1,2,4-Trichlorobenzene as solvent

In order to reduce the rate of this reaction to a measurable value, a further study was carried out using 1,2,4-trichlorobenzene as solvent and aluminium tribromide as catalyst343. Under these conditions, isopropylation was still too fast to measure directly, and the relative rates of methylation, ethylation and isopropylation were 1 57 > 2,500. For methylation with methyl bromide,... 

Fig. 4 -NMR spectrum of polyethylene sample measured at 120 °C using deuterium o-dichlorobenzene and 1,2,4-trichlorobenzene as solvents. (From Ref. . )...

Liquid phase decarboxylation of aromatic chloroformates to the corresponding chlorobenzenes was achieved using catal)4 ic AICI3. This reaction was performed in 1,2,4-trichlorobenzene as solvent (eq 57). ... 

STM-BJ experiments were performed to extract single-junction conductances of 44-BP bridged between a gold STM tip and an Au (111) substrate in non-polar solvents, such as mesitylene, isopropanol, and 1,2,4-trichlorobenzene, as well as under full electrochemical potential control in aqueous solutions of HCIO4 and LiClOq at various pH. 

The molecular weight distribution of SCT, petroleum and coal tar pitches were determined by Gel Permeation Chromatography at high temperature using 1,2,4-trichlorobenzene as the solvent and a UV-spectrophotometer at wave-length 320 mm as the detector. A comparison of the molecular weight distribution curves of SCT pitch and petroleum and coal tar pitches is presented in Figure 5. 

Solvents. Commercially available reagent grade solvents were used without purification except as noted. 1,2,4-Trichlorobenzene was fractionally distilled and the center cut with bp 92°-93°C/16 mm was used. 

The novel, low-melting-point salt [N-pentylpyridinium][cJoso-CB11H12] has been used as solvent in several dehalogenations of mono- and polychlorides and -bromides, catalyzed by several Pd phosphine complexes [69]. The debromina-tion of hexabromo- and 1,2,4,5-tetrabromobenzene was accomplished quite rapidly, whereas the dechlorination of 1,2,4-trichlorobenzene proceeded more slowly, but with excellent selectivity to 1,2-dichlorobenzene. The system could be recycled at least seven times without noticeable decrease of activity. 

More highly chlorinated aromatic solvents such as 1,2,4-trichlorobenzene can be used with similar results. 

The reactants are phthalic anhydride, urea and copper(n) chloride, which are heated in a high-boiling aromatic solvent such as 1,2,4-trichlorobenzene, nitrobenzene or m-dinitrobenzene in the presence of a catalyst, usually ammonium molybdate. The solvent also acts as a heat-transfer medium. On heating to 120 °C an exothermic reaction begins and this temperature is maintained for about an hour. The temperature is then raised to 160-180 °C and kept constant for 6-12 hours. During this time ammonia and carbon dioxide are evolved, together with some solvent the reaction is complete when ammonia evolution ceases. The remaining solvent is then removed by either steam or vacuum distillation. The yield is 90-95%. For many years the solvent process was in almost exclusive use. 

Ring opening of the benzocyclobutenes or the extrusion of CO2 and SO2 requires high temperatures. Therefore, the cycloadditions are carried out in solvents such as toluene, chlorobenzene, o-dichlorobenzene or 1,2,4-trichlorobenzene at elevated temperatures. Some representative examples are shovm in Table 4.2. 

A 70-ml stainless steel reactor was charged with C ) fullerene (50 mg), 20 ml of 1,2,4-trichlorobenzene, and perfluoro(3-oxo-penta-4-ene)sulfonyl fluoride (3 g) and cooled to 50°C and then evacuated and filled with nitrogen and the mixture heated to 200°C for 18 hours. The solvent was then removed and the product isolated as a brown solid. 

Operating Condition of GPC. The operating conditions were the same as before (2) except that the sample concentration was 0.5%. Solvent was 1,2,4-trichlorobenzene, temperature was 137°C, injection time was 120 sec, and the flow rate was 1 cc per minute. Four columns having nominal capacities of 7 X 106, 3 X 106, 105, and 103 were used. 

Monochlorobenzene is a flammable clear liquid (fp, -45"C bp, 132°C) used as a solvent, solvent carrier for methylene diisocyanate, pesticide, heat transfer fluid, and in the manufacture of aniline, nitrobenzene, and phenol. The 1,2- isomer of dichlorobenzene (ortho-dichlorobenzene) has been used as a solvent for degreasing hides and wool and as a raw material for dye manufacture. The 1,4- isomer (para-dichlorobenzene) is also used in dye manufacture and as a moth repellant and germicide. All three isomers have been used as fumigants and insecticides. The 1,2- and 1,3-(meta) isomers are liquids under ambient conditions, whereas the 1,4- isomer is a white sublimable solid. Used as a solvent, lubricant, dielectric fluid, chemical intermediate, and formerly as a termiticide, 1,2,4-trichlorobenzene is a liquid (fp, 17°C bp, 213°C). 

Trichlorobenzene (1,2,4-TCB) is used as a solvent. According to Shelton (1989), it is formed in small quantities during the chlorination of drinking water. Chronic exposure can adversely affect various organs. 

Mixed complexes such as lanthanide porphyrin diketonates have been prepared and these are soluble in organic solvents [83,84]. These mixed complexes are prepared in organic solvents like 4-phenylpyridine, or 1,2,4-trichlorobenzene with refluxing. After the reaction is complete, the solvent is removed by distillation under reduced pressure and the product purified by column chromatography. 

The so-called solvent extraction method by toluene, o-xylene or carbon disulfide is the most common and frequently used extraction method, in which metallofullerenes and hollow fullerenes are preferentially dissolved in solvents. The so-called Soxhlet extraction (a continuous and hot solvent extraction) or ultrasonic extraction is normally employed to increase the solvent extraction efficiency (Khemani et al., 1992). Insolubles in soot are easily separated from this solution by filtration. However, in many cases, the toluene or CS2 extraction is not sufficient, since nearly half of the metallofullerene still remains in the residual soot even after the extensive CS2 extraction. It has been found that metallofullerenes are further extracted from the residual soot by such solvents as pyridine (Inakuma et al., 1995) and 1,2,4-trichlorobenzene (Yamamoto et al., 1994a,b). The metallofullerenes were found to be concentrated in this pyridine or trichlorobenzene extracted fraction. When necessary, the metallofullerene extracts can be stored in carbon disulfide solution for an extended period of time, up to a year. 

It seems that chemists prefer solutions to solids. Solvent extraction is presently the most popular method for the isolation of EMFs from soot. Toluene, carbon disulfide, and xylene are popular solvents used to extract EMFs. The Soxhlet apparatus and ultrasonication technique [63] were applied to improve extraction efficiency. However, results show that nearly half of the EMFs remained in the extracted residue, which can be further processed using such solvents as pyridine and 1,2,4-trichlorobenzene (TCB). 

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