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. N - ethyi - N - y - hydroxy 35 benzalaniline-3-sulfonic acid. propylaniline. f3-hydroxyethylaniline in place of N,N-di-3-hydroxyethyl 20, 4 - (ethyl, 8-hydroxybutyl) amino N- ethyl- N - 6 - hydroxy benzalaniline-3-sulfonic acid, butylaniline. m-toluidine. About 70 parts (80% yield) of 4'-(ethyl, 2.4 - (ethyl, 6-hydroxyethyl)amino N-methyl-N-B-hydroxy g-hydroxyethyl)aminobenzalaniline-3-sulfonic acid were -nethylbenzalaniline-3-sulfonic acid. ethyl-m-toluidine. obtained. 22. 4 - (di- 6 hydroxyethylamino)-2'- N,N- di - S - hydroxyethyl bromobenzalaniline-3-sulfonic acid. m-bromoaniline, Example 4 23. 4- (di-y-hydroxypropylamino)-2'- N,N-di- y -hydroxypropyl 40 bromobenzalaniline-3-sulfonic acid. n-bromoaniline. 31 parts of concentrated sulfuric acid were added to 24. 4- (di- 8-hydroxybutylamino)-2'- N,N-di- 6 - hydroxybutyl chlorobenzaaniline-3-sulfonic acid. m-chloroaniline. 374 parts of water and 49 parts of N,N-di-6-hydroxyethyl 25, 4'-(ethylf, dihydroxypropyl)am N-ethyl-N-R, y-dihydroxy m-toluidine were dissolved in the resulting mixture. The Ea 2-methylbenzaaniline-3-sulfonic propyl-m-toluidine. acid. solution thus obtained was cooled to 15° C. and 27 parts 26. 4 (ethyl, gy-dihydroxypropyl)am N-ethyl-N-6, y-dihydroxy of 36% aqueous formaldehyde were added. 247 parts 45 into-benzalaniline-3-sulfonic acid. propylaniline. 27.4- (di-3, y-dihydroxypropylamino)- N,N-di- 3,y-dihydroxy of dilute sulfuric acid were then added, the dilute acid 2-methylbenzalaniline-3-sulfonic acid. propyl-m-toluidine. - consisting of 169 parts of water and 78 parts of concen 28. 4- (n-butyl, 6,y-dihydroxypropyl)- N. n-butyl-N-6,y-dihy amino-2-methylbenzalaniline-3-sul droxypropyl-m-toluidine. trated Sulfuric acid. Next, 87.5 parts of sodium m-nitro fonic acid. 29. 4- (n-butyl, 3-hydroxyethyl) am N-n-butyl-N-B-hydroxy benzenesulfonate trihydrate were added and then 56 parts ino-2-methylbenzalaniline-3-sul ethyl-m-toluidine. of iron filings were added over a period of approximately 50 2/2 hours while maintaining the temperature of the reac fonic acid. tion mixture at 16 C.-20 C. After completion of the iron addition, 75 parts of concentrated sulfuric acid were The benzalaniline-3-sulfonic acid compounds prepared added over a period of 2% hours while still maintaining in accordance with the process of our invention are not the temperature of the reaction mixture at 16° C.-20° C. 55 broadly new. They are useful, for example, in the prep After completion of the acid addition, the reaction mix aration of methine compounds, such as those described ture was stirred for two hours at a temperature of 16 in U. S. Patents 2,583,551 and 2,583,614, issued January C-20 C., following which it was decanted to separate 29, 1952, which are valuable dyes for cellulose acetate it from unreacted iron and filtered. The product, 4'-(di textile materials. Thus, following the procedure described f3-hydroxyethylamino)-2'-methylbenzalaniline-3-sulfonic 60 in U. S. Patents 2,583,551 and 2,583,614 the benzalani acid, was recovered on the filter as an orange solid. It line-3-sulfonic acid compounds are useful, for example, Was Washed several times with cold water and dried. 76 in the preparation of methine compounds having the parts (80% yield) of dried product were obtained. formula: Example. 5 (III) R CN 65 214 parts of m-nitrobenzene sulfonic acid-sulfuric acid R?X-(D-g-g YoN prepared as described in Example 1 were added to 545 Y parts of water and then 54 parts of N,N-di-B-hydroxy ethyl-m-chloroaniline were dissolved in the resulting mix or the formula: - ture. The reaction mixture thus obtained was cooled to 70 (IV) R CN 20 C. and 27 parts of 36% aqueous formaldehyde were added thereto. 56 parts of iron filings were added to the reaction mixture over a period of approximately two R Yo O OR hours while maintaining the temperature between 16° C. R and R1 have the meaning previously assigned to them, and 20° C. After the iron addition was complete, the 5 R2 represents an alkyl group having one to four, inclusive, 2,798,090 5 6 carbon atoms, a 6-methoxyethyl group or a B-ethoxyethyl benzalaniline-3-sulfonic acid compounds prepared in ac group and Y represents a methyl group, an ethyl group, cordance with the process of our invention are used to a methoxy group, an ethoxy group, a chlorine atom or a prepare methine compounds. bromine atom. These compounds are dyes for cellulose Example 30 acetate textile materials. 