Sulfates toluene benzylation

Benzyioxycarbonyi chioride (Cbz-Ci, benzyi cbioroformate) [501-53-1] M 170.6, b 103 /20mm, d 1.195, n 1.5190. Commercial material is better than 95% pure and may contain some toluene, benzyl alcohol, benzyl chloride and HCl. After long storage (e.g. two years at 4 , Greenstein and Winitz [The Chemistry of the Amino Acids Voi 2 p. 890, J Wiley and Sons NY, 1961] recommended that the liquid should be flushed with a stream of dry air, filtered and stored over sodium sulfate to remove CO2 and HCl which are formed by decomposition. It may further be distilled from an oil bath at a temperature below 85 because Thiel and Dent [Annalen 301 257 1898] stated that benzyioxycarbonyi chloride decarboxylates to benzyl chloride slowly at 100 and vigorously at 155 . Redistillation at higher vac below 85 yields material which shows no other peaks than those of benzyioxycarbonyi chloride by NMR spectroscopy. LACHRYMATORY and TOXIC. 

The previous extension of solvent mixtures involved solvent interfaces. This organic-water interfacial technique has been successfully extended to the synthesis of phenylacetic and phenylenediacetic acids based on the use of surface-active palla-dium-(4-dimethylaminophenyl)diphenylphosphine complex in conjunction with dode-cyl sodium sulfate to effect the carbonylation of benzyl chloride and dichloro-p-xylene in a toluene-aqueous sodium hydroxide mixture. The product yields at 60°C and 1 atm are essentially quantitative based on the substrate conversions, although carbon monoxide also undergoes a slow hydrolysis reaction along with the carbonylation reactions. The side reaction produces formic acid and is catalyzed by aqueous base but not by palladium. The phosphine ligand is stable to the carbonylation reactions and the palladium can be recovered quantitatively as a compact emulsion between the organic and aqueous phases after the reaction, but the catalytic activity of the recovered palladium is about a third of its initial activity due to product inhibition (Zhong et al., 1996). 

In a general sense, the kinetics and metabolism of toluene in humans, rats and mice are very similar the hippurate is in all cases by far the major metabolite, while in all species the ortho- and / ora-cresols are minor metabolites. To what extent formation of a potentially reactive sulfate conjugate of benzyl alcohol occurs (van Doom et al., 1980 Chidgley et al., 1986) is uncertain, mainly because mercapturates formed from toluene have not been characterized. Similarly, whether the covalent binding observed in rat liver microsomes has any toxicological relevance is uncertain. 

To a stirred solution of methyl 2,3-di-0-benzyl-6-0-t-butyldiphenylsilyl-a-D-glucopyranoside (0.617 g, 1.01 mmol) in toluene (5 ml) was added 1,1 -thiocarbonyldiimidazole (0.359 g, 2.01 mmol) at room temperature. The solution was heated at reflux. The reaction mixture was poured into 0.5 N HCI (50 ml) and extracted with CH2CI2 (3x50 ml). The organic layers were combined, washed with sat. sodium bicarbonate solution followed by brine, dried over sodium sulfate and filtered. The solvent was removed in vacuum to give a crude yellow oil, which was purified by column chromatography over silica gel (hexane-EtOAc, 7 3) to afford 0.676 g (93%) of methyl 2,3-di-O-benzyl-6-0-t-butyldiphenylsilyl-4-0-imidazolyl-thiocarbonyl-a-D-glucopyranoside as a colorless viscous oil. 

Benzylation of toluene with benzyl chloride, which is a typical example of Friedel-Crafts alkylation, is known to be catalyzed by Lewis-type superacids such as A1C13 and BF3. This type of catalyst has been mostly used for the Friedel-Crafts reaction, which is one of the most studied of organic reactions. This reaction was performed over several metal oxides and sulfates, and iron sulfates showed an unexpected effectiveness for the reaction (102-104). The catalytic activities of FeS04 and Fe2(S04)3 for the reaction were examined in detail the activities were remarkably dependent on calcination temperature, the maximum activity being observed with calcination at 700°C (105-107). Catalytic actions analogous to the above case were also observed with other Friedel-Crafts reactions, the benzoyl-ation of toluene with benzoyl chloride (108), the isopropylation of toluene with isopropyl halides (109), and the polycondensation of benzyl chloride UIO). 

Copper acetate, Cu(OCOCHj)2 or Cu(0C0CH3)2 H20, resembles copper sulfate in its oxidizing properties and is used for the oxidative coupling of terminal acetylenes [53, 357] and for the conversion of acyloins into a-diketones [353, 359]. Its presence favorably affects the acetoxylation of toluenes to benzyl acetates by sodium persulfate [360]. 

The model monosaccharides just listed were prepared from common precursor IV.l (Scheme 39), which was readily obtained by azidonitration of 3,4,6-tri-O-acetyl-D-galactal followed by deacetylation with sodium methoxide. Treatment of IV.l with acetone and toluene p-sulfonic acid monohydrate at room temperature led to predominant formation of the thermodynamically favored 3,4-O-isopropylidene (IV.2) in 61% yield while also producing 27% of the 4,6-O-isopropylidene derivative IV.3. The position of the isopropylidene IV.2 was verified by the use of NMR chemical shift analysis to confirm the position of the acetate group in the resultant acetylated adduct IV.4. Synthesis of the 4-O-sulfate derivative (IV.7) from IV.2 utilized a step that differentiated the 3-OH and 4-OH positions after benzylation and de-isopro-pylidination of IV.2, a selective methylation at the 3-OH of diol IV.5 was achieved via a tin procedure [91] to give methyl glycoside IV.6. Conversion of the azide into... 

Arata, K., Yabe, K., and Toyoshima, I. 1976. Friedel-Crafts reaction in the heterogeneous system—V. Friedel-Crafts benzylation and benzoylation of toluene catalyzed by calcined iron sulfates. /. Catal. 44 385-391. 

Although the nature of the active surface is not known, it can be said that the surface activity of various metal sulfates is virtually identical as revealed in a positional isomer distribution of benzyl-toluene. 

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