33:
408:
371:
341:
362:
163:
385:
353:
112:
450:
is not considered to be a degradation pathway for azo dyes. In order to prolong the lifetime of products dyed with azo dyes, it is essential to ensure stability against microbial attack, and tests have shown that azo dyes biodegrade negligibly in short term tests under aerobic conditions. Under
747:
Paola Gilli; Valerio
Bertolasi; Loretta Pretto; et al. (2002). "The Nature of Solid-State N−H···O/O−H···N Tautomeric Competition in Resonant Systems. Intramolecular Proton Transfer in Low-Barrier Hydrogen Bonds Formed by the ···OC−CN−NH··· ⇄ ···HO−CC−NN··· Ketohydrazone−Azoenol System. A
178:
Azo dyes are solids. Most are salts, the colored component being the anion usually, although some cationic azo dyes are known. The anionic character of most dyes arises from the presence of 1-3 sulfonic acid groups, which are fully ionized at the pH of the dyed article:
108:. Also called direct dyes, substantive dyes are employed for cellulose-based textiles, which includes cotton. The dyes bind to the textile by non-electrostatic forces. In another classification, azo dyes can be classified according to the number of azo groups.
502:. Since September 2003, the European Union has banned the manufacture or sale of consumer goods which contain the listed amines. Since only a small number of dyes produced those amines, relatively few products were actually affected.
403:
Azo pigments are similar in chemical structure to azo dyes, but they lack solubilizing groups. Because they are practically insoluble in all solvents, they are not readily purified, and thus require highly purified precursors.
67:
and do not occur naturally. Most azo dyes contain only one azo group but there are some that contain two or three azo groups, called "diazo dyes" and "triazo dyes" respectively. Azo dyes comprise 60-70% of all dyes used in
653:
817:
328:. Typical aniline partners are shown below. Since anilines are prepared from nitro compounds, some azo dyes are produced by partial reduction of aromatic nitro compounds.
645:
325:
431:. The lightfastness depends not only on the properties of the organic azo compound, but also on the way they have been absorbed on the pigment carrier.
714:
545:
223:
with another compound, the coupling partner. Generally, coupling partners are other aromatic compounds with electron-donating groups:
446:
In order for dyes to be useful, they must possess a high degree of chemical and photolytic stability. As a result of this stability,
331:
Many azo dyes are produced by reactions from pre-existing azo compounds. Typical reactions include metal complexation and acylation.
953:
Golka, K.; Kopps, S.; Myslak, Z. W. (June 2004). "Carcinogenicity of azo colorants: influence of solubility and bioavailability".
892:
679:
857:
Bafana, Amit; Devi, Sivanesan
Saravana; Chakrabarti, Tapan (28 September 2011). "Azo dyes: past, present and the future".
427:(including artist's paints). They have excellent coloring properties, mainly in the yellow to red range, as well as good
216:
199:
reaction. The anionic dye adheres to these articles through electrostatic forces. Cationic azo dyes typically contain
834:
731:
910:
Eva Engel; Heidi Ulrich; Rudolf Vasold; et al. (2008). "Azo
Pigments and a Basal Cell Carcinoma at the Thumb".
96:
Many kinds of azo dyes are known, and several classification systems exist. Some classes include disperse dyes,
490:. Accordingly, the production of benzidine azo dyes was discontinued in the 1980s in many western countries.
812:
434:
Azo pigments amongst food pigments are the oldest and also the most widely used. They were discovered by
893:"Health & Safety in the Arts, A Searchable Database of Health & Safety Information for Artists"
384:
1001:
17:
451:
anaerobic conditions, however, discoloration may be observed as a consequence of biodegradation.
