывания -45°C, кинематической вязкостью 57 мм²/с при температуре 20°C.177.9 kg (17.79 wt.%) Of isopropyl alcohol was introduced into the reactor, followed by 500 kg (50 wt.%) Of the condensation product of diethylenetriamine with oleic acid (trade name distilled olein, in which the main component is oleic acid C ₁₈ N ₃₄ O ₂ ,) and oxalic acid, with an acid number of 0.25 mg KOH / g, obtained by the method according to example 1. After complete dissolution, 250 kg (25 wt.%) Of glacial acetic acid was added. After the complete reaction at room temperature to a neutral pH, 0.1 kg (0.01 wt.%) Of oxyethylenated hydrogenated tall amine containing 5 ethoxyl groups in the molecule and 50 kg (5 wt.%) Of diethylene glycol butyl ether were added. Then, 1 kg (0.1 wt.%) Of monoethanolamine and 1 kg (0.1 wt.%) Of diethylamine were introduced, and then 20 kg (2 wt.%) Of a siloxane derivative under the trade name Foam Ban НР732 of the company

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100 wt.%) Was obtained, which is a clear liquid with a pour point of -45 ° C, kinematic viscosity of 57 mm ² / s at a temperature of 20 ° C.

Example 11

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100 мас. %), являющийся светлой жидкостью низкой вязкости с температурой застывания ниже - 60°C и кинематической вязкостью 1,2 мм²/с при температуре 20°C.596.72 kg (59.672 wt.%) Of methyl alcohol, 400 kg (40 wt.%) Of isopropyl alcohol, and then 1.32 kg (0.132 wt.%) Of the condensation product of diethylene triamine with distilled olein (oleic acid C ₁₈ ) were introduced into the reactor H ₃₄ O ₂ is the main component of distilled olein) and sebacic acid, with an acid number of 0.7 mg KOH / g, obtained by the method according to example 3, but in the condensation process, distilled olein in the amount of 0.95 mol per 1 mol of diethylene triamine and 0.05 mol of sebacic acid. After complete dissolution, 0.66 kg (0.066 wt.%) Of glacial acetic acid was added. After the complete reaction at room temperature to a neutral pH, 0.2 kg (0.02 wt.%) Of oxyethylenated hydrogenated tall amine containing 5 ethoxyl groups in the molecule and 0.4 kg (0.04 wt.%) Of propylene glycol were added. After complete dissolution, 0.6 kg (0.06 wt.%) Of 3-methoxypropylamine and 0.1 kg (0.01 wt.%) Of a siloxane derivative under the trade name Foam Ban НР732 of the company were introduced

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100 wt.%) Was obtained, which is a light liquid of low viscosity with a pour point below -60 ° C and a kinematic viscosity of 1.2 mm ² / s at a temperature of 20 ° C.

Some gas wells are equipped with pumps of such design capacity and design that allows metering corrosion inhibitors with a very low kinematic and dynamic viscosity in a wide temperature range, therefore, with a low content of active components. The required dosage of inhibitor may be 1000, 2000 or 3000 ppm per water-gas system with continuous dosing. The corrosion inhibitor according to example 11 is intended for such metering pumps.

Example 12 - comparative

440.9 kg (44.09 wt.%) Of methyl alcohol, 400 kg (40 wt.%) Of isopropyl alcohol, and then 66 kg (6.6 wt.%) Of the known condensation product of diethylene triamine with distilled olein according to the formula are introduced into the reactor (1 ') with an acid value of 1.1 mg KOH / g. After complete dissolution, 33 kg (3.3 wt.%) Of glacial acetic acid was added. After complete reaction at room temperature to a neutral pH, the product of formula (5 ') is obtained.

После полного растворения при комнатной температуре получен ингибитор коррозии в количестве 1000 кг (100,0 мас. %), являющийся светлой жидкостью низкой вязкости с температурой застывания ниже - 60°C и кинематической вязкостью 2,9 мм²/с при температуре 20°C.Then, 10 kg (1% mass) of oxyethylenated hydrogenated tall amine containing 5 ethoxyl groups in the molecule and 20 kg (2 wt.%) Glycerol were introduced. After complete dissolution, 30 kg (3 wt.%) Of 3-methoxypropylamine and 0.1 kg (0.01 wt.%) Of a siloxane derivative under the trade name Foam Ban НР732 of the company

After complete dissolution at room temperature, a corrosion inhibitor in the amount of 1000 kg (100.0 wt.%) Was obtained, which is a light liquid of low viscosity with a pour point below -60 ° C and a kinematic viscosity of 2.9 mm ² / s at a temperature of 20 ° C .

