O Tolualdehyde

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATIC COMPOUNDS] (Volll) o-tolualdehyde [529-20-4]... 

Tiffeneau rearrangement, 34, 19 Tiglic aldehyde, diethyl acetal, 32, 5 Tin, tetraethyl-, 36, 86 Tin tetrachloride, 36, 87 o-Tolualdehyde, 30, 99 TOLUENE-a,a-DIOL, 0-NITRO-, DIACETATE, 36, 58... 

NAPHTHALENE THIOL, 51, 139 Titanium tetrachloride, 54, 93 o-Tolualdehyde, by reduction of... 

FIGURE 8.7 Separation of aldehydes and ketones by CEC in the organo-silica monolith shown in Figure 8.6. Column 50 cm x 50 xm ID (46 cm effective length), separation at —25 kV mobile phase 70% acetonitrile-30% 5 mM Tris-HCL (pH = 2.3) analytes (1) ben-zaldehyde, (2) o-tolualdehyde, (3) butyrophenone, (4) valerophenone, (5) hexaphenone, and (6) heptaphenone. (Reprinted from J. D. Hayes, A. Malik, Anal. Chem., 72 4090 (2000). With permission. Copyright American Chemical Society 2000.)... 

Chemical/Physical. Under atmospheric conditions, the gas-phase reaction of o-xylene with OH radicals and nitrogen oxides resulted in the formation of o-tolualdehyde, o-methylbenzyl nitrate, nitro-o-xylenes, 2,3-and 3,4-dimethylphenol (Atkinson, 1990). Kanno et al. (1982) studied the aqueous reaction of o-xylene and other aromatic hydrocarbons (benzene, toluene, w and p-xylene, and naphthalene) with hypochlorous acid in the presence of ammonium ion. They reported that the aromatic ring was not chlorinated as expected but was cleaved by chloramine forming cyanogen chloride. The amount of cyanogen chloride formed increased at lower pHs (Kanno et al., 1982). In the gas phase, o-xylene reacted with nitrate radicals in purified air forming the following products 5-nitro-2-methyltoluene and 6-nitro-2-methyltoluene, o-methylbenzaldehyde, and an aryl nitrate (Chiodini et ah, 1993). 

Tetramethylhydrazine, see Dimethylamine Tetramethylsuccinonitrile, see Aldicarb Tetrazene, see Naphthalene 2-Thiazolidinethione-4-carboxylic acid, see Captan 1.1 -Thiobis-ethane, see Phorate 3.3 -Thiobis(methylene)-1.2.3-benzotriazin-4(3Afl-one, see Azinnhos-methyl Thiomalic acid, see Malathion Thiomethylbenzazimide, see Azinphos-methyl Thiophene, see Benzene Thiophenol, see Fonofos Thiophosphoric acid, see Phorate Thiram monosulfide, see Thiram o-Tolualdehyde, see oXylene m-Tolualdehyde, see m-Xylene p-Tolualdehyde, see p-Xylene Toluene, see Benzene. 2-ChlorobiDhenyl. 4 Chlorobinhenyl. Isobutylbenzene, Methylcyclohexane, Styrene, p-Xylene... 

NAPHTHALENETHIOL, 51, 759 o-Tolualdehyde, by reduction of o-tolu-nitrile with Raney nickel alloy in formic acid, 51,25 p-Toluenesulfonyl azide, with 2-(hy-... 

Further investigation with various silyl ketene acetals is summarized in Table 6. Silyl ketene acetals derived from various esters were reacted with /V-benzyloxy-carbonylamino sulfones 1 in the presence of 0.5-1 mol% Bi(0Tf)3-4H20. The corresponding (3-amino esters 24 were obtained in moderate to good yields (Table 6). Silyl enolates derived from esters as well as thioesters reacted smoothly to give the adducts. The /V - be n z v I o x v c ar bo n v I a m i n o sulfone derived from n-butvraldehyde lp led to moderate yields of (3-amino esters when reacted with (thio)acetate-derived silyl ketene acetals (Table 6, entries 1 and 2). A very good yield was obtained when the same sulfone was subjected to a tetrasubstituted silyl ketene acetal (Table 6, entry 3). The latter afforded moderate to good yields of (3-amino esters 24 with phenylacetaldehyde, / -tolu aldehyde, and o-tolualdehyde-derived sulfones (Table 6, entries 4-6). 

