:x a F o h P 7 0 0 1 B t r o N ww w a m - e h P 8 0 5 t u o S 4 0 vA S A B r a a M i D :x a F o h P C T B a m - e s A m - e e R S A B x a F :x a F o h P e C 1 5 4 h P 0 7 6 a m - e r u E r a C u E m o H B S A F S A o C r t s . p ro 9 0 5 t n o n o o i g a i t n h : - l a F p o 5 2 6 5 3 3 i a e n e n e n F F F i C e o B a r n n h . b w S : e :e h 2 - 8 : l i : l i : l i o l F P l t b e a n : r p m a i t u ES C . S a E p : : : C e g e l a i m A ö K u L f i c a o l F e m A i 3 1 g u a d n i d n i d n i - c c s + d n l a i c e H 1 + 8 1 + 5 + 5 + + 8 + + 8 + o r a o l .A o 9 4 t s 0 L 9 4 9 4 p r d H o r . e d l 6 1 t S - h n 2 e , n r s u , a m i 0 s u s u s u i r e 5 5 5 5 s u g i w g n m a h d a e ci h 9 9 o r a J s A G & ã S 2 2 · 2 2 y t i i r 3 t 2 6 2 6 5 l a i r t 7 7 1 1 t a r mo c r t r t r t m r e G m c / D c 2 l P 3 3 1 1 7 2 7 2 F a r o K a i s 1 i i i i d o 1 q a l a l a l a 1 1 h C a 6 o h i r Hb o i 3 6 e c a 2 2 3 3 e ß k r a P - r a u m r e n 27 0 1 - f a 3 3 v a P 9 - - - 42 6 3 / 0 0 6 5 g n o f 6 6 4 20 0 6 - 5 4 33 2 2 - 3 4 0 98 9 6 - 3 4 0 n f f f e m e 5 u m r o u m r o u m r o - 0 - 0 n e 5 11 1 0 1 13 6 9 4 m r n a u 83 4 o l u t s u o H - · s r e i t a l 4 0 6 , 6 l a c i y · l u C 5 2 - 4 0 N G – n o o t a an i h 0 t a l t a l t a l J 0 L 2 m r e 0 P S e .d t 5 · - s r o - s r o - s r o T u e - s r S U h c e n a · B A b @ a n a s k h y n z a r @ l o a b @ @ s a b g o b i l s a s a se i f s f o c . f . f c . c . mo c mo m mo W a S u e w h t p r a f s D L d a T t o N d d s g i t o o p N A R A N I F O D R O O C T o f a e t n e o t c i h i u f r u E H o r o c s e o r e b a i a t e AT r e m e e E T s u / n v a s e t e f y t e E s c n a d Y s D I S N d d d n a h v a h R E M e c i e s u o n k R O F N I e s u c A p c u c u o d E L L p i r E D f D A M K l l d o o n s i o r y i R O n N I a d n r , e e t t o d u c t o b a n i o t w d s s R C S e g c c a t i e h t i l C n R E o U T C D g t c u a t g n r p e w s n o c r e m d u t n e m g o , s n E o N I N A H i a s , AM o p o o n f t u p o E f a T I E r o e e h s d e n R p R O F l o T P I c o n D y n f r L A e s r u n E o d i m e h e d d T . t e t o i t e h TB A r R A G H c , s e A I e c n a B f d n a h l r e d s o p t N O i f O I r o l o r u o y u a u y R P E t m o a c e l AM e PR A s n g i , e m m e t r i p a l c c e f f e R r a l r e x , S N h t i l a c d I L I v a e R E P O E S D o t e N O I T y r e u X E a y n i l e s u t i w s d n a r o f e h t N I g n Y T e p , T , s b o i s a g e l w o n T I d n y n a s t t r a d h t R P R O F N a a G i f F O r o a a t a l b o r e s R O F t t e r a s n i h w t a c y n a m O b d n h t i r u c Y T R P a h t AM Y e S S E l u c l l R a l e a h s r e w U O t n t a y n a i v n o i y n a g c n a i c h t E N T I F d e v e t n e r D O r a , H T t b n o i R h AM m r t n o d l u o c i y R i t e d H G I h t o a f i d n R O d e t E B . d n a u o p r u p n o t o e h l u f C U i r o I T m r o f n i M R E T t c s i i a n R O p e h g n r e r o f d o t y O e n S T s r o a r a m S U S I t e v i g i S T M m r o f n o a l , N a a h S f s o r l b o t c a m c e f e b d i l b o H T r L P p e b m r o f n i E k e F O e R O F m e v c i e E D S a e n i e D D n i t n i s t t E I n o i t AT m r o f r i l a a g . e a i r p A n o i t a g e t A o t g n e h t I W c a y r O C S T D e e D N n o c i t t s c A A r o f a H T H T A i u s , e d n e h t a r u n o n o i t . n o U O H T t a f o a t n o c s R I e f R O c N c d n PA e h t t l n o i a O C S R E E I r r u o t o r o r u o D E B c e t C e p d r p f o N l l u f a t d P I T R r s u U L d a a , S E D d v o e , h t l a O I D N p e t a O R v d g n i i A B T r f i t n e d n . e n t r p a c r e I D i i c o o e t C W I s n e d O . i I r u o i N s I R F N c c u d o m s D r p d FS s n o i t u I T A L U I I r G N R o t r f A t N G e s e a e p m r p d C U O N h v o O m o A R R e f d s u . D v i g d e n i e t s v o e h e o S N c e l i h W e h t S i E r s i i W R N S T g n i y e d s t g n t e A C i e e d i S r r p s o p s n o G n i O R P A a d e I T N P t n e n e I a d , O e h G i t o n I e c o R r o U n x r u o G N d n S r a d D n i a t F f o e c a h t S N e p A R R a eh t E b E S E s e r o f a , l I V A S r u o P y S s e h s a t i u r s t r u f e h t e i r p H S p EH T I T N e p , t O s ru o s D E D I A B l p O r e i l G r AD i e h t .E L a ru o y gn -d o S c n e i re h e y r A i b F S N c - ev , E SE S s t LL TA a e y i l F, - t EB . , y