5 378 parts of 4'-(di-3-hydroxyethylamino)-2'-methyl While the prior art teaches that when 4-substituted benzalaniline-3-sulfonic acid were placed in 3200 parts aminobenzalaniline-3-sulfonic acid compounds are used of water and 92 parts of sodium bicarbonate were added to prepare methine dyes the reaction should be carried thereto. The reaction mixture resulting was heated slowly out in an organic solvent such as 50% aqueous methyl to 60° C. and stirred until solution was complete. 120 alcohol, we have discovered that the reaction can be O parts of methylcyanoacetate were then added after adding carried out using water as the reaction medium. The use two parts of a Wetting agent. The reaction mixture thus of water is advantageous in that it eliminates a solvent obtained was stirred for 16 hours without heating and the recovery operation and involves, the use of a non-fam product which forms was recovered on the filter by filtra mable inert diluent rather than a flammable inert diluent. tion. The yellow crystalline product collected on the In accordance with our discovery methine compounds 5 filter was washed well with cold water and then dried. having the formula: w 252 parts (82.9% of theory) of 4-(dig-hydroxyethyl (W) G. CN amino) - 2 - methylbenzylidenemethylcyanoacetate hav ing the formula: X-x-5-cC HO CECH CN Q1 . . . . . Z . 20 H v wherein Q represents a hydrogen atom, an alkyl group, ... ." . . . . Y. 5-cC a hydroxyalkyl group or an alkoxyalkyl group, Q1 repre Hochsc?, c-OCH's sents an alkyl group, a hydroxyalkyl group or an alkoxy - - - , CE . . . alkyl group, X represents a monocyclic aryl nucleus of the benzene series and Z represents a -cyano group or a 25 were thus obtained. It melts at 148° C-150° C. -COOR2 group, wherein R2 represents an alkyl group Example 31 having one to four, inclusive, carbonatoms, a 3-methoxy By the use of 364 parts of 4'-(di-3-hydroxyethylamino)- ethyl group or a 3-ethoxyethyl group and wherein the benzalaniline-3-sulfonic acid in place of 4-(di-3-hydroxy ethylamino)-2'-methylbenzalaniline-3-sulfonic acid in Ex N 30 ample 30, 225 parts (77.6% of theory) of 4-(di-3-hy N group droxyethylamino)-benzylidenemethylcyanoacetate melting Q at 133° C-135° C. were obtained. stands in para position to the Example 32 35 This reaction was carried out in the same manner as -U-OE-o group that described in Example 30 except that 348 parts of N 4'-(ethyl, 3 - hydroxyethyl)aminobenzalaniline-3-sulfonic are prepared by reacting a benzalaniline-3-sulfonic acid acid were used in place of 4'-(di-3-hydroxyethylamino)- having the formula: 2-methylbenzalaniline-3-sulfonic acid. The dye com (VI) Q 40 pound obtained separates as an oil which solidifies upon standing. 164 parts (60% of theory) of 4-(ethyl, 3 / hydroxyethyl)aminobenzylidenemethylcyanoacetate melt Q1 SOs ing at 76 C.-78 C. were obtained. wherein Q, Q1 and X have the meaning previously as Example 33 signed to them and the 378 parts of 4'-(di-3-hydroxyethylamino)-2'-methyl N benzalaniline-3-sulfonic acid were placed in 3200 parts N group of water and 92 parts of sodium bicarbonate were added. The reaction mixture thus obtained was heated slowly to Q1 60° C. and stirred until solution was complete, 73 parts stands in para position to the 50 of malononitrile were then added to the reaction mixture after adding two parts of a wetting agent. The reaction -C=N group mixture thus obtained was stirred for 16 hours without with malononitrile, an alkyl cyanoacetate or an alkoxy heating and the product which formed was recovered on alkyl cyanoacetate in water in the presence of an acid the filter by filtration. The yellow dye obtained on the binding agent. The reaction can be carried out at a tem 55 filter was washed well with cold water and then dried. perature of from about 0° C. to about 100° C. However, 220 parts (81% of theory) of 4-(di-6-hydroxyethyl a temperature of from about 20° C. to about 50 C. amino)-2-methylbenzylidenemalononitrile