Benzene butylbenzene

Note May contain minute quantitities of benzene, butylbenzene, xylenes, and nonaromatic compounds as impurities. Technical grades may contain as much as 10% benzene. 

Propyl benzene Butylbenzene Bi phenyl Terphenyl Methylindene... 

The variation of the free energy of the FET by stepwise electron transfer using mediator radical cations (benzene, butylbenzene, biphenyl) allows the energetic distinction between the diffusion-controlled (free) and the reaction-controlled electron transfer process. 

Application of this technique to the identification of methyl esters of the organic acids obtained by the controlled oxidation of bituminous coal allowed the more volatile benzene carboxylic acid esters to be identified (Studier et al., 1978). These were esters of benzene tetracarboxylic acid, tere-phthalic acid, toluic acid, and benzoic acid. Decarboxylation of the total acid mixture was shown to afford benzene, toluene, Cj-benzenes (i.e., ethylbenzene or xylenes), Cj-benzenes, butylbenzenes, Cj-benzenes, Cybenzenes, naphthalene, methylnaphthalene, C2-naphthalene, biphenyl, methylbi-phenyl, C3-biphenyl, indane, methylindane, Cj-indane, phenanthrene, and fluorene. 

Ratio toluene- /-f-butylbenzene. The partial rate factors are based on the relative rates for toluene benzene of ref. i. 

Figure 12 7 illustrates attack on the benzene ring by tert butyl cation (step 1) and subsequent formation of tert butylbenzene by loss of a proton from the cyclohexadienyl cation intermediate (step 2)... 

One drawback to Fnedel-Crafts alkylation is that rearrangements can occur espe cially when primary alkyl halides are used For example Friedel-Crafts alkylation of benzene with isobutyl chloride (a primary alkyl halide) yields only tert butylbenzene... 

Direct alkylation of benzene using 1 chlorobutane and aluminum chloride would yield sec butylbenzene by rearrangement and so could not be used... 

Carbon-hydrogen stretching vibrations with frequencies above 3000 cm are also found m arenes such as tert butylbenzene as shown m Figure 13 33 This spectrum also contains two intense bands at 760 and 700 cm which are characteristic of monosub stituted benzene rings Other substitution patterns some of which are listed m Table 13 4 give different combinations of peaks... 

Alternatively the alkylated aromatic products may rearrange. -Butylbenzene [104-57-8] is readily isomerized to isobutylbenzene [538-93-2] and j Abutyl-benzene [135-98-8] under the catalytic effect of Friedel-Crafts catalysts. The tendency toward rearrangement depends on the alkylatiag ageat and the reaction conditions (catalyst, solvent, temperature, etc). 

Reactions of acetylene and iron carbonyls can yield benzene derivatives, quinones, cyclopentadienes, and a variety of heterocycHc compounds. The cyclization reaction is useful for preparing substituted benzenes. The reaction of / fZ-butylacetylene in the presence of Co2(CO)g as the catalyst yields l,2,4-tri-/ f2 butylbenzene (142). The reaction of Fe(CO) and diphenylacetylene yields no less than seven different species. A cyclobutadiene derivative [31811 -56-0] is the most important (143—145). 

FIGURE l.l Hydrophobic interaction and reversed-phase chromatography (HIC-RPC). Two-dimensional separation of proteins and alkylbenzenes in consecutive HIC and RPC modes. Column 100 X 8 mm i.d. HIC mobile phase, gradient decreasing from 1.7 to 0 mol/liter ammonium sulfate in 0.02 mol/liter phosphate buffer solution (pH 7) in 15 min. RPC mobile phase, 0.02 mol/liter phosphate buffer solution (pH 7) acetonitrile (65 35 vol/vol) flow rate, I ml/min UV detection 254 nm. Peaks (I) cytochrome c, (2) ribonuclease A, (3) conalbumin, (4) lysozyme, (5) soybean trypsin inhibitor, (6) benzene, (7) toluene, (8) ethylbenzene, (9) propylbenzene, (10) butylbenzene, and (II) amylbenzene. [Reprinted from J. M. J. Frechet (1996). Pore-size specific modification as an approach to a separation media for single-column, two-dimensional HPLC, Am. Lab. 28, 18, p. 31. Copyright 1996 by International Scientific Communications, Inc.. Shelton, CT.]... 

The carbocation electrophile in a Friedel-Crafts reaction can be generated in ways other than by reaction of an alkyl chloride with AICI3. For example, reaction of benzene with 2-methylpropene in the presence of H3PO4 yields tert-butylbenzene. Propose a mechanism for this reaction. 

Benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylcne. butylbenzene, styrene, o-, m-, and p-diethylbenzenes... 

