2- benzophenones, oxidation

Compared to the time scale of their formation, the carbonyl oxides are quite long lived (10 -10 s), and so their subsequent reactions can be monitored kinetically. For most of the carbonyl oxides, the decay is best fit to a second-order rate law, indicating a bimolecular decomposition pathway. For benzophenone oxide, the ketone is the major product at room temperature, and no dimer can be detected. A bimolecular process involving O2 extrusion from two molecules of the oxides is suggested under these conditions. 

Chloro-2-(3-methyl-4H-l,2,4-triazol-4-yl)benzophenone (Oxidation of 7-chloro-l-methyl-5-phenyl-s-trizolo[4,3-a]quinoline) A stirred suspension of 7-chloro-l-methyl-5-phenyl-s-triazolo[4,3-a] quinoline (2,94 g, 0.01 mol) in acetone (110 ml) was cooled in an ice-bath and treated slowly with a solution prepared by adding sodium periodate (2 g) to a stirred suspension of ruthenium dioxide (200 mg) in water (35 ml). The mixture became dark. Additional sodium periodate (8 g) was added during the next 15 minutes. The ice-bath was removed and the mixture was stirred for 45 minutes. Additional sodium periodate (4 g) was added and the mixture was stirred at ambient temperature for 18 hours and filtered. The solid was washed with acetone and the combined filtrate was concentrated in vacuum. The residue was suspended in water and extracted with methylene chloride. The extract was dried over anhydrous potassium carbonate and concentrated. The residue was chromatographed on silica gel (100 g) with 10% methanol and 90% ethyl acetate 50 ml fractions were collected. The product was eluted in fractions 10-20 and was crystallized from ethyl acetate to give 0.405 g of melting... 

Hydration of the double bond led to a mixture of alcohols, which were separated and heated with potassium hydroxide in diethylene glycol at 225°C in the presence of a trace of hydrazine (H2NNH2) to cause partial demethylation.That was followed by a modified Oppenauer (potassium t-butoxide-benzophenone) oxidation. Then, bromination of the arylketone produced a dibromide that formed a 2,4-dinitro-phenylhydrazone (DNPH) derivative identical to one obtained from 1-bromothe-... 

Benzophenone Process. Benzophenone, (CgH5 )2C=0, reacts with ammonia to form diphenylmethanimine, (CgHg )2C=NH. In the presence of copper catalysts, this is oxidized with oxygen to benzophenone azine, (CgHg )2C=N—N=C(CgHg The formation of the imine and its... 

Benzophenone is produced by the oxidation of diphenylmethane (350). This free from chlorine (FCC) route is favored for perfume uses. The Friedel-Crafts reaction of benzene and benzoyl chloride in the presence of aluminum chloride is also possible this reaction may proceed in the absence of catalyst at a temperature of 370°C and pressure of 1.4 MPa (351). 

In the ketone method, the central carbon atom is derived from phosgene (qv). A diarylketone is prepared from phosgene and a tertiary arylamine and then condenses with another mole of a tertiary arylamine (same or different) in the presence of phosphoms oxychloride or zinc chloride. The dye is produced directly without an oxidation step. Thus, ethyl violet [2390-59-2] Cl Basic Violet 4 (15), is prepared from 4,4 -bis(diethylamino)benzophenone with diethylaruline in the presence of phosphoms oxychloride. This reaction is very useful for the preparation of unsymmetrical dyes. Condensation of 4,4 -bis(dimethylamino)benzophenone [90-94-8] (Michler s ketone) with AJ-phenjl-l-naphthylamine gives the Victoria Blue B [2580-56-5] Cl Basic Blue 26, which is used for coloring paper and producing ballpoint pen pastes and inks. 

Quinazoline 3-oxides were first prepared by Awers and von Meyen-burg in 1891 by the dehydration of o-acylamino benzophenone oximes with acetic acid-acetic anhydride and were assigned the in-dazole structure (33). This was then modified by Bischler to the... 

Oxidation of Pluviine (276), isolated from Narcissus pseudonarcissus. Narcissus incomparabilis, and Lycoris radiata Herb., with benzophenone and potassium rerr-butylate yielded a red phenol-betaine 277 from which one neutral covalent form can be drawn (Scheme 90). The betaine has absorption maxima Imax (loge) in a buffer at pH 10 at 240 (4.49), 325 (4.46), 360 (3.58), 380 (3.27), and 490 (3.26) nm. In dilute HCl, a salt is formed [lmax = 260 (4.57), 295 (4.39), 340 (3.76), 355 (3.84), 400 (3.62) nm] (57CB363). The oxidation of the alkaloid Caranine gives a similar betaine, the 1,3-dioxolo derivative 278 (56CIL348). 

Figure 12.3 Clrromatogr-ams of an ignition-resistant high-impact polystyrene sample (a) Microcolumn SEC fi ace (b) capillary GC trace of peak x . Peak identification is as follows 1, ionol 2, benzophenone 3, styrene dimer 4, palmitic acid 5, stearic acid 6, styrene trimers 7, styrene trimer 8, styrene oligomer 9, Irganox 1076 and Irganox 168 10, styrene oligomer 11, nonabromodiphenyl oxide and 12, decabromodiphenyl oxide. Reprinted with permission from Ref. (12).

A further variant of Method B is the conversion of the readily available aryl(2-methyl-aminoaryl)methanols 16 into the chloroacelyl derivatives 17, followed by oxidation to Ihe benzophenones 18 with chromium(VI) oxide. The products are transformed into benzodi-azepinones by treatment with sodium iodide and ammonium carbonate (Method D). Selected... 

Lewin and Cohen (1967) determined the products of dediazoniation of ben-zophenone-2-diazonium salt (10.42, Scheme 10-77) in five different aqueous systems (Table 10-7). About one-third of the yield is 2-hydroxybenzophenone (10.46) and two-thirds is fluorenone (10.45, run 1) copper has no effect (run 2). On the other hand, addition of cuprous oxide (run 3) has a striking effect on product ratio and rate. The reaction occurs practically instantaneously and yields predominantly fluorenone. As shown in Scheme 10-77, the authors propose that, after primary dediazoniation and electron transfer from Cu1 to 10.43 the sigma-complex radical 10.44 yields fluorenone by retro-electron-transfer to Cu11 and deprotonation. In the presence of the external hydrogen atom source dioxane (run 12) the reaction yields benzophenone cleanly (10.47) after hydrogen atom abstraction from dioxane by the radical 10.43. 

The use of ethyl ethylthiomethyl sulphoxide in this reaction leads to the desired addition products in much better yields (95-97%). These products were then converted into ketene dithioacetal monoxide derivatives 430 by a sequence of reactions (equation 258)505. Reaction of 2-lithio-l,3-dithiane-l-oxide with benzophenone affords a mixture of the diastereoisomeric tertiary alcohols 431 in a ratio which is temperature dependent (cis trans changes from 3 1 at — 78 °C to 1 1 at room temperature)268. 

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