Solvents, for reflux

Not all reactions in the solid phase convert bisphthalonitrile derivatives into ball-type Pcs. One example of such reactions is the conversion of the bisphthalonitrile derivative of phenolphthalein into ball-type Pc [50], As can be seen in Fig. 13, when a solid mixture of bisphthalonitrile 48 and metal salt was heated in a sealed tube at 320° C for 5 min, only mono Pcs 49 and 50 were formed. Further reaction of 49 or 50 with an excess of the corresponding metal salt in a refluxing solvent for 24 h resulted in the formation of ball-type Pcs 51 or 52. 

The corrosiveness of perchloroethylene to copper is determined using Soxhlet apparatus. Three pre-weighed strips of copper are used, one placed in the bottom flask, the second in the bottom of the Soxhlet attachment, and the third below the condenser. The specimens are exposed to refluxing solvent for 72 h after which the entire apparatus is flushed with distilled water to wash all acidic substances back to the flask. The water layer is titrated with 0.01 N NaOH to determine its acidity and the strips are weighed to determine weight loss. The results indicate quality of solvent. A different method is used to test copper corrosion by aromatic hydrocarbons. Here, a copper strip is immersed in a flask containing solvent and the flask is placed in boiling water for 30 min. Next, the copper strip is compared wifli ASTM standard corroded copper strips. 

The resin is extracted with 200 mL of refluxing solvent for at least 12 h. A 1 1 mixture of methanol and dichloromethane is an excellent eluent. However, the high concentration of organically bound chlorine makes it a poor choice, if the resin is to be used for analyses of chlorinated hydrocarbons. In that case the acetonitrile-water azeotrope (16.3% water) should be used despite lower recoveries of aliphatic hydrocarbons measured with surrogate standard additions. After cooling, extraction is resumed with fresh solvent for another 12 h period. 

The column is inserted into the extractor and eluted with approximately 200 mL of refluxing solvent (for solvent composition see Section 18.5) to which a suitable internal standard has been added. At the beginning of the extraction, the solvent passing through the column from the bottom up, removes a considerable volume of water from the interior of the resin beads (approximately 30 mL for a 75 mL resin bed). Depending upon the saUnity of the sample water, dissolved sea salt may precipitate in the boiling flask. Four to six hours of continuous extraction are usually sufficient to remove all adsorbed materials. Completeness of extraction may be checked as described in Section 18.6. 

Add 1 ml. of the alcohol-free ether to 0-1-0-15 g. of finely-powdered anhydrous zinc chloride and 0 5 g. of pure 3 5-dinitrobenzoyl chloride (Section 111,27,1) contained in a test-tube attach a small water condenser and reflux gently for 1 hour. Treat the reaction product with 10 ml. of 1-5N sodium carbonate solution, heat and stir the mixture for 1 minute upon a boiling water bath, allow to cool, and filter at the pump. Wash the precipitate with 5 ml. of 1 5N sodium carbonate solution and twice with 6 ml. of ether. Dry on a porous tile or upon a pad of filter paper. Transfer the crude ester to a test-tube and boil it with 10 ml. of chloroform or carbon tetrachloride filter the hot solution, if necessary. If the ester does not separate on cooling, evaporate to dryness on a water bath, and recrystallise the residue from 2-3 ml. of either of the above solvents. Determine the melting point of the resulting 3 5 dinitro benzoate (Section 111,27). 

Keta.Is, Trimethylpentanediol reportedly forms a cycHc ketal by heating it with benzophenone ia the presence of sulfonic acid catalysts at reflux temperatures ia toluene (64). These are said to be useful as aprotic solvents for ink-jet printing and as inflammation inhibitors for cosmetic preparations... 

Solvent Process. In the solvent process, or solvent cook, water formed from the reaction is removed from the reactor as an a2eotropic mixture with an added solvent, typically xylene. Usually between 3 to 10 wt % of the solvent, based on the total charge, is added at the beginning of the esterification step. The mixed vapor passes through a condenser. The condensed water and solvent have low solubiUty in each other and phase separation is allowed to occur in an automatic decanter. The water is removed, usually to a measuring vessel. The amount of water collected can be monitored as one of the indicators of the extent of the reaction. The solvent is continuously returned to the reactor to be recycled. Typical equipment for this process is shown in Figure 2. The reactor temperature is modulated by the amount and type of refluxing solvent. Typical conditions are ... 

Bisamides. Methylenebisamides are prepared by the reaction of the primary fatty amide and formaldehyde in the presence of an acid catalyst. AijAT-Methylenebisoleamide has been made via this route without the use of refluxing solvent (55). Polymethylenebisamides can be made from fatty acid, esters, or acid haUdes with diamines while producing water, alcohol, or mineral acid by-products. Eatty acids and diamines, typically ethylenediamine, have been condensed in the presence of NaBH and NaH2P02 to yield bisamides (56). When stearic acid, ethylenediamine, and methyl acetate react for 6 h at... 

The cooled contents of the 2S0-ml. flask containing ferrous chloride (Note 6) are added to the cold sodium cyclopentadienide solution while passing a stream of nitrogen through both flasks. The combined mixture is stirred for 1.25 hours at a temperature just below reflux. Solvent is removed by distillation, and the ferrocene is extracted from the residue with several portions of refluxing petroleum ether (b.p. 40-60°). The product is obtained by evaporation of the petroleum ether solution. Ferrocene may be purified by recrystallization from pentane or cyclohexane (hexane, benzene, and methanol have also been used) or by sublimation. The 3ueld is 31-34 g. (67-73%) (Note 7), m.p. 173-174°. 

