US2573652A

US2573652A - Acylation of aminosulfonic acids

Info

Publication number: US2573652A
Authority: US
Publication date: 1951-10-30
Anticipated expiration: 1968-10-30

Description

Patented Oct. 30., 1951 ACYLATION OF AMINOSULFONI C ACIDS OF DIBENZOTHIOPHENE Mario Scalera and Warren S. Forster,Somerville,

N. .L, assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application April 4, 1950,

Serial'No. 153,988

- 9 Claims. 1

This invention relates to the acylation of aminosulfonic acids. More particularly, it is concerned with the diacylation of diaminosulfonic acids of the dibenzothiophenedioxide series.

Many of the compounds of theftypes of the present invention are important dyestuff intermediates. Many of their a'cylated derivatives possess marked fluorescent properties, and are useful in overcoming the yellowish cast which often develops in white materials, especially cellulosic fabrics. These compounds are not claimed per se as part of the present invention, but do form in part the subject matter of the copending applications for United States Letters Patent of Scalera and Eberhart, Serial No. 45,425, filed August 20, 1943, now U. S. Patent No. 2,563,795, and Serial No. 168,392.'filed June 15, 1950, now U. S. Patent No. 2,563,493.

Despite their desirability, commercial exploitation of these materials has been hampered by the lack of a good method for theirpreparation. Although many aminosulfonic acids are readily acylated with acid halides in aqueous solution, 3,7 diaminodibenzothiophenediozids-2,8disulfonic acids cannot be satisfactorily acylated in this way. Further, the use of organic solvents proved not to be very satisfactory in this reaction, apparently because of the great insolubility of the starting material, and the inertness of the amino groups to'acylation under these conditions. Consequently the need has persisted for a simple and practical way of preparing these diacyl derivatives.

In general, the object of the present invention has been accomplished by carrying out the acylation in a non-polar solvent, on certain organic base salts of 3,7-diaminodibenzothiophenedioxide-2,8-'disulfonic acids. In view of the difficulties encountered in the past, the effectiveness of the modified process of the present invention is particularly surprising. Products of excellent quality are obtained in surprisingly high yield.

The exact cause for this surprising result is not entirely clear. While the use of the organic base appears to have the effect of breaking up the stable Zwitter ion structure of the diaminosulfonic acid, this cannot be the entire explanation. The Zwitter ion is also destroyed when the diaminosulfonic acid is dissolved in aqueous alkali, and yet such alkaline solutions cannotbe acylated, any attempt to force the reaction resulting only in the decomposition of the acid halide. It may be that steric hindrance plays a part in this great dificulty of acylation; and that this steric hindrance can only be overcome by acylation at elevated temperatures, which is made possible by the present method of operation in which there is no danger of hydrolyzing the acid chloride.

In any event, by converting the diaminosulfonic acid to its salt with the organic base, and treating the resulting salt with the acyl halide in a non-polar solvent, the desired acylation is accomplished successfully. The reaction gives excellent yields using a minimum excess of acid halide. The product is obtained substantially free from undesirable impurities. While the salt with the organic base may and perhaps preferably will be preformed, if desired it may also be formed in situ in the solvent. In the latter case, it is not certain just how far towards comple-- tion salt formation actually proceeds, but the practical results in producing the desired product are equally satisfactory.

According to the present invention, tertiary amines are particularly effective. This may be partly because they do not react with the acid halides to form stable acylated products, although they may form addition compounds. Such amines can be used to form well-defined salts with the 3,7-diaminodibenzothiophenedioxide- 2,8-disulfonic acid. These salts are smoothly acylated with aroyl halides in organic solvents.

the present invention if it is volatile with steam.

As a practical limitation, it is generally, but not always, found that if the boiling point of the amine is much above 200 C. its steam volatility is too low to give the best results in this invention. Among the suitable amines for the purpose of the present invention may be included triethylamine, pyridine, benzyldimethylamine, dimethylaniline, tripropylamine, N-ethylmorpholine, N- ethylpiperidine, cyclohexydimethylamine, diet-hylaniline, thiazole, the picolines, and the like.

