DE2045087C3 - Process for the production of alkanesulphonic acids - Google Patents

Description

The invention relates to a process for the production of alkanesulfonic acids from a reaction mixture, that in the Phciosulfoxydation of alkanes with 10 to 26 carbon atoms and after separation of one major portion of unreacted alkanes has been obtained by settling.

The alkanesulfonic acids commonly used as surface-active agents are generally produced by photosulfoxidation of alkanes. The previously customary method for applying the alkanesulfonic acids involves very laborious measures to get the desired product out of a reaction product, namely by first separating a larger part of the unreacted alkane by settling from the Photosulfi xydatii .is reaction mixture, then the mixture first for the purpose of evaporation of the it contains η sulfur dioxide j <-> heated, then freed from the sulfuric acid after its concentration by heating by settling, neutralized after this treatment and finally freed from alkane by steam distillation, whereby the desired alkanesulfonic acids are obtained in the form of an alkali salt. This known method is not only cumbersome, but also poses delicate problems in the heat output phase. For example, the reaction mixture, which is occasionally concentrated by heating the sulfuric acid separation, has to be cooled on the occasion of the alkanesulphonic acid neutralization, and furthermore the steam distillation following the neutralization causes an increase in the viscosity of the reaction mixture with increasing removal of the alkane, so that for the purpose of - _{) (} , Viscosity control has to heat the mixture again, and so on.

According to the teachings of the German Offenlegungsschrift 15 18 854 largely sulfuric acid free Alkansulfonsäu- be of a Sulfoxydationsgemisch γ, reindeer gewonner by said recovered in a separator by settling aqueous phase of the reaction mixture transferred to a flash evaporator and there nichuimgesetztem by distillation of a small amount of alkane and a considerable amount of water is released. Thereupon the liquid evaporation residue (from the Schnellvep steamer) is transferred to a separator and there it is allowed to separate into two phases considerable amount of unreacted alkane (see. Example 1 of German Offenlegungsschrift 15 18 854, fourth and third from last line).

By the method known from German Offenlegungsschrift 15 18 854, the Object to be achieved, from the reaction mixture (without passing steam) a larger proportion of water to evaporate in order to concentrate the sulfuric acid contained in the reaction mixture in such a way that it later, when allowed to settle, as a lower layer in the form of a concentrated aqueous sulfuric acid solution can be separated.

The invention was based on the object, from the photosulfoxydation mixture of To win unreacted alkanes largely free alkanesulfonic acids. This task can go through do not solve the measures known from German Offenlegungsschrift 15 18 854, since the apch dem known processes obtained alkanesulfonic acids only - in a separate reaction stage - from the than Contamination present larger amounts of unreacted alkanes would have to be freed.

The subject matter of the invention is thus a method of the type described at the outset, which is characterized is. that the reaction mixture is steam-distilled and then the sulfuric acid itself removed by settling in a known manner.

Since in the process according to the invention the viscosity of the reaction mixture at the time the residual alkane is removed by steam distillation is lower than before, it can be used at a comparatively low temperature, ie usually at 80 to 250 ° C. and a pressure of 50 to 760 mm Hg column and preferably at 100 to 110 ° C and a pressure of 50 to 100 mm Hg column. carry out; In addition, the separation performance can also be increased on this occasion. In addition, this steam distillation at a comparatively lower temperature improves the color of the alkanesulfonic acids. Since one can also achieve a simultaneous separation of sulfuric acid and sulfur dioxide in the process according to the invention, the degree of heat output is improved and the calorie consumption is reduced to about ² / j of the previous requirement. Table I below gives a comparison between the process according to the invention and the known process according to DE-PS 9 10 165 with regard to the separation of the unreacted alkane on the one hand and the sulfuric acid on the other. The deposition is expediently carried out in such a way that the concentration of the sulfuric acid separated from the sulfoxidation mixture is 50 to 95, preferably 65 to 80 percent by weight.

Table I.
conditions

Separation of the unreacted
Alkane

Performance (n-AIkan g / h)
Steam consumption (in grams per
Grams n-> alkane)
Temperature (in ⁰ C)
Color (KL color in 5%
aqueous sodium sulfonate solution)

procedure
known

11th
9

150
400

26th
3

100
250

continuation

conditions

procedure
known new

Separation of the sulfuric acid

Temperature (in ⁰ C) 140-150 100

Concentration of the 65 - 70 70

different sulfuric acid

(in percent by weight)

Acid separation time 30 10

(in minutes)

Acid separation (in weight - 88 90

percent)

As already explained, one feature is the steam distillation from separating the reaction mixture.

