Weakly acetonitrile

Generally it was found that resolution R is practically the same for isoeluotropic mixtures methanol and acetonitrile with water. The dependencies were obtained between capacity factors for derivatives of 3-chloro-l,4-naphtoquinone at their retention with methanol and acetonitrile. Previous prediction of RP-HPLC behaviour of the compounds was made by ChromDream softwai e. Some complications ai e observed at weak acetonitrile eluent with 40 % w content when for some substances the existence of peak bifurcation. 

The nitrato compound is a weak electrolyte in acetonitrile solution. 

The solution of purified dinoflagellate luciferin is yellow, showing absorption maxima at 245 and 390nm in an aqueous solution and at 241 and 388 nm in 40% acetonitrile containing 85 mM NaCl and 3 mM NaHCOs (Fig. 8.4). The compound is strongly fluorescent in blue (excitation maximum at 390 nm, emission maximum at 474 nm Fig. 8.5). The properties of this luciferin are nearly identical with those of the compound F of euphausiid shrimps (Section 3.2). The luciferin is rapidly oxidized in the presence of a trace of oxygen, and also inactivated by a weak acid, even by an acidity of pH 4 or the acidity... 

Finally, an example of an x-ray structure of a cationic complex shall be mentioned. From the data for 12, a surprisingly weak coordination (Si —N 1.932(8) A [146, 147]) of the acetonitrile donor to the silicon is inferred. The deviation from a pure tetrahedral geometry at the silicon is the largest yet observed (Table 4). 

The conductometric results of Meerwein et al. (1957 b) mentioned above demonstrate that, in contrast to other products of the coupling of nucleophiles to arenediazonium ions, the diazosulfones are characterized by a relatively weak and polarized covalent bond between the p-nitrogen and the nucleophilic atom of the nucleophile. This also becomes evident in the ambidentate solvent effects found in the thermal decomposition of methyl benzenediazosulfone by Kice and Gabrielson (1970). In apolar solvents such as benzene or diphenylmethane, they were able to isolate decomposition products arising via a mechanism involving homolytic dissociation of the N — S bond. In a polar, aprotic solvent (acetonitrile), however, the primary product was acetanilide. The latter is thought to arise via an initial hetero-lytic dissociation and reaction of the diazonium ion with the solvent (Scheme 6-11). 

The donor properties of N3P3CI6 appear to be too weak to allow complex formation with metal halides, but it has been reported that complex formation between N3P3Cl5 NHBu" and Cu" or Co" chlorides in acetonitrile solutions can be detected by u.v. spectroscopy. Attempts to isolate the complexes were unsuccessful. 

Au2(dcpm)2]X2 complexes with weakly interacting counterions (X = C104, PFg, Cp3S03, Au(CN)2 ) exhibit similar UV/Vis absorption spectra in acetonitrile. They show an intense absorption band at 277 nm ( = 2.6-2.9 x cm ) and a weak shoulder at 315 nm ( w400 cm ), which are assigned to... 

The co-condensation at low temperature of a metal vapor (commonly produced by resistance or electron-beam heating of metals) with a vapor of weakly stabilizing organic ligands (such as -pentane, toluene, tetrahydrofu-ran, acetone, or acetonitrile), using commercially available reactors, affords solid matrices, where reactions between the ligand molecules and metal atoms can take place (Scheme 1(A) Figure 1) [5]. 

Oxime carbamates have high polarity and solubility in water and are relatively chemically and thermally unstable. They are relatively stable in weakly acidic to neutral media (pH 4-6) but unstable in strongly acidic and basic media. Rapid hydrolysis occurs in strongly basic aqueous solutions (pH > 9) to form the parent oxime/alcohol and methylamine, which is enhanced at elevated temperature. Additionally, oxime carbamates are, generally, stable in most organic solvents and readily soluble in acetone, methanol, acetonitrile, and ethyl acetate, with the exception of aliphatic hydrocarbons. Furthermore, most oxime carbamates contain an active -alkyl (methyl) moiety that can be easily oxidized to form the corresponding sulfoxide or sulfone metabolites. 

C <4.7x10 Pa at 20 °C Water 20 mg at 20 °C Readily soluble in polar organic solvents Stable in neutral and weakly basic conditions Unstable in strongly acidic or basic conditions Stable in most of organic solvents such as acetone, acetonitrile and carbon tetrachloride Undergoes hydrolysis to yield methomyl oxime in alkaline solutions... 

Proton-coupled intramolecular electron transfer has been investigated for the quinonoid compounds linked to the ferrocene moiety by a 7r-conjugated spacer, 72 (171) and 75 (172). The complex 72 undergoes 2e oxidation in methanol to afford 74, which consists of an unusual allene and a quinonoid structure, with the loss of two hydrogen atoms from 72 (Scheme 2). The addition of CF3SO3H to an acetonitrile solution of 74 results in two intense bands around 450 nm, characteristic of a semi-quinone radical, and a weak broad band at lOOOnm in the electronic... 

Most protic solvents have both protogenic and protophilic character, i.e. they can split off as well as bind protons. They are called, therefore, amphiprotic. These include water, alcohols, acids (especially carboxylic), ammonia, dimethylsulphoxide and acetonitrile. Solvents that are protogenic and have weak or practically negligible protophilic character include acid solvents, such as sulphuric acid, hydrogen fluoride, hydrogen cyanide, and formic acid. 

The possible mechanisms for solvolysis of phosphoric monoesters show that the pathway followed depends upon a variety of factors, such as substituents, solvent, pH value, presence of nucleophiles, etc. The possible occurrence of monomeric metaphosphate ion cannot therefore be generalized and frequently cannot be predicted. It must be established in each individual case by a sum of kinetic and thermodynamic arguments since the product pattern frequently fails to provide unequivocal evidence for its intermediacy. The question of how free the PO ion actually exists in solution generally remains unanswered. There are no hard boundaries between solvation by solvent, complex formation with very weak nucleophiles such as dioxane or possibly acetonitrile, existence in a transition state of a reaction, such as in 129, or SN2(P) or oxyphosphorane mechanisms with suitable nucleophiles. 

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