Chlorotoluene oxidation

With hydrogen sulfide at 500—600°C, monochlorotoluenes form the corresponding thiophenol derivatives (30). In the presence of palladium catalysts and carbon monoxide, monochlorotoluenes undergo carbonylation at 150—300°C and 0.1—20 MPa (1—200 atm) to give carboxyHc acids (31). Oxidative coupling of -chlorotoluene to form 4,4 -dimethylbiphenyl can be achieved in the presence of an organonickel catalyst, generated in situ, and zinc in dipolar aprotic solvents such as dimethyl acetamide (32,33). An example is shown in equation 4. 

Dehalogenation of monochlorotoluenes can be readily effected with hydrogen and noble metal catalysts (34). Conversion of -chlorotoluene to Ncyanotoluene is accompHshed by reaction with tetraethyl ammonium cyanide and zero-valent Group (VIII) metal complexes, such as those of nickel or palladium (35). The reaction proceeds by initial oxidative addition of the aryl haHde to the zerovalent metal complex, followed by attack of cyanide ion on the metal and reductive elimination of the aryl cyanide. Methylstyrene is prepared from -chlorotoluene by a vinylation reaction using ethylene as the reagent and a catalyst derived from zinc, a triarylphosphine, and a nickel salt (36). 

Chlor-siure, /. chloric acid. -sMureanhydrid, n. chloric anhydride, chlorine(V) oxide, -schwefel, n. sulfur chloride (esp. the monochloride). -silber, n. silver chloride, -sili-cium, n. silicon tetrachloride, -soda, /. = Chlornatron. -stickstoff, m. nitrogen chloride. -Strom, m. stream of chlorine, -strontium, n. strontium chloride, -suifonsaure, /. chlorosulfonic acid, chlorosulfuric acid, -toluol, n. chlorotoluene. -fibertrager, m. chlorine carrier. 

However, this oxidation to carbonyl failed with the complexes of tetralin, o-chlorotoluene, 9,10-dihydrophenanthrene, and acenaphthalene [109]. The aniline complex can be oxidized to the nitrobenzene complex using H202 in CF3C02H [86] Eq. (38). This reaction parallels the analogous oxidation of aminocobaltici-nium [86, 111],... 

The results for the hydrolysis of chlorobenzene, o-chlorotoluene and p-chloroanisole in presence of cuprous oxide at different temperatures (Fig. 14) show a good selectivity for the reaction of the chlorobenzene. But, the p-chloroanisole is also transformed by a secondary demethylation reaction into the corresponding p-chlorophenolate. 

Ester (9) can easily be made from acid (H)- You might consider two approaches to this a one-carbon electrophile addition via chloromethylation (Table T 2.2) and oxidation or FGl (Table 2,3) back to p-chlorotoluene (12). The latter is easier on a large scale. The p-chlorotoluene (12) can be made either by direct chlorination of toluene or by the diazotisation route (p T 12) again from toluene. 

A useful application in the manufacture of ion-exchange resins may well be possible which avoids the use of carcinogenic chloromethyl ether. Here, a polymer of p-methyl styrene is chlorinated on the side chain with aqueous NaOCl and a phase-transfer catalyst. Sasson et al. (1986) have shown how stubborn . substituted aromatics like nitro/chlorotoluenes can be oxidized to the corresponding acids by using aqueous NaOCl containing Ru based catalyst. 

The only practical methods of preparing o-chlorobenzoic acid consist in the oxidation of o-chlorotoluene and the replacement of the amino group in anthranilic acid by a chlorine atom. Both of these methods have been fully discussed by Graebe,1 who recommends the former for the preparation of relatively large quantities. The oxidation of o-chlorotoluene by permanganate was originally described by Emmerling.2... 

The anodic chlorination in some cases allows one to achieve better regioselec-tivities than chemical alternatives (p/o ratio of chlorotoluene in chlorination of toluene anodic 2.2, chemical alternative 0.5-1.0) [215]. Anodic oxidation of iodine in trimethyl orthoformate afforded a positive iodine species, which led to a more selective aromatic iodination than known methods ]216]. Aryliodination is achieved in good yield, when an aryhodide is oxidized in HOAc, 25% AC2O, 5% H2SO4 in the presence of an arene ]217, 218]. Alkyl nitroaromatic compounds, nitroaromatic ketones, and nitroanihnes are prepared in good yields and regioselectivity by addition of the corresponding nucleophile to a nitroarene and subsequent anodic oxidation of the a-complex (Table 13, number 11) ]219, 220]. 

Promoters that will form organosodium compounds, such as anthracene and o-chlorotoluene, favor the alkylation reaction as well as sodium isoprop-oxide, which must act as a chain promoter. These compounds are needed for the phenylethylation of cumene. 

Figure 2. Schematic Diagram Illustrating the Difference Between Thermal, Cobalt Catalyzed, and Co/Mn/Br Catalyzed Oxidation of M-Chlorotoluene...

The Co/Mn/Br now eliminates the bottleneck caused by the presence of Co(in)s. The steady state concentration of Co(III) is also much lower caused by its rapid reduction by Mn(II). This reduces carboxylic acid decomposition. We have measured the rate of Mn(III) oxidaion of bromide in the presence and absence of p-xylene and do not find any difference in rate. Hence the system also eliminates the slow Co(III) + chlorotoluene reaction. This sequence of reactions is overall faster and more selective than either the thermal or cobalt catalyzed oxidation of m-chlorotoluene. 