Photos: © BASF SE, iStockphoto 08_101201e-01 03.2012 supersedes edition 08_101201e-00 dated 03.2011 Th Lut the ma me e de th pu ro a f by n riendly r esu est p B ur ASF l for fo ® n m ic – o aci aci f M d SA d Lutropur ® MSA – High-purity Methanesulfonic Acid from BASF

Highly effective, efficient and economical: that is probably the best way to describe Lutropur MSA − high purity methanesulfonic acid (MSA) from BASF.

Because of its unique property profile, methanesulfonic acid is becoming increasingly important. In numerous different applications and industries, ranging from chemical synthesis and metal surface treatment through to industrial cleaning, Lutropur MSA is helping our customers to be more successful.

Lutropur MSA is ideal for the manufacture of sustainable products. With Lutropur MSA it is often possible to meet more stringent environmental and safety requirements than with other acids.

If Lutropur MSA helps ... to achieve optimum industrial results to comply with rules and regulations to cut costs

... it’s because at BASF, we create chemistry. Contents

1. Product and Quality 2

2. Manufacturing Process 3

3. Properties 4 3.1. Physical properties 5 3.2. Chemical properties 6 a. Acid properties 6 b. Dissolving power 8 c. Redox stability 10 d. Further chemical properties 11

4. Ecological and Toxicological Aspects 12

5. Material Compatibility 13

6. Storage and Stability 14

7. Comparative Table of Acids 15

8. Advantages 16

9. Literature 16 1. Product and Quality

Lutropur MSA is pure methanesulfonic acid. Methanesulfonic acid (MSA) is a strong and odorless organic acid with a unique property profile that distinguishes it from all other acids.

