Chemical durene

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). 

The only significant U.S. producer of PMBs is Koch Chemical Company. The only PMBs produced ia any sizable quantity ate pseudocumene, durene, mesitylene, and hemimellitene. Koch s production capabiUty for pseudocumene is ca 35,000 t/yr the combiaed production rate of the other PMBs is less than 5,000 t/yr. 

Benzenetetracarboxylic dianhydride (pyromellitic dianhydride) is a typical bifunctional acid anhydride, and it is a useful raw material for preparing many useful chemicals. Polyimides and polyimidazopyrrolons prepared from this dianhydride have excellent heat and chemical resistance, as well as excellent mechanical and electrical properties. Pyromellitic dianhydride is produced by the oxidation of 1,2,4,5-tetraalkylbenzenes such as 1,2,4,5-tetramethylbenzene (commonly known as durene) and 4,6-diisopro-pyl-l,3-dimethylbenzene. Durene, in particular, is a fundamental raw material for the production of the dianhydride 1-8). 

In the field of aromatic separation, the trend of research is toward isolation of pure compounds for chemical purposes. Benzene, toluene, and some of the C8 aromatics have been separated and used commercially. However, the physical properties of the C9 and Cio aromatic hydrocarbons found in reformed stocks show that other aromatics could be separated from these mixtures by distillation, crystallization, or extraction processes. It is reasonably certain that if sufficient demand develops for the pure compounds, processes for their separation will become available. Present information indicates that perhaps methylethylbenzenes and trimethylbenzenes could be isolated in relatively high purity by distillation from aromatic stocks obtained by hydroforming, but no information is available as to their industrial uses. Similarly, durene (1,2,4,5-tetramethylbenzene) possibly could be isolated from its homologs by crystallization. Furthermore, large... 

Consider the chemical 1,2,4,5-tetramethylbenzene (abbreviated TeMB and also called durene). In an old CRC Handbook of Chemistry and Physics you find vapor pressure data that are given in mm Hg (torr see left margin). 

Pseudocumene is used as a component in liquid scintillation cocktails for clinical analyses. Pseudocumene and durene are oxidized to trimel-litic anhydride and pyromellitic dianhydride, respectively. Mesitylene is a key building block for important antioxidants and agricultural chemicals. Prehnitene, isodurene, pentamethylbenzene, and hexamethylbenzene... 

Macherey-Nagel, Duren, Germany Sumika Chemical Analysis Service, Konohana-ku Osaka, Japan Eka Chemicals Separation Products, Bohus, Sweden... 

Daicel Chemical Industries, Tokyo, Japan Macherey-Nagel, Duren, Germany Regis Technologies, Austin, TX, USA Phenomene, Torrance, CA, USA Showa Denko, Kanagawa, Japan... 

Although the design of a reactor system for the MTG process involves classical chemical engineering principles, the unique catalyst and reaction mechanisms impose important design constraints. These include the highly exothermic nature of the reaction, the need for essentially complete methanol conversion, steam deactivation of the catalyst, the "band-aging phenomena, and durene formation. 

Fig. 7. Some ft CRAMPS spectra (from ref. 19) (a) malonic acid, (b) adipic acid, (c) durene, (d) benzoic acid, (e) polystyrene, and (f) poly(butanediol terephthalate). Reproduced with permission from the American Chemical Society.

A comprehensive survey is given of the current and potential uses of component chemicals in the hydrocarbon product of the MTG process at Motunui. The utilisation of many of these components may depend significantly on how the product of major interest, i.e. durene, is isolated. Durene itself oonprises ca. 50% of the heavy gasoline stream its potential uses as well as those of its oxidation product pyromellitic acid and derivatives thereof, are reviewed in detail, as is available information on other durene derivatives such as durohydroquinone. 

Durene, or 1,2,4,5-tetramethyl benzene, is an attractive chemical feedstock. It is a solid at room temperature with a melting point of 79°C and comprises over 50% of the heavy gasoline. It can be isolated with reasonable purity and fair efficiency simply by allowing the heavy gasoline to cool, when it crystallises in high yield. 

In the final submission to the Crown, Applied Chemistry Ltd additionally promised to set up a company to manufacture as fine chemicals other durene derivatives, so that the full range of such derivatives would be available for further development work. It was further undertaken that such derivatives would be produced at a sufficient rate that market requirements would be met, subject, of course, to having the necessary quantity of durene and the time to meet such requirements. It is intended that any of the derivatives noted in... 

Whether chemicals other than those derived from durene will be manufactured is unclear at this time durene is the most attractive raw material in terms of availability and ease of extraction/purification, and as its products have some almost unique properties, it is by far the easiest to commercialise. The economic availability of many of the other components in the synthetic gasoline will probably depend on the method used to extract the 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. 

Akzo Nobel Chemicals GmbH, Phlllippstrasse 27, 52349 DUren, Germany (Tel 49 2421 49201 FAX 49 2421 492240)... 

Figure 2.62 X-ray crystallographic structure of (146)-4H with durene (142). Reprinted with permission from J. Org. Chem. 50 (1985) 4478, 1985 American Chemical Society.

Duren, T., Keil, F. J. Seaton, N. A. (2002). Composition Dependent Transport Diffusion Coefficients of CH/CF Mixtures in Carbon Nanotubes by Non-Equilibrium Molecular Dynamics Simulations. Chemical Engineering Science, 57(8), 1343-1354. 

A triplex electron-transfer mechanism involving interaction of dibenzoylmethanatoboron difluoride (DMB) and an aromatic co-sensitizer (A — toluene, ethylbenzene, biphenyl, and durene) with N was suggested based on the results from a chemically induced dynamic nuclear polarization study of the reaction ... 

---