The van Leusen reaction forms 5-substituted oxazoles through the reaction of p-tolylsulfonylmethyl isocyanide (1, TosMIC) with aldehydes in protic solvents at refluxing temperatures. Thus 5-phenyloxazole (2) is prepared in 91% yield by reacting equimolar quantities of TosMIC and benzaldehyde with potassium carbonate in refluxing methanol for 2 hrs. ... 

In 1960 Rapoport and his co-workers found that some 2,2 -biquinoline is formed when quinoline w as used as a solvent for dehydrogenations in the presence of palladiuin-on-carbon catalyst, and they showed that several related bases (including pyridine) gave 2,2 -biai yls when refluxed at atmospheric pressure with a 5% pal-ladium-on-carbon catalyst. With a pyridine-to-catalyst ratio of 10 1, 11% conversion of pyridine to 2,2 -bipyridine was observed after heating for 24 hr. 

The ketoester is mixed in a suitable round-bottom flask with excess 6 N sulfuric acid. The flask is fitted with a condenser and a mantle, and the mixture is refluxed gently for 3-4 days. The cooled reaction mixture is extracted with ether, the ether is washed with bicarbonate solution and water, then dried, and the solvent is evaporated. On distillation, the residue affords 2-methylcyclooctanone, bp 97-98718 mm, 86712 mm, 1 4656,... 

Cl Compound of Code No. CM 6912 25 g of the imine obtained under (B), dissolved in 400 ml of acetic acid, are heated at the reflux temperature for 1 hour. After evaporating the solvent in vacuo, the residue is taken up in methylene chloride. The solution is washed with a dilute sodium bicarbonate solution and then with water. After evaporating the solvent, the residue is chromatographed on silica, elution being carried out with an 80/20 mixture of ether and ethyl acetate. 9 g of benzodiazepine are thus obtained. Melting point 196. ... 

On evaporating the alcoholic solution under reduced pressure from a water bath held at 50-60° (Note 6) the residue weighs about 540 g. A mixture of 600 cc. of absolute alcohol and 10 cc. of concentrated sulfuric acid (Note 7) is then added. The mixture is then heated on the water bath under a reflux condenser for three hours. The excess of alcohol and some of the water formed are removed by distillation under reduced pressure and the residue again heated for two hours with 300 cc. of absolute alcohol and an additional 4 cc. of concentrated sulfuric acid. The alcohol is removed by distillation under reduced pressure, and when the ester has cooled to room temperature, the sulfuric acid is neutralized with a concentrated solution of sodium carbonate the ester (upper layer) is separated, and the aqueous solution extracted with ether, or preferably benzene about one-tenth of the yield is in the extract. The combined products are placed in a i-l. distilling flask and distilled under reduced pressure after the solvent and alcohol and water have been removed. The ester is collected at 94-990, chiefly at 97-98°/x6 mm. (Note 8). The yield of a product analyzing about 97-98 per cent ethyl cyanoacetate amounts to 474-492 g. (77-80 per cent of the theoretical amount) (Note 9). 

Ylides 2 can be prepared in situ from the sulfonium salts 1 with sodium hydride. These ylides 2 react with electrophiles, for example, acetylenes, to give the new stable ylides 3, for R1 =R2 = Me as a mixture of the cis- and trans-isomer, otherwise as the trans-isomer only. Compounds 3 are stable in refluxing tetrahydrofuran for 1 hour, but heating without solvent at 170-200r C for 3 to 5 minutes results in a 1,4-rearrangement to give thiaazulenes 4 quantitatively, with the exception of R1 = R2 = Et, where the yield is 25%.98... 

Phase-transfer catalysed oxidation of sulphoxides to sulphones using copper(II) permanganate or a mixture of potassium permanganate and copper(II) sulphate is also possible156. In this case hexane is used as the solvent for the organic phase and the reaction is carried out under reflux for 24 hours. Sulphones are prepared by this method in quantitative yields and the mechanism proposed is given in equation (51). 

Chloro-3-methylquinoxaline 4-oxide gave 3-chloro-2-quinoxalinecarbalde-hyde 1-oxide (172) (SeOi, PhH, reflux, h 72%) dioxane may be used as solvent for such oxidations yielding, for example, 3-amino-2-quinoxaline-carbaldehyde ethyl acetate may also be so used. 

The common microwave oven has been brought into the laboratory. Using special Teflon reaction vessels, components are mixed together, the vessel sealed and put into the microwave oven. Reaction times are greatly accelerated in many reactions, and reactions that took hours to be complete in refluxing solvents are done in minutes. Benzyl alcohol was converted to benzyl bromide, for example, using microwaves (650 W) in only 9 min on a doped Montmorillonite K-10 clay. This is a growing and very useful technique. 

Substituted amides suffer hydrolysis with greater difficulty. The choice of an acid or an alkaline medium vill depend upon (a) the solubility of the compound in the medium and (b) the effect of the reagent upon the products of hydrolysis. Substituted amides of comparatively low molecular weight (e.g., acetanilide) may be hydrolysed by boiling either with 10 per cent, sodium hydroxide solution or with 10 per cent, sulphuric acid for 2-3 hours. Other substituted amides are so insoluble in water that little reaction occurs when they are refluxed with dilute acid or dilute alkali for several hours. These include such substances as benzanilide (C(H(CONHC,Hg) and the benzoyl derivative of a naphthylamine (C.HjCONHCioH,) or a toluidine (C gCONHCjH,). For these substances satisfactory results may be obtained with 70 per cent, sulphuric acid this hydrolysis medium is a much better solvent for the substituted amide than is water or more dilute acid it also permits a higher reaction temperature (compare Section IV 192) ... 

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