Benefits in practical applications come, for example, from its nonoxidizing nature, the high solubility of its salts, the absence of color and odor, and the fact that it is Free of chlorine readily biodegradable. Consequently, MSA is becoming increasingly important in a number of applications and industries. Colorless Odorless

Using a unique manufacturing process, BASF is able to provide a colorless and ® odorless product that is virtually free Lutropur MSA of metal ions and sulfates. Chlorine- containing by-products are also ruled out by the halogen-free process. As a result, Sulfate Heavy metals < 1 ppm consumers in all relevant fields benefit < 20 ppm from being able to use MSA that is of very high purity. Oxidizable components < 1 ppm

MSA is supplied by BASF as a 70% aqueous solution under the brand name Lutropur MSA. Anhydrous MSA is available under the brand name Lutropur MSA 100.

Typical values Lutropur MSA Lutropur MSA 100

Concentration [wt.%] 70.0 > 99.8

Sulfate [ppm] < 20 < 30

Total chlorine (incl. Cl –) [ppm] < 1 < 1

Oxidizable constituents [ppm] < 1 < 1

APHA color value < 5 < 20

Heavy metal content [ppm] 1 < 1 < 1

1 The total concentration of the following metals is less than 1 ppm: Ag, Al, As, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Ti, V, Zn, Zr.

® = Registered trademark of BASF group 2 2. Manufacturing Process

In the manufacturing process developed and patented by BASF, sulfur, hydrogen and methanol are first converted into the intermediate product dimethyldisulfide (DMDS). The DMDS is refined by distillation and then catalytically oxidized with atmospheric oxygen to form methanesulfonic acid and water. A final distillation step ensures the unique purity of Lutropur MSA.

Both BASF’s original production facility in Ludwigs- hafen, Germany (commissioned in 2003, annual capacity 10,000 metric tons) and the extension (to be commissioned in 2012, annual capacity 20,000 metric tons) operate according to this process. With a total annual manufacturing capacity Hydrogen Sulfur Methanol of 30,000 metric tons, BASF is the world’s leading supplier of methanesulfonic acid.

The advantages of this process are that it is very safe Dimethyldisulfide and reliable, the raw materials are readily available, Air the whole process is free of chlorine, and it fits very well into the integrated production complex in Ludwigshafen. This continuous process also ensures Methanesulfonic acid consistently high product quality.

Innovative technology for producing high-purity methane - sulfonic acid – Lutropur MSA is manufactured in a plant that is an integral part of the Ludwigshafen production complex.

3 3. Properties

MSA combines a number of beneficial physical and On the boundary between organic and chemical properties. These properties make MSA the inorganic chemistry reagent of choice in many different applications. MSA is a strong organic acid with no oxidizing properties. With many of its properties, methanesulfonic acid Its high thermal stability compared with aromatic is on the boundary between organic and inorganic sulfonic acids is particularly useful in the synthesis of chemistry. For example: chemicals. One of the reasons why MSA is so widely used in the electronics industry is that the salts that Distribution between organic and inorganic it forms with metals are highly soluble. Many organic phase salts of methanesulfonic acid also exhibit very good This plays a role in catalysis: MSA works better solubility properties. Especially methanesulfonates of in an organic phase and can be washed out more heterocyclic nitrogen compounds often have a low easily than inorganic acids. Organic incrustations melting point and are used as ionic liquids. can also be removed more easily in cleaning processes. Other advantages from the ecological point of view are its ready biodegradability and its low Acid strength: the acid strength of MSA is carbon content (TOC). With a melting point of –54°C, between that of carboxylic acids and that of strong Lutropur MSA can be handled in the form of a liquid mineral acids. over a wide temperature range. Being odorless, Lutropur MSA can also be used in odor-sensitive applications and processors have a free choice when it comes to modifying the odor of their formulations. The most important properties for an acid, namely acid strength, odor and solubility of salts, are examined in more detail below. The toxicological and ecological aspects are covered in Chapter 4. A summary of the properties by comparison with other acids can be found in Chapter 7.

