KR20190028444A - Low corrosion alkanesulfonic acid for condensation reaction - Google Patents

Abstract

The present invention relates to a process for the addition of an aqueous solution of an alkanesulfonic acid to a reactor through a pipe or a container in which the condensation reaction is carried out after the addition of an aqueous solution of an alkanesulfonic acid and a method for reducing or restricting corrosion by addition of the aqueous solution to the reactor . The invention also relates to the use of an aqueous solution of an alkanesulfonic acid in the reduction or limitation of corrosion and the use of said aqueous solution in the condensation reaction.

Description

Low corrosion alkanesulfonic acid for condensation reaction

The present invention relates to a process for the addition of an aqueous solution of an alkanesulfonic acid to a reactor through a pipe or a container, wherein the condensation reaction is carried out after the addition of an aqueous solution of an alkanesulfonic acid, and a method for reducing or limiting corrosion by addition of said aqueous solution to the reactor . The invention also relates to the use of an aqueous solution of an alkanesulfonic acid in the reduction or limitation of corrosion and the use of said aqueous solution in the condensation reaction.

A condensation reaction is a reaction in which two or more molecules or moieties of one molecule are combined with a single molecule with the loss of the small molecule. A well known condensation reaction involves not only the release of water during the formation of a single molecule but also the release of other small molecules. In addition, individual moieties within the same molecule can react with each other, typically with the formation of rings (molecular condensation reactions) (Brueckner, R., Reaktionsmechanismen, 2. Aufl .; Spektrum: Heidelberg, Wiley-VCH: Weinheim, (2002), 16, 241-245). ≪ / RTI >

A typical example of a condensation reaction is the esterification between an ester and a carboxylic acid and an alcohol to produce one water molecule.

The condensation reaction can take place between two or more molecules, intra-molecules or inter-molecular to form a condensation polymer (polycondensation). Many condensation reactions are acid catalyzed. In the case of the acid-catalyzed condensation reaction, various acids such as organic acids or inorganic acids are generally suitable. Strong acids such as sulfuric acid, p-toluenesulfonic acid or methanesulfonic acid are often preferred because they allow a faster reaction. However, the strong acid has the disadvantage of inducing corrosion, such as iron oxide (rust), on the surface of the metal in contact with the acid during the condensation reaction or when the acid catalyst is added to the reaction. Some strong acids are known to induce less corrosion than other acids. For example, alkanesulfonic acids such as methanesulfonic acid (MSA) are less corrosive to stainless steel compared to sulfuric acid, and have become more popular in recent years. Methods for the preparation of alkanesulfonic acids are known in the art, for example in WO 2000/031027, WO 2015/086645, WO 2011/054703, or US 4,450,047.

If the acid-catalyzed condensation reaction is an equilibrium reaction, accompanied by the elimination of water, it is desirable to initiate the reaction with the lowest possible water content to further move the equilibrium towards the product. That is, the acid catalyst must contain a minimum amount of water. However, higher acid concentrations in the catalyst solution generally result in higher corrosion rates, especially in storage tanks, pipelines, fittings etc., which are very often made of steel material. In addition, higher corrosion rates may appear in the reactor, particularly at the beginning of the reactant dosing. It is therefore desirable to use as few acid catalysts as possible to minimize corrosion. On the other hand, higher acid catalyst dosages generally lead to faster reactions, leading to more efficient methods.

Thus, there has been a need to reduce corrosion formation in the condensation reaction and maintain a high reaction rate with a suitable amount of catalyst.

The technical problems derived from the above are defined in the claims and discussed and resolved by the present invention as described in the following detailed description and examples.

The invention relates to a process for the addition of an aqueous solution (A) to a reactor:

The aqueous solution (A) is added to the reactor through a pipe or a container,

The reactor, pipe and / or container has a corrosive surface (e.g., an iron-containing surface)

The aqueous solution (A) contains about 80 to 99 w / w%, preferably about 80 to 98, 85 to 98, 88 to 98, 90 to 98, 92 To 97, 92 to 96, or 93 to 95 w / w% of alkanesulfonic acid.