A number of solvents are suitable for the acylation process of the present invention. It is essential that they be stable to the reactants. In general, organic solvents boiling above about 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 illustrative examples, the following solvents are effective: benzene, monoand dichlorobenzene and the dichlorotoluenes; the xylenes; nitrobenzene and the nitrotoluenes; cymene, benzonitrile, ethyl benzoate, acetophenone, cyclohexanone, and anisole. A wide variety of diaminodibenzothiophenedioxide sulfonic acids may be successfully acylated in accordance with the process of the present invention. Typical examples of these acids include the following: 3,7-diaminodibenzothiophenedioxide-2-sulfonic acid, 3,7 -diaminodibenzothiophenedioxide-2,8-disulfonic acid and chloro derivatives.

As has been mentioned, the process of the present invention is especially useful with acid halides, particularly chlorides of alkoxy-substituted benzoic acids. There may be one or more alkoxysubstituents, usually, but not necessarily, containing about one to four carbon atoms. Typical examples of such halides include: ;the isomeric anisoyl chlorides, o-ethoxybenzoyl chloride, o-propyloxybenzoyl chloride, and 2,4- and 2,5-dimethoxy benzoyl chlorides. Y

It is an advantage of the present invention that the salts can be prepared by any suitable method. For example, the 3,7-diaminodibenzothiophenedioxide-2,8-disulfonic acid can be dissolved in water as its alkali salt and treated in aqueous solution with the salt forming base. In many casesthe desired salt'crystallizes directly from the solution. In other cases evaporation may be necessary. It is not necessary forthe purpose of this invention that the salt be strictly pure. l 1

The organic salt is readily dispersed in the selected organic solvent. An addition of, some excess free amine is often found advantageous, however it may be a different amine from the one used for salt formation. Another desirable practice at this point is to remove any water present by distilling apart of the solvent.

As was noted above, the salt can alsobe prepared by mixing the disulfonic'acid and the organic base, either in stoichiometric amount or in excess, directly in the organic solvent. A short heating period at this stage is found usually desirable, though not always necessary. The salt will form, at least to the extent required to initiate and maintain acylation. i

In either case, acylation isthen readily effected by admixing the selected aroyl halide'and the salt, or the salt-forming mixture in the presence of the solvent. heating should be maintained until reaction substantially ceases. Reaction is very slow below about 60. C. Temperaturesjust short of those producing volatilization. of solvent and/or reactants are to be preferred. The reaction mixture can then be worked up by the usual'known cussed in conjunction with the following spe-, These are intended as illustra tive and not by way of limitation. Except as,

ciflc examples.

otherwise noted, all parts arehy weight.

Stirring and preferably, also,

and their alkyl Example 1 ON- 1Y0 or'r H r 0 02135 2 CzH Q 3,7 diaminodibenzothiophenedioxide 2,8-disulfonic acid is dissolved in dilute sulfuric acid and treated with triethylamine. The triethylamine salt crystallizes from the cold solution, and is filtered and dried. A slurry of 30.4 parts of the resulting salt in 134 parts of chlorobenzene and 30.3 parts of triethylamine is heated under reflux with stirring and to it is added during about 30 minutes 27.? parts of ortho-ethoxybenzoyl chloride. The reaction mixture is heated under reflux for four hours and then to it is added an additional portion of 30.3 parts of triethylamine and 27.7 parts of ortho-ethoxybenzoyl chloride. Refluxing andstirring are continued overnight. The chlorobenzene and tri-' ethylamine are then removed by steam distilla: tion after adding sufflcient sodium carbonate to render the mixture alkaline to brilliant yellow.

The product is isolated in excellent yield in the usual mannerby filtration, washing with 2% brine and drying.

Example 2 A slurry of 122 parts of 3,7-diaminodibenzothiophenedioxide-2,8-disulfonic' acid, 157 parts of pyridine, and 1110 partsof monochlorobenzene is heated at reflux minutes before adding a solution of 185 parts of'2A-dimethoxybenzoyl chloride in 220 partsof chlorbenzene.

resents an excellent yield of 3,7-di(2,4-dimethoxybenzoylamine) dibenzothiophenedioxide+2,8-

disulfonic acid.

