UNITED STATES PATENT OFFICE. JOHN B. SLINIMI, OF BUFFALO, NEW YORK, ASSIGNOR. To NATIONAL ANILINE & CHEMICAL COMPANY, INC, OF NEW YORK, N. Y., A CORPORATION or NEW SOR3, PRODUCTION OF META-HYDROXYBENZALDEHYDE. 1,419,695. Specification of Letters Patent. Patented Jiae A3, 1922. No Drawing:-. Application filed January 6, 1921. Serial No. 435,544. To all whom it may concern: of meta-hydroxybenzaldehyde and a product 55 Be it known that I, JoHN B. SLIMM, re of improved quality. siding at Buffalo, in the county of Erie, We have discovered that meta-hydroxy State of New York, have invented certain benzaldehyde can be produced from the so new and useful Improvements in the Pro lution of the sodium bisulfite addition com duction of Meta-Hydroxybenzaldehyde; and pound of meta-animobenzaldehyde (result 60 I do hereby declare the following to be a ing from the reduction of the sodium bisul full, clear, and exact description of the in fite addition compound of meta-nitrobenzal vention, such as will enable others skilled in dehyde) by acidifying the solution and di 10 the art to which it appertains to make and aZotizing directly (without first boiling the use the same. Solution with acid to remove sulfur dioxide) 65 This invention relates to an improved and by Subsequently adding the diazotized so process of making meta-hydroxybenzalde lution to boiling dilute mineral acid in order hyde from meta-nitrobenzaldehyde or from simultaneously to remove nitrogen from the 5 the sodium bisulfite addition compound of diazonium compound and remove sulfur di meta-aminobenzaldehyde (obtainable - by oxide. The resulting meta-hydroxybenzai 70 converting meta-nitrobenzaldehyde into the dehyde can then be obtained from the solu sodium bisulfite addition compound, and tion by cooling and adding salt whereby reducing this compound). the meta-hydroxybenzaldehyde is precipi 20 It has heretofore been proposed to pro tated in a crystalline state. The process of duce meta-hydroxybenzaldehyde from iso the present invention therefore eliminates, 75 lated meta-aminobenzaldehyde by subject With corresponding decrease in apparatus ing the isolated meta-aminobenzaldehyde to requirement and time of operation, the boil ing of the solution of the meta-animobenzal diazotization and subsequent hydrolysis of dehyde bisulfite addition compound and the 25 the diazonium compound. It has also been Subsequent cooling and filtration which have 80 hydeproposed from to meta-nitrobenzaldehyde produce meta-aminobenzalde by con been heretofore practiced. The losses due to verting the meta-nitrobenzaldehyde into the side reactions, which take place in the de bisulfite addition compound, reducing this composition of the sodium bisulfite addition 30 compound to the corresponding compound compound of meta-aminobenzaldehyde by of meta-aminobenzaldehyde, decomposing heating prior to the diazotization, are elimi 85 the resulting bisulfite compound, and sepa nated, with resulting increase in yield of the rating and isolating the meta-aminobenzal meta-hydroxybenzaldehyde. dehyde. The invention will be further illustrated 35 According to the present invention, the by the following specific example, the parts production and isolation of meta-aminoben being by weight: 90 Zaldehyde, and the treatment of the isolated Production of the bisulfite addition com meta-aminobenzaldehyde, are avoided, and pound of meta-aminobenzaldehyde: 120 the meta-hydroxybenzaldehyde is produced pounds of meta-nitrobenzaldehyde, 100 40 directly from the bisulfite addition compound pounds of sodium bisulfite and 200 pounds of meta-aminobenzaldehyde, or indirectly of water are agitated with little heating in 95 from meta-nitrobenzaldehyde through the a water jacketed, steel, cone-bottomed mix bisulfite compound, without isolation of the ing tank until a complete solution is effect meta-aminobenzaldehyde. The meta-hy ed. 90 pounds of iron dust and 6 pounds 45 droxybenzaldehyde can thus be produced of hydrochloric acid (20° Bé.) are mixed from meta-nitrobenzaldehyde without sepa thoroughly with a little water and added to 00 ration or isolation of intermediate products. 125 pounds of water in a suitable tank and The present invention therefore involves an agitated therein for about 15 minutes with improvement over prior processes, above re slight heating. Water is added to the iron 50 ferred to, in apparatus requirements and in and acid to make the charge up to about 800 the time and number of operations required; pounds and the mixture is heated to about while the process is more easily controlled 45° C. The clear solution of the bisulfite and gives more uniform results from run to compound of meta-nitrobenzaldehyde is then run, as well as a somewhat increased yield run in, and more water is added if neces s 1,419,695 sary to bring the charge up to about 1550 pose more or less of this compound into sul pounds. The mixture is then heated very furous acid and a salt of meta-aminobenzal slowly to about 60° C., a mixture of 31 dehyde. However this may be, any unde pounds of iron dust and 3 pounds of hydro composed bisulfite compound will be decom chloric acid then added, and the mixture posed, and the sulfur dioxide set free, when 70 heated gradually to about 76. C., this last the solution of the diazonium compound is heating usually being effected by the heat of added to the hot acid liquor. reaction. The charge is kept at about 80. The