Methylation reagents for

Accordingly, under different conditions, DMC is used as a methylating reagent for a variety of substrates phenols, thiols, thiophenols, aromatic amines, arylace-tonitriles, arylacetoesters, aroxyacetonitriles, aroxyacetoesters, alkylarylsulfones, benzylarylsulfones, and lactones, either under CF or in batch conditions. 

Methyl fluorosulfate, methyl 2,4,6-trinitrobenzosulfonate, and trimethyloxonium tetrafluoro-borate have been shown to serve as methylating reagents for the formation of S-methyl benzo-thiepinium salts (Equations (8)-(10)) <77TL1985, 83LA425,84ZN(B)985,90ZN(B)1573>. 

DMF dimethyl acetal is an effective methylating reagent. For example, heterocyclic thiols are transformed to 5-methyl heterocycles in high yields (76-86%). DMF dibenzyl acetal is an interesting reagent for selective protection of nucleosides. For example, uridine and guanosine are selectively blocked at the -CONH function (eq 5). ... 

In a biotechnology-based approach, Japanese workers have reported on the microbial conversion of 2-methylnaphthalene to both 2-methyl-1-naphthol and menadione by Jiodococcus (64). The intermediate 2-methyl-1-naphthol can readily be converted to menadione by a variety of oxidizing agents such as heteropoly acids (65) and copper chloride (66). A review of reagents for oxidizing 2-methylnaphthalene and naphthol is available (67). 

There is no specific color or other reaction by which methyl chloride can be detected or identified. QuaUty testing of methyl chloride for appearance, water content, acidity, nonvolatile residue, residual odor, methanol, and acetone is routinely done by production laboratories. Water content is determined with Kad Fischer reagent using the apparatus by Kieselbach (55). Acidity is determined by titration with alcohoHc sodium hydroxide solution. The nonvolatile residue, consisting of oil or waxy material, is determined by evaporating a sample of the methyl chloride at room temperature. The residue is examined after evaporation for the presence of odor. Methanol and acetone content are determined by gas chromatography. 

Agglomeration-Based Fine Coal Cleaning. Most recently a search for nonaqueous collectors or reagents for fine coal cleaning has been undertaken. A number of Hquids have been tested and found to be suitable as agglomeration agents. These include heavy oil. Freon, pentane, hexane, heptane, 2-methylbutane, methyl chloride, and Hquid carbon dioxide. 

Analytical applications of pyrazolones have been reviewed by Busev et al. (65RCR237). Organic bases are easily characterized by formation of highly crystalline salts with picrolonic acid (l-(4-nitrophenyl-3-methyl-4-nitro-5-hydroxypyrazole). The last-named compound is used as a reagent for alkaloids, tryptophan, phenylalanine and for the detection and estimation of calcium (B-76MI40404). 

MANNICH - ESCHENMOSER Methylenation reagent Ammomethylation of activated methyl or methylene groups by in situ formed MeaN -CHR (Mannich) Me2N- -=CH2 X reagent for o methylenation (Eschenmoser)... 

Nitrones are among the most highly studied and useful reagents for the synthesis of five-membered-nng heterocycles. The first fluonnated nitrone, N-methyl-C-(trifluoromethyl)nitrone, was prepared recently and used to introduce Irifluoromethyl groups into such heterocycles... 

BH3, toluene converts the p-AOM ether into a methyl ether. For a comparison of the stability of this group with MTM, SEM, BOM, and EOM to various hydride reagents, see the section on SEM ethers. ... 

Benzyloxycarbonyloxy)phenyl]dimethylsulfonium methyl sulfate, NaOH, H20,51-95% yield. " This is a water-soluble reagent for benzyloxy carbamate formation. Analogous reagents for the introduction of BOC and Fmoc were also prepared and give the respective derivatives in similar high yields. 

Discussion. Because of the specific nature of atomic absorption spectroscopy (AAS) as a measuring technique, non-selective reagents such as ammonium pyrollidine dithiocarbamate (APDC) may be used for the liquid-liquid extraction of metal ions. Complexes formed with APDC are soluble in a number of ketones such as methyl isobutyl ketone which is a recommended solvent for use in atomic absorption and allows a concentration factor of ten times. The experiment described illustrates the use of APDC as a general extracting reagent for heavy metal ions. 

Besides simple alkyl-substituted sulfoxides, (a-chloroalkyl)sulfoxides have been used as reagents for diastereoselective addition reactions. Thus, a synthesis of enantiomerically pure 2-hydroxy carboxylates is based on the addition of (-)-l-[(l-chlorobutyl)sulfinyl]-4-methyl-benzene (10) to aldehydes433. The sulfoxide, optically pure with respect to the sulfoxide chirality but a mixture of diastereomers with respect to the a-sulfinyl carbon, can be readily deprotonated at — 55 °C. Subsequent addition to aldehydes afforded a mixture of the diastereomers 11A and 11B. Although the diastereoselectivity of the addition reaction is very low, the diastereomers are easily separated by flash chromatography. Thermal elimination of the sulfinyl group in refluxing xylene cleanly afforded the vinyl chlorides 12 A/12B in high chemical yield as a mixture of E- and Z-isomers. After ozonolysis in ethanol, followed by reductive workup, enantiomerically pure ethyl a-hydroxycarboxylates were obtained. 

Several 2-butenylboron reagents have been synthesized by the hydroboration of allenes9 36. Diisopinoeampheyl(3-methyl-2-butenyl)borane is an excellent reagent for the asymmetric iso-prenylation of aldehydes (typically 89 95% ee), and is conveniently synthesized by the hydroboration of 3-methyl-l,2-butadiene using diisopinocampheylborane9. 

Since these adducts undergo reductive desulfuration with Raney nickel, optically active aryl methyl sulfoxides are versatile reagents for the conversion of imines to optically active amines. 

Syntheses of many of these compounds are shown in Figures 2.100 and 2.101, with structural data in Tables 2.14 and 2.15. Apart from NO itself, convenient reagents for introducing the group include NO+ salts and MNTS ((V-methyl-jV-nitrosotoluene-p-sulphonamide, />-MeC6H4S02N(NO)Me). 

Balli and Felder (1978) and Balli and Ritter (1981) showed that diazo transfer can be applied advantageously to the diazotization of sufficiently nucleophilic heteroaromatic compounds such as 5-hydroxy- and 5-amino-3-methyl-l-phenyl-pyrazole if 3-ethyl-2-azido-benzthiazolium tetrafluoroborate (2.50) is used as diazo transfer reagent (for other applications of this diazo transfer reagent see Zollinger, 1995, Secs. 2.6-2.8). The diazonio group is introduced in the 4-position (2.51). 

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