! Lutropur MSA

strong organic acid nonoxidizing easy to handle high thermal stability low vapor pressure no toxic fumes low carbon content (TOC) odorless colorless readily biodegradable hardly any contribution to COD free of nitrogen, phosphorus and halogens resistant to hydrolysis

 3.1 Physical properties

Typical values Lutropur MSA Lutropur MSA 100

Appearance (23°C) clear, colorless liquid

Melting point [°C] –5 19

Odor without

Vapor pressure at 23°C [hPa]  0.001

Density [g/cm 3] 1.35 1.8

Kinematic viscosity mpas [mm 2/s] 8.2 8.3

Boiling point [°C] >100 (1,013 hPa) 168 (10 hPa)

Solubility in g MSA/l water miscible in all proportions ethanol miscible in all proportions tetrahydrofuran miscible in all proportions dimethylsulfoxide miscible in all proportions toluene 68 n-hexane 12

No odor methanesulfonic acid as a function of temperature. The curves show that compounds with a strong odor, Lutropur MSA is odorless. Because the intensity of such as hydrochloric acid, acetic acid and formic the odor is governed primarily by the vapor pressure acid, have a high vapor pressure, as would be of a compound, vapor pressure curves provide an expected. By contrast, methanesulfonic acid is indication of the odor intensity of a substance. characterized by an extremely low vapor pressure, Figure 1 shows the vapor pressure of hydrochloric which is consistent with its lack of odor. acid, sulfuric acid, formic acid, acetic acid and

Vapor pressure [bar] 10 3

10 1

10 -1

10 -3 Hydrochloric acid 10 -5 Formic acid Acetic acid 10 -7 Methanesulfonic acid Sulfuric acid Figure 1: 10 -9 Vapor pressure curves for 0 50 100 150 200 250 300 T [°C] selected acids.

5 3. Properties

The absence of any odor means greater safety at the 3.2 Chemical properties workplace, as there are no acrid vapors. Formulators have more freedom to control the odor of their 3.2 a. Acid properties – the anion makes all products if they use MSA, which does not have any the difference inherent odor to interfere with it. As a result, MSA is preferred for use especially in high-temperature The strength of acids has a wide-ranging influence processes, e.g. in pickling baths, process cleaning on the rate at which they react. For example, when solutions or the production of biodiesel, because limestone is dissolved, the protons present in the it can be handled safely. acid solution react with the insoluble calcium carbon - ate to form carbon dioxide, water and the soluble Methanesulfonic acid is hygroscopic (cf. Chapter 6 calcium salt of the acid being used (Figure 2). Storage). This property becomes more pronounced Therefore, the more protons, i.e. active species, the as its concentration increases, and this is put to use acid used is able to supply, the greater the efficiency in industrial applications. For example, with Eaton’s of the dissolving process.

reagent (7.5% P 2O5 dissolved in MSA), water can be separated off from organic compounds without these compounds being oxidized. [4]

Ka 2 HA 2 H + + 2 A –

Insoluble – A Acid anion CaCO 3

Soluble + CO 2 + H 2O CaA 2 Figure 2:

Dissolving CaCO 3

Acid strength is defined and calculated with the help

of the law of mass action. The acidity constant K a is obtained by applying the law of mass action to the proton transfer reaction: the higher the figure for this equilibrium constant, the stronger the acid. Figure 3

shows the equilibrium constants K a of various acids on a logarithmic scale. It can be seen from the comparison that hydrochloric acid, sulfuric acid and methanesulfonic acid are much stronger acids than, for example, acetic acid, formic acid, citric acid, phosphoric acid and amidosulfonic acid.

6 Ka 1000 [H +] • [A –] K = a [HA] 10

0.1

0.001 A S M

0.00001 Figure 3: Acetic Formic Citric Phosphoric Amidosulfonic Sulfuric Hydrochloric Equilibrium constants K of acid acid acid acid acid acid acid a selected acids.