In one embodiment of the invention, the reaction in the reactor is carried out after addition of the aqueous solution (A) to the reactor, wherein the aqueous solution (A) is reacted with a reactant (e. G. Or catalyst. The reaction is generally preferably a chemical reaction, and may be any type of reaction in which the aqueous solution (A) can be used. Such reactions are known in the art and include in particular alkylation or condensation reactions such as esterification and other reactions further exemplified herein. For example, the reaction is an acid or base catalyzed reaction. In this context, the aqueous solution (A) may be a catalyst for the acid catalyzed reaction or a neutralizing agent for the base catalyzed reaction; See, for example, EP 2358851. In one embodiment of the present invention, the reaction carried out in the reactor after the addition of the aqueous solution (A) is a condensation reaction, for example, an acid catalysed condensation reaction.

Surprisingly, it has been found in the context of the present invention that an aqueous solution (A) containing from about 80 to 99% w / w of an alkanesulfonic acid (based on the total weight of the aqueous solution (A)) is less than about 80% w / Or more than about 99 w / w% of the alkanesulfonic acid, the corrosion rate can be drastically reduced on a corrosive surface (e.g., an iron-containing surface). These results can even be improved at values of about 80-98, 85-98, 88-98, 90-98, 92-97, 92-96, or 93-95 w / w% alkanesulfonic acid. Also, as found in the context of the present invention, the addition of a small amount of nitric acid or a salt thereof (e.g., a nitrate salt of an alkali (earth) metal) can further reduce the corrosion rate.

Accordingly, the present invention also relates to a process for the preparation of a pharmaceutical composition which comprises about 80-99 w / w%, preferably about 80-98, 85-98, 88-98, 90-98, 92-97, Containing surface (e.g., an iron-containing surface), which comprises adding the aqueous solution (A) containing the alkanesulfonic acid, ) Corrosion rate. In one embodiment, the corrosive (e.g., iron-containing) surface may be the surface of the reactor, pipe and / or container. For example, the aqueous solution (A) is added to the reactor through the pipe and / or the container. In this context, the term "reducing" corrosion is intended to mean that the corrosion rate is lower when compared to the case where an aqueous solution containing more or less alkanesulfonic acid as defined herein is applied to the reactor, pipe and / . In this context, "lower" means that corrosion formation is at least about 1.2-fold, at least 1.5-fold, at least 1.8-fold, or at least 2- or even 2.5-fold lower.

Accordingly, the present invention relates to an aqueous solution (A) comprising about 80 to 99 w / w%, preferably about 80 to 98, 85 to 98, 88 to 98, 90 to 98, 92 to 97, Corrosive surface (e.g., an iron-containing surface), which comprises adding an aqueous solution (A) containing an alkane sulfonic acid to a corrosive surface (e. G., An iron containing surface) To a maximum of about 0.3 mm per year, preferably up to about 0.25 mm per year, a maximum of 0.2 mm per year, a maximum of 0.15 mm per year, or 0.1 mm per year. In one embodiment, the corrosive (e.g., iron-containing) surface may be a reactor, pipe, and / or container surface. For example, the aqueous solution (A) is added to the reactor through the pipe and / or the container.

In the context of the present invention, "corrosion" means any type of chemical and / or electrochemical conversion of a metal into a chemically more stable form, and in particular includes oxidation of metals, in particular oxidation of iron . As used herein, "corrosion rate" means the degree of corrosion formation and can be measured by methods known in the art and also those described and illustrated herein. Typically, corrosion rates are presented in mm / year. Methods of measuring corrosion rates are described, for example, in DIN 50905 (part 2) or ASTM G31-72, and are further described and illustrated herein.