specific procedure above described can C. for about one and one-quarter hours. A be somewhat modified and varied. The sul 0 mixture of 31 pounds of iron dust and 2 furic acid used in the diazotization may thus 75 pounds of hydrochloric acid is then added be replaced by an equivalent amount of hy and the charge heated gradually to about drochloric acid. So also, the sulfuric acid 86° C. and kept there for about one hour. Solution used in decomposing the diazonium The mixture is then made neutral or very compound and removing the sulfur dioxide 5 slightly, alkaline with caustic soda, heated may be replaced by its equivalent of E. to about 85-90° C. and filtered through a chloric acid solution, or by solutions of com 80 filter press. mon inorganic salts such as sodium chlo The procedure above described converts ride, or even by water alone; but the de the meta-nitrobenzaldehyde into its sodium composition proceeds more rapidly if some 20 bisulfite addition compound, and reduces the electrolyte is added, and particularly if an 85 latter to the bisulfite compound of meta acid such as sulfuric acid is used. For ex aminobenzaldehyde, which is obtained in so ample, instead of using 50 pounds of sul lution. furic acid, an equal amount of hydrochloric Production of meta-hydroxybenzaldehyde acid may be used; or 25 to 35 pounds of salt 25 from solution of meta-aminobenzaldehyde may be used; or a mixture of 50 pounds of 90 bisulfite addition compound: 1500 pounds hydrochloric acid and 25 pounds of salt. of solution, obtained, for example, as above The meta-hydroxybenzaldehyde produced : described, and containing about 56 pounds as above described can be further purified of meta-aminobenzaldehyde as the sodium by dissolving in dilute caustic alkali solu 30 bisulfite addition compound, are cooled to tion, filtering, and neutralizing with hydro 0°C. in a suitable container, such as awooden chloric acid. The meta-hydroxybenzalde 95 vat, and the solution agitated. Then 170 hyde is thus reprecipitated and can then be pounds of sulfuric acid of 50° Bé. are added, filtered off and dried. and 40 pounds of sodium nitrite are then in We claim: . ' 35 troduced at such a rate that the heat of re 1. The method of producing meta-hy 00 action does not bring the temperature of the droxybenzaldehyde, which comprises sub solution above 4° C. After all the sodium nitrite is added, the agitation is maintained hyde-bisulfitejecting a solution addition of meta-aminobenzalde.compound to diazo . for a period of from 1 to 2 hours during 40 tization, and simultaneously removing ni which time the temperature is kept below trogen and sulfur dioxide by heating the 105 4 C. The resulting diazotized solution is resulting solution of diazonium compound. then run slowly into a container which is 2. The method of producing meta-hy fitted with an agitator and contains a mix droxybenzaldehyde, which comprises sub ture of 150 pounds of water and 50 pounds 45 jecting a solution of the sodium bistulfite of sulfuric acid of 50 Bé. maintained at a addition compound of meta-aminobenzalde 10 temperature of about 100° C. by suitable hyde to diazotization with acid and sodium heating means, such as lead steam coils. As nitrite and adding the resulting solution of a result of the addition of the diazonium diazonium compound to a heated dilute min compound to the hot acid, the diazonium eral acid, whereby the diazonium compound 50 compound is decomposed and meta-hydroxy is decomposed and nitrogen and sulfur di 115 benzaldehyde produced. The resulting so oxide removed. lution is filtered and the filtrate collected 8. The process of producing meta-hy in a cooling apparatus such as a brine jacket droxybenzaldehyde, which comprises sub ed kettle; 100 pounds of common salt are jecting a solution of meta-aminobenzalde 55 added, and, upon cooling, the meta-hydroxy hyde-bisulfite addition compound to diazoti 20 benzaldehyde crystallizes out and is sepa Zation with acid and sodium nitrite, and si rated from the mother liquor by filtration. multaneously removing nitrogen and sulfur The addition of the solution of the dia dioxide by introducing the solution into a zonium compound to the boiling dilute acid dilute solution of mineral acid kept at a 60 liquor decomposes the diazonium compound temperature of about 100° C. 125 and removes nitrogen therefrom, and simul 4. The method of producing meta-hy taneously removes sulfur dioxide. It may droxybenzaldehyde, which comprises sub be that the addition of acid to the solution jecting a solution of the sodium bisulfite ad of the meta-aminobenzaldehyde-bisulfite dition compound of meta-aminobenzalde f5 compound for the diazotization may decom hyde to diazotization with dilute sulfuric 130 1,419,695 S3 acid and sodium nitrite at a temperature about zero to 4° C., adding the diazotized 10 of about zero to 4°C. and adding the diazo solution to dilute sulfuric acid maintained tized solution to dilute sulfuric acid main at a temperature of about 100° C., and sub tained at a temperature of about 100° C. sequently adding salt and cooling the solu 5. The method of producing meta-hy tion whereby the meta-hydroxybenzalde droxybenzaldehyde, which comprises sub hyde is separated in a crystalline state. 5 jecting a solution of the sodium bisulfite ad In testimony whereof I affix my signature. dition compound of meta-aminobenzalde hyde to diazotization at a temperature of JOHN B. SLIMM.