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A study of the hydrolysis of formamide is reported with the aims of isolating the water reaction for hydrolysis from the acid and base hydrolysis terms and determining the solvent deuterium kinetic isotope effect (dkie) on base-catalyzed hydrolysis. Respective activation parameters (ΔH‡and ΔS‡) of (17.0 ± 0.4) kcal mol–1and (–18.8 ± 1.3) cal mol–1K–1for the acid reaction and (17.9 ± 0.2) kcal mol–1and (–11.1 ± 0.5) cal mol–1K–1for the base reaction were determined from Eyring plots of the second-order rate constants over the range of 27–120°C. Kinetic studies at the minima of the pH/rate profiles in the pH range from 5.6 to 6.2 in MES buffers at 56°C, and in the pH range of 4.25–6.87 in acetate and phosphate buffers at 120°C are reported. At 56°C the available data fit the expression k56obs= 0.00303[H3O+] + 0.032[HO–] + (3.6 ± 0.1) × 10–9, while at 120°C the data fit k120obs= (0.15 ± 0.02)[H3O+] + (3.20 ± 0.24)[HO–] + (1.09 ± 0.29) × 10–6. Preliminary experimental estimates of Ea(ln A) of 22.5 kcal mol–1(15.03) for the water rate constant (kw) are calculated from an Arrhenius plot of the 56 and 120°C data giving an estimated kwof 1.1 × 10–10s–1(t1/2= 199 years) at 25°C. Solvent dkie values of kOH/kOD= 1.15 and 0.77 ± 0.06 were determined at [OL–] = 0.075 and 1.47 M, respectively. The inverse value is determined under conditions where the the first step of the reaction dominates and is analyzed in terms of a rate-limiting attack of OL–.Key words: formamide, activation parameters, water reaction, acid and base hydrolysis, solvent kinetic isotope effect.

The hydrolysis of p-nitrophenyldiphenyl phosphate (PNPDPP, 7) catalyzed by N-dodecylaminoethanol (6a), N-tetradecylaminoethanol (6b), N-methyl-N-tetradecylaminoethanol (6c), and N-hexadecylaminoethanol (6d) was investigated at 25°C at various pH values in aqueous media containing additives. Added ethanol or dimethoxyethane produces very little activity of 6a, b, c toward 7. The highest activities of 6a, b were found at pH 8.0 and 8.5 in solvents containing 20% glycerol or ethylene glycol. Under no conditions was N-hexadecylaminoethanol (6d) found to be active. The kinetics of the reaction of 6b with 7 were also investigated in a medium containing various amounts of glycerol, polyethylene glycol 400 (PEG 400), and water at pH 7.6-8.5. The best catalytic system comprised 3 mM 6b in 20% aqueous ethylene glycol, pH 8.5, which accelerated the hydrolysis of 7 by 1700-fold over the blank rate. Kinetic experiments conducted using [7]/[6b] = 1 and 2 demonstrate that 6b exhibits true turnover catalysis. A mechanism for the catalyzed reaction is proposed.Key words: ß-aminoethanols, hydrolysis, p-nitrophenyldiphenyl phosphate, micelles, polyhydroxy alcohols.

The kinetics of methanolysis of acetyl imidazole (1) and acetyl pyrazole (2) have been investigated under anhydrous conditions in the presence of Zn(ClO4)2, Co(ClO4)2, and HClO4 at 25°C. In all cases, the plots of the pseudo-first-order rate constant for methanolysis (kobs) vs. [metal ion] or [HClO4] show saturation behavior indicative of equilibrium binding of the M2+ or H+ to the amide. Relative to the spontaneous methanolysis rate constant (ko), the catalytic rate constant obtained at saturation, kcat, is larger for metal-ion catalysis than for H+ catalysis. The (kcatH+/ko) ratio is 10.7 and 1.25 for 1 and 2, respectively, while the (kcatM2+/ko) for these divalent metals varies from 150-fold for 1 to between 700 and 5700-fold for 2. By contrast, in water, proton is far more effective at promoting the hydrolysis of 1 than are metals, the aqueous (kcatH+/ko) ratio being 560, while the (kcatZn2+ /ko) and (kcatNi2+/ko) ratios are 15 and 3.2, respectively.Key words: methanolysis, kinetics, metal-ion catalysis, acetyl imidazole, acetyl pyrazole.