having the for appears to give the best results and is preferred. mula: Acid binding agents that can be used include, for ex . HO CHCH E. CN ample, sodium bicarbonate, sodium carbonate, potassium 60 bicarbonate and potassium carbonate. Slightly improved yields and a smoother reaction mixture result when a YoN wetting agent is employed in the reaction although good yields have been obtained when none was used. Only were obtained. It melts at 138 C-140 C. a small amount of wetting agent need be used to obtain 65 Example 34 the benefits just mentioned. While all wetting agents By the use of 140 parts of ethylcyanoacetate in place of have not been tried, it appears that any wetting agent methylcyanoacetate in Example 30, a good yield of 4 whether anionic, nonionic or cationic can be used. Du (di - B - hydroxyethylamino) - 2 - methylbenzylidene ponal, a long chain aliphatic alcohol sulfate, is representa ethylcyanoacetate having the formula: tive of the anionic wetting agents that can be used while 70 EO CHCH Triton X-100 which is made by condensing an alkyl N oN phenol with ethylene oxide is representative of the N C=C EO OH.cf. C-O CE nonionic wetting agents. . The following examples in which parts are expressed O as parts by weight illustrate the manner in which the 75 is obtained. 2,798,090 7 8 Example 35 are operable regardless of the size of the alkyl, hydroxy By the use of 180 parts of n-butylcyanoacetate in place alkyl or alkoxyalkyl group involved. However, those of methylcyanoacetate in Example 31, a good yield of compounds wherein the alkyl group contains one to four, 4 - (di- 6 - hydroxyethylamino)benzylidene - n - butyl inclusive, carbon atoms, the hydroxyalkyl group contains cyanoacetate is obtained. two to four, inclusive, carbon atoms and the alkoxyalkyl group contains three to four, inclusive, carbon atoms Example 36 appear to be the most practical and useful and, accord ingly, our invention is especially directed to such benzal By the use of 185 parts of 6-methoxyethylcyanoacetate aniline-3-sulfonic acid and methine compounds. Illus in place of methylcyanoacetate in Example 31, a good 0. trative alkyl, hydroxyalkyl and alkoxyalkyl groups have yield of 4-(di-6-hydroxyethylamino)benzylidene-3-meth been specifically disclosed in connection with the mem oxyethylcyanoacetate having the formula: bers R and Ri. The methine compounds described herein are valuable Ho CH, CH, N dyes for cellulose acetate textile materials. They may o 5 be advantageously directly applied to the cellulose acetate ?, N textile material undergoing coloration in the form of an O CHCH - -ochschioch, aqueous suspension which can be prepared by grinding - O the dye to a paste in the presence of a sulfonated oil, soap, sodium lignin sulfonate or other suitable dispersing is obtained. - - - 20 agent and dispersing the resulting paste in water. The methine compounds set forth in the tabulation Direct dyeing operations can with advantage be con given hereinafter are likewise readily prepared in ac ducted at temperatures of about 70° C.-90° C. but any cordance with the improved procedure described herein suitable temperature can be used. Thus, the cellulose before. . - - - - acetate textile material to be dyed or colored is ordinarily 37. 4 - dimethylamino - 2 - methylbenzylidenemethyl 25 added to the dye bath at a temperature lower than that cyanoacetate at which the main portion of the dyeing is to be effected, 38.4 - diethylaminobenzylidenemethylcyanoacetate . a temperature approximating 45 C.-55 C., for example, 39. 4 - (di - B - methoxyethylamino) - 2 - methylbenzyl following which the temperature is raised to that selected idenemethylcyanoacetate for carrying out the dyeing operation. The temperature 40. 4 - (di - B - ethoxyethylamino)benzylidenemethyl 30 at which the dyeing is conducted may, of course, be varied cyanoacetate somewhat depending upon the particular cellulose acetate 41. 4- (di - 6 - hydroxyethylamino) - 2 - chlorobenzyl textile material undergoing coloration and the particular idenemethylcyanoacetate amount of coloration desired. As understood by those 42. 