Nitrophenyl alkanoates

The functional micellized surfactant contained both imidazole and hydroxyethyl groups and the final products of reaction with p-nitrophenyl alkanoates are acyl derivatives of the hydroxyethyl group. However, these O-acylated products were formed from an acylimidazole intermediate which... 

Deacylation of p-nitrophenyl alkanoates Alkylammonium alkanoates C6H6, HaO. Effects of surfactant structure and H20 examined O Connor and Ramage, 1980... 

Deacylation of hydrophobic p-nitrophenyl alkanoates Hydroxamic acid and phenyl ester derivatives had alkyl or fluoroalkyl substituents. Rate effects depend on selectivity of binding of fluoro- and hydro-carbon derivatives Kunitake et ai, 1984... 

Fig. 6 Dependence of transition state stabilization (p/fTS) on acyl chain length for the cleavage of m- and p-nitrophenyl alkanoates by ar-CD (filled points) and /3-CD (open points). Data from Table A.5.9, with points for the CK and C12 esters from...

Table A5.10 Cleavage of 4-carboxy-2-nitrophenyl alkanoates [22] by cyclodextrins."...

Table A6.6 Basic cleavage of p-nitrophenyl alkanoates by amylose." ...

The cleavage of /7-nitrophenyl alkanoates (222 n = 1-8) at high pH is modestly catalysed by micelles formed from cetyltrimethylammonium bromide (CTAB) in aqueous solution. Rate constants exhibit saturation behaviour with respect to [CTAB], consistent with substrate binding in the micelles. The strength of substrate binding and transition state binding to the micelles increases monotonically with the acyl chain length, and with exactly the same sensitivity. As a result, the extent of acceleration... 

Other earlier analyses made by Hansch et al. are represented by Eq. 30 and 31. Hydrolysis of p-nitrophenyl alkanoates (13) with serum esterase 25) ... 

A quantitative assessment of the effects of head group bulk on, S k2 and E2 reactions in cationic micelles has been made.148 The kinetics of the acid-catalysed hydrolysis of methyl acetate in the presence of cationic, anionic, and non-ionic surfactants has been reported on.149 The alkaline hydrolysis of -butyl acetate with cetyltrimethylammonium bromide has also been investigated.150 The alkaline hydrolysis of aromatic and aliphatic ethyl esters in anionic and non-ionic surfactants has been studied.151 Specific salting-in effects that lead to striking substrate selectivity were observed for the hydrolysis of /j-nitrophenyl alkanoates (185 n = 2-16) catalysed by the 4-(dialkylamino)pyridine-fimctionalized polymer (186) in aqueous Tris buffer solution at pH 8 and 30 °C. The formation of a reactive catalyst-substrate complex, (185)-(186), seems to be promoted by the presence of tris(hydroxymethyl)methylammonium ion.152... 

Fig. 21 Reaction rate versus substrate concentration for hydrolysis of p-nitrophenyl alkanoates (NPAlk) in the presence of poly(AT-(n-dodecyl)-4-vinylpyridinium-co-Ar-ethyl-4-vinylpyridinium) bromide (PDEVP) closed squares n = 6, diamonds n- 8, open squares n- 10, circles n- 12, triangles n- 14. (Adapted from Ref. [71])...

Table 2 Substrate specificity lor 1-catalyzedhydrolysis ofp-nitrophenyl alkanoates (NPAlk) in 1 1 methanol-aqueous solution in the presence of polymer 1 aggregates. (Data from Ref. [76]) ...

Scrimin and co-workers have extensively studied the ester-cleavage abilities of various Cu(II)-chelating bidentate ligand [(2-hydroxymethyl)pyridine] amphi-phile, 9, and related bolaphile, 10, in micellar media [32], The corresponding metallomicelles are powerful catalysts for the cleavage of substrates, e.g. p-nitrophenyl alkanoates, that do not coordinate with the metal-complex core. Subsequent studies demonstrated that tridentate ligand amphiphiles such as 9,... 

Therefore, provided that there is an equilibrium between the micellar and aqueous pseudophases, the problem resolves itself into estimation of the distribution of reactants between aqueous and micellar pseudophase and calculation of the rate constants of reaction in each pseudophase. Menger and Portnoy [70] developed an equation which successfully accounted for micellar inhibited saponification of 4-nitrophenyl alkanoates. This model was also applied to spontaneous, unimolecular, hydrolyses of dinitrophenyl sulfate monoanions [66] and phosphate dianions [68] which are speeded by cationic micelles in water. 

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