CS208921B1 - Manufacturing process of tensides by sulphonation,subsequent hydrolysis and neutralisation - Google Patents

Description

The invention relates to a process for the production of surfactants from higher alkenes by sulfonation, followed by hydrolysis and neutralization.

The most common surfactants (surfactants) are anionic surfactants containing sulfonate groups. Among them, the so-called olefin sulfonates, which are a mixture of surfactants containing mainly alkenesulfonates and hydroxyalkanesulfonates, usually in the form of alkali metal salts, play an important role. They have excellent application properties for use in detergents and excel in rapid and perfect biodegradability. The advantageous surfactant and detergency properties of olefin sulfonates over other structurally similar surfactants are due to the presence of double bonds. Therefore, it is important to run the production process in such a way that as much alkene sulfonates as possible are produced.

Olefinine sulfonates are prepared from higher alkenes, usually linear 1-alkenes or mixtures containing predominantly 1-alkenes with a certain proportion

2-alkyl-1-alkenes and alkenes with double bond on the internal carbons of the hydrocarbon chain (the so-called internal alkenes). In sulfonation of 1-alkenes with sulfur trioxide, the main reactions follow the scheme:

208 921____________________________________________ i The sulfonation product contains about 50% alkenesulfonic acids and 50% sultones. The sulfonation of the internal alkenes proceeds similarly, from the 2-alkyl-1-alkenes only alkenesulfonic acids are formed. (H. BAUJ MANN, W. STEIN, M. VOSS, FETTE, SEIFEN,

Anstrichmittel, 72, 247 (1970)); A. Sea, M. Nagayama, Tenside Detergents, 10, 64 (1973); H. MAAG, F. PRAUN, P. SCHOBBERL, Tenside Detergents, 12.11 (1975)).

Hydrolysis and neutralization in an alkaline medium are used to convert the sultones contained in alkene sulfonation products to sulfonates. In this process, competitive substitution reactions proceed to form hydroxyalkane sulfonates and elimination reactions give alkenesulfonates. For these reactions (A. i MOŘI, M. NAGAYAMA) a mechanism has been proposed involving SN 1 and E 1 reactions in an aqueous medium or SN 2 reactions in a strongly alkaline aqueous medium; Reaction mechanism SN 1 - E 1

R-CH-CH-CHx _Ω

I ² I ² ♦ 0Η · axis,

R - CH - CH ² - CH ² I ² o ------- s --- OH

0,

Θ

R - CH - CH - CH 2 - SO 2 2 2 3

OH

Alkaline hydrolysis of the sultones was performed for all known processes (for example: US Pat. 2,066,117; US Pat. 3,488,384; US Pat. 3,492,239; DAS 1215,695; DAS 1,217,367; DAS 1643,782; DOS 2,060,719 DOS 2,249,360; DOS 2,423,959; British Pat. 1,357,606; DM MARQUIS: Hydrocarbon Processing 47, 109 (1968)) by mixing the olefin sulfonation product with an alkali hydroxide solution at least equimolar considering

of sponge used in sulfonation. Thereafter, the mixture was heated to temperatures between 80 to 250 ° C, usually to about 150 ° C, and held at elevated temperature for the time required to hydrolyze the sultones. The resulting olefin sulfonate solution finally contained a small excess (5 to 50 mol%) of hydroxide, which was neutralized as necessary with an inorganic acid or acid product of the sulface feedstock of surfactants.

The composition of the olefin sulfonates thus formed is reported (D. M. MARQUIS, S.N. SHARMAN, R. HOUSER, W.A. SWEENEY: J. Am. Oil Chem. Soc., 43, 607 (1966) based on 53% of alkene sulfonate and 47% of hydroxyalkane sulfonates.

Acidic hydrolysis of alkene sulfonation products (DAS 1214 617; DAS 1215 695; French Pat. 1419 652; French Pat. 1419 652) has been recommended for increasing the proportion of alkenesulfonates in olefin sulfonates.

1421 804; H. BAUMANN, W. STEIN, and M. VOSS: Fette, Seifen, Anstrichmittel, 72, 247 (1970), which increases the proportion of hydrolysis elimination products, i.e. alkenesulfonic acids, to the detriment of hydroxyaicansulfonic acids. However, acid hydrolysis has a number of serious drawbacks. The products are very dark colored and odorous, the acidic reaction mixture is extremely corrosive and the conversion of sultones to sulfonic acids is incomplete.

