Title of Invention

PROCESS FOR THE PREPARATION OF PHENYLENE-BIS-BENZIMIDAZOLE-TETRASULPHONIC ACID DISODIUM SALT

Abstract Phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt which is largely free from impurities can be prepared by reacting o-phenylenediamine with terephthalic acid and chlorosulphonic acid in the presence of strong acids with a reaction time of 10 to 15 hours.
Full Text Process for the preparation of pheavlene-bis-bepzimidazole-tetrasulphonic acid disodiutn salt
The present invention relates to a process for the preparation of the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt which is largely free from impurities.
The preparation of the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is known per se (DE A 440 96 89). The process can be explained by the following equation:
(Figure Removed)
Phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is then carried out at a temperature of about 120°C at a reaction time of one hour. Hydrolysis in ice water is then carried out, phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt crystallizing out; the crystallizate is filtered off. The still moist crystallizate is then taken up and dissolved in an alkaline hydroxide solution, such as sodium hydroxide solution, then treated with activated carbon and heated. The activated carbon is filtered off, and the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is precipitated out by adding sulphuric acid. Drying gives pulverulent phenylene-bis-benzimidazole-telrasulphonic acid disodium salt with a purity of 99% by weight.
During the performance testing of the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt prepared in this way, it is found that the use of this product
prepared in accordance with the above process leads to unacceptable discolorations in the formulations.
A cause of the discolorations are, inter alia, diphenylamine, 3,4-diamino-benzene-sulphonic acid and 2-(4' -carboxy-phenyl)-benzirnidazole-6-sulphonic acid.
An object of the present invention is the preparation of phenylene-bis-benzimidazole-telrasulphonic acid disodium salt in high purity which, in particular, does not contain any discolouring components.
We have found a process for the preparation of phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt by reacting o-phenylenediamine with terephthalic acid and chlorosulphonic acid in the presence of strong acids, which is characterized in that the reaction time is 10 to 15 hours.
The process according to the invention gives phenylene-bis-benzimidazole-tetra-sulphonic acid disodium salt in a purity greater than 98% by weight. By-products are merely
(Figure Removed)
The by-products are safe and cause no discoloration of the phenylene-bis-benzitnidazole-tetrasulphonic acid disodium salt.
The preferred reaction time for the process according to the invention is 11 to 12 hours.
In a preferred embodiment of the process according to the invention, the phenylene-bis-benz.imidazolc-tetrasulphonic acid obtained in the reaction or after hydrolysis is, in a firs! step, dissolved in water and treated with activated carbon, which is then
separated off, and where the phenylene-bis-benzimidazole-tetrasulphonic acid di-sodium salt is precipitated out of the filtrate with sodium chloride and separated off, and, in a second step, is again dissolved in water and sodium hydroxide solution and again treated with activated carbon, which is then again separated off, where pure phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt precipitates out of the filtrate by acidification and is then optionally also purified.
The phenylene-bis-benzimidazole-tetrasulphonic acid obtained in the reaction or after hydrolysis is dissolved in the first step in water in the temperature range from 40 to
80°C, preferably 45 to 55°C.
Preference is given here to preparing a 1 to 30% by weight, particularly preferably 5 to 7% by weight, solution of phenylene-bis-benzimidazole-tetrasulphonic acid.
Activated carbon for the process according to the invention (first and second step) can be all commercially available types.
To precipitate out the sodium salt, a 1 to 15, preferably 3 to 10, equimolar amount of sodium chloride is generally added.
The phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt obtained in the first step is dissolved in the second step in water in the temperature range from 30 to 80°C, preferably from 45 to 5()°C.
Preference is given here to preparing a 5 to 25°C by weight, particularly preferably 15 to 20% by weight, solution of phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt.
The phenylcne-bis-benzimiclazole-tetrasulphonic acid disodium salt obtained in the first step is dissolved and, after treatment with and removal of the activated carbon, precipitated out by acidification to about pH 3. The acidification is preferably carried
out using hydrochloric acid. Surprisingly, the disodium salt precipitates out here as well.
The phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt obtained in the second step can be washed again with phosphoric acid in a preferred embodiment.
The process according to the invention can be carried out, for example, as follows: Sulphuric acid, lerephthalic acid and o-phenylenediamine are initially introduced and the mixture is heated to, for example, 110°C under a nitrogen atmosphere. Then, over the course of 4 h, chlorosulphonic acid is metered in at a temperature between 110 and 120°C, and then the mixture is further stirred for 12 h. The phenylene-bis-benzimidazole-tetrasulphonic acid obtained after hydrolysis is dissolved at 35-40°C in water, treated with activated carbon and stirred for about 30 min at the same temperature. The activated carbon is filtered off, and the filtrate is admixed with sodium chloride and slowly cooled to room temperature with stirring over the course of about 2 hours for precipitation. The resulting phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is then filtered off and after-washed with 5 per cent strength sodium chloride solution.
The resulting phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is again introduced into water and, for dissolution, 45 per cent strength sodium hydroxide solution is added to a pH of 5, then activated carbon is added again. The mixture is maintained at 55°C and stirred for about 2 hours. The activated carbon is separated off and the filtrate is acidified with pure hydrochloric acid to pH 3 to precipitate out the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt again. The mixture is stirred for about 2 hours and cooled to room temperature. The phenylene-bis-ben/imidazole-letrasulphonic acid disodium salt is separated off in a mariner known per sc, e.g. by filtration.
The resulting phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt can then also be washed with a 2% by weight aqueous sodium chloride solution which