Example 13

Investigation of the anticorrosion properties of a water-soluble corrosion inhibitor for protecting boreholes and pipelines for natural gas according to the invention was carried out according to the Wheel Test in accordance with ASTM NACE 1 D 182 "Method for investigating the resistance of the protective layer created by pipe corrosion inhibitors in boreholes." This is a common weight loss test method used to evaluate the productivity of an inhibitor by simulating a continuous flow of a corrosive working fluid.

A. Preparation of corrosive water: prepared corrosive water in the composition: 9.62% NaCl and 0.305% CaCl ₂ and 0.186% MgCl ₂ ⋅ 6H ₂ O and 89.89% distilled water. Water was sparged with nitrogen for 30 minutes, and then for about 10 minutes with carbon dioxide, until the pH of corrosive water was obtained in the range of 4.4 to 4.8.

B. Preparation of paraffin oil (a mixture of isoparaffin hydrocarbons): the oil is homogenized at a temperature of 62 ° C and then bottled in test bottles.

C. Preparation of metal samples: Sand Blasted Mild Steel Shimstock type tiles (sandblasted mild steel with Shimstock film) dimensions b 0.13 × 12.7 × 76 mm washed with acetone, wiped with a dry cloth, weighed, stored in a desiccator .

In bottles with a capacity of 200 ml, from which air was previously removed, corrosive water in an amount of 90 ml and paraffin oil in an amount of 10 ml were introduced. Next, an inhibitor according to the invention in accordance with Example 6, 7, 8, 9, 10 was introduced in an amount of 30, 50 and 80 ppm by weight, and an inhibitor according to the invention in accordance with Example 11 in an amount of 1500, 2500 ppm by weight in a corrosive environment. The metal tiles described in paragraph C) are introduced into the thus prepared bottles. Carbon dioxide is re-dosed into the bottles for about 30 s and the bottles are tightly closed. The bottles are placed in a thermostat at a temperature of 65.5 ° C, in a rotation chamber that rotates at a speed of 15 revolutions / minute. The test was carried out for 72 hours. After the study, metal samples were removed from the bottles, washed with isopropyl alcohol, and exposed to a 10% hydrochloric acid solution for 10-15 seconds. The metal samples were subsequently washed with water, acetone and alcohol, and then weighed with an accuracy of 0.1 mg. The decrease in mass of the metal sample was evaluated, and the possible presence of a corrosion ulcer was additionally evaluated.

The percentage of corrosion protection was calculated by reducing the weight of the metal sample in the presence of an inhibitor W (inhib) and without an inhibitor W (0).

The percentage of protection,% P = W (0) -W (inhib) / W (0) × 100%.

The results of studies of the anticorrosion properties of corrosion inhibitors in accordance with Example 6, 7, 8, 10 and 11, containing a neutralized new mixture of imidazoline derivatives according to the invention, in accordance with formulas (5) and (6) and the results of studies of the anticorrosion properties of corrosion inhibitors in accordance with example 9, containing a neutralized mixture of modified imidazoline derivatives according to the invention, according to the formula (5), (6) and (5 '), in comparison with the corrosion inhibitor obtained in example 12, containing in place of neutralization mixture of modified imidazoline derivatives according to the formula (5) and (6), a neutralized known product obtained in a known manner as a result of the condensation reaction of diethylenetriamine with oleic acid according to the formula (5 ') is shown in the table below.

INDUSTRIAL APPLICABILITY

The above examples have shown that a water-soluble corrosion inhibitor for the protection of production pipes and pipelines for natural gas according to the invention, as well as a method for its production, must find application in industry.

Claims (58)

1. A method of obtaining a water-soluble corrosion inhibitor for the protection of pipes and pipelines for transporting natural gas, comprising the following steps: I) obtaining component a) - a mixture of modified derivatives of imidazoline, including i) carrying out the condensation reaction of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing from 4 to 12 carbon atoms in the molecule, with a molar ratio of diethylenetriamine to fatty acids and to aliphatic dicarboxylic acids 1 :( 0.80-0.99) :( 0.01-0.10) at a temperature of at least 140 ° C, preferably 150 ° C, to obtain a mixture of aminoamides of the general formulas (3) and (4)

where R ₁ : C ₁₁ -C ₂₁

where R ₂ : C ₂ -C ₂₀ with an acid number <10 mg KOH / g, with a subsequent increase in temperature to more than 180 ° C, preferably up to 220 ° C, and carrying out a condensation reaction to obtain a mixture of compounds of General formulas (1) and (2) where R ₁ : C ₁₁ -C ₂₁

where R ₂ : C ₂ -C ₁₀

with an acid number <1 mg KOH / g, used in an amount of from 0.1 to 50 wt. %, preferably from 1 to 30 wt. % ii) neutralizing the mixture of compounds of general formulas (1) and (2), carried out at room temperature in a reaction medium containing component e), which is aliphatic alcohols containing from 1 to 6 carbon atoms in the molecule, in an amount of from 15 to 99, 7 wt. %, aliphatic and / or aromatic monocarboxylic acid containing 1 to 7 carbon atoms in a molecule used in an amount of from 0.05 to 25 wt. % the mass ratio of the mixture of compounds of general formulas (1) and (2) to monocarboxylic acid is 1: (0.15-0.70), to obtain the final product, which is a mixture of compounds of general formulas (5) and (6)

