US2619490A - Acylation of diarylguanidine salts of diamino dibenzothiophenedioxide sulfonic acids - Google Patents

Description

Patented Nov. 25, 1952 ACYLATION OF DIARYLGUANIDINE SALTS OF DIAMINO 'DIBENZOTHIOPHENEDIOX- IDE SULFONIC ACIDS Hans Z. Lecher, Plainfield, and Dale R. 'Eberhart, Bound Brook, N. J., assignors to American Cyanamicl Company, New York, N. Y., a corporation of Maine No Drawing. Original application April 4, 1950,

Serial No. 153,992. Divided and this application April 26, 1951; Serial No. 223,174

'7 Claims.

The present invention relates to the acylation of aminosulfonic acids. More particularly, it is concerned with the acylation of aminosulfonic acids of the dibenzothiophenedioxide series. Specifically, this case is concerned with the acylation of diarylguanidine salts of those acids. As such this application is a division of our application for United States Letters Patent, Serial No. 153,992, filed April l, 1950.

Many of these compounds possess marked fluorescent properties and are particularly useful to overcome the yellowish cast which is caused by various factors in many diiierent white materials, especially cellulosic fabrics. These compounds, however, are not claimed per se in the present application. They form in part the subject matter of the copending applications of Scalera and Eberhart for United States Letters Patent, Serial No. 45,425, filed August 20, 1948; and Serial No. 168,392, filed June 15, 1950.

Despite their desirability in use, the commercial exploitation of these materials has been hampered by the lack of a generally suitable acylation method of preparing them. It has been found that the known methods of acylation are not suitable for industrial development when an attempt is made to apply them to these materials. Many difiiculties are encountered.

For example, while many amino compounds are readily acylated with acid halides in aqueous solution, 3,7-diaminodibenzothiophenedioxide-2,3-disulfonic acid, cannot be acylated at all in this way. Attempted reaction gives little or none of the desired product, the acid halide instead being mostly destroyed by hydrolysis. In still other cases, where the halide may not be quite so sensitive, and is not destroyed so rapidly or completely, the results are unsatisfactory for other reasons.

Non-polar organic solvents have been used successfully in many similar types of acylations. However, they have not been utilized with these aminosulfonic acids. Neither the free acids nor their metal salts can be satisfactorily acylated in an organic medium. Their solubility is too low. Further, the amino groups of the free acid are rendered comparatively inert to acylation under these conditions. This appears to be due to association With the sulionic acid groups in Zwitter ion form which appears to resist the action of the acyl halide.

If these difficulties could be successfully overcome, there would exist a demand for both the successful procedure and its products. It is,

therefore, the principal object of the present invention to devise an acylation method suitable for use with these compounds for which the known procedures were not satisfactory.

In general, the object of the present invention has been accomplished by carrying out the reac tion in a non-polar solvent with certain organic base salts of the amino sulfonic acids. In view of the difliculties encountered in the past, the effectiveness of the process of the present invention is particularly surprising, especially with those compounds, such as alkoxy-substituted benzoyl halides, that are exceptionally dificult to use because of their unusual sensitivity. In all cases, the products are obtained in satisfactory quality and yield.

The use of these organic base salts, in place of the free acids or their alkali metal salts, apparently has the effect of breaking up the stable Zwitter ion structure of the aminosulfonic acid, and of enhancing the solubility in the solvent. In any case, the desired acylation is accomplished by converting the aminosulfonic acid to its salt with the organic base and treating the resultant salt with the acyl halide in a non-polar solvent.

In accordance with the present invention, symmetrical diaryl guanidines have been found very suitable for this salt formation. They readily form well-defined crystallizable salts with the dibenzothiophene dioxide aminosulfonic acids of the present invention. These salts are smoothly acylated in organic solvents. After acylaticn is complete, the reaction mixture is made alkaline, breaking down the diaryl guanidine salt of the product. A particularly useful solvent is nitrobenzene, permitting an easy recovery of both the reaction product and the diarylguanidine. The reaction product is made alkaline with an organic alkali salt, for example sodium acetate, potassium propionate, sodium ethylate, sodium phenoxide, sodium lactate, potassium p-chlorophenoxide, and the like. The nitrobenzene retains the diaryl guanidine in solution and permits its removal with the organic solvent; the acylated sulfonic acid is out of solution as the alkali salt and can be isolated by known methods.

While .a wide variety of aminosulfonic acids may be acylated by the method of the present invention, it is particularly applicable to the aminosulfonic acids of the dibenzothiophene series, such as 3,7-diarninodibenzothiophenedioxide-2,8-disulionic acid and its alkyl and chloro derivatives.

