O-anisidine, 5-

Titrimetric Methods. Frequently, the reduction of gold solutions leads to finely divided precipitates which are difficult to recover quantitatively. In such cases, the reduction of Au(III) to Au(0) by, eg, hydroquinone, can be followed potentiometricaHy (49). The end point in such titrations also can be determined with indicators such as benzidine (50) or o-anisidine (51). Alternatively, the reduction can be effected with excess hydroquinone which is then back-titrated with Ce(IV) (52). lodometric deterrnination of Au(III) also is useflil (53). 

Uses. (9-Nitrochlorobenzene is used in the synthesis of azo dye intermediates such as o-chloroaniline (Fast YeUow G Base), i9-nitroani1ine (Fast Orange GR Base), o-anisidine (Fast Red BB Base), o-phenetidine, and (9-aminophenol (see Azo dyes). It also is used in corrosion inhibitors, pigments, and agriculture chemicals. -Nitrochlorobenzene is used principally in the production of intermediates for azo and sulfur dyes. Other uses include pharmaceuticals (qv), photochemicals, mbber chemicals (qv), and insecticides (see Insectcontroltechnology). Typical intermediates manufactured from the para isomer are -lutioaruline (Fast Red GC Base), anisidine, -aminophenol, -nitrophenol, -phenylenediamine, 2-chloro-/)-anisidine (Fast Red R Base), 2,4-dinitrochlorobenzene, and l,2-dichloro-4-nitrobenzene. 

Fig. 5. Direct red dyes, (a) Direct Red 81 described ia text (68) (b) Direct Red 2 (o-toLidiae coupled to two moles of naphthionic acid) (69) (c) Direct Red 23 (aniline coupled to 6,6 -ureylenebis-l-naplitliol-3-sulfonic acid with a second coupling with j aminoacetanilide) (70) and Direct Red 80 (2 mol 6-amino-3,4 -azobenzenedisulfonic acid coupled twice to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid) (73). Direct Red 24 (4-aniino-y -toluenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an alkaline coupling of o-anisidine) (71) (d) Direct Red 72 (Broenner s acid, ie, 6-artiino-2-naphthalenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an...

Guaiacols. Cresote, obtained from the pyrolysis of beechwood, and its active principles guaiacol [90-05-1] (1) and cresol [93-51-6] (2) have long been used ia expectorant mixtures. The compounds are usually classed as direct-acting or stimulant expectorants, but their mechanisms of action have not been well studied. Cresol is obtained by the Clemmensen reduction of vanillin (3), whereas guaiacol can be prepared by a number of methods including the mercuric oxide oxidation of lignin (qv) (4), the ziac chloride reduction of acetovanillone (5), and the diazotization and hydrolysis of o-anisidine (6). 

Nitric acid, 98 Nitric oxide, 98 Nitrilotriacetic acid, 98 p-Nitroaiiiline, 99 Nitrobenzene, 99 Nitrocarbono SA, 146 Nitrocellulose, 99 p-Nitrochlorobenzene, 99 Nitroethane, 99 Nitrofen, 99 Nitrogen, 99 Nitrogen dioxide, 99 Nitrogen oxides, 99 Nitrogen trifluoride, 99 Nitroglycerin, 100 Nitrokemia 200 Rt., 167 Nitromethane, 100 5-Nitro-o-anisidine, 99 5-Nitro-o-toluidine, 100 Nitrophenols, 100... 

Each of the following compounds has been prepared from o-anisidine (o-methoxyaniline). Outline a series of steps leading to each one. 

This procedure may be employed for m-chlorobromobenzene, b.p. 191-194° from tn chloroaniline m-dibromobenzene, b.p. 215-217°, from m-bromoaniline and o-bromoanisole, b.p. 114 116°/29 mm. from o anisidine (the sulphuric acid washing is omitt in the last example). 

Acetyl-o-anisidine Acetyl-m-anisidine Acetyl-p-anisldine Acetyl-o-phenetidine Acetyl-m-pbenetidine Acetyl-p-phenetidine (or phenacetin) Acetyl-a-naphthylamine Acetyl- p-naphthylamine... 

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