4 - (n - butyl, 6 - hydroxyethyl)aminobenzylidene skilled in the dyeing art, the intensity of dyeing can be methylcyanoacetate 35 varied by varying the proportion of dye to material under 43. 4- methylaminobenzylidenemethylcyanoacetate going coloration. The amount of dye used can be, for ex 44. 4 - ethylamino - 2 - methylbenzylidenemethylcyano ample, 6% to 3% (by weight) of that of the cellulose acetate - acetate textile material although lesser or greater amounts 45. 4- n-butylaminobenzylidenemethylcyanoacetate of dye can be used. 46. 4.- (di - 6 - hydroxyethylamino) - 2 - chlorobenzyl 40 We claim: ideneethylcyanoacetate 1. The process for preparing benzalaniline-3-sulfonic 47. 4 - (ethyl, 6 - hydroxyethyl)aminobenzylidene - n acid compounds which in their free acid form have the propylcyanoacetate formula: 48. 4- (ethyl, 8 - hydroxyethyl)aminobenzylidene - n 45 R butylcyanoacetate E. 49. 4 - (di - 6 - hydroxyethylamino) - 2 - methylbenzyl idene - 3 - ethoxyethylcyanoacetate R 50. 4 - (di - 3 - hydroxyethylamino) - 2 - chlorobenzyl X----( SO) idenemalononitrile - 51. 4- (ethyl, 3-hydroxyethyl)aminobenzylidenemalono 50 wherein X stands for a monocyclic aryl nucleus of the nitrile benzene series and R and R1 each represents a member 52. 4 - (n - butyl, (3 - hydroxyethyl)aminobenzylidene selected from the group consisting of an alkyl group, a malononitrile hydroxyalkyl group and an alkoxyalkyl group and where 53. 4-dimethylaminobenzylidenemalononitrile in the group 54. 4- (di - B - hydroxyethylamino) - 2 - methoxybenzyl 55 idenemalononitrile 55. 4 - (di - B - hydroxyethylamino) - 2 - ethoxybenzyl idenemalononitrile 56. 4 - (di - 3 - hydroxyethylamino) - 2 - ethylbenzyl idenemalononitrile 60 stands in para position to the 57. 4 - (di - B - hydroxyethylamino) - 2 - bromobenzyl idenemalononitrile -C=N grouping 58. 4- (di- B - methoxyethylamino) benzylidenemalono which comprises reacting an aniline compound having the nitrile - 65 para position to the amino group free and having the Any of the unacylated methine dye compounds dis formula closed in U. S. Patents 2,583,551 and 2,583,614 can be - prepared using the improved procedure described herein. R The methine compounds containing a hydroxyalkyl group Y-x can be acylated in accordance with the procedure de 70 R? scribed in U. S. Patents 2,583,551 and 2,583,614 to ob tain acylated methine dye compounds. wherein R, R1 and X have the meaning previously as So far as we are aware, the new and improved processes signed to them, with formaldehyde and meta-nitrobenzene described herein for the preparation of the benzalaniline sulfonic acid in the presence of sulfuric acid and iron at 3-sulfonic acid compounds and the methine compounds 5 a temperature of from 5 C. to 35° C. w 2,798,090 10 2. The process for preparing benzalaniline-3-sulfonic rwherein X stands for a monocyclic aryl nucleus of the acid compounds which in their free acid form have the benzene series and R and R1 each represents a member formula: - selected from the group consisting of an alkyl group, a hydroxyalkyl group and an alkoxyalkyl group and where Y-x-5-N...... 5 - in the group R. R? SO3. N wherein X stands for a monocyclic aryl nucleus of the R? benzene series and R and R1 each represents a member O stands in para position to the selected from the group consisting of an alkyl group, a hydroxyalkyl group and an alkoxyalkyl group and where -C=N grouping in the group which comprises forming metanitrobenzene sulfonic acid R by reacting nitrobenzene with an excess of sulfuric acid Yn 5 over that theoretically required to form meta-nitrobenzene sulfonic acid and reacting the meta-nitrobenzene sulfonic acid thus formed without isolation from its reaction mix stands in para position to the ture with formaldehyde and an aniline compound having the para position to the amino group free and having -C=N grouping 20 the formula which comprises reacting an aniline compound having the para position to the amino group free and having the formula R 25 wherein R, R1 and X have the meaning previously as / signed to them, in the presence of iron at a temperature R1 of from about 16° C. to about 20 C. 5. The process for preparing 4 - (di-3-hydroxyethyl wherein R, R1 and X have the meaning previously as amino)-2'- methylbenzalaniline - 3 - sulfonic acid which