Water reaction with anions

The alkah metal phosphides of formula M P and the alkaline-earth phosphides of formula M2P2 contain the P anion. Calcium diphosphide [81103-86-8] CaP2, contains P reaction with water Hberates diphosphine and maintains the P—P linkage. 

When bubbler systems are used for collection, the gaseous species generally undergoes hydration or reaction with water to form anions or cations. For example, when SOj and NH3 are absorbed in bubblers they form HSO3 and NH4, and the analytical techniques for measurement actually detect these ions. Table 13-1 gives examples of gases which may be sampled with bubbler systems. 

Any acid that undergoes quantitative reaction with water to produce hydronium ions and the appropriate anion is called a strong acid. Table gives the structures and formulas of six common strong acids, all of which are supplied commercially as concentrated aqueous solutions. These solutions are corrosive and normally are diluted for routine use in acid-base chemistry. At the concentrations normally used in the laboratory, a solution of any strong acid in water contains H3 O and anions that result from the loss of a proton. Example shows a molecular view of the proton transfer reaction of a strong acid. 

Any anion of a weak acid, including the anions of polyprotic acids, is a weak base. The acid-base properties of monoanions of polyprotic acids are complicated, however, because the monoanion is simultaneously the conjugate base of the parent acid and an acid in its own right. For example, hydrogen carbonate anions undergo two proton-transfer reactions with water ... 

The attack by the thiolate anion on the N-oxide oxygen of 62 produces the intermediate sulfenic acid derivative 65, which, in the presence of thiols, further reacts with the thiolate anion, to give the oxime 66, which has been isolated among the reaction products. By contrast, spontaneous loss of the halide anion from 65 affords the ni-troso intermediate 67 that, by losing NO and the thiyl radical directly, or through 68, produces the a-nitrosoolefm 69. By a Michael type reaction with water this last product immediately yields the final oxime 70, which has been isolated among the reaction products. 

Cation derived from a strong base Reaction with water neither ion Solution neutral Examples NaCl, K2SO4, Ca(N03)2 Reaction with water only the anion Solution basic Examples NaCHsCOO, KF, Mg(HS04)2... 

Schindewolf and WUnschel [112] have studied solvated electron reactions in liquid ammonia and water with several univalent anions and divalent cations. Ions such as NO3, N02, and BrO in water showed diffusion-limited behaviour and the ions Cd2+, Ni2+, Co2+, and Zn2+ in water displayed diffusion-limited behaviour or faster. Schindewolf and WUnschel considered that reactions of none of these ions were quite diffusion-limited in liquid ammonia. Applying the hydrodynamic correction suggests that the anionic reaction with solvated electrons may just be diffusion-limited, but the cations reaction with solvated electrons remains slower than diffusion-limited. 

STRATEGY The solution contains N02 , a base, so we expect the pH to be i higher than that of nitrous acid alone. The K+ ion has no protons to donate j and cannot accept a proton, so it has no measurable effect on the pH of the ] solution. Identify the proton transfer equilibrium and use it to find the pH by means of an equilibrium table. Consider the initial molarity of HN02 (before reaction with water) to be 0.500 mol-L1. Because nitrite ions have also been added to the solution, set their initial molarity equal to the molar-5 ity of added salt (each KN02 formula unit supplies one N02 anion). Then proceed as described in Toolbox 10.1. Because the concentrations of the 1 added ions are much higher than 10-7 mol-L 1, we assume that we can S ignore the contribution to the pH from the autoprotolysis of water. 

A further possibility arises where the carbocation intermediate of the solvolysis is so unstable as to react with water at the limiting rate of solvent relaxation with a rate constant of 1011 s 1. It is then likely that the reaction with water occurs at the stage of a carbocation anion pair and that the back... 

Baeyer-ViUiger oxidation involves NADPH and flavin (FAD) as cofactors and was originally proposed by Walsh et al. based on data obtained from cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus (Fig. 24) [156]. In a first step, enzyme-bound flavin is reduced, followed by the addition of oxygen yielding a hydroperoxide anion. Reaction with the ketone substrate gives a Criegee intermediate, which is then converted into the product under dissociation of water. The cofactor FAD is recovered via oxidation with NADP+. 