A wide variety of symmetrical diaryl substituted guanidines can be used successfully in the process of the present invention. Among these may be included diphenylguanidine, phenyl-opresent invention. It is essential that they have solvent action on the product and that they be stable to the reactants. In general, organic solvents boiling above about 120 degrees C. are to be preferred. Suitable solvents include both aliphatic and aromatic hydrocarbons and their halogeno and nitro derivatives, as well as esters, ethers, and ketones. By way of specific example, the following solvents are effective: monoand dichlorobenzene and the chlorotoluenes; the xylenes; nitrobenzene and the nitrotoluenes; cymene, acetylene tetrachloride, acetophenone, cyclohexanone, and anisole.

It is an advantage of the present invention that the salts can be prepared by any suitable method. For example, the aminosulfonic acid can be dissolved in water, neutralized, and treated in aqueous solution with a soluble salt of the guanidine. The desired salt crystallizes directly from the solution. It is not necessary for the purpose of this invention that the salt be strictly pure or dry. It is dispersed in the selected organic solvent. A convenient practice at this point is to remove any water present by distilling a part of the solvent. Acylation is then readily efiected by adding the acyl halide to the mixture.

A suitable acyl halide may be selected from a wide variety of aliphatic and aromatic carboxylic acids. These include, for example, benzoyl chloride and its alkylated, nitrated, and halogenated derivatives; butyryl chloride, ethanesulfonyl chloride, chloroacetyl chloride, crotonyl chloride, propionyl bromide, p-toluenesulfonyl chloride, thiophene-Z-carboxylic acid chloride, alphanaphthoyl chloride, 2-hydroxy-3-naphthoyl chloride, benzoyl bromide, nicotinyl chloride and acetylsulfanilyl chloride, as well as such bifunctional compounds as terephthaloyl chloride, succinoyl chloride, and adipoyl chloride. As has been mentioned, the process of the present invention is particularly useful in utilizing the acid chlorides of alkoxy-substituted benzoic acids, such as the isomeric anisoyl chlorides, o-ethoxybenzoyl chloride, o-propyloxybenzoyl chloride, and 2,4- and 2,5-dimethoxy benzoyl chlorides.

Example 1 NaSO3 SOaNa C5l OONH- S NHCOC@H5 On A solution is prepared from 26.3 parts of di-otolylguanidine, 11.9 parts of concentrated hydrochloric acid, and water to the volume of 200 parts of water. This is slowly added to a solution prepared by adding 20.3 parts of 3,7-diaminodibenzothiophenedioxide 2,8-disulfonic acid to 100 parts of water, neutralizing with 5 N sodium hydroxide solution, and diluting to the volume of 200 parts of water. The salt which crystallizes out is filtered, washed, and dried.

NaSOz- A mixture of 7.2 parts of benzoyl chloride, 50 parts of chlorobenzene, and 4.4 parts of the above prepared di-o-tolylguanidine salt is gradually heated. Condensation begins at about degrees C., as evidenced by hydrogen chloride evolution, and is complete at reflux. The reaction mixture is then cooled, and neutralized by the addition of 11.3 parts of phenol in 29 parts of 5 N sodium hydroxide solution. The product is stirred, filtered and washed with nitrobenzene. It is then slurried in water and salt, boiled to remove traces of nitrobenzene, cooled, filtered, washed and dried.

The di-o-tolylguanidine is retained in the nitrobenzene solution and is readily recovered for re-use by steam distillation to remove the nitrobenzene.

Example 2 NaSOa- SO3I\'u CGHSCHZCHCONH- NHCOCH=CHC5H5 A mixture of 24 parts of nitrobenzene and 4.4 parts of the di-o-tolylguanidine salt, prepared as described in Example 1, is heated to 120 degrees C. and treated with 2.5 parts of cinnamoyl chloride. The mixture is then heated further to degrees C. to complete the reaction, cooled to 85 degrees C., and treated with a solution of 1.9 parts of phenol in 5 parts of 5 N sodium hydroxide. The resulting bright yellow precipitate is filtered, washed with nitrobenzene and acetone and dried.

Example 3 The di-o-tolylguanidine salt of 3,7-diaminodibenzothiophenedioxide 2,8-disulfonic acid is prepared according to the procedure described in Example 1. This salt (8.8 parts) is heated at degrees C. in 48 parts of nitrobenzene with 8.3 parts of 2,4-diethoxybenzoyl chloride until a test for primary amino groups becomes negative. The resulting mixture is treated at 148-50 degrees C. with 8.0 parts of finely powdered anhydrous sodium acetate. After being stirred approximately two hours at this temperature, the mixture is cooled, filtered, and washed with 48 parts of nitrobenzene. The product is slurried in water, freed of nitrobenzene by steaming, filtered and dried.

Example 4 The acylation reaction of Example 3 is repeated. The reacted mixture is cooled to 70 degrees 80 degrees C. and treated with a solution of eight parts of 5 N sodium hydroxide solution in eight parts of alcohol. The rest of the product is worked up as in Example 3, and results in an excellent yield of very pure product.