In the context of the present invention, for example, the iron-containing surface of the reactor, pipe and / or container in contact with the aqueous solution (A) described herein may be the surface of any iron-containing material. In particular, when the surface is exposed to an oxidizing compound (oxidizing agent) such as oxygen, sulfur or an organic or inorganic acid (preferably an organic acid such as an alkanesulfonic acid, sulfuric acid, citric acid, acetic acid, , A surface of an iron-containing material having a general ability to withstand corrosion (e.g., to rust). In this context, the iron-containing material may be any type of ferroalloy such as, for example, cast iron alloys, austenitic alloys (see for example Roempp Online, Version 3.5, Georg Thieme Verlag 2009) (See, for example, Jeffus, Cengage Learning (2002), Welding: Principles and Applications), elinvar, fernico, ferroalloy ferroalloy, invar, kovar, staballoy, and others. In general, the iron alloy may comprise additional (metal) compounds such as, for example, nickel, chromium, cobalt, carbon, molybdenum, hydrogen, manganese, silicon, nitrogen, and / or the like. For example, in the context of the present invention, the iron-containing surface may comprise about 10 to 22, 12 to 20, or 13 to 17 w / w% chromium, and / or about 0.20 w / (e. g., a steel) alloy comprising about 0.1 to about 15 w / w%, or about 0.05 to about 0.12 w / w% carbon, and / or about 15 to 22 w / . In one embodiment, the chromium content can be about 16 to 20 w / w% and / or the nickel content can be about 10 to 14 w / w% and / or the manganese can be about 1 to 3 w / w% Can be positive. Other metals may be present in varying amounts, for example, from about 1 to 5 (preferably from 1.5 to 4 or 2 to 3) w / w% molybdenum, and / or from about 0.1 to 2 or 0.5 to 1 w / w% . Also, the steel alloy may not contain chromium, nickel, or molybdenum, for example, it does not contain nickel and / or molybdenum. In the context of the present invention, the iron alloy may also be passivated by a passivation layer formed, for example, by chromium in the presence of ambient air or oxygen. For example, contact with the aqueous solution (A) May be steel alloys, for example carbon steel alloys according to DIN EN 10088, AISI, SAE names or others.

Examples of steel alloys in the context of the present invention include those listed in Tables 1, 2, 3, or 4.

Table 1: Examples of steel alloys according to AISI and DIN EN 10088 classifications, including respective selected contents of Cr, Ni, Mo and C

Examples for iron containing surfaces in contact with the aqueous solution (A) described herein are 1.4401, 1.4404, 1.4541, 1.4571, 1.4462, 1.4539, 1.4016, And 1.4006. Specific examples are 1.4401, 1.4404, 1.4541, 1.4571, 1.4462, 1.4539, 1.4016 and 1.4006, more particularly 1.4401, 1.4404, 1.4541, 1.4571, 1.4016 and 1.4006, more particularly 1.4016 and 1.4006 .

As used herein, the term "reactor ", in contact with the aqueous solution (A) containing the alkanesulfonic acid described herein, may have any size and shape suitable for allowing the (condensation) reaction to be carried out, (E. G., An iron-containing surface) as defined above and below. Examples are batch type reactors, stirred tank reactors or tubular reactors. The reactors may be operated in a continuous, batch or semi-batch manner.

As used in the context of the present invention, the term "pipe" refers to an aqueous solution (A) having alkaline sulfonic acid as described herein and having a corrosive surface as defined hereinbefore and hereinafter Lt; / RTI > The pipe may be of any size or shape suitable for adding the aqueous solution (A) to the reactor, for example it may be round or may contain corners (preferably it is round) Which may be a channel, which may have a continuous diameter, or may be formed as a nozzle (i.e., having a larger diameter at one end and decreasing at the other end) Diameter), may have other shapes or combined shapes.

As used in the context of the present invention, as an alternative to or in connection with a pipe, a "container" has herein a corrosive surface as defined hereinbefore and hereinafter (e.g. an iron containing surface) Is added to the reactor. The container may be any size or shape suitable for adding the aqueous solution (A) to the reactor, for example, it may be a bottle, a flask, a container, a barrel, a tank, a can, and the like.