where R ₁ : C ₁₁ -C ₂₁ ; R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ )

where R ₂ : C ₂ -C ₁₀ ; R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ ), II) adding to component a) in an amount of from 0.15 to 75 wt. %, preferably from 1.5 to 35 wt. %, and to the specified component e) of the following additional components: component b), which is an oxyethylenated fatty amine containing from 14 to 22 carbon atoms and from 2 to 20, preferably from 3 to 15, ethoxyl groups in the molecule, in an amount of from 0.01 to 10 wt. %; component c), which is an alkalizing agent, in an amount of from 0.06 to 25 wt. %, preferably from 1.0 to 20 wt. %; and component f), which is an anti-foaming agent, in an amount of from 0.01 to 2 wt. % 2. The method according to p. 1, characterized in that in step I) a mixture of imidazoline derivatives is neutralized, which is a condensation product of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms in the molecule and aliphatic dicarboxylic acids containing from 6 to 10 carbon atoms in a molecule. 3. The method according to p. 1, characterized in that in stage I neutralize a mixture of compounds of General formulas (1) and (2), to which is added from 0.05 to 20 wt. % condensation product of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms in the molecule, obtained at a temperature of 180 ° C - 280 ° C, preferably 220 ° C - 260 ° C, of the General formula (1 ') where R ₃ : C ₁₁ -C ₂₃

the mass ratio of the mixture of compounds of general formulas (1), (2) and (1 ') to monocarboxylic acid is 1: (0.15-0.70), to obtain the final product, which is a mixture of compounds of general formulas (5) , (6) and (5 '), where R ₁ : C ₁₁ -C ₂₁ ;

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ )

where R ₂ : C ₂ -C ₁₀ ; R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ ) where R ₃ : C ₁₁ -C ₂₃ ;

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ ). 4. The method according to p. 1, characterized in that in stage I the specified neutralization reaction is carried out in a reaction medium containing aliphatic alcohols, with the addition of water. 5. The method according to p. 1, characterized in that in stage II to the specified additional components add component d), which is an aliphatic polyols, in an amount of from 0.04 to 50 wt. % 6. A water-soluble corrosion inhibitor for protecting pipes and pipelines for transporting natural gas, containing a mixture of modified imidazoline derivatives, aliphatic alcohols, hydroxyethylenated fatty amines, an alkalizing agent and an anti-foaming agent obtained by the method of claim 1. 7. The corrosion inhibitor according to claim 6, characterized in that as component a) it contains the product of neutralizing a mixture of imidazoline derivatives with acetic and / or benzoic acid, said mixture of imidazoline derivatives being a condensation product of diethylene triamine with fatty acids containing from 12 to 22 carbon atoms in the molecule, and aliphatic dicarboxylic acids containing from 6 to 10 carbon atoms in the molecule. 8. The corrosion inhibitor according to claim 6, characterized in that as said aliphatic alcohol it contains methanol, isopropanol, ethanol or mixtures thereof. 9. The corrosion inhibitor according to claim 6, characterized in that as said alkalizing agent it contains 3-methoxypropylamine, monoethanolamine, diethylamine or mixtures thereof. 10. The corrosion inhibitor according to claim 6, characterized in that it contains a siloxane derivative, preferably branched siloxane polymers, as an anti-foaming agent. 11. The corrosion inhibitor according to claim 6, characterized in that as component e) it contains aliphatic alcohols with the addition of water. 12. The corrosion inhibitor according to claim 6, characterized in that it further comprises component d), which is an aliphatic polyol, in an amount of from 0.04 to 50 wt. % 13. The corrosion inhibitor according to claim 12, characterized in that it contains ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol or mixtures thereof as an aliphatic polyol. 14. The corrosion inhibitor according to claim 6, characterized in that as component a) it contains the product of neutralizing a mixture of imidazoline derivatives of general formulas (1) and (2) with the addition of a compound of general formula (1 ') where R ₁ : C ₁₁ -C ₂₁

where R ₂ : C ₂ -C ₁₀

where R ₃ : C ₁₁ -C ₂₃

which is a mixture of compounds of General formulas (5), (6) and (5 ') where R ₁ : C ₁₁ -C ₂₁ ;

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ )

where R ₂ : C ₂ -C ₁₀ ; R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ ) where R3: C ₁₁ -C ₂₃ ;

R ₄ : H, C ₁ -C ₆ , aromatic radical (C ₆ H ₅ ).