996:
135:, aryl azo compounds have vivid colors, especially reds, oranges, and yellows. An example is
340:
588:
370:
144:
8:
498:
Certain azo dyes degrade under reductive conditions to release any of a group of defined
200:
592:
955:
935:
826:
746:
619:
576:
464:
97:
972:
927:
874:
830:
789:
765:
727:
624:
606:
416:
412:
136:
48:
939:
896:
555:
964:
919:
866:
822:
757:
719:
614:
596:
559:
550:
265:
Azo dyes are also prepared by the condensation of nitrated aromatic compounds with
73:
52:
37:
601:
968:
712:
Hunger, Klaus; Mischke, Peter; Rieper, Wolfgang; et al. (2000). "Azo Dyes".
105:
909:
784:
690:
499:
487:
460:
220:
132:
195:
Most proteins are cationic, thus dyeing of leather and wool corresponds to an
990:
878:
723:
610:
554:, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "
428:
376:
140:
69:
577:"Classifications, properties, recent synthesis and applications of azo dyes"
563:
32:
976:
931:
769:
628:
526:
511:
472:
435:
407:
390:
212:
196:
101:
60:
748:
115:
59:
and substituted aryl groups. They are a commercially important family of
63:, i.e. compounds containing the C-N=N-C linkage. Azo dyes are synthetic
516:
483:
447:
119:
923:
761:
361:
521:
479:
242:
In practice, acetoacetic amide are widely used as coupling partners:
162:
84:, and some foods. Chemically related derivatives of azo dyes include
870:
575:
Benkhaya, Said; M'rabet, Souad; El Harfi, Ahmed (31 January 2020).
352:
171:
815:. In Caballero, Benjamin; Finglas, Paul M.; Toldrá, Fidel (eds.).
423:
Azo pigments are important in a variety of plastics, rubbers, and
468:
266:
167:
111:
81:
77:
152:
126:
424:
324:
For textile dying, a typical nitro coupling partner would be
270:
148:
813:"Colors: Properties and Determination of Synthetic Pigments"
574:
156:
56:
64:
782:
486:; exposure to them has classically been associated with
459:
Many azo pigments are non-toxic, although some, such as
711:
856:
174:
equilibria shown here in simplified form (Ar = aryl).
55:
R−N=N−R′, in which R and R′ are usually
88:, which are insoluble in water and other solvents.
988:
952:
159:discs use blue azo dye as the recording layer.
715:Ullmann's Encyclopedia of Industrial Chemistry
326:disodium 4,4′-dinitrostilbene-2,2′-disulfonate
76:industries. Azo dyes are widely used to treat
821:. Oxford: Academic Press. pp. 284–290.
568:
127:Physical properties, structure, and bonding
640:
638:
467:orange, or pigment orange 1, 2, and 5 are
618:
600:
335:Illustrative azo dyes or their precursors
707:
705:
703:
677:
454:
406:
161:
110:
31:
635:
415:, an azo pigment (also classified as a
269:followed by reduction of the resulting
261:C(O)Me → ArN=NCH(C(O)Me)(C(O)NHAr′) + H
14:
989:
493:
27:Class of organic compounds used as dye
810:
700:
673:
671:
656:from the original on 29 November 2022
783:H. T. Clarke; W. R. Kirner (1941).
539:
217:electrophilic substitution reaction
24:
827:10.1016/B978-0-12-384947-2.00191-4
680:"European Ban on Certain Azo Dyes"
668:
551:Compendium of Chemical Terminology
25:
1013:
441:
85:
895:. City of Tucson. Archived from
383:
369:
360:
351:
339:
946:
903:
885:
818:Encyclopedia of Food and Health
398:
850:
804:
776:
740:
211:Most azo dyes are prepared by
206:
13:
1:
602:10.1016/j.heliyon.2020.e03271
532:
969:10.1016/j.toxlet.2003.11.016
687:Quality and Environment, TFL
139:. Some azo compounds, e.g.,
40:, an orange colored azo dye.
7:
505:
10:
1018:
799:, vol. 1, p. 374
170:diazo dyes participate in
91:
724:10.1002/14356007.a03_245
678:Püntener, A.; Page, C.