Invention is that one gives the - after settling of the over the conditions of this distillation

Main part - remaining part of unreacted 20 information in Table II below Alkane at the same time as the sulfur dioxide

Table II

parameter

area

Minimum Maximum Optimum Reason for the limitation re.
Minimum maximum

Distillation temperature 80
(in ⁰ C)

Distillation pressure
(in mm Hg)

250 100-100

760 50-100

Concentration of the 50

after the concentration
separated sulfuric acid
(in% by weight)

95

65-80 distillation is expensive

Distillation and
Apparatus are closed
expensive

Acid deposition rate is too low

Color deterioration
in the reaction product

Distillation is expensive

Color deterioration in the reactive product

The drawing is a schematic? presentation of the System with which one can work in one embodiment of the invention.

The invention of some preferred exemplary embodiments is explained in more detail below without referring to them to be limited.

example 1

A reactor 1 was initially charged with 5 liters of an n-alkane and then via line 2 with 600 per hour! Reaction gas in the form of a sulfur dioxide-oxygen mixture in a mixing ratio of 2 to 1 volume and via line 4 or 5 filled with 401 more n-alkane and additional water every hour, and photosulfurization was caused by igniting a 100 W high pressure silver lamp. The reaction product obtained in this way was transferred through line 6 to the separator tank 7, where it was divided into unreacted n ^ alkane and a heavy mixture of 30 percent by weight sulfonic acids, 30 percent by weight water, 10 percent by weight sulfuric acid, 28 percent by weight n ^ alkane and 2 percent by weight sulfur dioxide. This heavy mixture was introduced via line 8 into the distillation tower 9 with a diameter of 5 cm and a height of 30 cm, in which with the aid of steam ^{supplied through line 10 and superheated to 150 ° C.}

- was carried out o a steam distillation at 15O ⁰ C, the tower was heated simultaneously from .außer forth. The distillate, consisting of n-alkane, water and sulfur dioxide, was transferred through line 11 to the ScheiJer.ank 12, where it was converted into water

-, -, flowed off via line 13, in n-alkane, that of the line 14 was fed, and divided into sulfur dioxide, which was removed via line 15. The one in tower 9 The remaining residue of sulfonic acids and 70 percent by weight sulfuric acid was passed through a line 16 withdrawn and transferred to the separator tank 17, in the eF see in sulfuric acid and sulfonic acid divided. The sulfonic acids produced here were fed into the neutralization tank 20 via line 18 transferred, from which the alkanesulfonates were finally queried via line 20.

In the following Table III the execution ■ conditions and the results of this experiment are compiled:

Table III

Work desk

conditions

Result

Work step conditions

Result

Separation through treated amount 26th distillation (n-alkane in g / h) Drip amount (in grams 3 per gram of n-alkane) Temperature (in ⁰ G) 150 Pressure (in mm Hg) 760 Withdrawal rate regarding 100 SO ₂ (in%) Separation of the Temperature (in ⁰ C) 150 sulfuric acid Concentration of 70

separated sulfuric acid (in percent by weight) time required for separation (in minutes)
Separation rate (in ⁵ / b) 9ö

Properties Sulphonic acid content 80

the reduced (in percent by weight)

different n-alkane content (in Ge 0.5

Sulfonic acid weight percent)

Sulfuric acid content 2.7

(in percent by weight)

Water content (in terms of 16.8

weight percent)

Sulfur dioxide content

(in percent by weight)

Color (KL color in 400

5% aqueous

Na sulfonate solution)

Example 2

Example 1 was repeated except that the steam distillation in the tower 9 was carried out at only 130 ° C with superheated to 13O ⁰ C steam and external heating and that of the effluent via conduit residue iin respect to sulfuric acid was only 65% pure.

L> iC ι ^ ϋΓΟιΐιυΐΐΓΐΐΠραυΰιιιΓι ^ ίίΓι ^ έΓι luF uicacn VcTaUCn

and the results obtained with it are shown in Table IV below.

Properties Sulphonic acid content 70

the reduced (in percent by weight)

different n-alkane content 0.5

Sulfonic acid (in percent by weight)

Sulfuric acid content 4.7

(in percent by weight)

Water content 24.8

(in percent by weight)

Only a trace of sulfur dioxide

(in percent by weight)

Color (KL color in 300

5% aqueous

Na sulfonate solution)

Example 3

Example 1 was repeated with the modification that the distillation tower was charged with ^{steam at only 100 °} C. with external heating and was kept at an internal pressure of only 50 mm Hg. The sulfuric acid flowing out of the tower was 70%.

