Methylation, toluene

Some less reactive tertiary amines can be mixed with an excess of methyl toluene-/)-sulphonate, m.p. 28 , and the mixture (without a solvent) heated to a much higher temperature. The mixture is allowed to cool, but before solidification occurs, it is thoroughly stirred with ether to extract unused sulphonate, and the insoluble quaternary metho-toluene-/)-sulphonate may then crystallise. If ciystallisation does not occur, dissolve this residue in ethanol and treat one portion with ethanolic picric acid (to precipitate the methopicrate) and another portion with cold concentrated ethanolic sodium iodide (to precipitate the methiodide). (M.ps. of the siilphon.ates, pp. 553 -554.)... 

Although the uses of dimethyl sulfate and methyl toluene-p-sulfonate are well known, in many cases these reagents have been used in solution, e.g. in nitrobenzene, in addition to the older... 

The action of methyl toluene- -sulfonate on adenine (113 R = H) is reported to give the 3-methyl derivative (114), while the action... 

R = H, R" = NHAc) reacts with methyl toluene-p-sulfonate at 120°-l 30° to yield a quaternary salt which is thought to be 147 (R = H, R = NHAc) reaction is believed to occur at N-1 in spite of the proximity of the hydrogen atom in the 10-position. ... 

The formation of quinoxaline quaternary salts is often difficult. However, reaction of quinoxaline with ethyl iodide in boiling acetonitrile gives ethyl quinoxalinium iodide in 76% yield, and treatment of the parent base with methyl toluene-p-sulfonate at room temperature gives methyl quinoxalinium toluene-p-sulfonate in quantitative yield. ... 

Treatment of 2-aminoquinoxaline with methyl toluene-p-sulfonate at G. W. H. Cheeseman, unpublished work. 

Benzene, bromo, 55, 51 Benzene, 1 -bromo4-chloro, 55, 51 Benzene, 4-bromo-l,2-dimethyl-, 55, 51 Benzene, l-bromo-4-fluoio-, 55, 51 Benzene, l-bromo-4-methoxy-, 55, 51 Benzene, 1-bromo-3-methyl-, 55, 51 Benzene, l-bromo-4-methyl- [Toluene, 4-bromo-], 55, 49... 

Amine BJ. H.P. Methlodide PIcrate Methyl /)-toluene- sulphonate Other Derivatives... 

More toluene is formed than is needed in the catalytic reforming of naphtha. Benzene is always in tight supply. Table 8.7 shows the catalytic reformate production percentages of benzene, toluene, and xylene vs. the U.S. chemical demand. When the price is right it is economical to hydrodealkylate (add hydrogen, lose the methyl) toluene to benzene. This is best done on pure toluene, where the yield can be as high as 98.5%. The reaction can be promoted thermally or catalytically. As much as 30-50% of all benzene is made this way. 

Methylation of 3-hydroxy-5-phenyl-l,2,4-thiadiazole (23) with dimethyl sulfate and sodium hydroxide at room temperature gives the N-2 compound (24). When methylation is carried out using methyl toluene-4-sulfonate at 100°C compound (24) and the meso-ionic derivative (25) are produced (Scheme 7) <84JCS(Pl)75>. 

Janus [11] has recently shown that urea can also be smoothly methylated with methyl toluene-p-sulfonate at 80°-90°C to give good yields of crystalline 2-methylpseudourea toluene-p-sulfonate. 

Methyl toluene-p-sulphonat e combines with many tertiary amines to yield crystalline derivatives ... 

Dissolve 2-3 g of methyl toluene-p-sulphonate in 10 ml of dry toluene, add 1 g of the amine and boil the mixture for 20-30 minutes. Cool, and filter the precipitated quaternary salt. Recrystallise by dissolving the solid in the minimum volume of boling ethanol and then adding ethyl acetate until crystallisation commences. Filter the cold mixture, dry rapidly on a porous plate and determine the m.p. immediately. 

The benzyltrialkylammonium salts (R3N,CH2,Ph Cle) are prepared similarly 3 g of redistilled benzyl chloride replaces the methyl toluene-p-sulphonate. 

Like the trialkyloxonium superelectrophiles, the salts of trimethyl sul-fonium (CH3)sS+, selenonium (CEL Se"1", and telluronium (CE Te4" ions have also been shown by Laali et al. to undergo superelectrophilic activation.41 These onium salts methylate toluene in FSChH-SbFj, but with the weaker Bronsted superacid CF3SO3H (triflic acid, //q —14.1), no methylation takes place (eq 12). 

Di-tert,-butylphosphino)-biphenyl has been used by Buchwald [5] et al. as the most efficient ligand in the Pd-catalyzed amination of aryl chlorides. 2-Chloro-4-methyl-toluene can be aminated with pyrrolidine in 98% yield using sodium-tert.-butoxide [eq. (e)]. 

Pd-catalyzed CO- bond forming reactions were performed by Buchwald [8] et al. with 2-dimethylamino-2 -di-(tert.-butyl)-biphenyl as ligand. 3,4-Dimethylphenol can be arylated smoothly with 2-chloro-4-methyl-toluene in the presence of sodium hydride [eq. (f)]. 

Oxazoles and benzoxazoles yield salts with acids, alkyl halides, methyl toluene-p-sulfonate, triethyloxonium fluoroborate, etc. Quaternization is subject to the well-known steric effect of bulky substituents 2-phenylbenzoxazole, for instance, does not react with ethyl iodide even at 240 °C. The weakly basic nature of oxazole (see Section 4.18.2.4) is reflected in the instability of its simple salts, such as hydrochlorides and picrates, which are readily hydrolyzed, even in air. 2-Aminooxazoles and 2-aminobenzoxazoles are alkylated at the ring nitrogen atom the anilinonaphthooxazole (124), on the other hand, reacts with methyl iodide to yield a mixture of methyl derivatives (equation 1). 

Methyl />-toluenesulfonate may be prepared in a somewhat similar manner with good yields. One kilo of methyl alcohol (90-95 per cent) is placed in a round-bottom flask, placed in an ice-salt bath. One kilo of powdered pure -toluenesulfo-chloride (crude material may be used but the yield of product drops to about 75 per cent) is added with mechanical stirring. From a separatory funnel 840 g. of 25 per cent sodium hydroxide solution is added drop by drop. The temperature must be held at about 23-270 for the best results. When all this alkaline solution is added the reaction mixture is tested with litmus if not alkaline, more alkali is added until the neutral point is reached. Upon standing several hours the ester sinks and the alcohol forms the top layer. The alcohol may be siphoned off and used in subsequent experiments, the methyl / -toluene-sulfonate is washed with water to remove a little salt and then with 5 per cent hydrochloric add to dissolve the iron. Finally it is... 

Synonyms and trade names dimethyl benzene, xylol, methyl toluene, 1,4 -dimethyl-benzene... 

SYNS METHYLESTER KYSELINY p-TOLUEN-SULFONOVE (CZECH) METHYL-4-METHYLBENZ-ENESULFONATE METHYL-p-TOLUENESULFONATE METHYL TOLUENE-4-SULFONATE D METHYL TOS i LATE METHYL-p-TOS i LATE p-TOLUOL-SULFONSAEURE METHYL ESTER (GERMAN)... 

SYNS DIMETHYLBENZENE KS XEN (POLISH) METHYL TOLUENE NCI-C55232 RCRA WASTE NUMBER U239 VIOLET 3 XILOLI (ITALIAN) XTXENEN PUTCH) D XYLOL pOT) XYLOLE (GERMAN)... 

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