In one embodiment of the invention, for example, the corrosive (e.g., iron-containing) surface of a reactor, pipe and / or container is contacted with aqueous solution (A) in the presence of oxygen, for example in the presence of ambient air .

An aqueous solution (A) as described herein and for use in the context of the present invention is prepared by dissolving an alkanesulfonic acid in an amount of from about 80 to 99% w / w, preferably from about 80 to 98, 85% 98, 88 to 98, 90 to 98, 92 to 97, 92 to 96, or 93 to 95 w / w% of the alkanesulfonic acid. In one embodiment, the alkanesulfonic acid may be selected from methanesulfonic acid, ethanesulfonic acid, or higher alkanesulfonic acids (e.g., C ₁ to C ₂₀ alkanesulfonic acids, linear or branched, preferably linear). In one embodiment of the invention, the alkanesulfonic acid of the aqueous solution (A) is methanesulfonic acid (MSA). In the context of the present invention, the aqueous solution (A) is prepared by reacting nitric acid or a salt thereof (e.g. a nitrate salt of an alkali (earth) metal such as Na-nitrate, Mg-nitrate, K- May be further included. In one embodiment of the present invention, the aqueous solution (A) may contain not more than about 2000 ppm, preferably about 100 to 1500 ppm, 300 to 1300 ppm, 500 to 1200 ppm, or 700 to 1000 ppm nitric acid or a salt thereof .

In the context of the present invention, in the process of adding the aqueous solution (A) to the reactor, the aqueous solution (A) described herein is added to the reactor via a pipe and / or a container, Can be carried out in the reactor after addition of the aqueous solution (A) to the reactor. The (acid-catalyzed) condensation reaction may be of any type. In the context of the present invention, for example, it can be obtained from the group consisting of esterification, etherification, aldol condensation, intramolecular condensation (cyclization), polycondensation, silica condensation, phosphate condensation, rearrangement, dehydration, Can be selected. In the context of the present invention, a typical example for the condensation reaction is a water-releasing condensation reaction. More particularly in this context may be esterification, for example, esterification between a carboxylic acid and an alcohol to produce an ester and a single water molecule. Examples include the preparation of dimethyl ether or diethyl ether.

The esterification used herein generally involves the reaction between an acid and an alcohol under the elimination of water. Suitable acids may be inorganic or organic acids, preferably organic acids. The organic acid may be any type of aliphatic or aromatic carboxylic acid. The aliphatic carboxylic acid may have a linear or branched hydrocarbon chain, which may be saturated or unsaturated (e. G., A double bond or a triple bond) and may have additional functional groups. The alcohol may be monofunctional (e.g., methanol), a diol (e.g., ethylene glycol), or a polyol (e.g., glycerin). Examples of esterification reactions include the preparation of acrylates, plasticizers, acetates (solvent esters), oleochemical esters, cellulose acetates or polyesters. Specific examples of oleo chemical esters are the preparation of fatty acid methyl esters (FAME) from various fatty acids and methanol containing feedstocks, which is an essential step in the production of biodiesel. In certain cases, esterification may also be accompanied by the acid catalyzed transesterification described in WO 2011/018228. The esterification reaction is known in the art and is also exemplified herein, for example, EP127104, WO 2015/063189, WO 2013/064775, or US 6,673,959.

Polycondensation is a specific type of polymerization reaction. Polymers are prepared from bifunctional or multifunctional compounds (monomers) by removal of small molecules (e. G., Water, alcohols, hydrogen halides). Examples are the formation of polyesters, polyamides, polyacetals and resins (phenolic resins, furan resins, epoxy resins, amino resins, etc.).

Thus, in one embodiment of the invention, the reaction carried out in the reactor described herein is an acid catalyzed reaction, preferably an acid catalyzed condensation reaction. In certain embodiments of the present invention, the condensation reaction is an esterification known in the art and is also an esterification described and exemplified herein, for example, esterification of one or more carboxylic acids with one or more alcohols, Esterification of the above alcohol, or esterification of at least one fatty acid and methanol.

