CS266182B1 - Process for preparing naphthalene-1,3,6-trisulfonic acid - Google Patents

Abstract

The solution relates to a method for preparing naphthalene 1,3,6-trisulfonic acid. The essence is that the reaction mixture of naphthalene monosulfonic acids, optionally in a mixture with oleum, is introduced into the present 100% sulfuric acid and optionally oleum or into the present reaction mixture obtained by trisulfonation of naphthalene and oleum so that the temperature of the resulting reaction mixture does not exceed 60 ° C. The reaction is completed by adding the remainder of the sulfonating agent and heating to a higher temperature.

Description

The invention relates to a process for the preparation of naphthalene-1,3,6-trisulfonic acid.

Previously known methods for preparing the above compound consist in monosulfonation of naphthalene at a temperature below 100 ° C, preferably around 80 ° C to give naphthalene-1-sulfonic acid, which is converted to naphthalene-2-sulfonic acid by heating to 145 ° C in multiplied in such a way that both I ζοιηΐΊ y jjioti in the out of glacial '· iis-ikční πιιιι' · <ι | present in the ratio 15:85. The reaction mixture is then cooled, diluted by the addition of 100% sulfuric acid and, at a temperature below the boiling point of sulfur dioxide, i.e. below 44 DEG C., oleum is usually added in one to three portions, each time heating the reaction mixture to react the added oil. A possible variant of this technology is the addition of oil at higher temperatures without dilution with the monohydrate, but with uncertain yields and losses of sulfur dioxide by evaporation. The disadvantage of the above process is that the introduction of the monohydrate into the naphthalenesulfonic acid reaction mixture at temperatures around 80 ° C catalyzes the conversion of naphthalene-2-sulfonic acid to naphthalene-1-sulfonic acid, thereby reducing the yield and purity of naphthalene-1,3. 6-trisulfonic acids.

These disadvantages are eliminated by the process for the preparation of naphthalene-1,3,6-trisulfonic acid according to the invention, which consists in introducing a reaction mixture of naphthalene monosulfonic acids, optionally in a mixture with oil, into the present 100% sulfuric acid and optionally oil or into the present reaction mixture. of the mixture obtained by trisulfonation of naphthalene and oleum so that the temperature of the resulting reaction mixture does not exceed 60 ° C, after which the reaction is completed by adding the remainder of the sulfonating agent and heating to a higher temperature.

The process of the present invention avoids the undesired rearrangement of naphthalene-2-sulfonic acid to naphthalene-1-sulfonic acid, thereby increasing the yield and purity of naphthalene-1,3,6-trisulfonic acid. _v h

The following examples are provided to illustrate the invention:

Example 1

2.0 mol. of technical grade naphthalene are mixed with 3.5 mol. sulfuric acid 100% and the mixture was heated to 80 ° C over 45 minutes where it was maintained for 1 hour. Next, the temperature was raised to 145 ° C over 1 hour and maintained for one hour. The reaction mixture is transferred to a heated separator heated to 145 ° C and metered into the reactor with the present 2.5 mol. sulfuric acid 100% so that the temperature in the reactor does not exceed 60 ° C, but preferably 40 ° C. After dosing the reaction mixture, the dosing of oil in an amount of 2.8 mol is started. sulfur dioxide up to a temperature of max. 85 ° C but preferably 40 ° C. An additional 2.0 mol is added in one portion. sulfur dioxide in the form of oil and the temperature thus rises from 40 ° C to 70 to 85 ° C. The reaction mixture was heated to 150 ° C for 1.5 h and maintained at this temperature for 2.5 h. It is then cooled to 60 [deg.] C. and a further 1.26 mol are added in one portion. sulfur dioxide as oleum to complete the reaction. The whole is heated in 1.5 hours to 155-160 ° C and kept at this temperature for 1.5 hours.

Composition of the reaction mixture in the organic phase (% by weight)

-1,3,6- -1,3,7- -1,3,5-sulfones -2,6 + 2,7- -1,3,5,776,6

16.0

6.4

0.5

0.6

By working up the reaction mixture after sulfonation to the stage of 1-aminonaphthalene-8-hydroxy-3,6-disulfonic acid, the so-called H-acid, the yield of the whole chain was 44.9% th. against 41.3% th. achieved by the classical procedure with comparable quality of input raw materials.

Example 2

It is an exact replication of Example No. 1, except that a portion of the reaction mixture after dosing 1 dose of oleate from the previous operation was used instead of 100% sulfuric acid for the presentation. Yield and composition identical to Example 1.

CS 266 182 Bl 3

Example 3

After monosulfonation carried out according to the procedure of Example δ. 1, the reaction mixture is transferred to a heated separator heated to 145 ° C and metered into the reactor with the present 2.5 mol. sulfuric acid 100% at the same time as the oil so that the temperature in the reactor does not exceed 60 ° C but preferably 40 ° C. ratio ifhvkov / m 1 i «• saying nničnl> i oleem jo optional in eotém lozruozf nánndy from the ratio RS: OL = 100 8: 0 which is actually example No. 1 up to the ratio RS: OL = 100 8: 100 8 However, when dosing both components, it is desirable that the reaction mixture be at least slightly ahead of the oil. The opposite ratio, ie the lead in the dosing of olea, including the extreme case of dosing the reaction mixture into olea, on the other hand, led to a deterioration in quality and yield (IV). The most advantageous RS: OL weight ratio appears to be from 1.5 to 3: 1, which provides the best yield and quality (IV). After dosing with oil, ev. the remainder of the oleate is added either in one or two portions in the manner described in Example 1.

Composition of the reaction mixture in the organic phase (8 wt.)

-1,3,6- -1,3,7- -1,3,5-sulfones -2,6- + 2,7- -1,3,5,7-tetra

78.1 15.3 6.6 st st st

Treatment of the reaction mixture at a ratio of 1.5: 1 after sulfonation to the H-acid stage gave a yield of 46.7 8 th.

Example 4

Instead of the monohydrate, a part of the reaction mixture from the previous operation is introduced in a similar manner to Example 2. Yield and composition identical to Example No. 3.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of naphthalene 1,3,6-trisulphonic acid by monosulphonation of naphthalene at 80 ° C and heating to 145 ° C to give naphthalene-1-sulphonic acid and naphthalene-2-sulphonic acid and subsequent trisulphonation, characterized in that the monosulphonation obtained the reaction mixture of naphthalene-1-sulfonic acid and naphthalene-2-sulfonic acid, optionally in a mixture with oil, is introduced into the present 1008 sulfuric acid and optionally oil or into the present reaction mixture obtained by trisulfonation of naphthalene and oil so that the temperature of the resulting reaction mixture did not exceed 60 ° C, after which the reaction was completed by adding a sulfonating agent and heating to 155-160 ° C.