2,798,090 United States Patent Office Patented July 2, 1957 1. 2. A particular feature of our invention is that nitro ; benzene can be sulfonated to meta-nitrobenzene sulfonic 2,798,090 acid and the meta-nitrobenzene sulfonic acid thus formed PROCESS FOR PRE PARNG BENZALANILENE-3- is used without isolation from its reaction mixture in the SULEONCACED COMP8UNDS preparation of the benzalaniline-3-sulfonic acid com Max W. Krell and Flaven E. Johnson, Kingsport, Texin, pounds. This is a big improvement over the hydrochloric assignors to Eastman Kodak CoEspany, Rochester, acid process wherein meta-nitrobenzene, sulfonic acid is N.Y., a corporation of New Jersey formed by sulfonating nitrobenzene with sulfuric acid, isolated from its reaction mixture, and then reacted with No Drawing. Application March 2, 1953, O formaldehyde and an aniline compound in the presence Serial No. 339,923 of hydrochloric acid in that the meta-nitrobenzene sui fonic acid does not have to be separately recovered and 12 Claims. (C. 260-509) the sulfuric acid present in the sulfonation operation supplies the sulfuric acid used in the reaction between This invention relates to an improved process for pre 15 the aniline compound, formaldehyde and meta-nitro paring benzalaniline-3-sulfonic acid compounds which in benzene sulfonic acid. Additionally, the advantages their free acid form have the formula: above enumerated with respect to better yields, lower (I) R costs and reduced corrosion are also obtained. The reaction between the aniline compound, formalde / 20 hyde and meta-nitrobenzene Sulfonic acid in the presence R of sulfuric acid and iron is preferably carried out at a SOs temperature of from 5 C. to 35° C. A temperature of wherein X stands for a monocyclic aryl nucleus of the from about 16° C. to about 20° C. appears to be espe benzene series and R and R1 each represents an alkyl cially advantageous. Similarly, the iron is preferably group, a hydroxyalkyl group or an alkoxyalkyl group and 25 added as fast as foaming and temperature control will wherein the group permit and preferably should not take over 3 hours. R Following the conditions just set forth, product yields of Y 80% or more are normally obtained. The reaction has been carried out at temperatures as low as 0° C. and as 30 high as 50 C. with the addition of iron taking up to 8 stands in para position to the hours but conditions falling outside the preferred range B ordinarily give much inferior results to those obtained -C=N grouping - when the prefered conditions are employed. grouping. The aryl nucleus X may be substituted by substituents It is an object of this invention to provide an improved 35 such as, for example, the methyl group, the ethyl group, process for preparing benzalaniline-3-sulfonic acid.com a methoxy group, an ethoxy group, a chlorine atom or a pounds having the formula above given, whereby these bromine atom. Illustrative of the alkyl groups repre compounds are efficiently and economically prepared in sented by R and R1 are the methyl, the ethyl, the n-propyi, good yield. A particular object is to provide a new and the isopropyl and the n-butyl groups. Illustrative of the improved process for preparing said benzalaniline-3- 40 hydroxyalkyl groups represented by R and R1 are the sulfonic acid compounds using nitrobenzene as a starting (3-hydroxyethyl group, the 6-hydroxypropyl group, the compound. y-hydroxypropyl group, the 6, y-dihydroxypropyl group 4'-(ethylg-hydroxyethyl)aminobenzalaniline-3-sulfonic and the 8-hydroxybutyl group. Similarly, the 3-methoxy acid, 4'-(butyl, 6-hydroxyethyl)aminobenzalaniline-3- ethyl and the 3-ethoxyethyl groups are illustrative of the sulfonic acid and 4'-(butyl, p-hydroxyethyl)amino-2'- 45 alkoxyalkyl groups R and R1 represent. methylbenzalaniline-3-sulfonic acid have been prepared Illustrative of the aniline compounds having the by reacting N-ethyl-N-3-hydroxyethylaniline, N-butyl-N- formula numbered II are N,N-di-3-hydroxyethylaniline, B-hydroxyethylaniline and N-butyl-N-(3-hydroxyethyl-m- N,N-di-3-hydroxyethyl-m-toluidine, N,N-di- (3-hydroxy toluidine, respectively, with formaldehyde and sodium ethyl- m - ethylaniline, N-ethyl-N-3-hydroxyethylaniline, meta-nitrobenzene, sulfonate in the presence of hydro N,N-dimethylaniline, N,N-diethylaniline, N,N-di-n- chloric acid and iron. Dippy, Hogarth, Watson and propylaniline, N,N-di-n-butylaniline, N,N-di-6-methoxy Williams, J.Soc. Chem. Ind., vol. 56, pages. 