Identification of Unsulfonated Azonaphthol AS Dyes LOUIS KOCH
AND
ROBERT F. RIILLIGAN, H . K o h n s t a n t m Research Laboratories, Brooklyn, .V. Y .
T
Preparation of Reduction Products. Two gimis of finely ground dye are suspended in 50 ml. of diosane, and the solvent is often been handicapped by the lack of systematic procedures heated to boiling. To this are added 50 ml. of water, followed at and data for the identification of the scission products formed once by 20 grams of dry sodium hydrosulfite. The mixture is upon reduction. While numerous methods are available for the then gently heated, with constant stirring, until decolorization has ensued (5 to 15 minutes will be required for the reduction to initial hydrogenolysis of the dyes (3, 4,9, 10, 1I), the separation reach completion). and characterization of the reduction compounds are often tedious The reduction mixture is poured into 350 ml. of water, aiid and time-consuming. heated on a steam bath or hot plate to effect coagulation of the In previous papers (5, i ) simple and rapid procedures for the precipitated 1-aminonaphthol AS. The solid is separated from the hot liquid by filtration, washed with 50 ml. of water, and dried identification of unsulfoiiated aiid sulfonated azo-2-ii:iplitliol at 60" C. Purification of the crude product by crystallization dyes, by the c:itnlytic reductio11 of the azo bond and sutwqueiit fwni :dcohol yields the desired compound. characterization of tlie srission products, liave been piwe,ited. The filtrate, containing the reduction product of the diazo This work continuc,s tlie search for specific means of identifying component of the dye, is made alkaline with 10 grams of solid sodium hydroxide, and then treated with 5 ml. of benzoyl chloride. unknown azo colors, niid presents a method for the elucidation of Lpon vigorous agitation the benzoyl derivative separates as a the chemical structure of the unsulfoiiated azonaphtliol .IS pigsolid or pasty mass which is allowed to stsnd overnight. .\fter ments. collecting on a smiill Uiichner it is washed thoroughly with \v:iter A review of tlie cliemicd literature revwled few refereiices conand crystallized from a suitahle solvent ( 5 ) . -111 melting points were taken with a Tliiele tube, filled with cerned with the identificatioii of these dyes. Battegay, Latigdioctyl phthalate, and a standardized 360 C. thermometer was jahr, and Rettig (1) reported the synthesis oi 1-amiiiorial)litlioI employed. -111 the customary precautions regarding the rate of AS, melting point 180-181 C. by the sodium hydrosulfite scisheating and depth of thermometer immersion in this type of sion of phenylazoriaphtliol -IS. Because their primary interest apparatus were carefully followed. lay ill the chemistry of this compound only, they did not pursue this work any further. Rowe aiid Levin (8) attacked the probStiMM4RY AND CONCLUSIONS lem of identifying these pigments by osidixing them \\.it11 fuming A repid arid simple method has been developed for the ideiitifinitric acid. The diazoniuni nitrate that was formed \viis divided cation of unsulfonated azonnphtliol AS dyes, by reduction with into two portions aiid was then coupled to 2-iiaplitliol aiicl iinplisodium hydrosulfite and separation of tlie reduction product> by thol AS, to give dyes with knoa-ii melting poiiits. Their itivestifiltration. Melting point determinations on the dye, and the gation did not fully identify the original color, because tile characbenzoyl derivative of the reduction product of the diazo coniterixatioii of the coupling component wa.5 not undert:ilmi. Lochner (6) offered a method for identifying iixphthol AS dyes based 011 microscopic examination of the optical Table 1. Identification of Unsulfonated Azonaphthol AS Dyes", properties of crystals obtained from Melting Point oi Benzovl Derivsacetic acid. tive 0f"Reduction 31elting Point of Dye Although the author3 liad contemObserved Product of Diazo (uncor- LiteraReduction Product of Diazo Component corrected)(Tnplated the use of the apparatus of Diazo Comuoneiit rected) ture Component Cheronis and Koeck ( 2 ) for the hydroc. c. c. genolysis of the azo bond, it was found 155-6 p-Aiiiaidine 213 1. p-Anisidine 210-12 172-3 o-Phenetidine 218 2 . p-Phenetidine 216-17 that a niodificatioii of the procedure of Oil 201 3. o-Phenetidine 220-1 123-4 Battegay, Langjahr, and Rettig (I) could 221 4. m-Toluidine 220-1 193-4 220 3. 