In the context of the present invention, specific examples of suitable condensation reactions in organic synthesis include acyloin condensation, aldol condensation, benzoin condensation, Claisen condensation, Claisen-Schmidt condensation, Darzens ) Condensation, Dieckmann condensation, Guareschi-Thorpe condensation, Knoevenagel condensation, Michael condensation, Pechmann condensation, Rap-Stormer ) Condensation, Ziegler condensation, or Beckmann rearrangement. As described and shown herein, the use of the aqueous solution (A) described herein leads to a reduction or limitation of the corrosion rate on the iron-containing surface. In particular, acids are known to be corrosive to iron-containing surfaces. Thus, even more surprisingly, it is believed that a relatively high concentration of alkanesulfonic acid (e.g., MSA) in the present invention (e.g., about 80, 85, 88, 90, 92, 93, 94 , 95 w / w%) can be added to the iron-containing surface (A) as long as the concentration is maintained below a certain limit, for example about 99, 98, 97, 96 or 95 w / w% Lt; RTI ID = 0.0 > corrosion rate. ≪ / RTI > However, water (oxygen contained in water) may contribute to corrosion formation depending on the iron alloy in contact with the aqueous solution (A). Therefore, since the amount of water during the water-releasing condensation reaction may increase with time, the rate of corrosion can be increased as the amount of water exceeds the amount of water initially contained in the aqueous solution (A) added to the reactor It is possible. In one embodiment of the present invention, the total water content of all components added to the reactor is about 20 w / w% or less, preferably about 15, 12, 10, 8 , 7, 6, 5, 4, 3, 2 or 1 w / w%. In the context of the present invention, if desired, the water formed by the condensation reaction over time is removed so that the water content of the condensation reaction mixture does not exceed the water added to the reactor by addition of aqueous solution (A) The total water content of all components added to the reactor does not exceed about 20 w / w%, preferably about 15, 12, 10, 8, 7, 6, 5 , 4, 3, 2 or 1 w / w%. The water removal can be carried out by methods known in the art, for example by evaporation, distillation, adsorption or phase separation.

In the context of the present invention, with respect to the (acid-catalyzed condensation) reaction which can be carried out in the reactor after the addition of the aqueous solution (A) described herein to the reactor, an extract for the (condensation) reaction and further components , A catalyst, a solvent, a neutralizing agent, or an extractant) may be added to the reactor before, during, or after the addition of the aqueous solution (A) to the reactor. Those skilled in the art will recognize suitable extracts and additional ingredients for each (condensation) reaction, which are also described and illustrated herein. In addition, one or more (condensation) reaction extracts and additional components with aqueous solution (A) may be added simultaneously or subsequently to the reactor, i. E. The same pipes and / or containers as described herein.

As also shown in the context of the present invention, the corrosiveness of acids and / or water increases with increasing temperature. That is, the effect found in the context of the present invention that the defined aqueous solution (A) and the aqueous solution (A) to be used as described herein lead to reduced or limited corrosion rates on corrosive surfaces such as iron-containing surfaces, Can be higher. Thus, in one embodiment of the present invention, during or after the addition of the aqueous solution (A) (including the mixture) to the pipe, container and / or reactor described herein, a corrosive (e.g., iron containing) When contacted, the temperature of the aqueous solution (A) described herein or the temperature of any mixture comprising the aqueous solution (A) added to the reactor in which the (condensation) reaction can be carried out and further compounds or further extracts is at least about 35 ° C, 45 ° C, 50 ° C, 55 ° C, 60 ° C, 65 ° C, 70 ° C, 75 ° C, or 80 ° C. That is, for example, the aqueous solution (A) (including the mixture) may be added to a reactor, a pipe, and / or a container, or when stored in a reactor, a pipe, and / At least about 30 ° C, 35 ° C, 40 ° C, 45 ° C, 50 ° C, 55 ° C, 60 ° C, 65 ° C, 70 ° C and 75 ° C Deg.] C, or 80 [deg.] C.