The transfer of Br+ from the bromonium ion of adamantylideneadamantane (1-Br+/CF3SO3−) to the reactive alkenes cyclohexene, ω-alken-1-ols, 3a–c, and 4-pentenoic acid, 4, in 1,2-dichloroethane at 25 °C has been investigated. 1H NMR analysis of the reactions of equimolar 1-Br+/CF3SO3− and olefin indicates the products to be the expected cyclic ones in the cases of 3a–c and 4, and trans-2-bromocyclohexyltrifluoromethane sulfonate in the case of cyclohexene, along with adamantylideneadamantane (Ad=Ad). Detailed kinetic analysis shows that the reaction rates are suppressed by the addition of free Ad=Ad, suggestive of a common species rate depression. In the case of certain of the cyclization reactions such as that of 4-penten-1-ol, 3a, the cyclization reaction is bimolecular in acceptor olefin. A primary deuterium kinetic isotope effect of 2.0 on the cyclization of 3a-OH relative to 3a-OD exists. The role of the second molecule appears to be that of a general base in assisting the cyclization of an intermediate ω-hydroxy cyclic bromonium ion. A general mechanistic scheme for Br+ transfer from 1-Br+ to the reactive alkenes is proposed.

A distorted anilide (3,4-dihydro-2-oxo-1,4-propanoquinoline (3)) has been synthesized, its structure determined by X-ray diffraction, and its hydrolysis profile from pH 0–13 investigated. The amide unit in 3 is distorted in that the N lone pair is twisted 35° and tilted 15° out of optimum conjugation with the C=O II system. Due to this distortion, 3 hydrolyses rapidly in H2O at 25 °C. The pH/rate constant profile exhibits domains consistent with OH− attack on 3[Formula: see text] and H2O attack on a protonated form of 3[Formula: see text]; pKa (3-H+) = 0.56). The kinetic pKa is most consistent with an N-protonated form. It is also shown that this mechanism of hydrolysis is common to the series of bridged anilides consisting of 3, 3,4-dihydro-2-oxo-1,4-ethanoquinoline (1), and 2,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine (2). Keywords: distorted amide, hydrolysis, X-ray structure.

The photoelectron spectra of trimethylsilyl phenyl ketone and phenyl tert-butyl ketone are presented and analyzed in terms of their constituent orbitals. A hyperconjugative interpretation for the low energy ionization potentials of the acyl silanes is postulated. A combination of p.e. spectroscopy and u.v. data are used to infer the level of the LUMO in these systems and to construct a partial energy level diagram.

The photoelectron (pe) spectrum of ascaridole (1) shows an unusually high binding potential for the π-bond. Several possible explanations both conjugative and inductive in nature can be envisioned to account for these observations. To probe which of these mechanisms was prominent, several symmetrical bisallylic oxygen compounds as well as their saturated analogues were synthesised and their pe spectra recorded. Substitution at the allylic centres was chosen to be nearly constant in each case, but the orientation of the symmetrically placed oxygens varied about the π-bond from 0° in ascaridole (1) to 90° in 1,4-dimethoxybicyclo[2.2.2]oct-2-ene (6). In each unsaturated case the position of the ionization attributable to the π-bond is the same. Conjugative interactions of the oxygens with the π-bond cannot account for the pe results since these are expected to show marked dependence upon geometrical constraints. It is postulated that in these systems, the greater electronegativity of oxygen relative to carbon is responsible for the observed result.

The photoelectron spectra of cis- and trans-2-aminocyclopentanol and cis- and trans-2-(N,N,-dimethylamino)cyclopentanol have been recorded and interpreted. The cis isomers exhibit N lone pair ionizations at higher ionization energy, and O lone pair ionizations at lower ionization energy than their trans isomers.The results are most consistent with the existence and observation of intramolecular hydrogen-bonding in the cis isomers. Infrared data on these systems also show that the cis isomers exist in the intramolecularly hydrogen-bonded state.

