Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C309/00—Sulfonic acids; Halides, esters, or anhydrides thereof

Definitions

• the invention relates to a process for the preparation of naphthalene-1-sulfonic acid and -1,5-disulfonic acid by sulfonation of naphthalene.
• naphthalene-1-sulfonic acid by sulfonating naphthalene with 96% sulfuric acid at 20 to 50 ° C and naphthalene-1,5-disulfonic acid by sulfonating naphthalene with 20% oleum at 20 to 55 ° C (Ullmanns Encyclopedia of Industrial Chemistry, Volume 12, (1960), pages 593 to 595).
• Screw machines such as can be used for the process according to the invention, are known (Herrmann, screw machines in process engineering, Springer Verlag (1972)).
• a screw machine is a device containing one or more screws and a housing enclosing the outer contour of the shafts. Snails consist of rotating shafts with webs attached to the outside in one or more screw lines. Screw machines are used to convey, mix, plasticize and / or compress substances.
• screw machines are preferably used which have a good mixing action transversely to the conveying direction and at the same time have a narrow residence time spectrum. It is particularly preferred to use a single-shaft screw kneader for the method according to the invention, the screw shaft of which carries out an axially oscillating movement in addition to the rotation, or a self-cleaning co-rotating twin-shaft screw machine which, in addition to the intermeshing screw threads, also contains mutually cleaning kneading elements with an increased mixing action compared to the screw threads.
• 1.0 to 5.0 moles of sulfur trioxide can be used per mole of naphthalene.
• naphthalene-1-sulfonic acid it is preferred to use 1.0 to 1.2, in particular 1.0 to 1.1, mol, sulfur trioxide and for the preparation of naphthalene-1,5-disulfonic acid, 2.0 to 2.4, in particular 2 , 0 to 2.1 mol, use sulfur trioxide.
• the sulfuric acid can be used in an amount of 0.4 to 5.0 moles of H 2 SO 4 per mole of naphthalene.
• Preferably 0.5 to 2.0 mol, in particular 0.5 to 0.9 mol, of H 2 SO 4 per mol of naphthalene can be used for the preparation of naphthalene-1-sulfonic acid and 0 for the preparation of naphthalene-1,5-disulfonic acid , 9 to 3.0 moles, in particular 0.9 to 1.5 moles of H 2 SO 4 , per mole of naphthalene.
• sulfuric acid can be used, for example, as concentrated sulfuric acid (monohydrate) or in a mixture with sulfur trioxide (as oleum).
• Sulfur trioxide in the form of oleum is preferably used, the content of sulfur trioxide being between 20 and 65% by weight; preference is given to using the customary about 65% oleum.
• the inventive process in the temperature range between -10 and +25 0 C is carried out, preferably in the temperature range between -5 ° and + 15 ° C. It is generally advantageous at temperatures above + 5 ° C to produce naphthalene-1,5-disulfonic acid sulfur trioxide only in an amount of 2.0 to 2.5 mol, in particular 2.0 to 2.1 mol, each Mol of naphthalene to be used, while at temperatures below + 5 ° C larger amounts of sulfur trioxide can be used. Such use of higher amounts of sulfur trioxide can be advantageous and desirable for further processing of the naphthalene-1,5-disulfonic acid obtained in the absence of water.
• screw machines In order to be able to maintain the low reaction temperature in the exothermic sulfonation reaction, screw machines are advantageously used which are equipped with appropriate cooling devices.
• naphthalene in solid form, can e.g. via a dosing screw or in liquid form via an appropriate measuring device, e.g. a dosing pump to be fed to the screw machine. It may be advantageous to cool and crystallize liquid naphthalene before feeding it to the screw machine, e.g. in a crystallizing screw.
• the first zone of the screw machine is advantageously equipped with cooling in order to cool the naphthalene to or below the selected reaction temperature.
• the selected amount of sulfuric acid is added at one or more points in the direction of conveyance of the screw machine, with sulfuric acid and naphthalene being mixed. Because of the exothermicity that occurs during the reaction, it can, as already stated, be advantageous to distribute the addition of the sulfuric acid over several sections of the screw machine, one after the other in the conveying direction, and on the other hand to provide a further cooling section after the addition of the sulfuric acid.
• sulfur trioxide is metered in in the selected amount; this metering can also be carried out at once or at several points one behind the other in the conveying direction.