Synonym Gamma-Chloropropylene Oxide 3-Chloro-1,2-Propylene Oxide Chlorosulfonic Acid Chlorothene Chiorotoluene, Alpha Alpha-Chlorotoluene Omega-Chlorotoluene Chlorotrifluoroethylene Chlorotrimethylsilane Chlorsulfonic Acid Clilorylen Clip Chromic Acid Chromic Anhydride Chromic Oxide Chromium (VI) Dioxychloride Chromium Oxychloride Chromium Trioxide Chromyl Chloride Cianurina Citric Acid Citric Acid, Diammonium Salt Clarified Oil Clorox Cc Ral Coal Tar Oil Cobalt Acetate Cobalt Acetate Tetrahydrate Cobalt (II) Acetate Cobalt Chloride Cobalt (II) Chloride Cobaltous Acetate Cobaltous Chloride Cobaltous Chloride Dihydrate Cobaltous Chloride Hexahydrate Cobaltous Nitrate Cobaltous Nitrate Hexahydrate Cobaltous Sulfate Heptahydrate Cobalt Nitrate Cobalt (II) Nitrate Cobalt Sulfate Compound Name Epichlorohydrin Epichlorohydrin Chlorosulfonic Acid Trichloroethane Benzyl Chloride Benzyl Chloride Benzyl Chloride Trifluorochloroethylene Trimethylchlorosilane Chlorosulfonic Acid Trichloroethylene Cumene Hydroperoxide Chromic Anhydride Chromic Anhydride Chromic Anhydride Chromyl Chloride Chromyl Chloride Chromic Anhydride Chromyl Chloride Mercuric Cyanide Citric Acid Ammonium Citrate Oil Clarified Sodium Hypochlorite Coumaphos Oil Coal Tar Cobalt Acetate Cobalt Acetate Cobalt Acetate Cobalt Chloride Cobalt Chloride Cobalt Acetate Cobalt Chloride Cobalt Chloride Cobalt Chloride Cobalt Nitrate Cobalt Nitrate Cobalt Sulfate Cobalt Nitrate Cobalt Nitrate Cobalt Sulfate... 

The influence of substituents on the catalytic oxidation of toluene was investigated by Trimm and Irshad [330]. Toluene, chlorotoluenes and xylenes were oxidized over a M0O3 catalyst at 350—500° C. Partial oxidation products are aldehydes, acids and phthalic anhydride (in the case of o-xylene). Unexpectedly, both xylenes and chlorotoluenes are oxidized faster than toluene. The authors conclude that apparently the electromeric effect of the chlorosubstituent is more important than its inductive (—I) effect. The activation energies of the xylenes and chlorotoluenes all fall in the same range (17—18 kcal mol"1), while a much higher value is reported for toluene (27 kcal mol 1). 

SAMPLE SOLUTION (a) Reaction with ethylene oxide results in the addition of a —CH2CH2OH unit to the Grignard reagent. The Grignard reagent derived from o-bromotoluene (or o-chlorotoluene or o-iodotoluene) is appropriate here. 

Cognate preparations, p-Chlorobenzoic acid. Proceed exactly as for o-chlorobenzoic acid. Use 1250 ml of water, 50 g (0.4 mol) of p-chlorotoluene (Expt 6.71) and 75 g, 37.5 g and 37.5 g (0.95 mol total) of potassium permanganate. When the oxidation is complete, steam distil the mixture to recover any unreacted p-chlorotoluene (3-4 g). Filter the reaction mixture from hydrated manganese dioxide and wash the precipitate with two 100 ml portions of water. Precipitate the p-chlorobenzoic acid in the filtrate (1) by the addition of 75 ml of concentrated hydrochloric acid. Filter the cold solution with suction, wash with cold water and dry in an oven at 100 °C. The yield of p-chlorobenzoic acid, m.p. 234-235 °C, is 55 g (89%). Recrystallisation from hot water raises the m.p. to 238-239 °C. 

In the case of ortho-substituted aryl halides, which are less reactive towards Ni°(bpy)n the formation of the arylzinc intermediate likely involves the occurrence of a Ni°-bpy-Zn(II) complex, which by reduction leads directly to the oxidative addition-transmetallation process. According to this, the nickel catalyst is NiBr2bpy, without extra bipyridine. It is thus possible to prepare arylzinc halides from not easily reduced 2-chlorotoluene or 2-chloroanisole, but also, more importantly, from aryl bromides or chlorides bearing reactive functional groups (COR, C02R, CN). These compounds can then be added... 

The ET mechanism is proposed on the basis of the high value of p = —2.4 obtained from the Hammett plot, as well as the observation of benzyl chloride and chlorotoluene as the main products when the oxidation is carried out in the presence of high concentrations of LiCl [41]. Similarly, activation of benzylic C-H bonds by other strong oxidants such as Mnm or PbIV has been suggested to occur through an initial electron transfer, especially in the case of aromatic substrates with low ionization potentials [42]. However, there have been no reports of complex formation between the metal and the arene prior to ET, and no such reactive complex has been isolated and characterized by X-ray crystallography. 

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