Nucleophilic substitution reactions aqueous solution

Alternatively, the Sn2 nucleophilic substitution reaction between alcohols (phenols) and organic halides under basic conditions is the classical Williamson ether synthesis. Recently, it was found that water-soluble calix[n]arenes (n = 4, 6, 8) containing trimethylammonium groups on the upper rim (e.g., calix[4]arene 5.2) were inverse phase-transfer catalysts for alkylation of alcohols and phenols with alkyl halides in aqueous NaOH solution to give the corresponding alkylated products in good-to-high yields.56... 

The enormous number of coordination compounds undergo many reactions, but a large number of reactions can be classified into a small number of reaction types. When one ligand replaces another, the reaction is called a substitution reaction. For example, when ammonia is added to an aqueous solution containing Cu2+, water molecules in the coordination sphere of the Cu2+ are replaced by molecules of NH3. Ligands are held to metal ions because they are electron pair donors (Lewis bases). Lewis bases are nucleophiles (see Chapter 9), so the substitution of one nucleophile for another is a nucleophilic substitution reaction. Such a reaction can be illustrated as... 

Nucleophili substitution, in phosphate esters, mechanism and catalysis of, 25, 99 Nucleophilic substitution, single electron transfer and, 26, 1 Nucleophilic substitution reactions in aqueous solution, 38, 161 Nuckophilic vinylic substitution, 7, 1... 

Solvent effects, reaction coordinates, and reorganization energies on nucleophilic substitution reactions in aqueous solution, 38, 161... 

We have examined the competing isomerization and solvolysis reactions of 1-4-(methylphenyl)ethyl pentafluorobenzoate with two goals in mind (1) We wanted to use the increased sensitivity of modern analytical methods to extend oxygen-18 scrambling studies to mostly aqueous solutions, where we have obtained extensive data for nucleophilic substitution reactions of 1-phenylethyl derivatives. (2) We were interested in comparing the first-order rate constant for internal return of a carbocation-carboxylate anion pair with the corresponding second-order rate constant for the bimolecular combination of the same carbocation with a carboxylate anion, in order to examine the effect of aqueous solvation of free carboxylate anions on their reactivity toward addition to carbocations. 

Amino derivatives of 1,2,3- and 1,2,4-triazoles are useful precursors to the corresponding nitro-substituted triazoles. 3-Amino-1,2,4-triazole (98) undergoes diazotization on reaction with nitrous acid the resulting diazonium salt (110) can react with a range of nucleophiles, including an aqueous solution of sodium nitrite which yields 3-nitro-1,2,4-triazole (111). Diazotization of 3,5-diamino-l,2,4-triazole (112), followed by heating with an aqueous solution of sodium nitrite, yields 3,5-dinitro-1,2,4-triazole (113). ... 

The arene oxide valence tautomer of oxepins in principle should undergo nucleophilic substitution reactions (Sn2) which are characteristic of simple epoxides. In reality oxepin-benzene oxide (7) is resistant to attack by hard nucleophiles such as OH-, H20, NH2- and RNH2. Attempts to obtain quantitative data on the relative rates of attack of nucleophiles on (7) in aqueous solution hqye been thwarted by competition from the dominant aromatization reaction. 

The now classic example of this type, excluding nucleophilic substitution reactions, is the solubilization of potassium permanganate in benzene by [18]crown-6 derivatives. The resulting solution proved a mild and efficient oxidizing agent for many organic compounds. For example, a-pinene is oxidized to cw-pinonic acid in 90% yield (Scheme 8) in contrast to a 40-60% yield in aqueous solution. An additional advantage is that the products of these reactions (e.g. potassium salt of cw-pinonic acid in Scheme 8) are frequently insoluble in the hydrocarbon solvents and consequently are unable to react further. 

Consider the reversible transformation of the soil fumigant methyl bromide (CH3Br) to methyl chloride (CH3C1) in aqueous solution (a nucleophilic substitution reaction, see Chapter 13) ... 

Esters are formed in nucleophilic substitution reactions in which the nucleophile is a carboxylate anion. The anions of carboxylic acids are relatively weak nucleophiles towards sp3-hybridized carbon. Swain s nucleophilic constant, n, for acetate ion is 2.7183, slightly smaller than that for chloride. Thus acetate is selectively alkylated by alkyl halides in aqueous solution, e.g. 

Water-soluble calix[ ]arenes (62 n = 4, 6, and 8) containing trimethylammonio-methyl groups act as efficient inverse phase-transfer catalysts in the nucleophilic substitution reactions of alkyl and arylalkyl halides with nucleophiles in water.126 (Inverse phase-transfer catalysts facilitate reactions between two immiscible reactants via the transport of an organic substrate into an aqueous solution of a second substrate, in which reactions take place.)... 

Short-lived organic radicals, electron spin resonance studies of, 5, 53 Small-ring hydrocarbons, gas-phase pyrolysis of, 4, 147 Solid state, tautomerism in the, 32, 129 Solid-state chemistry, topochemical phenomena in, 15, 63 Solids, organic, electrical conduction in, 16, 159 Solutions, reactions in, entropies of activation and mechanisms, 1, 1 Solvation and protonation in strong aqueous acids, 13, 83 Solvent effects, reaction coordinates, and reorganization energies on nucleophilic substitution reactions in aqueous solution, 38, 161 Solvent, protic and dipolar aprotic, rates of bimolecular substitution-reactions in,... 

Most reactions in two-phase systems occur in a liquid phase following the transfer of a reactant across an interface these are commonly known as extractive reactions. If the transfer is facilitated by a catalyst, it is known as phase-transfer catalysis [2]. Unusually, reactions may actually occur at an interface (interfacial reactions) examples include solvolysis and nucleophilic substitution reactions of aliphatic acid chlorides [3 ] and the extraction of cupric ion from aqueous solution using oxime ligands insoluble in water [4], see Section 5.2.1.3(ii). 

Solvent effects, reaction coordinates, and reorganization energies on nucleophilic substitution reactions in aqueous solution, 38, 161 Solvent, protic and dipolar aprotic, rates of bimolecular substitution-reactions in, 5,173 Solvent-induced changes in the selectivity of solvolyses in aqueous alcohols and related mixtures, 27, 239... 

This helped to derive the Hughes-Ingold rules for predicting the effect of solvent polarity on the reaction rate.1 We have used the combined QM-MOVB/MM method to study three nucleophilic substitution reactions in aqueous solution, which are summarized below. 

The vertical ionization potential for a solvated chemical species can be the measure of its reactivity in the solution phase, especially for a single electron transfer reaction. It has been reported that the ionization potentials of anions in solution are conelated with the kinetic parameter for nucleophilic substitution reaction. This implies that an important aspect of the activation process of the reaction is a single electron transfer from anion to substrate. The ionization potential for solvated species has been available as the threshold energy E by photoeiectron emission spectroscopy for solution (PEES). This spectroscopic technique is able to provide the , values of almost any solvated species, such as organic, inorganic, cations, anions and neutral molecules in aqueous and nonaqueous solutions. 

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