Example 5 Example 3 is repeated substituting for the di-o-tolylguanidine salt in that procedure 8.5 parts of the corresponding diphenylguanidine salt, prepared by adding an aqueous solution of diphenylguanidine hydrochloride to the sodium salt of 3,'7-diaminodibenzothiophenedioxide 2,8- disulfonic acid. On working up the product as in Example 3 an excellent yield of suitably pure product is obtained.

Example 6 SOaNa 6 A solution of 20.7 parts of p-hydroxybenzoic stituting aniline for morpholine in the above acid in 100 parts of water containing 12 parts of procedure. sodium hydroxide, is gradually treated at 25 While the foregoing examples produce sodium degrees C. with 84.4 parts of p-toluenesulfonyl salts rather than free acids, this does not interchloride. Alkalinity is maintained by the simul- 5 fere with utilization of the product. The salts taneous addition of approximately 2.4 additional may be converted to the acids and vice versa by parts of sodium hydroxide. The product is then any or" the usual methods. The other alkali precipitated with acetic acid, filtered, washed, metal and ammonium salts may be prepared and dried at 60 degrees C. 5.8 parts of the from the acid. In any case, since the compounds p-tosyloxybenzoic acid, thus prepared is con- 10 will be most often employed with soap or other verted to acid chloride in the usual way with 3.6 alkaline materials, it makes little diiference parts of thionyl chloride. Excess thionyl chloride whether a salt or the acid is the starting mateis removed in a stream of air. 2.5 parts of the rial, since the free acid will probably be conresulting acid chloride is added at 80 degrees C. verted to a salt in that use.

to 12 parts of nitrobenzene containing 2.2 parts 5 We claim:

of he di-0 1y e n Salt prepared as in 1. The method of acylating a sulfonic acid Example 1. The reaction is completed at 240 of 3,7-diaminodibenzothiophenedioxide, which degrees C., the mixture then being cooled to 75 comprises heating a mixture comprising a symdegrees C. and neutralized with a solution of metrical-diarylguanidine salt of the selected 0.59% part of phenol in 2 parts of 5 N sodium aminosulfonic acid, an acid halide, and an inert hydroxide solution. The product is filtered, organic solvent. washed with nitrobenzene followed by acetone, 2. A process according to claim 1 in which, and dried at 110 degrees C. after completion of the reaction, the product is Example 7 NaSO3 some ooNn- \S/ -NH( :0 02

0 CH3 o CH3 15.2 parts of p-anisic acid is added gradually precipitated by treatment with an alkalineto 58 parts of chlorosulfonic acid at 5-11 degrees reacting organic metal salt. C. After one-half hour the mixture is gradually 3. A process according to claim 1 in which the warmed to '75 degrees C. and maintained at this organic solvent is nitrobenzene. temperature one hour. It is then cooled, drowned 40 4. A process according to claim 1 in which the in ice, and filtered. 2.9 parts of the resulting symmetrical diarylguanidine is symmetrical sulfonyl chloride is treated with 8 parts of mordiphenylguanidine. pholine. The reaction mixture is slowly treated 5. A process according to claim 1 in which the with 5 N sodium hydroxide, the temperature acid halide is an aroyl chloride. rising to 25 degrees C. After acidification with 6. A process according to claim 5 in which the hydrochloric acid, the 2-methoxy-5-carboxyaroyl chloride is an alkoxy-substituted benzoyl benzene sulfonyl morpholine is filtered. It melts chloride. at 218-219 degrees C. 7. A process according to claim 1 in which the 2.6 parts of this product is converted to the symmetrical diarylguanidine is symmetrical dicorresponding carboxylic acid chloride by treato-tolylguanidine. ment with 1.6 parts of thionyl chloride, in the HANS Z. LECHER. usual manner. This is then added to a mixture DALE R. EBERHART. of 12 parts of nitrobenzene and 2.2 parts of the di-o-tolylguanidine salt prepared in Example 1. REFERENCES $171733 After twenty minutes at 14.0 degrees-145 degre The following references are of record in the C., the mixture is treated with a solution of 0.9 m of t patent:

part of phenol in 2 parts of 5 N sodium hydroxide, m I

with immediate formation of a yellow precipitate. UNITED STALES PATENTS The product is filtered hot, washed with nitro- Number Name Date benzene followed by acetone, and dried. 50 2,563,493 Scalera Aug. 7, 1951 The analogous disulfonanilide, which has sim- 2,563,795 Scalera Aug. '7, 1951 ilar properties, is obtained in a similar Way, sub-

Claims (1)

1. THE METHOD OF ACYLATING A SULFONIC ACID OF 3,7-DIAMINODIBENZOTHIOPHENEDIOXIDE, WHICH COMPRISES HEATING A MIXTURE COMPRISING A SYMMETRICAL-DIARYLGUANIDINE SALT OF THE SELECTED AMINOSULFONIC ACID, AN ACID HALIDE, AND AN INERT ORGANIC SOLVENT