2,4-Diniethylaniline 221-3 be used to greater advantage because it 144-5 220 6. o-Toluidine 222-3 157-8 225 7 . p-Toluidine 230-2 was time-saving and the Ereseiice of in142-3 233 8 . 2-hIeth~l-4-chloroaniline 237-9 Oil organic salts did iiot interfere with the o- Anisidine 229 9. o-Anisi m e 239-41 160-ld 2-Napbthylanune 211 10. 2-Saphthylamine 244-6 isolatioii of the scission products. 111 :i 162-3d Aniline 245-6 237 11. .Iniline 104-5 o-Chloroaniline 241 245-7 12. o-Chloroaniline preliminary appliwtion of the proposed 191-2 p-Cbloroaniline 249 151-3 13. p-Chloroaniline . ~ ~ . ~ ~ 120-1 m-Chloroaniline method to a series of crude naphthol 256-8 ... 14. m-Chloroaniline n-Phenylenediamine 241-2 271 270-1 15, m-Sitroaniline .IS dyes, difficulties were often en251-2 27&2 . . . 4-Jlethoxy-o-phenylenediamine 16. 8-Sitro-4-aminosnisole 1-Saphthylamine 1584 270 276-8 17. 1-Sapht hylamine countered iii obtairiing 1-amirio~iaphthol 2-Methyl-5-chloroaniline 111-2 ,.. 277-9 18. 2-Met hyl-5-chloroaniline 2-Methyl-p-phenylenediamine 301-2 AS \\.it11 a coiistant melting point. 281-2 268 19. 4-Sitro-2-niethylaniline 4-JIethyl-o-phenylenedi amine 263-4 284 282-3 ' 0 . 2-Sitro-4-1iiethylaniline PurificiLtioIi, iii some cases, led to pwdo-Phenylenediamine 303-4 283-5 279 21. o-Sitronniline n-Phenvlenediamine 338-9 290 285-7 p-Sitroaniline uct,s which had chemical c1i:iracteristicb 225-6 i-.\Iethj.l-m-phenylenediaiiiine 304 297-8 ' 3 . 5-Sitro-2-methylaniline 119-20 other than those of the desired substance, 2,5-Dichloroaniline 310-11 24. 2,5-Dichloroaniline 226-7 4-Chloro-o-phenylenediamine 304 310-12 2 5 . 4-Chloro-2-nitroaniline and indicated the possibility that the 239-40 2-Chloro-p-Dheiiylenedianiine 313 318-19 26. 2-Chloro-4-iiitroaniline material recorded by Battegay, Langjahr, Snplithol .4S is 2-hydroxyn aplitlioic a cid anili de, and the dyes have the general structure and Rettig (1) was a mixture. \The11 the dyes were crystallized from dioxane before reduction, yellow l-aminonaphthol AS, melting point 188-90" C., was readily isolated in all cases.
HE analysis of unknown azo dyes, in this laborntory, ha;
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GENERAL PROCEDURE
Preparation of Samples. It is necessary, in all cases, t o purify the coloring matter by recrystallizing a t lcast once from dioxane.
H-diazotized aryl nniine
1-Aiiiiiioiiaphthol AS, the coupling component reduction product, was crystallized from ethanol, A1.P. observed 188-90' C. (uncorrected); h1.P. literature 180-1' C . A11 literature melting point data are from tables of Iioye and Levin ( 8 ) . d T o differentlate further between dyes 10 and 11, run ii mixed melting polnt with a n authentic sample of benaanilide. b
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312
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31 3
V O L U M E 19, NO. 5, M A Y 1 9 4 7 ponent, enable the andyst to diffrt~~nti:rtc~ iirtneeti tlic coloi,.: of this class. ACKNOWLEDGMEVT
The authors Irish to esprt’ss their appreciation t o their director,
IT.C. Bainbridge, for his encouragement, and to Virgini:i Haase for her assistance in hringing the project to completion. LITERATURE CITED
(1) Battegay, Laiigjahr, a n d Rettig. Chimie et Iritiiistrir, 11, 453-5 (1924).
N. l)., and Koeck, M.,J . Chem. Education, 20, 48s (1943). (3) Grandmougin, Bcr., 39,2494, 3661, 3929 (1906). (4) Knecht. E., J . SOC.Dyers Colourists, 45, 133 (1929). Koch, L., Milligan R . F., and Zuckerman S., IKD.ENG. (’) CHEM., .\N.nzene,drying the residue in a n atmosphere of carbon dioxidt,, and weighing. Fox (4)determined rubber in guayulc by extracting first with acetone, then with benzene. He then prccaipitated the rubber from benzene x i t h alcohol, and dried and iwigkied the precipitate. Whittelsey (15) deterniincd rubber in guayulr by extracting the sample with wat.er and alcohol to rvinove the rubber. He evaporated the carbon tetrachloride on a -tram bath and boiled the rubber film n-ith alcohol and xater t>o r(movc any resin or water-solubles extracted with the rubber. After pouring off the water and alcohol he dried the film and weighed it as rubber. Hall and Goodspeed (6) and Hall and Long f;) in t,heir survey of the rubber content of Xorth American plant,s extracted t,he samples for 3 hours with boiling acetone and thrn for 3 hours with boiling benzene. The acetonc extract was
