Toluene condensation reactions

The cross-condensation reaction of benzyl benzoate (46) and 44 was carried out under solvent-free conditions. Treatment of a 1 1 mixture of 46 and 44a with Bu OK at 120 °C for 1 h gave the cross-condensed product 47a in 42% yield (Scheme 7). Similar reaction of 46 with 44b gave 47b in 45% yield. Because heating of46,44, and Bu OK in toluene under reflux for 16 h did not give any product, it is clear that the solvent-free reaction is again effective for the cross-condensation. In these cases, self-condensation of 44 itself did not occur probably because of the high reactivity of 46 [9]. 

Poly(dioxaboralane)s (82) (Fig. 51) with controllable molecular weights were reported to be readily obtained through the condensation reaction between 9,9-dihexylflourene-2,7- diboronic acid and pentaerythritol in toluene with an associated azeotropic removal of water. The molecular weights of the resulting polymers, which ranged between 10,000 and 76,900, were found to depend on the processing conditions of the polymers.117... 

Figure 51 Poly(dioxaboralane)s (82) obtained through the condensation reaction between 9,9-dihexylflourene-2,7-diboronic acid and pentaerythritol in toluene. (Adapted from ref. 117.)...

The formation of the technically important 2 -hydroxy-3 -naphthoylanilines (Naphthol AS derivatives) is accomplished primarily by a condensation reaction between 2-hydroxy-3-naphthoic acid and an aromatic amine in the presence of phosphorus trichloride at 70 to 80°C. Appropriate reaction media are organic solvents, such as toluene or xylene. In stoichiometric terms, one mole of 2-hydroxy-3-naphthoic acid reacts with 0.4 to 0.5 moles of phosphorus trichloride. The solution is allowed to cool to room temperature, then neutralized with a sodium carbonate solution, and the Naphthol AS derivative is isolated by filtration. Mechanistically, the reaction is thought to proceed via the phosphoazo compound (11) ... 

S. (-)-(Camphorsulfonyl)imine. A 1 -L, round-bottomed flask is equipped with a two-inch egg-shaped magnetic stirring bar, a Dean-Stark water separator, and a double-walled condenser containing a mineral oil bubbler connected to an inert gas source. Into the flask are placed 5 g of Amberylst 15 ion exchange resin (Note 4) and 41.5 g of the crude (+)-(1 S)-camphorsulfonamide in 500 mL of toluene. The reaction mixture is heated at reflux for 4 hr. After the reaction flask is cooled, but while it is still warm (40-50°C), 200 mL of methylene chloride is slowly added to dissolve any (camphorsulfonyl)imine that crystallizes. The solution is filtered through a 150-mL sintered glass funnel of coarse porosity and the reaction flask and filter funnel are washed with an additional 75 mL of methylene chloride. 

On the other hand, Ishizu et al. [58] reported the synthesis of cyclic polystyrene using interfacial condensation reaction of a/o-dibromopolyslyrcnc prepared from living polystyrene initiated with sodium naphthalene and terminated with 1,4-dibromobutane and then tetramethylenediamine as depicted in Fig. 11. The reaction was carried out in organic solvent/water to yield in more than 90%. The effect of solvent on the yield of cycUc polymer was observed, and the yield of cyclic product obtained in DMSO was higher than that in toluene. Since DMSO dissolves in both water and toluene, the reaction proceeded faster than that in toluene. 

The oil described above was utilized directly in the condensation reaction with the epichlorohydrin. A mixture of 0.1 mole of methyl 3-(4-hydroxyphenyl)propionate, 0.2 mole potassium carbonate and 0.4 mole epichlorohydrin in 250 mL acetone was heated to reflux for 24 hours. The reaction medium was then filtered and evaporated. The residue was taken up in 100 mL toluene and washed with 100 mL 1.0 N NaOH and 100 mL water (2 times). The toluene phase was then dried over magnesium sulfate and evaporated to provide the crude product as an oil. Purification was effected by vacuum distillation (156°C/0.4 mm) and provided methyl 3-[4-(2,3-epoxypropoxy)phenyl]propionate. The NMR and IR spectra and elemental analysis data were consistent with the assigned structure. 

Both 4- and 5-methyloxazoles are normal compounds rather like toluene, but if the alkyl group is at position 2 it is capable of undergoing a variety of addition and condensation reactions. 

On the other hand, the reaction of isatin with N,N-dimethylethylenediamine in water yields the spiro-diazolaneoxindole whereas the corresponding condensation reaction performed by azeotropic distillation in toluene yielded the unusual 2 1 adduct as the result of the addition of an unstable azomethine ylide to isatin (Scheme 63). 

Very good linear dependence for hydrodealkylation was found except for zeolite samples with high Si/AI ratio. The higher values of the initial reaction rates obsen/ed on these samples are presumably due to another type of catalytic centers (for example one-electron acceptor centers) on very high siliceous zeolites (Si/AI >1000). The dependence of turnover number (TON) for the particular toluene transformation reactions as a function of the strong acid sites concentration has shown [24] that hydrodealkylation occured on strong acid sites and didn t depend on the concentration of these sites. However, TON dependence for hydrocracking and condensation reactions was non-linear and influenced by the concentration of active sites. 

The alkylation of the naphthenic cation causes formation of complex aliphatic carbonium ions. Transformation of such intermediates according to Poustma [30] gives the molecules of light saturated hydrocarbons and aromatics. It is generally accepted that the formation of condensed aromatic rings being a coke precursors is difficult in the pores of ZSM-5 zeolite. The fact that the products of the toluene transformation reaction in all cases contained 1 - and 2-methylnaphthalene seems to prove their formation from the olefinic or naphthenic carbocations. Transformation of the naphthenic carbocations occuring in zeolite pores and on the external zeolite surface is the most probable source of methyinaphthalene isomers [23]. 

In carrying out the reaction to produce the compound of formula 11 above, temperature and pressure are not critical and this reaction can be carried out at room temperature and atmospheric pressure. If desired, lower or elevated temperatures can be utilized. This condensation reaction is advantageously effected at a temperature of from about 0° C. to about 120° C. In a preferred embodiment of this invention, the reaction is particularly preferably carried out in the presence of p-toluene-sulphonic acid in benzene by heating to a temperature of about 80° C. for 2 hours under reflux conditions. 

The entire procedure is performed in an anhydrous atmosphere because of the hygroscopic nature of the reaction products. Methylimidazole (20.8 g, 0.253 mol) and the alkyl iodide (iodomethane 35.9 g, 0.253 mol 2-iodopropane 43.0 g, 0.253 mol) are dissolved in a 250-mL two-necked round-bottomed Schlenk flask equipped with a reflux condenser in lOOmL toluene. The reaction mixture is vigorously stirred overnight under reflux. During this time, a white solid forms, which is filtered off after cooling to room temperature, washed twice with 40 mL hexane, and dried in vacuo to yield 56.0 g (99%, Me2ImHI) or 57.7 g (90%, Me PrlmHI) of the product in the form of a white powder. 

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