Example 3 The trimethylamine salt of 3,7-dia'minodi5' benzothiophenedioxide 2,8 disulfonic acid is prepared by treatment with excess of aque ous trimethylamine solution and evaporation to dryness. The salt is acylated by heating with 2,4-diethoxybenzoyl chloride in chlorobenzene,

as described in Example 2. The mixture is then treated with soda ash and steam distilled to re- 3,7-diaminodibenzothiophenedioxide 2,8 disulfonic acid is dissolved in dilute sulfuric acid and treated with triethylamine. The triethylamine salt crystallizes from the cold solutionL 15.2 parts of the salt is slurried in 10 parts of pyridine and parts.-

and is filtered and dried.

of. chlorobenzene. After heating to reflux/the mixture is gradually treated with'20.2 parts of oephenylbenzoyl chloride. Heating and stirring are continued until acylation is complete. The resulting slurry is made alkaline with aqueous sodium carbonate and steam distilled to remove the solvents. The product is then salted out with sodium chloride, filtered, washed with brine, and dried.

Example 5 nso; solrr OON- Noo H g H 0000113 oo00m,

A mixture of 10.4 parts of pyridine, 83 parts of chlorobenzene and 10.1 parts of the tri'ethylamine salt of 3,7-diaminodibenzothiophenedioxide-2,8- disulfonic acid is heated to reflux and treated with 15.9 parts of o-carbomethoxybenzoyl chloride. product is separated, dissolved in aqueous sodium carbonate and salted out with sodium chloride. It is then filtered and dried.

I Example 6 HSOz sonar re s d H 02 H CHaO- 001% 43GB}; 50H:

'A slurry 0f 16 parts of pyridine, 110 parts'of chlorobenzene, and 15.2 parts of the triethylamine salt of 3,7-diaminodibenzothiophenedioxide-2,8-'disulfonic acid is heated to reflux and gradually treated with a solution of 18.5 parts of 2,4-dimethoxybenzoyl chloride in 22 parts of chlorobenzene.

When acylation is completed, the solid When acylation is complete,--as

gradually treated with 15.4 parts or phenoxyacetyl chloride. When acylation is complete the mixture is cooled, made alkaline with sodium carbonate, and subjected to steam distillation. The product is salted out in the usual way and filtered.

. Example 8 HS 0. SOaH NO-OC ON- NOC- CN I H H A mixture of 16 parts of pyridine, 145 parts of chlorobenzene, and 15.2 parts of the triethylamine salt of 3,7-diaminodibenzothiophenedioxide-2,8-disulfonicacid is heated to reflux and gradually treated with 16.7 parts of pcyano benzoyl chloride. After three hours of stirring and refluxing, the mixture is cooled, made alkaline with sodium carbonate solution, and subjected to steam distillation. The brightyellow product is then salted out with sodium chloride, filtered, washed with brine, and dried. It is obtained in excellent yield.

Example 9 H803 sari Example 10 HS 02 803E CsHsS 02- C ON- NO COS 02C 0H! l H 02 "H shown by the disappearance of any test for primary amino groups, the mixture is cooled, made alkaline with aqueous sodium carbonate, and subjected to steam distillation. Theproduct is then salted out by the addition of sodium chloride.

Example 7 otrrsoomo 01 S/ *i ooomoofim H 02 H A mixture of 145 parts of chlorobenzene, 16 parts of pyridine, and 15.2 parts of the triethylamine salt of 3,7-diaminodibenzothiophenediox- A slurry of 7.6 parts of the triethylamirie salt of 3,7v diaminodibenzothiophenedioxidea2,8-disulfonic acid, inlO parts of pyridine, and .225 parts of chlorobenzene, is heated to 80 C. and treated slowly with 12.7 parts of p-phenylsulfonylbenzo'yl chloride. Acylation is completed at reflux temperature, the .mixture then being treated with aqueous sodium carbonate, and steam distilled free of pyridine. The yellow product is salted out by the addition of sodium chloride, filtered, washed, and .dried.

Example 11 10.1 parts of the triethylamine salt of 3,7- diaminodibenzothiophenedioxide 2,8 disulfonic acid is slurried in 2'75 parts of chlorobenzene and ide-2,8-disulfonic acid is heated to reflux and 15 parts of pyridine and heated to reflux. To this is gradually added 10.9 parts of p-methylsulfonylbenzoyl chloride. When acylation is complete,'the mixture is treated with aqueous sodium'carbonate and steam distilled free of pyridine; The yellow product is salted out with sodium chloride and filtered and dried.

