Benzene tetramethyl

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... 

Pentamethyl benzene.—Fraction V, and xylene which is methylated beyond the tetramethyl benzene stage, may be worked up for pentamethyl benzene. If xylene is to be methylated to obtain pentamethyl benzene, one more mole of methyl chloride should be used, and the mixture of xylene and anhydrous aluminium chloride methylated for one hundred and ten hours instead of the one hundred used for durene. Otherwise the procedure is exactly the same as for durene. The reaction mixture is decomposed and fractionated in the usual way, and the material boiling above 205° (fraction V) is separated into three frac-... 

Fraction III may be methylated to the tetramethyl benzene stage by heating on the steam bath with 100 g. of anhydrous aluminium chloride and passing in 225 g. of methyl chloride. The filtrates from the durene likewise yield more durene when heated... 

CuHu Alkyl benzenes 1.2.3.4- Tetramethyl-benzene Alkyl benzene i 1.2.3.4- Tetrahydro- Benzene 204.1 68 0.06 h... 

Durene or Durol (sym-l,2,4,5-Tetramethyl-benzene), C6H2(CH3)4, mw 134.21, colorless crysts with camphor-like odor sp gr 0.838, mp 79—81°, bp 189—191° sublimes and volatilizes with steam sol in ale, eth benz insol in w occurs in coal tar. It can be prepd by heating ortho xylene methyl chloride in presence of A1 chloride ... 

Figure 3.16 Charge transfer band for the complex between 1, 2, 4, 5-tetramethyl-benzene and tetiacyanoethylene. [Adapted from Britain. Gerrge and Wells, Introduction to Molecular Spectroscopy-Theory and Experiment. Academic Press, 1972.1...

Property 1,3,5-Trimethyl- benzene 1,2,4- Trimethyl- benzene 1.2.3- Trimethyl- benzene 1,2,4,5-Te tram ethylbenzene 1,2,3,5-Tfetramethyl-benzene 1,2,3,4-Tetramethyl-benzene Pentamethyl- benzene Hexamethyl- benzene... 

Coordination interactions are not the only way to use self-assembly to produce closed, capsular systems capable of binding guest species in solution. Work by Julius Rebek Jr (Scripps, USA)43 has shown that multiple hydrogen-bonding interactions, because of their relatively weak, but directional, nature, are ideal for the strict self-assembly of closed spherical molecules and capsules. For example, component 10.49 consists of two intrinsically curved diphenylglycoluril units linked by a durene-based (1,2,4,5-tetramethyl benzene-based) spacer. In both solution and in the solid state, 10.49 self-assembles spontaneously to produce the tennis ball-shaped dimer (10.49)2 shown in Figure 10.43. The formation of the dimer has been observed by ... 

Liquid-phase fluorination of methyl-substituted benzene derivatives depends strongly on the structure and concentration of the substrate, its molar ratio to xenon difluoride and the catalyst used (Scheme 32). HF-catalyzed fluorination of 1,2,4,5-tetramethylbenzene with an equimolar amount of xenon difluoride gave a small amount of 1,4-difluoro product, while reaction with two equivalents of xenon difluoride also gave the demethylated product l-fluoro-2,4,5-trimethylbenzene, which was also formed by HF-catalyzed fluorination of 1,3,4-trimethylbenzene34. In contrast, trifluoroacetic acid catalyzed fluorination is much more complex, and forms the four products l-(trifluoromethyl)-2,3,5,6-tetrametylbenzene, 2,4,5-trimethylbenzyl trifluoroacetate, l-fluoro-2,3,5,6-tetramethyl-benzene and l-(trifluoromethyl)-2,3,4,5-tetramethylbenzene, the distribution depending on the amount of trifluoroacetic acid used. Similar results were also observed in the fluorination of 1,2,3-trimethylbenzene and 1,3,5-trimethylbenzene34. 

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