It has now been found that it is possible to reduce the proportion of undesired hydroxyalkane sulfonates, thereby improving the product properties by a novel process for the production of surfactants by sulfonation, followed by hydrolysis and neutralization starting from either alkenes or mixtures of alkenes having carbon numbers of 8 to 22. sulfur dioxide, diluted with air or other inert gases to a concentration of 1 to 20% by volume of sulfur trioxide, whereupon sulfonation products are treated by hydrolysis and neutralization with alkali hydroxide solutions to form salts of the corresponding sulfonated products, characterized in that the reaction of acidic reaction products with alkaline hydro-; the xides are conducted with an immediate excess of alkaline; %, preferably 0 to 25 mol%, based on the sulfonate present. groups and this excess is maintained throughout! during the reaction at 85 to 210 ° C and at a water concentration of at least 45% in the reaction mixture.

The method of the invention is based on the study of the kinetics of hydrolysis of the alkene sulfonation products, in which it has now been found that the formation of dipolar ions from sultones is an equilibrium solvolytic dissociation and its equilibrium shifts in favor of dipolar ions by increasing the solvent concentration. The rate of dissociation following subsequent elimination or substitution can be greatly affected by the equilibrium dissociation position. The ratio between elimination and substitution rates depends on the instantaneous excess of alkali hydroxide. With an excess of hydroxide, the rate of substitution increases and thus the proportion of hydroxyalkane sulfonates increases.

The sulfonation itself is carried out by known, batchwise or continuous processes, in which liquid alkenes are reacted with sulfur trioxide gas with diluted air or other suitable inert gas to a concentration of 1 to 20 volume% (M. MORAK, Chemical Industry, 26/51, 296 ( 1976)).

The hydrolysis and neutralization are carried out according to the invention in such a way that the instantaneous excess of alkali hydroxide is maintained at most 50 mol% during the entire course of the reaction and this excess is based on the sulphonate groups present. It is believed that the sulfonation product contains a negligibly low proportion of free sulfuric acid or sulfur trioxide. This assumption is always justified in sulfonation with sulfur dioxide in the absence of moisture.

In the hydrolysis and neutralization batch process, the sulfonation product is mixed with an alkali hydroxide solution in an amount to neutralize the free sulfonic acids, and any excess of hydroxide above this immediately required amount is at most 50 mol%. Neutralization of the free sulfonic acids takes place immediately after mixing even immediately to form salts, i.e. sulfonates. With time; As the hydrolysis proceeds, further sulfonic acids and sultones are released. Sulfonic acids liberated: neutralized by the presence of excess alkali hydroxide. Thus, in a multi-stage process, another portion of the alkali hydroxide is added after a certain time, but in such an amount that the excess of the hydroxide is again no more than 50 mol%. Of course, the smaller the excess of hydroxide is selected, the more batches (steps) must be used to neutralize the product at the end of hydrolysis and neutralization and possibly a small excess of hydroxide is present. Smaller excess alkali hydroxides are more favorable for the properties of the final olefin sulfonate and hence also high degree processes are more advantageous in terms of product quality. As the number of stages increases, the process of approaching the most favorable case, the one-step process with the continuous addition of the alkali hydroxide solution, is followed by initially mixing the sulfonation product with an equimolecular amount of hydroxide to the free sulfone groups and then adding the necessary hydroxide continuously at consumed by the progressive hydrolysis. The hydroxide may be in excess to 50 mol% or without excess, in which case the excess is close to zero. The regulation of the hydroxide addition can be carried out according to the pH of the reaction mixture. For practical reasons, it may sometimes be more appropriate to divide

208 921 addition of hydroxide to several stages and it is preferred to take lower excesses, i.e. up to 25 mol%.

In a continuous arrangement, the hydrolysis and neutralization are preferably carried out in non-homogeneous stationary reactors in which the flow of liquid approaches a reciprocating, i.e., tubular or cascade stirred reactor, or a combination of these systems. Before entering the hydrolysis itself, the sulfonation product is again mixed with the hydroxide solution, the amount of which is determined as in the previous paragraph. Passage through the reactor or the reactor system consumes hydroxide as the hydrolysis proceeds, so additional streams of hydroxide need to be fed to other locations in the reactor. The number of sites for the hydroxide can be arbitrarily high. However, it is useful to use 2 to 6 seats. With a number of feed points higher than 6, this multistage process is already substantially close to the single-stage with continuous addition of hydroxide. The control of the process can again be carried out according to the pH of the reaction mixture, especially at advantageous low excesses of hydroxide.