In Table V below are the operating conditions and the results of this experiment compiled.

only trace table V

Work step

conditions

Result

Table IV

Work step

conditions

Result

Separation through
distillation

Separation of the
sulfuric acid

treated amount 22 (n-alkane in g / h)

Amount of steam (in grams 7 '$ per gram of n-alkane)

Temperature (in "C) 130

Pressure (in mm Hg) 760

Withdrawal rate with regard to 100 SO ₂ (in%)

Temperature (in "C) 130

Concentration of the separated 65 sulfuric acid (in percent by weight)

Time required for the 10 disconnection (in minutes)
Separation rate (in%) 80

Separation by treated amount 27

Distillation (n-alkane in g / h)

Amount of steam (in grams 3.5 per gram n-alkane) Temperature (in "C) 100

Pressure (in mm Hg) 100

Withdrawal rate with regard to 50 SO ₂ (in%)

Separation of the temperature (in "C) 100

Sulfuric acid Concentration of the separated 70 'sulfuric acid (in weight ^{4: 1} percent)

Time required for the 10 disconnection (in minutes)
Separation rate (in%) 90

so properties sulfonic acid content 80

the reduced (in percent by weight)

different n-alkane content 0.4

Sulfonic acid (in percent by weight)

Sulfuric acid content 2.5 (in percent by weight)

Water content (in 17.1 percent by weight)

Sulfur dioxide content only trace (in percent by weight)

Color (KL color in 300

5% aqueous
Na sulfonate solution)

Example 4

Example 1 was repeated with the modification that the distillation tower was heated to 110 ° C. from the outside Superheated steam charged and at an internal pressure

of 100 mm Hg, which came out of the tower sulfuric acid flowing off was 70%.

The following table VI shows the implementation conditions and compiled the results of this experiment,

It was first used for the purpose of removing sulfur dioxide and then again for the purpose of concentrating The sulfuric acid contained in it is heated. After removing the so concentrated sulfuric acid from it was then neutralized and then transferred to the distillation tower 9, where the steam distiller

Table VI conditions Result fdJgcndcr Weis = aufearheii; 10 subject Attempt
_ - rrv _ I- _ 11 _. conditions Result ! amount treated 27 ι was. The result of this the separation of fi-alkanes is in general terms Arbtiwsclirilt ifn-alkane in g / h) VtI compiled. Temperature (in "C) 100 Separation through Amount of steam (in grams 3.5 15th Withdrawal rate (in%) 100 distillation per gram of n-alkane)
"Temperature (in ⁰ C) 110 Temperature (in "C) 140-150 ! Pressure (in mm Hg) 100 Table VII Concentration of ab ^ 65-70 Withdrawal rate regarding 100 different sulfuric acid SO ₂ (in%) Work step (in percent by weight) Temperature Hn ° C \ 1in 20th Time required for the Ab 30th ! Concentration of the ab ίο ' SO ₂ withdrawal separation (i ι min.) different sulfuric acid by heating Separation rate (in%) 88 Ahtrp-Πηπησ eggs ! (in percent by weight) sulfuric acid treated amount
(n-alkane in g / h) 11th sulfuric acid .fceitbedarf for the Ab 10 25th concentration Temperature (in ⁰ C)
Amount of steam (in grams 150
9 separation (in minutes)
<Separation rate (\ y \ tyo * \ 90 per gram of n-alkane) ■ iril'll \ »11111 ulk \ / Na sulfonate content 60 Sulfonic acid content
l | (in percent by weight)
(Ti-alkane content 80
0.5 30th Sulfuric acid (in percent by weight) i | 'in percent by weight)
Sulfuric acid content 2.6 separation Na sulfate content 3.5 (in percent by weight) by settling (in percent by weight) properties
the ab
divorced Water content (in Ge 16.9 (Alkane) distillation
lation n-alkane content 0.5 Sulfonic acid weight percent) 35 (in percent by weight) sulfur dioxide content only trace Water content (in Ge 36 i | in percent by weight) properties weight percent)
Color (KL color in 400 color (KL color in 250 of the ab 5% aqueous ; '3% aqueous divorced Ha Su! Fonat! Ös-J ^ g> Ka sulfonate solution) 40 Sodium- Comparative example sulfonate The reaction mixture obtained according to Example 1 _β ι Jj ι · 1 sheet of drawings

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Claims (1)

90 ΩΚ7 Claim: Process for the production of alkanesulphonic acids from a reaction mixture which occurs during photosulphoxydation of alkanes with 10 to 26 carbon atoms and nsch separation of a larger part of unreacted alkanes has been obtained by settling, characterized in that the reaction mixture is steam distilled and then the sulfuric acid is known per se Way removed by settling.