From the acidity constants, together with the law of mass action, it is possible to calculate the number of protons that are obtained from 1 mol of each acid. For instance, 1 mol of citric acid donates only 50 mmol of protons, acetic acid donates as little as 4 mmol of protons and even amidosulfonic acid only donates 270 mmol, whereas 1 mol of hydrochloric acid or methanesulfonic acid releases 1 mol of protons − i.e. active species − in aqueous solution (Table 1). This means that a lower molar concentra - tion of methanesulfonic acid is needed to release a certain number of protons than would be required if acetic acid, formic acid, phosphoric acid or amidosulfonic acid were used. Normally, users are more interested in the required mass concentration of the acid than in the molar concentration. If acids are to be compared on the basis of their mass concentrations, attention must be given not only to 1000 mmol ... releases the acid strength, but also to the molecular weight. Acetic acid 4 Formic acid 10 Citric acid 50 Phosphoric acid 80 Amidosulfonic acid 270 Methanesulfonic acid 1000 Hydrochloric acid 1000 Sulfuric acid 1095 Table 1: + Protons released by 1 mol mmol H of acid.

7 3. Properties

The molecular weight and the acid dissociation con - stant can be used to calculate the number of protons that are released from solutions with the same mass concentration. Figure 4 shows the concentrations of protons in 5% aqueous solutions of common acids. It can be seen from the diagram that only hydro- chloric acid and sulfuric acid release more protons than methanesulfonic acid at a concentration of 5%. All the other acids – acetic acid, formic acid, citric acid, phosphoric acid and amidosulfonic acid – Figure : provide far fewer protons at this concentration. Proton concentration and pH of 5% acids. Conversely, this means, of course, that considerably + less methanesulfonic acid pH H [mol/l] than acetic acid, formic 5% w/w acid, citric acid, phos - 2 phoric acid or 1.2 amidosulfonic acid needs to be used to obtain a certain concentration 1 of protons (a certain 0.8 pH value).

0 0.4 A S M -1 0 Acetic Formic Citric Phosphoric Amidosulfonic Sulfuric Hydrochloric acid acid acid acid acid acid acid

3.2 b. Dissolving power

To be efficient, processes often require the reaction They even dissolve more readily than many chlorides. products (salts) produced in the process to have a By contrast, the corresponding sulfates and, espe - high level of solubility. Otherwise, these salts give cially, phosphates are only very sparingly soluble. rise to deposits, which usually hamper processes. The methanesulfonates of metals such as barium, Looking at the solubilities, one can see that the salts calcium, strontium, magnesium and manganese that of methanesulfonic acid have very high solubility are formed when common precipitates are dissolved levels. are highly soluble in water. Thus, methanesulfonic acid is able to keep metallic and nonmetallic cations in solution in the form of the corresponding sulfonates without any problem − even under neutral pH conditions.

8 Ba2 + g/L Cd2 + 1200 Hg2 +

NH4 + Pb2 +

800 Zn2 + Sr2 + Figure 5: Saturation concentration of metal salts in water in g/L at 23°C [2, 3] Mn2 + 400 Ca2 +

Ni2 + 0 Ag +

Al3 + K+

Methanesulfonate + + Co2 Na Sulfate Chloride Mg2 + Cu2 + Phosphate

Sn2 + Fe2 + Li + Cations arranged according to increasing solubility of sulfates

Methanesulfonate Sulfate Chloride Phosphate Ag + 713 9 0 0 Table 2: 3+ Comparison of the solubility of Al 913 363 50 0 metal salts in water; saturation Ba 2+ 567 0 356 0 concentrations in g/L at 23°C. Ca 2+ 656 3 611 0 [2, 3] Cd 2+ 975 66 108 0 Co 2+ 630 335 502 0 Cu 2+ 56 215 655 0 Fe 2+ 690 266 626 0 Fe 3+ 502 0 919 0 Hg 2+ 707 0 65 0 K+ 736 109 288 600 Li + 79 269 397 1 Mg 2+ 378 317 78 0 Mn 2+ 89 532 518 0 Na + 716 197 326 23 NH + 737 50 271 5 Ni 2+ 665 378 568 0 Pb 2+ 1075 0 9 0 Sn 2+ 1066 305 931 0 Sr 2+ 782 0 82 0 Zn 2+ 792 536 1772 0 9 3. Properties

