Chloride, cupric coupling

The palladium chloride process for oxidizing olefins to aldehydes in aqueous solution (Wacker process) apparendy involves an intermediate anionic complex such as dichloro(ethylene)hydroxopalladate(II) or else a neutral aqua complex PdCl2 (CH2=CH2)(H2 0). The coordinated PdCl2 is reduced to Pd during the olefin oxidation and is reoxidized by the cupric—cuprous chloride couple, which in turn is reoxidized by oxygen, and the net reaction for any olefin (RCH=CH2) is then... 

The oxidative dimerization of the anion of methyl phenyl sulfone (from a Grignard reagent) in ethereal solution in the presence of cupric chloride in 5% yield has been reported47. Despite the reported48 poor stability of the a-sulfonyl C-centered radicals, Julia and coworkers49 provoked the dimerization (in 13 to 56% yields) of the lithiated carbanion of alkyl phenyl sulfones using cupric salts as oxidants. The best results are obtained with cupric triflates in THF-isobutyronitrile medium (56% yield for R = H). For allyl phenyl sulfones the coupling in the 3-3 mode is predominant. 

Homocoupling of alkyl halides in aqueous media can be mediated by manganese/cupric chloride to give the dimerization products in good yield. Cross-coupling can also be controlled to give the desired... 

The hemispherical electrode may be coupled with a ring [20] to form a rotating ring-hemisphere electrode (RRHSE) as shown as Fig. 9(d). The ability of this combination to detect intermediate reaction products is demonstrated in Fig. 10, where a series of cathodic sweep curves for the reduction of Cu2 + in acidic cupric chloride solution are... 

An improved synthesis of dithieno[3,2-A2, 3 -<7]thiophene 15a has been achieved from 2,3-dibromothiophene 304 (Scheme 57). Lithiation of 2,3-dibromothiophene 304 using -butyllithium followed by oxidative coupling with cupric chloride provided 3,3 -dibromo-2,2 -bithiophene 305 in 79% yield. Treatment of 305 with 2 equiv of -butyllithium in ether at —78 °C under nitrogen for 40 min and then adding benzenesulfonic acid thioanhydride and leaving the reaction mixture to reach room temperature afforded dithieno[3,2-A2, 3 -<7]thiophene 15a in 70% yield <2002TL1553>. 

Di(3-benzo[6]thienyl)methane is obtained by treatment of 3-benzo-[6]thienylmagnesium bromide with 3-chloromethylbenzo [ thiophene.486 Two molecules of 3-benzo[6]thienylmagnesium iodide may be coupled by treatment with cupric chloride,305 but not with cupric bromide or nickel bromide,349 to yield 3,3 -di(benzo[6]thienyl). A claim349 to have prepared the same compound by the Ullmann reaction is probably not justified.305 The Ullmann reaction otherwise seems to be of general application in the benzo [6]thiophene series.87-483 Halobenzo[6]thiophenes76 105 511 can be selectively metallated in the 2-position by the use of w-butyllithium (Section VII). 

Keywords terminal alkyne, Glaser coupling, cupric chloride, microwave irradiation, butadiyne... 

For those redox couples that involve a metal ion plus the metal, the logical electrode system is the metal itself. In other words, if the measured quantity is to be cupric ion [copper(II)], a practical indicator electrode is a piece of copper metal. All second-class electrodes involve an active metal in combination with an insoluble compound or salt. Thus, the silver/silver chloride electrode actually is a silver/silver ion electrode system that incorporates the means to control the silver ion concentration through the chloride ion concentration [Eq. (2.14)]. A related form of this is the antimony electrode, which involves antimony and its oxide (an adherent film on the surface of the antimony-metal electrode) such that the activity of antimony ion is controlled by... 

Coupling, of benzenediazonium chloride with acetoacetic acid, 32, 84 of diazotized />-aminoacetophenone with quinone, 34, 1 of diazotized 3,5-dichloro-2-aminoben-zoic acid to give 4,4, 6,6 -tetra-chlorodiphenic acid, 31, 96 of diphenyldichloromethane to tetra-phenylethylene, 31,104 Creased flask, 37, 55 Creosol, 33,17 Crotonaldehyde, 33, 15 34, 29 diethyl acetal, 32, 5 Cupric acetate monohydrate, 36, 77 Cuprous oxide-silver oxide, 36, 36, 37 Cyanamide, 34, 67 36, 8 Cyanoacetamide, 32, 34 Cyanoacetic acid, 31, 25 38, 16, 18 Cyanoacetylurca, 37,16 /i-Cyanobenz d[Pg.99]

Diphenylyl-o-arsinic acid.— This is isolated by coupling sodium arsenite with diazotised o-aminodiphenyl in alkaline solution at 50° to 00° C. in the presence of a cupric salt. Yield, about 60 per cent. It crystallises from boiling water in bristle-like needles, M.pt. 206° C. When reduced in warm concentrated hydrochloric acid by sulphur dioxide in the presence of an iodide, it yields diphenylyl-o-dichloroarsine, a heavy oil, soluble in chloroform, insoluble in water. The chloride, with alcoholic potash, yields the oxide, an amorphous substance with no definite melting-point. 

The radical 36 can react with cupric chloride by two pathways, one of which leads to addition and the other to substitution. Even when the addition pathway is taken, however, the substitution product may still be formed by subsequent ehmination of HCl. Note that radical reactions are presented in Chapter 14, but the coupling of an alkene with an aromatic compound containing a leaving group prompted its placement here. Note also the similarity to the Heck reaction in 13-10. 

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