The gas-phase selective oxidation of o-xylene to phthalic anhydride is performed industrially over vanadia-titania-based catalysts ("7-5). The process operates in the temperature range 620-670 K with 60-70 g/Nm of xylene in air and 0.15 to 0.6 sec. contact times. It allows near 80 % yield in phthalic anhydride. The main by-products are maleic anhydride, that is recovered with yields near 4 %, and carbon oxides. Minor by-products are o-tolualdehyde, o-toluic acid, phthalide, benzoic acid, toluene, benzene, citraconic anhydride. The kinetics and the mechanism of this reaction have been theobjectof a number of studies ( 2-7). Reaction schemes have been proposed for the selective pathways, but much less is known about by-product formation. 

Oxidation of ortho-xylene. The spectra of the adsorbed species arising from interaction of ortho-xylene with the surface of the vanadia-titania catalyst in the presence of oxygen are shown in Figure 4. The spectra show some parallel features with respect to those discussed above concerning the oxidation of toluene and meta- and para-xylene. Also in this case the o-methyl-benzyl species begins to transform above 373 K, with production of adsorbed o-tolualdehyde (band at 1635 cm 0 and of a quinone derivative (band at 1670 cm. Successively bands likely due to o-toluate species (1530,1420 cm 0 grow first and decrease later with production of CO2 gas. 

This scheme and our data agree with the product distribution in o-xylene oxidation reported by many authors (1-7) as well as with experiments of oxidation of intermediates (37) o-tolualdehyde and phthalide are observed as the main intermediates in the 523-573 K temperature range, while phthalic anhydride selectivity grows in the 473-573 K range and later only slightly decreases above 600 K when also maleic anhydride appears and conversion is very high. 

The crude product is distilled from a Claisen flask under reduced pressure. The yield of o-tolualdehyde boiling at 68-72°/6 mm., Wd 1-5430, is 41-44 g. (68-73%) (Note 3). 

A procedure for the preparation of o-tolualdehyde from o-toluanilide by the Sonn-Miiller method has been published in Organic Syntheses. In addition to the alternative methods of preparation listed there, o-tolualdehyde has been prepared from o-xylyl bromide and hexamethylenetetramine, by the Stephen reduction of o-tolunitrile, and by the procedure of the present preparation. ... 

Detailed mechanistic studies about both oxidations have been carried out.901,1006,1033 On the basis of the observed intermediates, a reaction network [Eq. (9.184)] was suggested in the oxidation of o-xylene indicating o-tolualdehyde as the first intermediate 1034,1035... 

Aromatic aldehydes and ketones (o-tolualdehyde acetophenone) accumulator column 3 88-96 92 2-17 12 d... 

Lyubarski et al. [192] studied the oxidation of tolualdehyde, phthalic anhydride and maleic anhydride, separately and in mixtures, using a recirculation reactor with a high temperature V2Os catalyst at 400—460° C. o-Tolualdehyde (and o-xylene) were found to stabilize phthalic anhydride, even with a 10 1 excess of the latter. Phthalic anhydride, in turn, appeared to inhibit the maleic anhydride oxidation. Consequently, the tolualdehyde oxidation seemingly follows a parallel scheme... 

Regarding the kinetics, the oxidation of o-xylene and o-tolualdehyde were compared for catalysts with different V/Ti ratios (Table 36). The ratio between partial and complete oxidation (X for o-xylene and Y for o-tolualdehyde) are influenced similarly, indicating that a change in the catalyst structure influences all the reaction steps. The oxidation of o-tolualdehyde in mixtures with o-xylene revealed that o-tolualdehyde reduces the o-xylene oxidation rate by a factor of about 2. The authors conclude that a redox model is inadequate and that hydrocarbon adsorption cannot be rate-determining. Adsorption of various products should be included, and equations of the Langmuir—Hinshelwood type are proposed. It should be noted that the observed inhibition is not necessarily caused by adsorption competition, but may also stem from different... 

Comparison between selectivities for o-xylene and o-tolualdehyde oxidation on V2O5—Ti02 catalyst at 450°C... 

The performance of a number of single oxides of transition metals was studied by Skorbilina et al. [295] using a differential reactor. As usual, o-tolualdehyde, phthalic anhydride and carbon oxides are the main reaction products. The initial selectivity with respect to partial oxidation products decreases in the order Co > Ti > V > Mo > Ni > Mn > Fe > Cu from 71% to 33%. The relatively high initial selectivities demonstrated by the deep oxidation catalysts (e.g. Co, Ni, Mn) indicates that the primary activation is probably the same for all these catalysts, while the differences that actually determine the character of the catalyst are connected with the stability of intermediates and products. 

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