With hydroxide anions (or with water at pH >5) pyrylium salts form pseudobases 16 (2-hydroxy-2//-pyrans) that tautomerize to acyclic 3-penten-l,5-diones 17 via a thermally allowed electrocyclic reaction. Most ring transformation reactions of pyrylium salts involve a similar ring-opening. 

Strong nucleophiles such as organolithium or organomagnesium derivatives do not react with substituted or unsubstituted phosphabenzene or arsabenzene (39, Y = P or As) by nucleophilic substitution as in the case of pyridines, but by addition to the heteroatom forming intermediate anions 40. These can then be converted into nonaromatic compounds by reaction with water to yield 1-alkyl-1,2-dihydro-derivatives 41, or they can be alkylated by an alkyl halide with the same or a different alkyl group, when two products may result a 1,2-dialkyl-1,2-dihydro 40-derivative 42, or a -derivative 43. The former products are kinetically controlled, whereas the latter compounds are thermodynamically controlled, so that one may favor the desired product by choosing the appropriate reaction conditions. 

Often the carboalkoxy group can be hydrolyzed by simple reaction with water, and the ease of this hydrolysis is higher at lower MA/NC ratio, e.g., in the series [Rh,(CO)16(COOMc)]- < [Rh4(CO)u(COOMe)]- < [Rh6 (( ()) i4 (C00Mei 2 ]2 M Sometimes, when the carboalkoxy group is not extremely sensitive to hydrolysis, the carboalkoxy anion has been obtained by simple use of anhydrous sodium carbonate suspended in alcohols (99). 

Water thus causes the electrolytic dissociation of the hydrogen chlpride, which means the formation of a hydroxonium cation on one side and a chloride anion on the other side, so that the solution conducts electrical current. Ions of other acids are formed by analogical reaction with water. )... 

If the atom that is forming the new bond to carbon is the same over a range of nucleophiles—it might be oxygen, for example, and the nucleophiles might be HO-, PhO-, AcO-, and TsO-—then nucleophilicity does parallel basicity. The anions of the weakest acids are the best nucleophiles, The order for the nucleophiles we have just mentioned will be HO > PhO- > AcO- > TsO-. The actual values for the rates of attack of the various nucleophiles on MeBr in EtOH relative to the rate of reaction with water (= 1) are given in Table 17.14... 

Besides its use as a mechanistic probe, deuteriation of anions under kinetically controlled conditions is a potentially promising way to access deuteriated molecules in a regio- and stereo- controlled manner, in opposition to the thermodynamic equilibration in the presence of an excess of deuterium donor. Thus, treatment of the lithium anion of 2-methyltetralone (p E = 7.31, pfsfEa = 10.8, pKkr = 18.1 in water)335, by one equivalent of a solution of deuterium chloride in deuterium oxide, generates the intermediate O-deuteriated enol whose reaction with water or with an excess of deuterium chloride in deuterium oxide conducts to, respectively, the tetralone or the deuteriated tetralone (Scheme 69)336. 

Hydrolysis in General. The word hydrolysis is used not only in the above way but also in referring to more general chemical reactions in which a molecule or ion is converted into two or more molecules or ions by reaction with water. The examples discussed above are cases of anion hydrolysis and cation hydrolysis, such as... 

Electrolysis of benzothiete sulfone 269 yields the phenylmethanesulfinate anion (major) and the o-toluenesulfinate anion (minor).Thermolysis 618,619 gj. photolysis of thiete 1,1-dioxides proceeds via ring-opening to vinyl sulfines, for example. 288, which have been trapped by reaction with water, phenol,methanol, or norbornenes. These intermediates may recyclize to unsaturated sultines (cyclic sulfinate esters) (e.g., 289) or lose sulfur monoxide to give mainly the trans isomers of a,j3-unsaturated carbonyl compounds (e.g., 290). Mass spectra also indicate the formation of unsaturated sultines. ... 

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