For the hydrolysis and neutralization of the present invention, a temperature in the range of 85 to 210 ° C is required. Elevated temperatures reduce the formation of hydroxy compounds and are additionally necessary to achieve complete conversions of the sultones. The maximum 210 [deg.] C. is given by practical considerations in that darker products are produced at higher temperatures, and the need to use equipment at operating pressures greater than 2 MPa.

The concentration of water in the reaction mixture during hydrolysis and neutralization is also essential according to the invention. It is limited to a lower limit of 45%, because at low water concentrations the equilibrium of the solvolytic dissociation of the sultons is shifted little in favor of dipolar ions. As a result, subsequent elimination or substitution reactions have a slower rate and, in particular, complete conversion of the sultones to sulfonates cannot be achieved. Water is metered into the reaction mixture, preferably together with the alkali hydroxide, either by a separate stream in addition to the water supplied by the aqueous hydroxide solution or by one stream in an appropriately diluted hydroxide solution. It is best to operate at 45 to 70% water to give the products a sufficiently high commercial concentration, although at even higher water concentrations, the hydrolysis and neutralization process, especially in terms of speed, is more favorable.

Hydrolysis and neutralization can be followed by further processes such as final product pH adjustment or bleaching. The bleaching process by adding sodium hypochlorite solution can also be combined with hydrolysis and neutralization.

The process according to the invention has advantages over the prior art processes in particular in that a better surfactant is obtained from the same raw materials. In addition, the consumption of alkali hydroxide and mineral acid for production is less and even the final pH adjustment can be omitted from the process, or combined with hydro208 921 lysis and neutralization, using a suitable device. The improved quality of olefin sulfonate products results in improved detergency and solubility due to reduced hydroxyalkane sulfonate content. A good measure of such changes in product quality is the reduction of the Kraft point. The improved solubility carries practical advantages in the storage and transport of olefin sulfonates, as well as in the manufacture of detergents therefrom.

He did

A mixture of 1-alkenes with a mean molar mass of 228 g / mol (C ₁₅ to C ₁₈ ) at a rate of 456 g / h (2 mol) was sprayed onto the inner wall of a 6 mm internal diameter tube of 1200 mm into the continuous falling sulfation reactor. / h). In sou-; Sulfur dioxide gas diluted with air to a concentration of 3% by volume was introduced into the stream

188.8 g SO ₃ / h (2.36 mol / h). The reaction tube was maintained at 30 ° C by circulating tempered water in the reactor outer jacket. After passing through the reactor, gas was separated from the sulfonation product in a separator. It had an acid number of 1.62 mval / g and a saponification number, found at boiling for 3 hours with 0.1 N sodium hydroxide solution, of 3.30 mval / g. The sulphonation product thus contained, by neglecting the presence of the by-products and a small amount, sulfuric acid, 49% of the alkanesultones in addition to the alkenesulfonic acid. Further hydrolysis and neutralization treatment was carried out in a batch process as follows: 100 g of the sulfonation product was poured into a solution of 6.5 g of sodium hydroxide in 163 g of water with vigorous stirring at 80 ° C. The amount of hydroxide was calculated here to neutralize the free sulfonic groups from the acid value. Neutralization of the free sulfone groups to form salts, i.e. sulfonate groups, occurs upon mixing; immediately, resulting in a zero excess of hydroxide, calculated on the sulfonate groups. The reaction mixture was rapidly heated to 98 ° C and 50% sodium hydroxide solution was added dropwise to the reaction mixture at a rate such that the pH of the reaction mixture was between 6.5 and 9. The consumption of sodium hydroxide was added dropwise at 98 ° C over 5 hours. 6.7 g of 100% NaOH. The total hydroxide consumption corresponded to the consumption calculated from the saponification value of the sulfonation product. Upon further heating, the hydroxide was no longer consumed and the hydrolysis and neutralization were complete after 5 hours. The water concentration in the reaction mixture was about 60%. The obtained surfactant had an active substance content determined by a two-phase titration of 37.8% and a Kraft point (according to CSN 68 1101) between 25 and 27 ° C.