In triethylamine instead of benzene the reaction products are completely different, and are indicative of a homolytic process involving an initial electron transfer from triethylamine followed by a hydrogen atom transfer. Scheme 10-68 gives the major products, namely 1,3,5-tri-tert-butylbenzene (10.36, 20%), the oxime 10.39 (18%), formed from the nitroso compound 10.38, and the acetanilide 10.37 (40%). ESR and CIDNP data are consistent with Scheme 10-68. In their paper the authors discuss further products which were found in smaller yields. 

As might be expected, an increase in pressure reduces the selectivity of the nitronium ion (since the reactivity is effectively increased) and also increases the amount of ortho substitution this has been shown from the relative rates of nitration of benzene and /-butylbenzene in acetic acid at 45 °C60. 

Kinetic studies at 25 °C showed that for benzene, toluene, o-, m-, and p-xylene, /-butylbenzene, mesitylene, 4-chloroanisole, and p-anisic acid in 51 and 75 % aqueous acetic acid addition of small amounts of perchloric acid had only a slight effect on the reaction rate which followed equation (100). At higher concentrations of perchloric acid (up to 0.4 M) the rate rose linearly with acid concentration, and more rapidly thereafter so that the kinetic form in high acid concentration was... 

A kinetic isotope effect, kH/kD = 1.4, has been observed in the bromination of 3-bromo-l,2,4,5-tetramethylbenzene and its 6-deuterated isomer by bromine in nitromethane at 30 °C, and this has been attributed to steric hindrance to the electrophile causing kLx to become significant relative to k 2 (see p. 8)268. A more extensive subsequent investigation304 of the isotope effects obtained for reaction in acetic acid and in nitromethane (in parentheses) revealed the following values mesitylene, 1.1 pentamethylbenzene 1.2 3-methoxy-1,2,4,5-tetramethyl-benzene 1.5 5-t-butyl-1,2,3-trimethylbenzene 1.6 (2.7) 3-bromo-1,2,4,5-tetra-methylbenzene 1.4 and for 1,3,5-tri-f-butylbenzene in acetic acid-dioxan, with silver ion catalyst, kH/kD = 3.6. All of these isotope effects are obtained with hindered compounds, and the larger the steric hindrance, the greater the isotope... 

Subsequently, rate coefficients were determined for the zinc chloride-catalysed bromination of benzene, toluene, i-propyl-benzene, r-butylbenzene, xylenes, p-di-f-butylbenzene, mesitylene, 1,2,4-trimethyl-, sym-triethyl-, sym-tri-f-butyl-, 1,2,3,5-and 1,2,4,5-tetramethyl- and pentamethylbenzenes, all at 25.4 °C and in acetic acid, and it was shown that the reaction was inhibited by HBr.ZnCl2 which accumulates during the bromination and was considered to cause the first step of the reaction (formation of ArHBr2) to reverse320. The second-order coefficients for bromination of o-xylene at 25.0 °C were shown to be inversely dependent upon the hydrogen bromide concentration and the reversal of equilibrium (155)... 

Finally, rates of mercuration have been measured using mercuric trifluoro-acetate in trifluoroacetic acid at 25 °C450. The kinetics were pure second-order, with no reaction of the salt with the solvent and no isomerisation of the reaction products rate coefficients (10 k2) are as follows benzene, 2.85 toluene, 28.2 ethylbenzene, 24.4 i-propylbenzene, 21.1 t-butylbenzene, 17.2 fluorobenzene, 0.818 chlorobenzene, 0.134 bromobenzene, 0.113. The results follow the pattern noted above in that the reaction rates are much higher (e.g. for benzene, 690,000 times faster than for mercuration with mercuric acetate in acetic acid) yet the p factor is larger (-5.7) if the pattern is followed fully, one could expect a larger... 

Rate coefficients have also been measured at a range of temperatures for some aromatics in aqueous perchloric acid-trifluoroacetic acid (Table 168)468, and, surprisingly, the lower reactivity of benzene relative to toluene and /-butylbenzene appears to arise from a more negative activation entropy. This effect if real is... 

Rates (101k) of dedeuteration by 0.6 M KNHa in liquid ammonia at 0° were also determined by Hall et al. as follows Benzene, 1000 toluene, 410 (ortho), 360 (meta), 440 (para) /-butylbenzene, 32 (ortho), 210 (para). The toluene values are in fair agreement with those in Table 177, and the low reactivity at the or/Ao-position of /-butylbenzene was considered to be of steric origin. (G. E. Hall, E. M. Libby and E. L. James, J. Org. Chem., 28 (1963) 311). 

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