564:10.1351/goldbook.A00560
478:Azo dyes derived from
420:
175:
131:As a consequence of π-
123:
41:
36:Chemical structure of
859:Environmental Reviews
455:Safety and regulation
410:
238:+ Ar′H → ArN=NAr′ + H
221:aryl diazonium cation
165:
114:
35:
393:, a cationic azo dye
145:acid-base indicators
756:(45): 13554–13567.
593:2020Heliy...603271B
494:European regulation
215:, which entails an
201:quaternary ammonium
118:is an example of a
956:Toxicology Letters
811:Diacu, E. (2016).
696:on 13 August 2012.
465:ortho-nitroaniline
421:
411:Synthesis of C.I.
176:
124:
122:, used for cotton.
98:metal-complex dyes
42:
924:10.1159/000109363
797:Collected Volumes
790:Organic Syntheses
762:10.1021/ja020589x
417:diarylide pigment
413:Pigment Yellow 12
285:→ ArN(O)=NAr′ + H
137:Disperse Orange 1
49:organic compounds
16:(Redirected from
1009:
1002:Organic pigments
981:
980:
950:
944:
943:
907:
901:
900:
889:
883:
882:
854:
848:
847:
845:
843:
808:
802:
800:
793:
780:
774:
773:
750:J. Am. Chem. Soc
744:
738:
737:
709:
698:
697:
695:
689:. Archived from
684:
675:
666:
665:
663:
661:
642:
633:
632:
622:
604:
572:
566:
543:
387:
373:
364:
355:
343:
256:
255:
254:
237:
236:
235:
106:substantive dyes
82:leather articles
53:functional group
38:Solvent Yellow 7
21:
1017:
1016:
1012:
1011:
1010:
1008:
1007:
1006:
987:
986:
985:
984:
951:
947:
908:
904:
899:on 10 May 2009.
891:
890:
886:
871:10.1139/a11-018
865:(NA): 350–371.
855:
851:
841:
839:
837:
809:
805:
795:
781:
777:
745:
741:
734:
710:
701:
693:
682:
676:
669:
659:
657:
644:
643:
636:
573:
569:
544:
540:
535:
508:
500:aromatic amines
496:
457:
444:
401:
394:
388:
379:
374:
365:
356:
347:
346:Direct Brown 78
344:
319:
315:
311:
307:
303:
299:
295:
292:ArN(O)=NAr′ + C
288:
284:
280:
260:
253:
250:
249:
248:
246:
234:
231:
230:
229:
227:
209:
190:
186:
129:
94:
28:
23:
22:
15:
12:
11:
5:
1015:
1005:
1004:
999:
983:
982:
945:
902:
884:
849:
835:
803:
775:
739:
732:
699:
667:
634:
567:
537:
536:
534:
531:
530:
529:
524:
519:
514:
507:
504:
495:
492:
488:bladder cancer
461:dinitroaniline
456:
453:
443:
442:Biodegradation
440:
400:
397:
396:
395:
389:
382:
380:
375:
368:
366:
359:
357:
350:
348:
345:
338:
336:
322:
321:
317:
313:
309:
305:
304:→ ArN=NAr′ + C
301:
297:
293:
290:
286:
282:
278:
273:intermediate:
263:
262:
258:
251:
240:
239:
232:
208:
205:
193:
192:
188:
184:
143:, are used as
133:delocalization
128:
125:
93:
90:
26:
9:
6:
4:
3:
2:
1014:
1003:
1000:
998:
997:Azo compounds
995:
994:
992:
978:
974:
970:
966:
963:(1): 203–10.
962:
958:
957:
949:
941:
937:
933:
929:
925:
921:
917:
913:
906:
898:
894:
888:
880:
876:
872:
868:
864:
860:
853:
838:
836:9780123849533
832:
828:
824:
820:
819:
814:
807:
798:
792:
791:
786:
779:
771:
767:
763:
759:
755:
751:
743:
735:
733:3-527-30673-0
729:
725:
721:
717:
716:
708:
706:
704:
692:
688:
681:
674:
672:
655:
651:
650:Food-Info.net
647:
641:
639:
630:
626:
621:
616:
612:
608:
603:
598:
594:
590:
587:(1): e03271.