Cation Solubility [g/L] Bi 3+ 73 Ce 3+ 1131 Table 3: Ce + 976 Solubility of other metal Cs + 130 methanesulfonates in water at Dy 3+ 1573 23°C, saturation concentration in g/L [3] Er 3+ 153 La 3+ 1110 Nd 3+ 1069 Pr 3+ 1089 Rb + 1079 Sm 3+ 1165 Y3+ 153 Yb 3+ 972 Hydroxylammonium 722 Propylammonium 867 Dicyclohexylammonium 85

Many other salts of MSA, including rare-earth salts and compounds with nitrogenous bases, also have a remarkably high solubility (cf. Table 3). 3.2 c. Redox stability

Because of the excellent solubility of the organic and MSA is very resistant to strong oxidizing agents. inorganic methanesulfonates, methanesulfonic acid is For example, it does not react, in the presence of used in applications where this feature, combined hydrogen peroxide, nitric acid or permanganate. This with the other beneficial properties of MSA, provides means, amongst other things, that MSA can be used crucial advantages: in formulations that contain such oxidizing agents. Even in hot chromosulfuric acid, MSA is relatively all types of acid cleaning processes stable. This is also evident in the determination of electroplating the COD value, which, at about 4 mg O 2/g COD, is neutralization of active chemical and equivalent to only about 2% of the amount of oxygen pharmaceutical ingredients required theoretically for complete oxidation [6]. extractive metallurgy and mining metal recycling MSA is also resistant to strong reducing agents, such as nascent hydrogen. dissolving of rock industrial washing processes In the cyclic voltammogram this high redox stability ionic liquids can also be seen in the electrochemical stability of MSA. MSA is stable over a remarkably wide range. At about 3.8 volt, the electrochemical window (ECW) of stability is very wide (cf. Figure 6).

10 Cyclic voltammetry: 90% MSA, 10% H 2O + 1% KCl reference electrode Ag/AgCl (3M)

3.00

2.60

2.20

1.80 Oxidative MSA-decomposition 1.40 O2-formation (from Water) 1.00

0.60

0.20

-3000 -2500 -2000 -1500 -1000 -500 0.20 0 500 1000 1500 2000 2500 3000

0.60 H -formation 2 1.00 (from Water + MSA) 1.40

1.80

] 2.20 – 2 2.60

I 3.00 [ m

A U [mV] • c m

Figure 6: 3.2 d. Further chemical properties Electrochemical window of MSA Not only the redox stability of MSA, but its high level of stability generally should be highlighted. Apart from the formation of salts, MSA hardly reacts chemi - cally with anything and is therefore practically inert. That also means that, under practical conditions, no unwanted secondary reactions take place.

MSA

is not subject to hydrolysis does not undergo addition reactions does not undergo substitution reactions is stable in air to 180°C

11 . Ecological and Toxicological Aspects

! Eco-tox profile

readily biodegradable virtually VOC free low TOC Methanesulfonic acid is formed as the result of the hardly any contribution to COD photochemical oxidation of dimethylsulfide in the free of nitrogen atmosphere and is thus part of the natural sulfur free of phosphorus cycle [5]. MSA also has a lower vapor pressure free of halogens than other acids (cf. Chapter 3), which is a further advantage from the point of view of safety at work and environmental protection. Therefore − unlike carboxylic acids such as acetic acid or glycolic acid − Methanesulfonic acid is readily biodegradable it is virtually free of volatile organic compounds (VOC). according to OECD Guideline 301 A, forming carbon dioxide, sulfate, water and biomass as decomposition Further advice and information can be found in products. Of all the organic sulfonic acids, MSA is the safety data sheets for Lutropur MSA and the best choice from the environmental point of view Lutropur MSA 100. because its oxygen demand for degradation is lower than that of all other organic sulfonic acids. As a result of its high resistance to oxidation, the measured chemical oxygen demand (COD) is also well below the figure for e.g. readily oxidizable carboxylic acids such as acetic acid.

