Reagents initiator

These reagents initiate a catalytic cycle that regenerates the active silyation species.92 (See p. 83 for a similar cycle in the Mukaiyama reaction.)... 

Figure 6 CL emission profile with the time (a) after mixing of reagents, initiation of reaction, entrance and exit from the flow cell (FC) of the chemiluminescent solution (b) and typical peaks recorded after successive injections of the same analyte into the manifold (c).

Stability of the Reagent The stability of the original Karl Fischer reagent initially prepared with an excess of methanol was found to be fairly poor and hence, evidently needed frequent standardization. However, it was estabtished subsequently that the stability could be improved significantly by replacing the methanol by 2-methoxyethanol. 

The reaction of carbon dioxide with Grignard reagents initially gives a magnesium salt of a carboxylic acid, RC02MgX ... 

C, KOH equimolar amount with respect to ketoxime, tenfold excess of DMSO (of total mass of reagents), initial C2H2 pressure 12-14 atm. 

Baxendale and Wilson (1957) reported that in an oxygen-free environment Fenton s reagent initiates very rapid polymerization of methyl acrylate, methacrylic acid, methyl methacrylate, acrylonitrile, and styrene, and the... 

Nevertheless, equation (2.17) may help in determining the determinant and detecting the type of interrelated reactions from it. It should be noted here that, in the broad sense of the word, interrelated (interfering) reactions are only those proceeding via general intermediate substances, capable reagents, initiators or catalysts of secondary reactions. Otherwise, this class of reaction may be added to by consecutive reactions, which are not coherent. 

Cleavage of the S-S bond in4-aryl-3,5-bis(methylthio)-l,2-dithiolium salts occurs on treatment with a cyclopentadienide species which results in the formation of an ot,(3-unsaturated dithioester 518. Deprotonation by excess reagent initiates an intramolecular cyclization which yields a 5/7-cyclopenta[A]thiopyran-4-thione (Scheme 202) <1996LA109>. 

In the first case, the chemical reaction practically does not disturb the adsorption-desorption equilibrium between the colloidal particle adsorption layer and the liquid phase. The composition of the adsorption layer during the MO reduction may be expressed in terms of the reagents initial concentrations and the current [MO] value. In the second case, the reaction volume of the colloidal particle is limited by its adsorption layer, which composition during MO reduction may be found from the known [reag]0 and [MO]. In the intermediate case, the current composition of the colloidal particle adsorption layer and hence the cp([pear]o, [MO]) value will explicitly depend on Io-... 

In an example illustrating an approach featuring the intermediacy of a ruthenium hydride reagent, initial isomerization of the starting compound 168 generated the intermediate 169, which was thereafter annulated to the target indole 170 (Scheme 19) <2006JOC4255>. 

A new example of the aza-Payne rearrangement has been used to prepare a-hydroxyaziridines <2005OL3267>. The epoxy imine 673 is prepared by a sequential epoxidation and imination. Reaction of 673 with a series of alkyllithium reagents initially adds to the imine which then does an aza-Payne rearrangement to form the hydroxy-aziridine 674 (Scheme 165). While the method generally suffers from poor yields, the one-step nature of the transformation lends greatly to its appeal. 

Benzyl halides can be catalytically carbonylated to esters in the presence of (Rh2(CO)4ChJ and [Ni(PPh3)2(CO)2]. Esters can also be obtained from alkyl and benzyl halides using stoichiometric quantities of Na2[Fe(CO)4] (Scheme 15). Although aryl halides do not react with this reagent, initial... 

However a subsequent study by the same group revealed that, by employing the trialkylstannane equivalent (66) to the reagent initially described and employing a strong Lewis acid at low temperatures instead of a palladium cata-... 

The toxicity of organotin derivatives and the difficulty in removing tin residues has spurred considerable eflforts to devise catalytic systems or, preferably, completely tin-free processes for conducting radical reactions. The use of poly(methylhydrosiloxane) in conjunction with a small amount of hexabutylditin oxide, a combination of reagents initially proposed by Grady and Kuivila [21a], has recently been applied to Barton-McCombie type deoxygenations [21b]. Several silanes have been examined... 

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