As will be apparent to those skilled in the art, the temperature can be increased in the reactor once the (condensation) reaction described herein is initiated and / or it can be intentionally increased to initiate the (condensation) reaction. When a water release reaction (e. G., A water-releasing condensation reaction) is carried out in a reactor, the water content of the mixture contained in the reactor can be increased if it is known in the art and not removed as described herein. In one embodiment, the temperature of the pipe, the container, and / or the reactor is maintained during or after the addition of the aqueous solution (A) (including the mixture) to the pipe, the container, and / , Before or after (e.g., before) the measurement. For example, the temperature can be measured before the total amount of water contained in the reactor exceeds the amount of water contained in the aqueous solution (A) described herein and the aqueous solution (A) for use as described herein. For this purpose, additional components added to the reactor, such as extracts and / or other components (e.g., reactants other than catalysts, solvents, neutralizing agents, or extracts) do not have substantially water, (Alone or all of the foregoing components) does not comprise more than about 5 w / w% water, preferably less than about 4, 3, 2, 1 or 0.5 w / w% water I can do it. In one embodiment, the temperature can be measured before the total amount of water contained in the reactor, relative to the total amount of all components added to the reactor, is about 20 w / w%, preferably about 15, 12, 10, 8, 7, 6, 5, 4, 3, 2 or 1 w / w%. Preferably, the extract and / or other ingredients for the (condensation) reaction added to the reactor (e.g., reactants other than the catalyst, solvent, neutralizing agent or extract) do not have substantially water, In an amount of less than about 5 w / w%, preferably less than 4, 3, 2, 1 or 0.5 w / w%. In this context, the pressure applied to the reactor for the condensation reaction may be especially below about 200 bar, preferably below about 100 bar, or below about 10 bar. In one embodiment, the pressure is less than about 5 bar, such as less than about 2 bar, ambient pressure, or less than about 1 bar (e.g., about 0.5 bar).

In the context of the process according to the invention in which the aqueous solution (A) described herein is added to the reactor in which an acid catalyzed (condensation) reaction can be carried out after the addition of the aqueous solution (A), the aqueous solution (A) And serves as a catalyst. In the present invention, the aqueous solution (A) may be added in an amount suitable for each (condensation) reaction performed after the addition to the reactor. For example, in the case of acting as a catalyst - in particular in the case of water-releasing condensation reactions, such as esterification - the aqueous solution (A) is present in an amount of about 0.1 to 10 w / w% Preferably from about 0.2 to 5, or from 0.5 to 2 w / w%.

Corresponding to the method for reducing or restricting the corrosion rate of the iron-containing surface described herein, the invention further provides a method for reducing or limiting the corrosion rate on the iron-containing surface as defined herein, Lt; / RTI >

Corresponding to the method of addition of the aqueous solution (A) described herein, the present invention further relates to the use of the aqueous solution (A) in the (condensation) reaction described herein.

The present invention further relates to condensation products obtainable or obtainable by the condensation reactions described herein.

It should be noted that, as used herein, the singular forms "a" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "reagent" includes one or more of the above different reagents, and reference to a " method " refers to an equivalent step and a method known to those skilled in the art that can be modified or substituted for the methods described herein Include references to.

Unless otherwise indicated, the term "at least" preceding a set of elements should be understood to refer to all elements in the series. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be included in the present invention.

As used herein, the term "and / or" includes the meaning of "and" or "and" all or any other combination of the elements connected by the term ".

As used herein, the term "about" or "approximately" means within 20%, preferably within 10%, and more preferably within 5% of the value or range provided. As used herein, the term " about "or" about " also includes each exact value or range.

Throughout this specification and claims below, unless the context requires otherwise, the word "comprises" and variations such as "comprises" and "comprising" refer to integers or steps, And does not exclude any other integer or step, or group of integers or steps. As used herein, the term " comprising "may be replaced by the term " containing" or "including" or sometimes "having"

As used herein, "consisting of" excludes any element, step, or ingredient not embodied in the claims element. As used herein, "consisting essentially of" does not exclude materials or steps that do not materially affect the basic and novel features of the claims.