In contrast, using previously known methods, a product of inferior quality is obtained, as evidenced by the following experiment: Sulfonation of the same raw material is carried out under the conditions described above and treatment of the sulfonation product is as follows: 171 g of water with vigorous stirring at 80 ° C. The amount of hydroxide was calculated here to neutralize the free sulfone groups as well as the sulfone groups which are only released during the hydrolysis, i.e. the saponification value of the sulfonation product, and in addition a 5% excess was used. At the start of the hydrolysis, only the hydroxide is consumed to neutralize the free sulfone groups and at this point is calculated in excess of 113 mol% on the sulfonate groups. The reaction mixture was rapidly heated to 98 ° C and held at this temperature for 5 h. Then a small excess of sodium hydroxide was neutralized with sulfuric acid! A surfactant with an active substance content of 35.9% was obtained and its Kraft point was in the range of 65 to 70 ° C. When the same experiment was carried out but in addition with a reduced water content of the reaction mixture to 35%, so that only 100 g was used instead of 171 g of water, then hydrolysis was not complete even after 6 h, resulting in an unusable product.

Example 2

The sulfonation product obtained in the same manner as in Example 1 was treated as follows:

! 100 g of the sulfonation product was poured into a solution of 7.78 g of sodium hydroxide in 178 ml of water at 85 ° C in an autoclave. In this process, the free sulfone groups are neutralized to form salts, i.e. sulfonate groups, immediately. This results in a 20% immediate excess of sodium hydroxide over sulfonates. This is gradually reduced as the result of hydrolysis of the sultones to sulfonates. The reaction heat of neutralization was used to heat the reaction mixture and at the same time the content of the autoclave was heated from the beginning by electric resistance heating, so that the temperature of the reaction mixture rose to 120 ° C 1 minute after mixing. At this time, a second portion of sodium hydroxide (3.86 g) was added to the autoclave. At an instant conversion of the sultones to sulphonates of 35%, the instantaneous excess of sodium hydroxide was 10%. The contents of the autoclave were further heated so that after 2.5 minutes from the first mixing with the hydroxide, the temperature of the reaction mixture was 150 ° C.

At this time, a third portion of 2.22 g of 50% sodium hydroxide solution was added to the autoclave. When! the conversion of the sultones by 50% was an excess of hydroxide again of 10%. The temperature of the reaction mixture was further maintained at 150 ° C. After 5 minutes from the first mixing, a fourth portion of 2.96 g of 50% sodium hydroxide was added. At a 70% conversion of the sultones, the immediate excess of the hydroxide was 10%. 10 minutes after the first mixing, a fifth portion of 2.52 g of 50% sodium hydroxide was still added at 150 ° C. At a conversion of the sultones of 87%, the excess hydroxide at this point was 10%. The autoclave content was then held at 150 ° C for 15 minutes, so that the total reaction time from the first mixing was 25 minutes. Then the contents of the autoclave were rapidly cooled and reacted) the product was analyzed, ί The water concentration throughout the reaction was about 65%. The surfactant obtained had an active substance content of 34.9% by biphasic titration and a Kraft point (according to CSN 68 1101) between 23 and 26 ° C.

Claims (3)

SUBJECT A process for the preparation of surfactants by sulfonation, followed by hydrolysis and neutralization, starting either from individual alkenes or from mixtures of alkenes having a carbon number of 8 to 22, wherein the sulfonation is carried out with gaseous sulfur trioxide diluted with air or other inert gases to a concentration of 1 to 20 % by volume of sulfur trioxide, whereupon the sulphonation products are treated by hydrolysis and neutralization with alkali hydroxide solutions to form salts of the corresponding sulphonated products, characterized in that the reactions of the acid reaction products of sulphonation with alkali hydroxides are conducted with an immediate excess of alkali hydroxide of at most 50 mol%, VYNALEZU 208 921, preferably 0 to 25 mol%, calculated on the sulphonate groups just present, and this excess is maintained at 85 to 85% throughout the course of the reaction. 210 ° C and at a water concentration of at least 45% in the reaction mixture. 2. The process according to claim 1, wherein the reaction of the acidic reaction products with the alkali hydroxides is carried out in one step by continuously adding the alkali hydroxide solution. 3. The process of claim 1 wherein the reaction of the acidic reaction products with the alkali hydroxides is conducted in more than one step by successively adding the alkali hydroxide solution.