1ms been adjusted to pH 3 using small amounts of phosphoric acid; drying is carried out, for example, at 140°C and 2 mbar.

then

Use of the process according to the invention gives a product which is analytically perfecl in the trace region, which is best suited for use in cosmetic formulations and does not have the discoloration disadvantages detailed in the introduction. Surprising! v, the presence of problematical trace components is prevented.
Phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt can be used as UV-A filler in cosmetic products.
Example
1 703 g of sulphuric acid, 96% are initially introduced and 232 g of terephthalic acid are intioduced, then, after the system has been flushed with nitrogen, 302 g of o-phenylenediamine are added in portions, which causes the temperature to increase to 97°C. The temperature is then increased to 1 l()°C. 2 200 g of chlorosulphonic acid are then metered in over the course of 4 h, the temperature being maintained between 110-12()°C, and, after the metered addition, the mixture is stirred for a further 12 h at said temperature.
The reactor contents are cooled to room temperature, and 4 000 g of water at 5°C are metered in over the course of 4 h, which causes the temperature to increase to about 47°C, then the mixture is after-stirred for a further 2 h and then filtered, giving 1 200 g of moist phenylene-bis-benzimidazole-tetrasulphonic acid.
This press cake is introduced into 11 000 g of water at 40°C and dissolved, then 30 g of activated carbon are added. The mixture is stirred for 30 min under nitrogen and then filtered. The filtrate is admixed at 50°C with 600 g of sodium chloride and stirred for 2 h at this temperature, the temperature being reduced to 25°C towards the end of (he stirring period; and then the mixture is filtered. The resulting product is
washed with 2 800 g of 5% by weight sodium chloride solution, giving 1 362 g of phenylene bis-benzimidazole-tetrasulphonic acid disodium salt.
The resulting phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is introduced into 4 500 g of water at 50°C and suspended (pH 2.4); then, at 50°C, 168 g of 45 pet cent strength sodium hydroxide solution is added to adjust the pH to 5 and to dissolve the product, then 30 g of activated carbon are added, the mixture is heated to 55°C and after-stirred for 2 h and filtered, the filtrate is treated with 162 g of pure hydrochioi-jc acid, then the temperature is maintained at 50°C and a pH of 3 is adjusted, the mixture is stirred for 2 h under nitrogen and cooled to 25°C; the mixture is then filtered and the filter cake is then washed with 4 000 g of 2 per cent strength sodium chloride solution which has been adjusted to pH 3 using a small amount of phosphoric acid, giving 1 155 g of the thus purified phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt.
The thus purified phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is then dried for 10 h at 140°C and 2 mbar, giving 700 g of end-product (residual moisture 2%), The resulting phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt has a purity of 98% by weight and comprises as by-products merely

(Figure Removed)
The by-products are safe and cause no discoloration of the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt.