In the present application, the terms "comprising", "consisting essentially of", and "consisting of" in each case may be replaced by two other terms.

The invention relates in particular to the following items:

One. As a method of adding the aqueous solution (A) described herein to the reactor,

The aqueous solution (A) is added to the reactor through a pipe or a container,

Wherein said reactor, pipe and / or container has a corrosive surface,

Wherein the aqueous solution (A) contains from about 80% w / w to about 99% w / w of the alkanesulfonic acid, based on the total weight of the aqueous solution (A).

2. The method according to item 1, wherein the acid catalyzed reaction is carried out in the reactor after addition of the aqueous solution (A) to the reactor.

3. The method according to item 1 or 2, wherein the reaction is a condensation reaction.

4. The method according to any one of items 1 to 3, wherein the reactor, the container and / or the pipe are in contact with the aqueous solution (A) in the presence of oxygen.

5. The method according to any one of items 2 to 4, wherein the extract of the reaction is added before, during or after the addition of the aqueous solution (A) to the reactor.

6. The method according to any one of items 1 to 5, wherein the temperature of the aqueous solution (A) is at least about 20 캜 when in contact with the iron-containing surface.

7. Item 6, wherein the temperature is measured before the total amount of water in the reactor is above 20 w / w% based on the total weight of all components added to the reactor.

8. The method according to any one of items 1 to 7, wherein the alkanesulfonic acid is methanesulfonic acid.

9. The method according to any one of items 2 to 8, wherein the reaction is selected from the group consisting of esterification, aldol condensation, polycondensation, etherification, intramolecular condensation, dehydration, and Beckmann transfer.

10. The method according to any one of items 3 to 9, wherein the condensation reaction is a condensation reaction that releases water.

11. The method according to any one of items 1 to 10, wherein the surface of the reactor, pipe and / or container containing iron further contains chromium and / or nickel.

12. The method according to any one of items 1 to 11, wherein the aqueous solution (A) further comprises nitric acid or a salt thereof.

13. The method according to any one of items 1 to 12, wherein the aqueous solution (A) is added to the reactor in an amount of about 0.1 to 10 w / w% based on the total weight of all components added to the reactor.

14. The method according to any one of items 1 to 13, wherein the pressure of the reactor is from 0.5 to 10 bar.

15. A method for reducing the corrosion rate of an iron-containing surface, comprising adding the aqueous solution (A) according to any one of items 1 to 14 to an iron-containing surface.

16. A method for limiting the corrosion rate of an iron-containing surface at a rate of up to 0.3 mm / year, comprising adding the aqueous solution (A) according to any one of items 1 to 15 to an iron-containing surface.

17. Use of the aqueous solution (A) according to any of items 1 to 16 for reducing or limiting the rate of corrosion on an iron-containing surface.

18. The use of the aqueous solution (A) according to any one of items 1 to 17 in the condensation reaction according to any one of items 3 to 14.

19. A condensation product obtainable by the condensation reaction according to any one of items 3 to 14.

The following examples illustrate the invention without limiting the scope of the invention as defined by the claims.

Example

The corrosion behavior of the corrosive media was measured using the weight measurement and visual evaluation of metal coupons. This was done for different things and therefore included different types of coupons, medium (alkaline to acid), test temperature (room temperature to 80 ° C), potential corrosion inhibitor and test time.

Equipment and materials:

· Chemical balance

· VWR (PA, USA) A, 125 ㎖ beaker (PP) having a screw cap supplied by the four

· Metal coupon 50 × 20 × 1 mm ^*

^*See Tables 2 to 4 for used steel alloys

· Test solution ^**

^**See Tables 2 to 4 for aqueous acid solutions.

Ethyl to Degrees (degreasing) acetate

• Desalted water (NH ₃ free) to set test medium

step:

One. The metal coupon was digested in ethyl acetate, then washed with demineralized water and dried. To avoid further contamination, these treated metal coupons were contacted only with a disposable glove (e. G., Dermatril).