586:
582:
578:
571:
565:
561:
557:
556:azo compounds
553:
552:
547:
542:
538:
528:
525:
523:
520:
518:
515:
513:
510:
509:
503:
501:
491:
489:
485:
481:
476:
474:
470:
466:
462:
452:
449:
439:
437:
432:
430:
429:lightfastness
426:
418:
414:
409:
405:
392:
386:
381:
378:
377:Direct Blue 1
372:
367:
363:
358:
354:
349:
342:
337:
334:
333:
332:
329:
327:
291:
276:
275:
274:
272:
268:
257:+ Ar′NHC(O)CH
245:
244:
243:
226:
225:
224:
222:
218:
214:
204:
202:
198:
182:
181:
180:
173:
169:
164:
160:
158:
154:
150:
146:
142:
141:methyl orange
138:
134:
121:
117:
113:
109:
107:
103:
102:reactive dyes
99:
89:
87:
83:
79:
75:
71:
66:
62:
61:azo compounds
58:
54:
50:
46:
39:
34:
30:
19:
960:
954:
948:
918:(1): 76–80.
915:
911:
905:
897:the original
887:
862:
858:
852:
840:. Retrieved
816:
806:
796:
788:
785:"Methyl Red"
778:
753:
749:
742:
713:
691:the original
686:
658:. Retrieved
649:
584:
580:
570:
549:
541:
527:Glycoazodyes
512:Azo coupling
497:
477:
473:carcinogenic
458:
445:
436:Peter Griess
433:
422:
402:
399:Azo pigments
391:Basic Red 18
330:
323:
264:
241:
213:azo coupling
210:
197:ion exchange
194:
177:
130:
95:
86:azo pigments
51:bearing the
44:
43:
29:
912:Dermatology
842:29 November
660:29 November
484:carcinogens
207:Preparation
187:H → RSO
116:Trypan blue
991:Categories
646:"Azo dyes"
533:References
517:Ponceau 4R
448:photolysis
172:tautomeric
120:direct dye
879:1181-8700
611:2405-8440
522:Ponceau S
480:benzidine
469:mutagenic
438:in 1858.
203:centers.
155:and some
18:Diazo dye
977:15177655
940:34959909
932:18032904
770:12418911
654:Archived
629:32042981
506:See also
463:orange,
267:anilines
168:phenolic
78:textiles
45:Azo dyes
620:7002841
589:Bibcode
581:Heliyon
281:+ Ar′NH
147:. Most
92:Classes
74:textile
975:
938:
930:
877:
833:
768:
730:
627:
617:
609:
425:paints
219:of an
104:, and
936:S2CID
694:(PDF)
683:(PDF)
546:IUPAC
271:azoxy
166:Many
149:DVD-R
973:PMID
928:PMID
875:ISSN
844:2022
831:ISBN
766:PMID
728:ISBN
662:2022
625:PMID
607:ISSN
482:are
471:and
277:ArNO
191:+ H
157:CD-R
72:and
70:food
65:dyes
57:aryl
47:are
965:doi
961:151
920:doi
916:216
867:doi
823:doi
758:doi
754:124
720:doi
615:PMC
597:doi
560:doi
558:".
316:+ H
247:ArN
228:ArN
183:RSO
993::
971:.
959:.
934:.
926:.
914:.
873:.
863:19
861:.
829:.
794:;
787:.
764:.
752:.
726:.
718:.
702:^
685:.
670:^
652:.
648:.
637:^
623:.
613:.
605:.
595:.
583:.
579:.
548:,
475:.
419:).
310:10
298:12
153:+R
100:,
80:,
979:.
967::
942:.
922::
881:.
869::
846:.
825::
801:.
772:.
760::
736:.
722::
664:.
631:.
599::
591::
585:6
562::
320:O
318:2
314:6
312:O
308:H
306:6
302:6
300:O
296:H
294:6
289:O
287:2
283:2
279:2
259:2
252:2
233:2
189:3
185:3
151:/
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
