Alkylating reagents extractive alkylation

Ethers, Esters, and Related Derivatives of Alcohols.—Oestrogens are effectively methylated at the phenolic oxygen by extraction from alkaline solution into di-chloromethane containing iodomethane, with a tetra-n-hexylammonium salt as a phase-transfer reagent ( extractive alkylation ). Conditions are mild, and the reaction is very rapid. In combination with g.l.c. analysis of the methyl ethers, it provides a simple and convenient method for the analysis of oestrogen mixtures. H-... 

A iridine traces in aqueous solution can be determined by reaction with 4-(p-nitroben25l)pyridine [1083-48-3] and potassium carbonate [584-08-7]. Quantitative determination is carried out by photometric measurement of the absorption of the blue dye formed (367,368). Alkylating reagents interfere in the determination. A iridine traces in the air can be detected discontinuously by absorption in Folin s reagent (l,2-naphthoquinone-4-sulfonate) [2066-93-5] (369,370) with subsequent chloroform extraction and hplc analysis of the red dye formed (371,372). The detection limit is ca 0.1 ppm. Nitrogen-specific thermal ionisation detectors can be used for continuous monitoring of the ambient air. 

The refined grade s fastest growing use is as a commercial extraction solvent and reaction medium. Other uses are as a solvent for radical-free copolymerization of maleic anhydride and an alkyl vinyl ether, and as a solvent for the polymerization of butadiene and isoprene usiag lithium alkyls as catalyst. Other laboratory appHcations include use as a solvent for Grignard reagents, and also for phase-transfer catalysts. 

General Method for Forming Derivatives with Reagent III. To make the derivatives. 111 was dissolved in 5 mL dimethylformamide, and the alkyl halide was added to the salt solution. The mixture was allowed to stand at room temperature for 24 h, and the dimethylformamide was removed under reduced pressure. The residue was dissolved in water, and the derivative was extracted with 25 mL of chloroform. The derivative was then precipitated from the chloroform with ether-hexane. ... 

Derivatization (GC) 848 alkylating reagents 861 alkyl halide/catalyst 861 dialkyl acetals 863 diazoalkanes 862 extractive alkylation 863 pyrolytic alkylation 865 al) ldimethylsilyl reagents 855... 

Reactions of trident and ambident anions of hydroxy compounds with alkylating reagents were also studied.121 The ion-pair extraction method was found to be superior alkylating agents were methyl iodide (soft) and dimethyl sulfate (hard). Upon alkylation by ion-pair extraction the 5-methyl-substituted selenolene-2-one system gives mainly C-alkylation with the soft acid, methyl iodide, and mainly O-alkylation with the hard acid, dimethyl sulfate. 

In the main, the original extractive alkylation procedures of the late 1960s, which used stoichiometric amounts of the quaternary ammonium salt, have now been superseded by solid-liquid phase-transfer catalytic processes [e.g. 9-13]. Combined soliddiquid phase-transfer catalysis and microwave irradiation [e.g. 14-17], or ultrasound [13], reduces reaction times while retaining the high yields. Polymer-supported catalysts have also been used [e.g. 18] and it has been noted that not only are such reactions slower but the order in which the reagents are added is important in order to promote diffusion into the polymer. 

The phosphine sulfide CYANEX 471X has been proposed as an alternative to the foregoing reagents for palladium platinum separation. Here, the faster extraction of palladium affords separation factors of 10 1, with a 10 min contact time. The chemistry of the process is similar to that of the alkyl sulfides. Various other separations have been published for example, TBP will extract platinum(IV) chloroanions preferentially to pal-ladium(II). 

Alkyl ethynyltellurides from dialkylditellurides and pressurized acetylene in the presence of electrophilic reagents (typical procedure) To a mixture of di-isopropyl ditellurides (4.5 g, 13 mmol), powdered KOH (20 g, 303 mmol), methyl iodide (2 g, 14 mmol), dibenzo-18-crown-6 (0.2 g) and benzene (50 mL) was heated (40-50°C) in a 1 L rotating autoclave under acetylene pressure (14 atm) for 5 h. After addition of water the mixture was extracted with benzene, the organic layer was separated and dried over KjCOj. After evaporation of benzene the residue was diluted with ether and precipitated dibenzo-18-crown-6 was fdtered off. After evaporation of ether the residue was distilled in vacuo giving the product (2.3 g, 96% yield). 

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