F-Butylbenzene

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

The kinetics of the chlorination of some alkylbenzenes in a range of solvents has been studied by Stock and Himoe239, who again found second-order rate coefficients as given in Table 57. Although the range of rates varies by a factor of 104, there was no marked change in the toluene f-butylbenzene reactivity ratio, and it was, therefore, concluded that the Baker-Nathan order is produced by a polar rather. than a solvent effect. 

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)... 

The greater steric hindrance to acetylation was also shown by a comparison of the rate of (103At2) of acetylation of toluene (0.763), ethylbenzene (0.660), i-propylbenzene (0.606) and f-butylbenzene (0.462) with those (determined by the competition method) for benzoylation both sets of data (Table 112) were obtained with dichloroethane as solvent at 25 °C, all reagent concentrations being 0.1 A/421. Relative rates of acylation other aromatics under the same conditions have also been obtained and are given in Table 113422. The different steric requirements for acetylation and benzoylation are further shown by the following respective relative rates for acylation of naphthalene derivatives in chloroform at 0 °C naphthalene (1 position) 1.00,1.00, (2 position) 0.31,0.04 2,3-dimethylnaphthalene (1 position) 1.59, 172, (5 position) 7.14, 38.2, (6 position) 3.68, 7.7422a. 

Another surprising feature appears in the reactions of certain alkyl-benzenes with tetrabromo- and tetraiodo-benzyne generated by the aprotic diazotisation of the corresponding anthranilic acids S9K While only one product (41, X = Br or I, R = H or Me) was obtained in the reactions with benzene or -xylene, three products, (42, X = Br or I, R = Me, Pr1, or But), (43, X = Br or I, R = Me, Pr1, or But) and a naphthalene derivative a> were obtained in reactions with toluene, cumene (isopropylbenzene), and f-butylbenzene. 

The flash vacuum pyrolysis of alkynes, arynes, and aryl radicals has been reviewed. A discussion of secondary reactions and rearrangements is included. The pyrolysis of cyclopentadienes has also been examined. The rates for the initial C—H bond fission and the decomposition of C-C5H5 have been calculated. A single-pulse shock study on the thermal decomposition of 1-pentyl radicals found alkene products that are formed by radical isomerization through 1,4- and 1,3-hydrogen migration to form 2- and 3-pentyl radicals. The pyrrolysis of f-butylbenzene in supercritical water was the subject of a report. ... 

Butylbenzene, see Butylbenzene f -Butylbenzene, see Isobutylbenzene n-Butylbenzene, see Butylbenzene s-Butylbenzene, see sec-Butylbenzene secondar/-Butylbenzene, see sec-Butylbenzene f-Butylbenzene, see ferf-Butylbenzene ferffar/ Butylbenzene, see ferf-Butylbenzene Butyl benzyl phthalate, see Benzyl butyl phthalate n-Butyl benzyl phthalate, see Benzyl butyl phthalate Butyl cellosolve, see 2-Butoxyethanol n-Butyl cellosolve, see 2-Butoxyethanol Butylene, see 1-Butene 1-Butylene, see 1-Butene... 

Fig. 12.11 Distribution ratios of various metallic species between 0.5 mol dm (C4H9CH3NC0)2CHC2H40C2H40CgHi3 [DMDB(2-3,6-OD,l,3-DA)P] f-butylbenzene solutions and HNO3 solutions.

The first reactions concerned (Simons and Archer, 27) alkylation of benzene with propylene to form isopropylbenzene, with isobutene to form f-butylbenzene and di-f-butylbenzene, and trimethylethylene to form amylbenzene. Later on (Simons and Archer, 28) studied these and other reactions in more detail and showed that high yields could be obtained and that the product was not contaminated with tars or other obnoxious impurities. It was shown that the products obtained with trimethylethylene were mono- and di-f-amylbenzene, that phenyl-pentane resulted from the use of pentene-2, and that cyclohexene produced cyclohexylbenzene. Cinnamic acid reacted with benzene (Simons and Archer, 29) to form /3-phenylpropionic acid and allyl benzene reacted with benzene to form 1,2-diphenylpropane. It is interesting to note that although allyl alcohol reacted with benzene to form 1,2-diphenylpropane, the intermediate in the reaction, allylbenzene, was isolated and identified. This shows that in this case the hydroxyl reacted at a more rapid rate than the double bond. Both di- and triisobutylene reacted with phenol (Simons and Archer, 30) at 0°, when using hydrogen fluoride containing only relatively small quantities of water, to form f-butyl-benzene, but diisobutylene with 70% hydrogen fluoride produced p-f-octylphenol. Cyclohexene reacted with toluene to form cyclohexyl-toluene and octene-1 rapidly reacted with toluene to form 2-octyltoluene (Simons and Basler, 31). 

The transfer constant for f-butylbenzene is low, since there are no benzylic C—H bonds present. Primary halides such as n-butyl chloride and bromide behave similar to aliphatics with low transfer constants, corresponding to a combination of either aliphatic C—H bond breakage or the low stability of a primary alkyl radical on abstraction of Cl or Br. The iodide,... 

As outlined above, the process of substitution by the nitronium ion is satisfactorily described by an SE2 mechanism in which k2 E > k v In certain circumstances the process could be changed so that this condition did not hold, and the step in which the proton is lost could become kinetically important. One such circumstance is that in which the hydrogen atom being replaced is situated between bulky substituents steric hindrance would then make it difficult for the nitro group to move from its position in the intermediate complex to that between the bulky substituents k2 would be diminished, and a kinetic isotope effect might appear. It is for this reason that 1,3,5-tri-f-butylbenzene and its derivatives are interesting (table 6.1) whilst the hydrocarbon undergoes... 

Arnett, E. M., and J. M. Bollinger Evidence for a ladenburg benzene intermediate in the photoisomerization of 1.2.4.5-tetra-f-butylbenzene to 1.2.3.5-tetra-f-butylbenzene. Tetrahedron Letters 1964, 3803. 

Neophyl chloride in 13—75% current yield forms f-butylbenzene (94%) and isobutylbenzene (6%) as side product by rearrangement of the intermediate neO phyl radical 487>. Reduction of monobromomaleic acid at pH 0—4 yields up to 50% of the dimer 163 (Eq. (228)). With increasing pH the amount of dimer... 

Arene thiocyanation. Thiocyanation of arenes with metal thiocyanates usu-illy results in both arenethiocyanates and the more stable areneisothiocyanates. The reaction can be effected with CuSCN supported on charcoal. Thus iodo- and romoarenes react with this supported reagent (excess) in f-butylbenzene at 150° v give the corresponding thiocyanates in 70-80% yield. 

Di-r-butylbenzenes.1 This reagent undergoes a Diels-Alder reaction with phenyl vinyl sulfoxide, an acetylene equivalent (8,399), with loss of benzenesulfenic acid to give o-di-f-butylbenzene in 77% yield. 

Diels-Alder reactions of 1 with a variety of alkynes provides a route to various substituted o-di-f-butylbenzenes. 

More difficult to explain, however, are the results of FIK measurements on f-butylbenzene [853]. The isotope effect /CHj / cd3 was about 1.1 at 60 ps, rose suddenly to about 2 at about 100 ps and then rose much more gradually with increasing time. The sudden rise is not in accord with QET. 

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