Reference

2-Chloro-4-aminotoluene-5-sulfonic acid

2-Chloro-4-aminotoluene-5-sulfonic acid. Vladutiu, Liana Maria; Atanasiu-Meves, Carmen Violeta Maria; Spiliadis, Apostol; Dobrescu, Dumitru; Aldea, Viorel Ion (Combinatul Chimic, Giurgiu, Rom.). Rom. RO 76842 B 30 Aug 1981, 4 pp. (Romanian). (Romania). CODEN: RUXXA3. CLASS: IC: C07C143-40. APPLICATION: RO 78-94821 28 Jul 1978. DOCUMENT TYPE: Patent CA Section: 41 (Dyes, Organic Pigments, Fluorescent Brighteners, and Photographic Sensitizers) Section cross-reference(s): 25 The title acid (I) [88-51-7], for use as an org. pigment intermediate, is manufd. by chlorination at 50-75° of 4-nitrotoluene (II) [99-99-0] in the presence of Fe filings as catalyst, redn. of the resulting 2-chloro-4-nitrotoluene (III) [121-86-8] with a Raney Ni catalyst in a low-mol.-wt. alc. at III concn. 5-40%, 40-60°/15 atm, and catalyst concn. 0.1-5% (based on III), and sulfonation of the resulting 4-amino-2-chlorotoluene (IV) [95-74-9]. Thus, Cl was added to 548 g II and 5.2 g Fe filings for 6 h at 60-70° under strong stirring to give 86-89% III, which was reduced (200 g, contg. 10% II) in 500 mL MeOH in the presence of 5 g Raney Ni at 40-60°/15 atm with 1.8 mL H/g min for 3.75 h to give 137 g (96% yield) IV and 15 g 4-aminotoluene. IV (92 g) was sulfonated by 72 g H2SO4 in o-dichlorobenzene at 100-120° for 4 h to give 85% I at IV conversion 98%.

Azo pigments

Azo pigments. Stefancsik, Ernest Anton (du Pont de Nemours, E. I., and Co., USA). Ger. Offen. DE 2803990 3 Aug 1978, 10 pp. (German). (Germany). CODEN: GWXXBX. CLASS: IC: C09B029-14. PRIORITY: US 77-764234 31 Jan 1977. DOCUMENT TYPE: Patent CA Section: 40 (Dyes, Fluorescent Whitening Agents, and Photosensitizers) Azo pigments (I, R, R1 = Me, Cl, only 1 R or R1 = Me; M = Ca, Sr) were prepd., which do not show a shade change or viscosity increase on aging of aq. suspensions, by adding CaCl2 to the diazonium salt and Sr(NO3)2 to the unisolated pigment. Thus, 4-amino-2-chlorotoluene-5-sulfonic acid [88-51-7] was diazotized, aq. CaCl2 added to the diazotized suspension, and the suspension added to 3-hydroxy-2-naphthoic acid [92-70-6], Na rosinate and Sr(NO3)2 were added, and the reaction mixt. was boiled to give an azo pigment with no change in viscosity or color while a pigment prepd. similarly with Sr(NO3)2 alone showed changes in viscosity and color.