Because it contains no phosphorus, MSA, unlike phosphoric acid, does not contribute to eutrophica - tion and the associated increase in algal growth in aquatic environments. It is free of halogens and nitrogen and has a low toxicological risk potential to complete its attractive property profile.

12 5. Material Compatibility

Lutropur MSA from BASF is less corrosive than other grades of methanesulfonic acid that are available. [1]

Nonetheless, as with all strong acids, attention must be paid to the choice of suitable materials.

Corrosiveness depends to a large extent on parame - ters such as temperature and concentration. In general, it is reduced by the presence of substances such as surfactants, oils and amines, but may be increased by halogens such as chloride.

Suitable materials for use in conjunction with pure 70% methanesulfonic acid (Lutropur MSA) are: Polyethylene, Polypropylene For use with anhydrous methanesulfonic acid Selected Palatal ® grades (polyester, polystyrene resins) (Lutropur MSA 100) we recommend the following Teflon ® (PTFE) materials: Glylon ® (modified PTFE) Polyethylene, Polypropylene Glass, enamel, ceramics Teflon (PTFE) Tantalum, zirconium Glylon (modified PTFE) High-quality special steels such as Glass, enamel, ceramics • 1.4539 [904L; X1NiCrMoCu25-20-5] Tantalum, zirconium • 1.4571 [316Ti; X6CrNiMoTi17-12-2] Compatibility tests are advisable if these materials • 1.4591 [Alloy 33; X1CrNiMoCuN33-32-1), will be in contact with methanesulfonic acid for long periods.

Compared with other strong acids, methanesulfonic acid is not so corrosive: if similar quantities are used, the surface removal rates of MSA are normally many times less than those of sulfuric acid or hydrochloric acid. Because of the low vapor pressure, under normal conditions, there is no gas phase corrosion with MSA − by contrast with, for example, hydrochloric, formic or nitric acid.

The corrosiveness of strong acids such as MSA can be reduced significantly by the use of suitable corrosion inhibitors. We would be happy to advise you on suitable inhibitors for your system.

Please get in touch with us if you have any questions concerning materials.

13 6. Storage and Stability

Provided the product is stored properly in its sealed original packaging, the shelf life is at least Name Methane- sulfonic acid 24 months for Lutropur MSA

9 months for Lutropur MSA 100 Formula CH 3SO 3H Acid strength -1.9

pK S1, 2, 3 Methanesulfonic acid is hygroscopic. Storage tanks and packing units must therefore be sealed tightly Number of acid protons 1 and filled with dry protective gas. Irrespective of the Molar mass [g/mol] 96.107 precise content of the concentrated acid solution, its concentration in an open container at 23°C and COD [mg/g]  55% relative humidity is about 49% (cf. Figure 7). Solubility in water [g/L] ∞

Qualitative relative data

Vapor pressure ++

Mass gain [%] Odor ++ 120 Corrosiveness 0

100 Reducibility ++ Resistance to oxidizing ++ 80 agents MSA 100% Stability in aqueous MSA 70% ++ 60 medium

Solubility of salt ++ 40 Temperature stability ++

20 Stability in storage ++

0 Biodegradability ++ 0 10 20 30 40 50 Hours TOC 0

VOC ++

Figure 7: Hygroscopic properties of MSA

When Lutropur, especially Lutropur MSA 100, is being taken out of containers, care must be taken to ensure that only stable materials are used and that no contamination (even in minute quantities) of the product takes place. Otherwise, the product may take on a dark color, though the properties in general will remain unaffected.

