Reagents definition

The iodoform test. Dissolve 0 -1 g. or 5 drops of the compound in 2 ml. of water if it is insoluble in water, add sufficient dioxan to produce a homogeneous solution. Add 2 ml. of 5 per cent, sodium hydroxide solution and then introduce a potassium iodide - iodine reagent dropwise with shaking until a definite dark colour of iodine persists. Allow to... 

Equation (5.40) also applies to the case when some of the excess B groups present are in the form of monofunctional reagents. In this latter situation the definition of r is modified somewhat (and labeled with a prime) to allow for the fact that some of the B groups are in the BB-type monomers (unprimed) and some are in the monofunctional (primed) molecules ... 

Ammonia is a cyclic reagent that is recovered by the end of the Solvay process for sodium carbonate from hme and salt. Although there is nothing obscure about the intermediate reactions, ammonia definitely participates in a catalytic sequence. 

The purpose of the researeh - ereation of a photometrie teehnique of definition of Pt(II) at the presenee of a Pd(II) and Rh(III) with the help 3,5-di-Br-PADAPH - 2-(3, 5 -dibromo-2 -pyridilazo)-5-diethylaminophenol - the most perspeetive reagent from analogues of PAR-s. 

In spite of numerous advances in the field of detection there are not and never have been any genuinely substance-specific chemical detection reactions. This means that, unlike the spectrometric methods, the methods of detection normally employed in chromatography cannot be employed for an unequivocal identification of compounds, they can only provide more or less definite indications for the characterization of the separated substances. Universal reagents are usually employed for a first analysis of the separation of samples of unknowns. This is then followed by the use of group-specific reagents. The more individual the pieces of information that can be provided from various sources for a presumed substance the more certainly is its presence indicated. However, all this evidence remains indicative it is not a confirmation of identity. 

The study of the Schlenk equilibrium for organozinc compounds represents a major chapter in the understanding of these reagents in general [26]. Before elaborating the studies on zinc carbenoids, it is appropriate to briefly review the definitive investigations on organozinc halides themselves. 

The last definition has widespread use in the volumetric analysis of solutions. If a fixed amount of reagent is present in a solution, it can be diluted to any desired normality by application of the general dilution formula V,N, = V N. Here, subscripts 1 and 2 refer to the initial solution and the final (diluted) solution, respectively V denotes the solution volume (in milliliters) and N the solution normality. The product VjN, expresses the amount of the reagent in gram-milliequivalents present in a volume V, ml of a solution of normality N,. Numerically, it represents the volume of a one normal (IN) solution chemically equivalent to the original solution of volume V, and of normality N,. The same equation V N, = V N is also applicable in a different context, in problems involving acid-base neutralization, oxidation-reduction, precipitation, or other types of titration reactions. The justification for this formula relies on the fact that substances always react in titrations, in chemically equivalent amounts. 

The reagent is added to the cold solution (or frequently at 50-60 °C) until the yellow or orange-yellow colour of the supernatant liquid indicates that a small but definite excess is present. 

A. Hausberger I think a sulfur-tolerant catalyst would definitely be an advantage in that the requirement for critical control of the sulfur removal system would be eliminated. If you can allow some sulfur to pass on through the methanator into the product gas, the amount of reagent or regeneration cost of the sulfur removal system would be reduced. As to what level of sulfur could be tolerated, that is a hard question to answer since I don t think that there is a sulfur-tolerant catalyst. 

In the first instance, acidity influences the acid-base equilibria of the reactants. The amine is a Bronsted base. Aniline, a typical substrate, has pKa = 4.6, which means that the protonation shown in Scheme 3-11 is almost complete under normal conditions of diazotization (pH < 1). The base is definitely a much better reagent than the anilinium ion for nitrosation because the latter is an electrophilic substitution. One expects — simply on the basis of the equilibrium shown in Scheme 3-11 — that the rate of diazotization should decrease linearly with increasing acid concentration or, at higher acidities, with the Hammett acidity function h0 (for acidity functions see Rochester, 1970 Cox and Yates, 1983). 

It might be mentioned that matters are much simpler for organometallic compounds with less-polar bonds. Thus Et2Hg and EtHgCl are both definite compounds, the former is a liquid and the latter is a solid. Organocalcium reagents are also known, and they are formed from alkyl halides via a single electron transfer (SET) mechanism with free-radical intermediates. "... 

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