We claim:
1. Process for the preparation of phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt by reacting o-phenylene-diamine with terephthalic acid and chlorosulphonic acid in the presence of strong acids of the kind such as herein described, characterized in that the reaction time is 10 to 15 hours, wherein the phenylene-bis-benzimidazole-tetrasulphonic acid obtained in the reaction is, in a first step, dissolved in water and treated with activated carbon, which is then separated off, and where the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt is precipitated out by adding sodium chloride and separated off and, in a second step, is again dissolved in water and again treated with activated carbon, which is then again separated off, where pure phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt precipitates out of the filtrate by acidification and is then optionally also purified.
2. Process as claimed in Claim 1, wherein the reaction time is 11 to 12 hours.
3. Process as claimed in claims 1 or 2, wherein the phenylene-bis-benzimidazole-tetrasulphonic acid obtained in the reaction is dissolved in the first step in water in the temperature range from 40 to 80°C.
4. Process as claimed in any of Claims 1 to 3, wherein the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt obtained in the first step is dissolved in the second step in water in the temperature range from 30 to 80°C.
5. Process as claimed in any of Claims 1 to 4, wherein the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt obtained in the first

step is dissolved in the second step in water and, after treatment with and removal of the activated carbon, is precipitated out by acidification to about pH 3.
6. Process as claimed in any of Claims 1 to 5, wherein the acidification in the second step is carried out with hydrochloric acid.
7. Process as claimed in any of Claims 1 to 6, wherein the phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt obtained in the second step is washed with phosphoric acid.

Documents:

846-DELNP-2003-Abstracr-(31-01-2008).pdf

846-delnp-2003-abstract.pdf

846-DELNP-2003-Claims-(03-07-2008).pdf

846-DELNP-2003-Claims-(31-01-2008).pdf

846-delnp-2003-claims.pdf

846-DELNP-2003-Correspondence-Others-(03-07-2008).pdf

846-DELNP-2003-Correspondence-Others-(19-03-2008).pdf

846-delnp-2003-correspondence-others.pdf

846-DELNP-2003-Description (Complete)-(31-01-2008).pdf

846-delnp-2003-description (complete).pdf

846-delnp-2003-description (complete)03-07-2008.pdf

846-DELNP-2003-Drawings-(31-01-2008).pdf

846-DELNP-2003-Form-1-(31-01-2008).pdf

846-delnp-2003-form-1.pdf

846-delnp-2003-form-13.pdf

846-delnp-2003-form-18.pdf

846-DELNP-2003-Form-2-(31-01-2008).pdf

846-delnp-2003-form-2.pdf

846-delnp-2003-form-3.pdf

846-delnp-2003-form-5.pdf

846-delnp-2003-form-6.pdf

846-DELNP-2003-GPA-(31-01-2008).pdf

846-delnp-2003-gpa.pdf

846-DELNP-2003-Others-Document-(19-03-2008).pdf

846-delnp-2003-pct-306.pdf

846-delnp-2003-pct-332.pdf


Patent Number 221813
Indian Patent Application Number 0846/DELNP/2003
PG Journal Number 32/2008
Publication Date 08-Aug-2008
Grant Date 07-Jul-2008
Date of Filing 30-May-2003
Name of Patentee SYMRISE GMBH & CO. KG.
Applicant Address MUHLENFELDSTRASSE 1, 37603 HOLZMINDEN, GERMANY.
Inventors:
# Inventor's Name Inventor's Address
1 RALF BERTRAM GRIMMENSTEIN 10, D-37603 HOLZMINDEN, GERMANY
2 STEPHAN HILLERS OBERE STR. 54, D-37603 HOLZMINDEN, GERMANY
3 OSKAR KOCH LISSABONSTR. 36, D-37079 GOTTINGEN, GERMANY
4 HARRY ERFURT KOHLSTELLE 2, D-37170 USLAR, GERMANY
5 GERALD REINDERS BUCHENWEG 7a, D-33154 SALZKOTTEN, GERMANY
6 ROLAND LANGNER JAHNSTR. 9, D-37639 BEVERN, GERMANY
PCT International Classification Number A61 K 7/42
PCT International Application Number PCT/EP01/13509
PCT International Filing date 2001-11-21
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 100 59 254.6 2000-11-29 Germany