Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
  • C07C303/42—Separation; Purification; Stabilisation; Use of additives
  • C07C303/44—Separation; Purification

Definitions

• ß-naphthol In the large-scale production of. ß-naphthol is first reacted with naphthalene with sulfuric acid and the resulting ß-aphthalinsulfonic acid is subsequently converted into ß-naphthol by alkali melt (Ullmann, Enzyklopadie der techn. Chemie, 4th edition, vol. 17 (1979), pp. 115-120);
• the mixture formed in the sulfonation of naphthalene contains, in addition to the desired ⁇ -naphthalenesulfonic acid, the most important by-product also ⁇ -aphthalinsulfonic acid.
• ⁇ -aphthaline sulfonic acid the most important by-product also ⁇ -aphthalinsulfonic acid.
• This hydrolysis process can be improved by introducing steam into the sulfonation mixture.
• the naphthalene formed during hydrolysis becomes constantly removed and achieved a corresponding shift in the hydrolysis balance.
• This "steam hydrolysis” can reduce the ⁇ -acid content from approx. 5% by weight to less than 0.3% by weight. Based on the content of naphthalene monosulfonic acids, this means that the ⁇ -acid content is less than 0.5% by weight.
• steam has generally been introduced into the molten sulfonation mixture, which is either still in the sulfonation vessel or in a special hydrolysis vessel. Temperatures between 140 ° C. and 160 ° C. and steam introduction times of up to 8 hours are customary (DE-Auslegeschrift 1,080,566 and 1,167,333 and US Pat. No. 1,922,813).
• trickle column can be used successfully if the sulfonation mixture is circulated from a receiver vessel over the column and treated with steam in countercurrent.
• the invention therefore relates to a process for the hydrolysis of ⁇ -naphthalenesulfonic acid in a naphthalene-sulfonation mixture by treatment with steam, characterized in that the
• the "total amount of sulfonation mixture introduced at the top of the column” is composed of the sulfonation mixture which has not yet been treated with water vapor and which is introduced for the first time at the top of the column and the bottom effluent from the column which has already been treated with water vapor and then again added to the top.
• This total amount added at the top of the column can be easily measured, for example using a flow meter or calibrated accordingly
• the total residence time of the sulfonation mixture in the column is preferably at least 30 minutes, in particular 30 to 180 minutes.
• the total residence time can be increased by lengthening the column or by increasing the total amount of sulfonation mixture charged at the top of the column (i.e. roughly speaking, by the number of passes through the column).
• FIG. 1 The principle of the method is illustrated in FIG. 1.
• the molten sulfonation mixture is poured into the container (1) equipped with a stirrer and heating jacket and fed via line (2) to the top of the heated packed column (4) with the aid of the pump (3).
• the melt trickles down on the packing in a thin film and comes into contact with the rising water vapor, which is fed in via line (5) at the bottom of the column.
• the water vapor containing naphthalene leaves the column via line (6) and is fed to a condenser where it is condensed.
• the naphthalene is separated from the condensate water and thus recovered.
• the steam treatment in the trickle column is continued until the proportion of ⁇ -naphthalenesulfonic acid in the total content of the monosulfonic acids in the sulfonation mixture has reached the desired value, e.g. 0.4% by weight.
• the steam hydrolysis should not be continued for an unnecessarily long time, since there is always a small but undesirable hydrolysis of ⁇ -aphthaline sulfonic acid.
• An apparatus made of glass components corresponding to FIG. 1 was used for the experiment.
• a 20 liter round bottom flask served as the storage container.
• a glass tube of 80 mm diameter with packed bed was used as the trickle column; the filling height of the packing was 1 m.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (3)

• 1989
  • 1989-11-14 DE DE19893937748 patent/DE3937748A1/de not_active Withdrawn
• 1990
  • 1990-11-06 EP EP19900916743 patent/EP0500660A1/de not_active Withdrawn
  • 1990-11-06 JP JP51532890A patent/JPH05501412A/ja active Pending
  • 1990-11-06 WO PCT/EP1990/001849 patent/WO1991007383A1/de not_active Application Discontinuation
  • 1990-11-13 CS CS905603A patent/CS560390A2/cs unknown
  • 1990-11-13 CN CN 90109857 patent/CN1052476A/zh active Pending

Patent Citations (3)

Non-Patent Citations (1)

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