1 7. Comparative Table of Acids

Sulfuric Hydro - Nitric Phos- Formic Acetic Citric Sulfamic p-tolue - Glycolic Fluoro- Oxalic acid chloric acid phoric acid acid acid acid nesulfo - acid boric acid acid acid nic acid acid

H2SO 4 HCl HNO 3 H3PO 4 HCOOH CH 3COOH C6H8O7 NH 2SO 3H C7H7SO 3H C2H4O3 HBF 4 C2H2O4 -3 -6.0 -1.3 2.0 3.82 .76 3.09 1.0 0.7 3.82 -0. 1.23 +1.9 6.8 .75 .19 12.5 5.1

2 1 1 1 1 1 2 1 1 1 1 2

98.08 36.61 63.013 97.995 6.026 60.053 192.125 97.095 172.205 76.052 87.813 90.036

na na na na 1 1091 665 na 758 800 na 208

∞ 85 ∞ ∞ ∞ ∞ 605 17 700 1000 600 95

++ – – 0 ++ – – – – ++ ++ ++ + ++ ++

++ – – – ++ – – – ++ 0 ++ + ++ ++

– – – – 0 + + + 0 0 + – – 0

0 ++ – – ++ ++ ++ ++ ++ ++ + ++ +

++ 0 ++ ++ – – 0 – 0 + – + +

++ ++ ++ ++ ++ ++ ++ – – ++ ++ ++ ++

– – ++ ++ – – ++ ++ – ++ 0 – + – –

++ – – ++ 0 + 0 + 0 + – – 0

++ ++ ++ ++ ++ ++ 0 – – + + + ++

na na na na ++ ++ ++ na – – ++ na –

na na na na 0 – – – na – – – na –

++ ++ ++ ++ – – – – ++ ++ ++ – – ++ – –

na = not applicable ++ very beneficial +. 0. –. – – unfavorable

15 8. Advantages

The unique property profile of MSA becomes espe - cially evident in a direct comparison with other acids. The advantageous properties of MSA can be read off directly from the table. Reasons to choose MSA!

Lutropur MSA ... Compared with ... High solubility of its metal salts sulfuric acid, phosphoric acid Odorless formic acid, acetic acid, hydrochloric acid Chemically stable amidosulfonic acid, glycolic acid Nonoxidizing nitric acid, sulfuric acid Less corrosive hydrochloric acid, sulfuric acid, nitric acid Unlimited solubility in water amidosulfonic acid Virtually free of VOCs formic acid, acetic acid, glycolic acid Free of phosphorus phosphoric acid Free of nitrogen nitric acid, amidosulfonic acid Free of halogens hydrochloric acid, tetrafluoroboric acid Strong organic acid formic acid, acetic acid, glycolic acid, citric acid Easy to handle because liquid and odorless amidosulfonic acid, citric acid, hydrochloric acid, formic acid

9. Literature

[1] – M. Finsgar, I. Milosev, Corrosion Science, 52 [5] – S. C. Baker, D. P. Kelly, J. C. Murrell, Nature 350 (2010) 2430 - 2438 (1991) 627

[2] – T. Trella, Synthese und Charakterisierung von [6] – W. Janicke, Chemische Oxidierbarkeit organi - Methansulfonaten, Diploma degree, 2010, Heinrich scher Wasserinhaltsstoffe, Dietrich Reimer Verlag, Heine Universität Düsseldorf Berlin 1983 (WaBoLu-Berichte 1/1983)

[3] – M. D. Gernon, M. Wu, T. Buszta, P. Janney, Environmental benefits of methanesulfonic acid, Green Chemistry 1 (1999) 127-140

[4] – P. E. Eaton, G. R. Carlson, J. T. Lee, J. Org. Chem. 38 (1973), 4071

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