Benzene 1,3 5 triacetic acid

Fig. 21. Zimm-plot of an A/B2 random polycondensate. A3 benzene 1.3.5.-triacetic acid B2 decamethylene glycol. Measurement have been made in benzene at 20 °C, with the two wave lengths of Xa = 546 nm ( ) and A0 = 436 nm (O). h = (4 jiIX) sin 0/2138)...

Poly(benzene- 1,3,5-triacetic acid-co-decamethylene glycol) 1541... 

Ethylbenzene, Thallium triacetate Ucmura, S. et al., Bull. Chem. Soc., Japan., 1971, 44, 2571 Application of a published method of thallation to ethylbenzene caused a violent explosion. A reaction mixture of thallium triacetate, acetic acid, perchloric acid and ethylbenzene was stirred at 65°C for 5 h, then filtered from thallous salts. Vacuum evaporation of the filtrate at 60°C gave a pasty residue which exploded. This preparation of ethylphenylthallic acetate perchlorate monohydrate had been done twice previously and uneventfully, as had been analogous preparations involving thallation of benzene, toluene, three isomeric xylenes and anisole in a total of 150 runs, where excessive evaporation had been avoided. 

Thallium Triacetate. Pasty residue from evaporation of mixture of thallium triacetate, acetic acid, perchloric acid, and ethyl benzene exploded.16... 

Oxidizing agents such as nitric acid, air, hydrogen peroxide, and lead tetraacetate convert ditellurium compounds to tellurinic acid derivatives. Diphenyl ditellurium suspended in hot dilute nitric acid formed benzenetellurinic acid nitrate. Air oxidizes dissolved diaryl ditellurium compounds to tellurinic acid anhydrides. Diphenyl ditellurium and lead tetraacetate in benzene solution form phenyl tellurium triacetate ... 

Refluxing with acetic anhydride in the presence of 0.2g % of 2-naphthalenesulfonic acid as catalyst has also been used [Orton and Bradfield J Chem Soc 983 1927]. Other suitable drying agents include CUSO4 and chromium triacetate P2O5 converts some acetic acid to the anhydride. Azeotropic removal of water by distn with thiophene-free benzene or with butyl acetate has been used [Birdwhistell and Griswold 7 Am Chem Soc 77 873 7955]. An alternative purification uses fractional freezing. 

Reaction of arenes with lead tetraacetate in TFA (trifluoroacetic acid) can afford symmetrical dimeric compounds in moderate to good yields.(see section 7.1.3.2) Unsymmetrical biaiyls can be produced by reaction of aryllead triacetates substituted with electron-donating as well as electron-withdrawing groups with p-xylene or more highly methylated benzenes. For example, in the arylation with 4-fluorophenyllead triacetate the yields vary from 0% for nitrobenzene, 2% for benzene and toluene to 80% for pentamethylbenzene and 88% for mesitylene. 

This is analogous to the extraction of sugars with boronic acids described earlier. The recovery of phenylalanine from a fermentation broth has been simplified by using a microporous poly(tetrafluoroethylene) membrane with tri-/j-octylmethylammonium chloride in toluene in the pores.133 Phenylalanine can also be separated using the quaternary ammonium salt with 2-nitrophenyl octyl ether in a cellulose triacetate membrane.134 Kerosene flowing in hollow fiber membranes can remove 99.9% of organic pollutants, such as benzene, p dichlorobenzenc, chloroform, and carbon tetrachloride, from wastewater outside the fibers.135... 

One important variation of this general procedure which is in commercial practice is the use of a chlorinated solvent, such as methylene chloride, as the solvent in the reaction. Since methylene chloride has a low boiling point, the temperature of the reaction is controlled by refluxing. Andther process, which has been used to a lesser degree, is a fibrous acetylation process. In this ipethod, the reaction is carried out in the presence of several parts of benzene or a similar nonsolvent. The cellulose does not dissolve, but is converted to cellulose triacetate while remaining in fibrous form. The catalyst in this process is getaerally perchloric acid. 

Many cellulose derivatives form lyotropic liquid crystals in suitable solvents and several thermotropic cellulose derivatives have been reported (1-3) Cellulosic liquid crystalline systems reported prior to early 1982 have been tabulated (1). Since then, some new substituted cellulosic derivatives which form thermotropic cholesteric phases have been prepared (4), and much effort has been devoted to investigating the previously-reported systems. Anisotropic solutions of cellulose acetate and triacetate in tri-fluoroacetic acid have attracted the attention of several groups. Chiroptical properties (5,6), refractive index (7), phase boundaries (8), nuclear magnetic resonance spectra (9,10) and differential scanning calorimetry (11,12) have been reported for this system. However, trifluoroacetic acid causes degradation of cellulosic polymers this calls into question some of the physical measurements on these mesophases, because time is required for the mesophase solutions to achieve their equilibrium order. Mixtures of trifluoroacetic acid with chlorinated solvents have been employed to minimize this problem (13), and anisotropic solutions of cellulose acetate and triacetate in other solvents have been examined (14,15). The mesophase formed by (hydroxypropyl)cellulose (HPC) in water (16) is stable and easy to handle, and has thus attracted further attention (10,11,17-19), as has the thermotropic mesophase of HPC (20). Detailed studies of mesophase formation and chain rigidity for HPC in dimethyl acetamide (21) and for the benzoic acid ester of HPC in acetone and benzene (22) have been published. Anisotropic solutions of methylol cellulose in dimethyl sulfoxide (23) and of cellulose in dimethyl acetamide/ LiCl (24) were reported. Cellulose tricarbanilate in methyl ethyl ketone forms a liquid crystalline solution (25) with optical properties which are quite distinct from those of previously reported cholesteric cellulosic mesophases (26). 

Another CTA preparation is the fibrous acetylation method. In this process part or all of the acetic acid is replaced with an inert diluent, e.g., toluene, benzene or hexane to maintain the cellulose fibrous structure during the reaction. Perchloric acid is usually employed as the catalyst in this process. This process is used exclusively for the preparation of cellulose triacetate. 

Derivatives of streptovaricins also can be converted to their atropisomers, sometimes at lower temperatures than the streptovaricins themselves. In refluxing benzene an equilibrium mixture of streptovaricin C triacetate and its atropisomer is formed. This reaction led to a complication in assigning the structure of streptovaricin C by x-ray crystallography (149), since the x-ray study was carried out on a cyclic / -bromobenzene-boronate formed by heating streptovaricin C triacetate in benzene with /7-bromobenzeneboronic acid and the atropisomeric cyclic /7-bromo-... 

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