Example 12 HSO SOzH COIYT IITOC- SOzCH3 S O: H

Example 13 ceding examples. After completion of acylation, the mixture is treated with 10% sodium carbonate solution and freed of pyridine by steam distillation. The product is isolated in the ordinary manner.

We claim:

1. The method of acylating a sulfonic acid of 3,7-diaminodibenzothiophenedioxide which comprises admixing an aroyl halide and a member from the group of (a) mixtures of the selected aminosulfonic acid with a steam-volatile tertiary amine, and (b) salts of a steam-volatile tertiary amine and the selected aminosulfonic acid, in the presence of an inert organic solvent under substantially anhydrous conditions; maintaining the mixture under reaction conditions until reaction substantially ceases and isolating the reaction product.

. 7 HS 03 sm-n cH=C -soiN NS 02-6-0213 I s I A mixture of 15.2 parts of the triethylamine salt, prepared as described above, 150 parts of chlorobenzene, and 16 parts of pyridine is stirred and refluxed while being treated with 22 parts of p-toluenesulfonyl chloride. The reacting mixture is worked up in the usual manner, giving a pale green product.

Example 14 13.2 parts of thiophene-2-carboxylic acid chloride. After stirring and refluxing for three hours the mixture isworked up in the usual manner.

Q A mixture of 150 parts of chlorobenzene, 16 parts of pyridine, and 15.2 parts of the triethylamine salt prepared as described in the above examples, is stirred and refluxed while being treated with 17.2 parts of Z-naphthoyl chloride. The reaction is completed and the product worked up asrdescribed in the above examples.

Example 16' A mixture of' 10 parts of chlorobenzene, 22 parts of diaminodimethyldibenzothiophenedioxide disulfonic acid, and 100 parts of pyridine is treated with 26 parts of para anisoyl chloride and refluxed, according to the procedure of the pre- 2. The method of aroylating a sulfonic acid of 3, -diaminodibenzothiophenedioxide, which comprises admixing an aroyl halide and a mixture of the selected aminosulfonic acid and a steamvolatile tertiary amine in the presence of an inert organic solvent under substantially anhydrous conditions; maintaining the mixture under reaction conditions until reaction substantially ceases and isolatingthe reaction product 3. A process according to claim 2 in which the aminosulfonic acid is 3,7-diaminodibenzothiophenedioxide-2,8-disulfonic acid.

4. A process according to claim 2 in which the amine is' a trialkylamine.

5. A process according to claim 2 in which the amine is pyridine.

6. The method of aroylating a sulfonic acid of "3,7-diaminodibenzothiophenedioxide, which comprises admixing an aroyl halide and a salt of said aminosulfonic acid and a steam-volatile tertiary amine-in the presence of an inert organic solvent under substantially anhydrous conditions; maintaining the mixture under reaction conditions until reaction substantially ceases; and isolating the reaction product.

' 7. A process according to claim 6 in which the aminosulfonic acid is 3,7-diaminodibenzothiophenedioxide-2,8-disulfonic acid.

8. A process according to claim 6 in which the amine is a trialkylamine.

9. A process according to claim 6 in which the amine is pyridine.

MARIO SCALERA. WARREN S. FORSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,497,130 Lubs Feb. 14, 1950 2,497,131 Lubs Feb. 14, 1950

Claims

1. THE METHOD OF ACYLATING A SULFONIC ACID OF 3,7-DIAMINODIBENZOTHIOPHENEDIOXIDE WHICH COMPRISES ADMIXING AND AROYL HALIDE AND A MEMBER FROM THE GROUP OF (A) MIXTURES OF THE SELECTED AMINOSULFONIC ACID WITH A STEAM-VOLATILE TERTIARY AMINE, AND (B) SALTS OF A STEAM-VOLATILE TERTIARY AMINE AND THE SELECTED AMINOSULFONIC ACID, IN THE PRESENCE OF AN INERT ORGANIC SOLVENT UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS; MAINTAINING THE MIXTURE UNDER REACTION CONDITIONS UNTIL REACTION SUBSTANTIALLY CEASES AND ISOLATING THE REACTION PRODUCT.