signed to them, with formaldehyde and meta-nitrobenzene 30 comprises reacting N,N-di-3-hydroxyethyl-m-toluidine sulfonic acid in the presence of sulfuric acid and iron with formaldehyde and meta-nitrobenzene Sulfonic acid at a temperature of from about 16° C. to about 20° C. in the presence of sulfuric acid and iron at a temperature 3. The process for preparing benzalaniline-3-sulfonic of from 5 C. to 35 C. acid compounds which in their free acid form have the 6. The process for preparing 4'-(di-3-hydroxyethyl formula: 35 amino)-2'-methylbenzalaniline-3-sulfonic acid which com R prises reacting N,N-di-3-hydroxyethyl-m-toluidine with B formaldehyde and meta-nitrobenzene sulfonic acid in the R1 presence of sulfuric acid and iron at a temperature of from about 16° C. to about 20° C. 40 7. The process for preparing 4'-(di-3-hydroxyethyl wherein X stands for a monocyclic aryl nucleus of the amino)-2'-methylbenzalaniline-3-sulfonic acid which com benzene series and R and R1 each represents a member prises forming meta-nitrobenzene sulfonic acid by re selected from the group consisting of an alkyl group, a acting nitrobenzene with an excess of Sulfuric acid over hydroxyalkyl group and an alkoxyalkyl group and where that theoretically required to form meta-nitrobenzene in the group 45 sulfonic acid and reacting the meta-nitrobenzene Sulfonic R acid thus formed without isolation from its reaction mix Yn ture with formaldehyde and N,N-di-3-hydroxyethyl-m- toluidine in the presence of iron at a temperature of from 5° C. to 35° C. stands in para position to the 50 8. The process for preparing 4'-(di-3-hydroxyethyl E. amino)-2'-methylbenzalaniline-3-sulfonic acid which com -C=N grouping prises forming meta-nitrobenzene sulfonic acid by re which comprises forming metanitrobenzene Sulfonic acid acting nitrobenzene with an excess of sulfuric acid over by reacting nitrobenzene with an excess of sulfuric acid that theoretically required to form meta-nitrobenzene over that theoretically required to form meta-nitrobenzene 55 sulfonic acid and reacting the meta-nitrobenzene sulfonic sulfonic acid and reacting the meta-nitrobenzene Sulfonic acid thus formed without isolation from its reaction mix acid thus formed without isolation from its reaction mix ture with formaldehyde and N,N-di-3-hydroxyethyl-m- ture with formaldehyde and an aniline compound having toluidine in the presence of iron at a temperature of from the para position to the amino group free and having about 16° C. to about 20 C. 60 9. The process for preparing 4'-(di-3-hydroxyethyl the formula amino) benzalaniline-3-sulfonic acid which comprises re R acting N,N-di-3-hydroxyethylaniline with formaldehyde and meta-nitrobenzene sulfonic acid in the presence of R N-X sulfuric acid and iron at a temperature of from 5 C. to 35 C. wherein R, R1 and X have the meaning previously as 10. The process for preparing 4'-(ethyl, g-hydroxy signed to them, in the presence of iron at a temperature ethyl)-aminobenzalaniline-3-sulfonic acid which com of from 5 C. to 35 C. prises reacting N-ethyl-N-3-hydroxyethylaniline with 4. The process for preparing benzalaniline-3-sulfonic formaldehyde and meta-nitrobenzene sulfonic acid in the acid compounds which in their free acid form have the 70 presence of sulfuric acid and iron at a temperature of formula: from 5 C, to 35° C. 11. The process for preparing 4'-(di-6-hydroxyethyl prisesamino)-2'-chlorobenzalaniline-3-sulfonic reacting N,N-di-3-hydroxyethyl-m-chloroaniline acid which com 5 with formaldehyde and meta-nitrobenzene Sulfonic acid 2,798,090 2 in the presence of sulfuric acid and iron at a temperature . References Cited in the file of this patent of from 5° C. to 35° C. . . . 12. The process for preparing 4'-(n-butyl, B-hydroxy UNITED STATES PATENTS ethyl)amino-2'-methylbenzalaniline-3-sulfonic acid which 2,048,006 Hutton ------July 21, 1936 comprises reacting N-n-butyl-N-6-hydroxyethyl-m-tolui- 5 2,583,551 Dickey et al. ------Jan. 29, 1952 dine with formaldehyde and meta-nitrobenzene sulfonic 2,583,614 Taylor et al. ------Jan. 29, 1952 acid in the presence of sulfuric acid and iron at a tem FOREIGN PATENTS perature of from 5 C. to 35° C. is 586,127. Great Britain ------Mar. 7, 1947