Durene synthesis

Koch Chemical Company is the only U.S. suppHer of all PMBs (except hexamethylbenzene). Its process has the flexibility of producing isodurene, prehnitene, and pentamethylbenzene, should a market develop. Koch s primary process (20) is based on isomerization, alkylation, and disproportionation conducted in the presence of a Friedel-Crafts catalyst. For the synthesis of mesitylene and hemimellitene, pseudocumene is isomerized. If durene, isodurene, or prehnitene and pentamethylbenzene are desired, pseudocumene is alkylated with methyl chloride (see Alkylation Friedel-CRAFTSreactions). 

Durene, pentamethyl benzene and hexamethyl benzene have usually been prepared from benzene or one of its methylated derivatives by the Friedel-Crafts synthesis.1 Durene has been made from bromine derivatives of methylated benzenes by the Fittig reaction.2 It has also been obtained in 20 per cent yield by passing methyl alcohol and acetone vapors over heated alu-... 

S. Surble, F. Millange, C. Serre, T. Duren, M. Latroche, S. Bourrelly, P. L. Llewellyn, and G. Ferey, Synthesis of MIL-102, a chromium carboxylate metal-organic framework, with gas sorption analysis, J. Am. Chem. Soc., 128, 14889-14896(2006). 

CpFe+-Induced Octafunctionalization of Durene in the Synthesis of Metallodendrimer Precursors... 

To minimise the durene formation caused by high pressure operation, the loop pressure in the integrated process has been reduced by the introduction of a combined MeOH/DME synthesis. Fig. 9 shows the durene content in a typical cycle from the 1 MTPD plant. Also shown is the durene content in the C5+ fraction assuming that equilibrium between the tetramethylbenzenes has been established by isomerisation. In the integrated synthesis such an isomerisation step can be carried out within the loop. 

If the hexafunctionalization of hexamethylbenzene leads to stars, the octafunctionalization of durene leads to dendritic cores. The first of these octaalkylation reactions was reported as early as 1982, and led to a primitive dendritic core containing a metal-sandwich unit. Thus, as the hexafunctionalization, this reaction is very specific. Two hydrogen atoms in each methyl group are now replaced by two methyl, allyl, or benzyl groups (Scheme 11.4).19 Applications to the synthesis of dendrimers containing 8 or 24 redox-active groups have recently been reported.20... 

Scheme 11.14 Synthesis of 24-iron-sandwich complexes starting from durene.

AI3-25182 Benzene, 1,2,4,5-tetramethyl- Durene Durol EINECS 202-465-7 NSC 6770 1,2,4,5-Tetramethylbenzene p-Xylene, 2,5-dlmethyl-. Used In organic synthesis, plasticizers, polymers, fibers. An agricultural chemical used as a fungicide, bactericide and wood preservative. Crystals mp = 79,3° bp = 196,8° d = 0,8380 Xm = 278 nm (cyclohexane) insoluble in H2O, soluble in EtOH, EtzO, MezCO, CeHs, CCI4, petroleum ether LDso (rat orl) = 6989 mg/kg. 

Pyromellitic dianhydride (PMDA) is prepared by the oxidation of durene, which is 1,2,4,5-tetramethylbenzene. The synthesis is eompletely analogous to the synthesis of phthalic anhydride. 

Dhanabalan A, van Duren JKJ, van Hal PA, van Dongen JLJ, Janssen RAJ (2001) Synthesis and characterization of a low bandgap conjugated polymer for bulk heteiojnnctitm photovoltaic cells. Adv Fund Mater 11 255... 

If deprotonation of a polymethylbenzene complex is carried out in the presence of an excess base and compatible electrophile such as an alkyl iodide or allyl- or benzyl bromide, the deprotonation-alkylation sequences spontaneously follow one another in situ until steric inhibition is reached. This reaction has been exploited with arene = CgMeg for the synthesis of star-shaped molecules (examples below) and living polymers and with arene = durene or mesitylene for the synthesis of dendritic cores (see for instance Chap. 21.2.2). 

The regioselective synthesis of of-iodo ketones is achieved in good yields by CAN in presence of iodine. The more highly substituted of-iodo ketones are preferentially formed (scheme 34) (Horiuchi and Kiji, 1988). In a study of the iodination of 1,3,5-trimethylbenzene (mesitylene) and 1,2,3,4,5-tetramethylbenzene (durene) by CAN/I2, it was shown that the reactive intermediate is most likely the I ion and that the reaction can be considered as an electrophilic aromatic substitution reaction (Galli, 1991). 

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