346T-348T ethylaniline, N,N-di-g-ethoxyethylaniline, N,N-di-3-hy (1937). ... droxyethyl-m-chloroaniline, N,N-di- (3-hydroxyethyl-m- We have discovered that the benzalaniline-3-sulfonic methoxyaniline, N-ethyl-N-3-hydroxyethyl-m-toluidine, acid compounds having the formula numbered. I can be 55 N-6-hydroxyethyl-N-(3-ethoxyethylaniline, N-n-butyl-N-6- prepared by reacting aniline compounds having the -hydroxyethylaniline, N-ethyl-N-y-hydroxypropylaniline, formula: N-ethyl-N-8-hydroxybutylaniline, N-ethyl- N - 6,y-dihy droxypropylaniline, N-n-propyl-N-6, y-dihydroxypropyl (II) R m-toluidine, N,N-di-3, y-dihydroxypropyl-m-toluidine, N 60 methyl-N-6-hydroxyethyl-m-toluidine, N,N-di-6-hydroxy ethyl-m-bromoaniline, N,N-di-y-hydroxypropyl-m-bromo wherein X, R and R1 have the meaning previously as aniline and N,N-di-3-hydroxybutyl-m-chloroaniline. signed to them with formaldehyde and meta-nitrobenzene "The following examples, in which parts are expressed sulfonic acid in the presence of sulfuric acid. and iron. 65 as parts by weight, illustrate the process of our invention. The aniline compound is not substituted in the para position to the amino group. The use of Sulfuric acid Example 1 in place of hydrochloric acid gives. much better yields 123 parts of nitrobenzene, were slowly, added, with and results in much lower costs for producing these good agitation to. 460 parts of 20% oleum at 50° C. By products. Additionally, the use of sulfuric acid rather 70 the time addition of the nitrobenzene was complete the than hydrochloric acid considerably reduces the problem temperature of the reaction mixture had risen to 75, C.- of corrosion. 80° C. Following the addition of the nitrobenzene the 2,798,090 3 4 reaction mixture was heated very slowly to 95 C. and reaction mixture was stirred for four hours at 16 C-20 maintained at 95 C. for two hours after which it was C. and then filtered after decanting the reaction mixture allowed to cool to room temperature. from any unreacted iron. The product, 4'-(di-6-hydroxy 214 parts of the meta-nitrobenzene sulfonic acid re ethylamino)-2'-chlorobenzalaniline-3-sulfonic acid was re action mixture prepared as described above were added covered on the filter as an orange solid. It was washed to 545 parts of water and then 49 parts of N,N-di-6- well with water and dried. 77 parts (80% yield) of hydroxyethyl-m-toluidine were dissolved in the resulting dried product were obtained. mixture. The reaction mixture thus obtained was cooled The benzalaniline-3-sulfonic acid compounds set forth to 20 C. and 27 parts of 36% aqueous formaldehyde in the tabulation given hereinafter are likewise readily were added thereto. 56 parts of iron filings were then O prepared in accordance with the process of our invention added to the reaction mixture during approximately two using the procedure described hereinbefore. In each case hours while maintaining the temperature between 16° C. the benzalaniline-3-sulfonic acid compound and the ani and 20 C. After the iron addition was complete, the line compound from which it is prepared is given. reaction mixture was stirred for four hours at 16° C.- 20 C. and then filtered after decanting the reaction mix 15 Benzalaniline-3-Sulfonic Acid Compound Aniline Compound ture from any unreacted iron. 4'-(di-3-hydroxyethyl amino)-2'-methylbenzalaniline-3-sulfonic acid having the 6. 4 - (di- 6 - hydroxyethylamino)-2'- N,N- d - 3 - hydroxyethyl methoxybenzalaniline-3-sulfonic acid. n-methoxyaniline. formula: 7. 4 - (di-g-hydroxyethylamino)-2'- N,N-di- 3-hydroxyethyl ethoxybenzaaniline-3-sulfonic acid. m-ethoxyaniline. HOCH, CH, 8. 4- (di- 3-hydroxyethylamino)-2'- N,N-di- 6 - hydroxyethyl 20 ethylbenzalaniline-3-sulfonic acid. methylaniline. 9. 4 - (dinnethylamino) benzalaailine-3- N,N-dimethylaniline. - / sulfonic acid. - HOCC 10. 4.- (dimethylamino)-2-methylben N,N-dimethylamino - m - CE SOE zal-aniline-3-sulfonic acid. toluidine. 1. 4 - (diethylamino)-2-methylben - N,N - diethylamino - m was recovered as an orange solid, washed well with water za-aniline-3-sulfonic acid. toluidine. and dried. 85.5 parts (90% yield) of dried product were 25 12. 4 - (di-n - propylamino) benzalani N,N-di-n-propylaniline. line-3-sulfonic acid. obtained, 13. 4- (di-n - butylamino) benzalani N,N-di-n-butylaniline. Example 2 line-3-sulfonic acid. 4. 4- (di- 3-methoxyethylamino)-2'- N,N-di- B - methoxyethyl By use of 45 parts of N,N-di-3-hydroxyethylaniline in methylbenzalaniline-3-sulfonic acid. m-toluidine, 15. 4.- (di-6- ethoxyethylamino) benzal N,N- di - 6 - ethoxyethyl place of N,N-di-6-hydroxyethyl-m-toluidine in Example aniline-3-sulfonic acid, aniline. 1, 81 parts (89% yield) of 4'-(dig-hydroxyethylamino)- 30 16. 4 - (ethyl, S - hydroxyethyl) annino N - ethyl - N - 3 - hydroxy benzalanine-3-sulfonic acid, ethylaniline. benzalaniline-3-sulfonic acid were obtained. 17. 4.- (n-propyl, 3-hydroxyethyl)am N-n-propyl-N-5-hydroxy inobenzalaniline-3-sulfonic acid. ethylamiline. Example 3 18. 4- (n-butyl, 3-hydroxyethyl) an N-n-butyl-N-B-hydroxy ethylaniline. Example 1 was repeated using 41 parts of N-ethyl-N- 19.ind-benzalaniline-3-sulfonic 4- (ethyl, y -hydroxypropyl)amino acid.