2. Weighed in chemical balance.

3. The coupon was filled with 100 g of the test solution in a PP beaker and then closed.

4. PP beakers with coupons in the test solutions were then stored at the indicated temperatures (e.g., 40 ° C, 60 ° C, and 80 ° C).

5. At pre-measured time intervals (1d, 3d, 7d, 14d), the coupons were removed with forceps, cleaned, dried and weighed. In addition, visual changes in coupons and solutions were recorded. The coupon was then placed back in the test solution.

6. At the end of the test period, one year of corrosion was calculated. For each setting, a double test was performed.

7. Calculation of corrosion rate per year:

Mass loss [g]

Density of metal coupon [g / cm3]

Area of metal coupon [㎠]

Duration = immersion date [d] (for Tables 2 to 4: respective values for 14 d are shown)

Table 2: Corrosion rate 40 ° C [mm / year]

Table 3: Corrosion rate 60 ° C [mm / year]

Table 4: Corrosion rate 80 ° C [mm / year]

Claims (19)

As a method of adding the aqueous solution (A) to the reactor,
The aqueous solution (A) is added to the reactor through a pipe or a container,
Wherein said reactor, pipe and / or container has a corrosive surface,
Wherein the aqueous solution (A) contains from about 80% w / w to about 99% w / w of the alkanesulfonic acid, based on the total weight of the aqueous solution (A). The process according to claim 1, wherein the acid catalyzed reaction is carried out in the reactor after addition of the aqueous solution (A) to the reactor. 3. The process according to claim 1 or 2, wherein the reaction is a condensation reaction. 4. A process according to any one of claims 1 to 3, wherein the reactor, the container and / or the pipe are in contact with the aqueous solution (A) in the presence of oxygen. The method according to any one of claims 2 to 4, wherein the extract of the reaction is added before, during or after the addition of the aqueous solution (A) to the reactor. 6. The process according to any one of claims 1 to 5, wherein the temperature of the aqueous solution (A) is at least about 20 DEG C when contacted with the iron-containing surface. The method of claim 6, wherein the temperature is measured before the total amount of water in the reactor is greater than 20 w / w% based on the total weight of all components added to the reactor. 8. The process according to any one of claims 1 to 7, wherein the alkanesulfonic acid is methanesulfonic acid. 9. The process according to any one of claims 2 to 8, wherein the reaction is selected from the group consisting of esterification, aldol condensation, polycondensation, etherification, intramolecular condensation, dehydration and Beckmann rearrangement. Method of addition of aqueous solution (A) to the reactor. 10. The method according to any one of claims 3 to 9, wherein the condensation reaction is a condensation reaction in which water is released. 11. A process according to any of the claims 1 to 10, wherein the surface of the reactor, pipe and / or container containing iron further comprises chromium and / or nickel, . 12. The process according to any one of claims 1 to 11, wherein the aqueous solution (A) further comprises nitric acid or a salt thereof. 13. A process according to any one of claims 1 to 12, wherein the aqueous solution (A) is added to the reactor in an amount of about 0.1 to 10 w / w% based on the total weight of all components added to the reactor A) to the reactor. 14. The process according to any one of claims 1 to 13, wherein the pressure of the reactor is from 0.5 to 10 bar. A method for reducing the corrosion rate of an iron-containing surface, comprising adding the aqueous solution (A) according to any one of claims 1 to 14 to an iron-containing surface. A method for limiting the corrosion rate of an iron-containing surface at a rate of up to 0.3 mm / year, comprising adding the aqueous solution (A) according to any one of claims 1 to 15 to an iron-containing surface. The use of the aqueous solution (A) according to any one of claims 1 to 16 for reducing or limiting the rate of corrosion on an iron-containing surface. The use of the aqueous solution (A) according to any one of claims 1 to 17 in the condensation reaction according to any one of claims 3 to 14. A condensation product obtainable by the condensation reaction according to any one of claims 3 to 14.