• sulfur trioxide can of course already be metered in together with sulfuric acid in the section of the screw machine intended for metering in sulfuric acid and / or in the section of the screw machine provided for metering in sulfur trioxide.
• the reaction mixture is obtained as a viscous, pasty mass.
• the sulfonation mixture can then i. 1 known manner and the naphthalene-1-sulfonic acid or the naphthalene-1,5-disulfonic acid in a known manner, for example by crystallization in the form of hydrates or after addition of sodium hydroxide solution as sodium salts and then isolated (FIAT Final Report 1016 (1947 The sulfonation mixture can also be used for subsequent reactions without dilution with water or ice.
• the sulfonation is carried out in a diluent, the reaction product of the process preferably being used as the diluent.
• part of the reaction mixture is returned from the exit of the screw machine to the entrance and re-entered together with new starting material; part of the implementation product is therefore circulated.
• the recycling of the circulated reaction mixture can be carried out in a manner known per se, e.g. done by a screw conveyor.
• This particular embodiment of the process according to the invention has the advantage that the amount of sulfuric acid to be used can be kept particularly low, it is then generally between 0.5 to 3.0, preferably 0.7 to 1.5, moles per mole of naphthalene.
• sulfonations are carried out in stirred tanks, in which, however, the removal of large amounts of heat in a short time is extremely difficult due to the unfavorable ratio of the volume to the wall surface.
• either one of the reactants has to be added very slowly, so that long reaction times are necessary, or work in dilution with low concentrations of the reactants.
• sulfuric acid, liquid sulfur dioxide and chlorinated hydrocarbons are known as diluents.
• naphthalene and the naphthalenesulfonic acids are in solid form, so that a certain amount of solvent, generally sulfuric acid, is necessary; when sulfonating with sulfuric acid, this excess is necessary at the same time to absorb the water of reaction formed and to prevent excessive dilution of the sulfonating agent sulfuric acid. Since the viscosity of the reaction mixture easily becomes too high with a low solvent addition, so that sufficient mixing and thus rapid dissipation the heat of reaction to the cooled walls is no longer guaranteed, the amount of solvent can also not be too low (literature citation).
• the better possibilities of temperature control result in smaller amounts of undesirable by-products. Furthermore, the better temperature control results in advantages in the dimensioning of the cooling units and use of the cooling energy supplied.
• Naphthalene-1-sulfonic acid and -1,5-disulfonic acid are known technical intermediates.
• the sulfonic acids are composed as follows:
• reaction mixture is fed back to the inlet of the reaction screw machine via a second, double-shaft, co-rotating screw, cooled to 5 ° C., 800 mm in length, 32 mm in shaft diameter, without kneading elements.
• the sulfonic acid mixture has the following composition:
• reaction mixture consisting of approximately 72.5% naphthalenesulfonic acids, approximately 27% sulfuric acid and approximately 0.5% sulfur trioxide are removed per hour.
• the sulfonic acids are composed as follows:
• the reaction mixture drawn off at the end of the screw machine is worked up as follows: 1 kg of the reaction mixture is discharged in water or water / ice mixture, so that the temperature of the solution formed is kept at 80 to 90 ° C. The amount of water is chosen so that the resulting solution contains about 40% sulfuric acid. The hot solution is slowly cooled to 20 ° C, the resulting crystals are spun off and washed with 50% sulfuric acid.
• the washed, well-thrown off wet material contains approx. 95% naphthalene-1,5-disulfonic acid (as tetrahydrate) and approx. 5% residual moisture (as 50% sulfuric acid).
• Example 3 In contrast to Example 3, a temperature of 0 ° C. is maintained in the reaction screw and + 10 ° C. in the return screw.
• reaction mixture consisting of approx. 74% naphthalenesulfonic acids, approx. 25.5% sulfuric acid and c a. 0.5% sulfur trioxide worked up.
• the sulfonic acid mixture has the following composition:

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• 1977
  • 1977-06-22 DE DE19772728070 patent/DE2728070A1/de active Pending
• 1978
  • 1978-06-15 EP EP78100171A patent/EP0000155A1/fr not_active Withdrawn
  • 1978-06-20 IT IT7849943A patent/IT7849943A0/it unknown
  • 1978-06-20 JP JP7384378A patent/JPS549253A/ja active Pending

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