In an effort to determine the effect of an intramolecular hydrogen bond on the ionization energy of a simple π-system, the photoelectron spectra of syn- and anti-7-norbornenol have been determined. The difference in the ionization energy of the π(C—C) and nÖH orbitals is 0.30 eV for the former, and 0.85 eV for the latter. The photoelectron spectrum of the syn- isomer shows that the π(C—C) bond is roughly 0.2 eV more difficult to ionize than its counter-part in the non-hydrogen bonded geometric isomer and has been interpreted as arising from hydrogen bond induced stabilization of the π-bond. That the spectral differences in the alcohols is not simply due to differing orbital interactions between the two isomers can be demonstrated by the photoelectron spectra of syn- and anti-7-methoxynorbornene. In these systems which allow no possibility of hydrogen bonding the π(C—C) – nÖR difference is the same for both isomers.

N1s binding energies for 36 pyridines substituted at the 2-, 3-, and 4-positions have been determined by X-ray photoelectron spectroscopy. The differences in BE relative to pyridine are analysed in terms of existing theoretical approaches (electrostatic, ground potential, and relaxation potential models) and compared with [Formula: see text] values calculated for analogous monosubstituted benzenes. One finds good correlations of [Formula: see text] with solution determined σ-substituent values although some substituent values deviate from the correlation probably due to solution effects which are not present in the gas phase. Correlations between [Formula: see text] and 14N nmr chemical shifts are poor, particularly for electron withdrawing substituents. The relationship between [Formula: see text] and gas phase basicity values (ΔG0) is good, and it appears as if the [Formula: see text] is more sensitive to the substituent than ΔG0. MINDO/3 calculations on the methoxypyridines and their conjugate acids employing full geometry optimizations are presented and analysed in order to determine the effect of geometric relaxation on the gas phase basicity.

The photoelectron spectra of several well defined molecules exhibiting intramolecular hydrogen bonding has been determined and the analysis of the spectra is in accord with recent molecular orbital calculations of related systems. The experimentally determined enthalpies of the hydrogen bonds in cis-2-aminocyclopentanol and cis- and trans-2-aminocyclohexanol do not correlate in any simple fashion with the shifts in the ionization energies of the nO and nN orbitals compared to a model which precludes hydrogen bonding. The spectral differences attributed to hydrogen bonding in the cis and trans 2-substituted cyclanols cannot be attributed to differences in the through-bond interaction of the n orbitals on either atom since the cis and trans isomers of 1,2-dimethoxycyclopentane and 1,2-dimethoxycyclohexane show virtually identical pe spectra. A discussion of the applicability of Koopmans' theorem and the effect of the hydrogen bond in both the ion and ground states is presented.

Several tridentate ligands incorporating pyridine and substituted imidazoles were prepared and their physical properties studied as models for the enzyme carbonic anhydrase (CA). The H+ and M2+ binding abilities (pKa and [Formula: see text]) were determined. In the case of the imidazole ligands, N-methylation reduces the metal binding ability of the ligand by some 3–4 [Formula: see text] units over the analogues in which the imidazole has N—H. 1H-nmr studies of the simple ligands as a function of [Zn2+] show that the ligands are bound symmetrically as 1:1 and 2:1 complexes depending upon the ligand/metal ratio. Increasing the steric bulk of the ligands by introduction of 4,5-diisopropyl substituents on the imidazole inhibits the 2:1 (ligand/metal) complex. Titration experiments of several ligands bound to equimolar Zn2+ and Co2+ are described and analysed.

The photoelectron spectra of several peroxides and their interpretation is presented. The effects of substituents is separated from vicinal orbital interactions using as a guideline the effect of similar substitution on the ether analogues. It is found that by comparison of Raman spectroscopic frequencies of the peroxide ground state, and vibrational frequencies for the ion (via pes), that the HOMO of peroxides is antibonding with respect to the O—O linkage. Additionally, the dependence of the splitting of the two highest occupied molecular orbitals on dihedral angle is verified by the pe spectra of several well-defined cyclic peroxides. Finally, the pe spectrum of tetramethyl-1,2-dioxacyclobutane (tetramethyl dioxetane) is presented indicating that it is not unlike other cyclic peroxides.

He(I) photoelectron (pe) spectroscopy is applied to determine the preferred gas phase conformations of a limited number of flexible allylic ethers and alcohols. Based on earlier observations that the π-ionization energy is increased more when the allylic C—O bond is coplanar (with the π-system) than when it is perpendicular, the pe spectrum of cis and trans-4-tert-butyl-2-cyclohexanol and their corresponding ethers, and 5α-hydroxy(and methoxy)-10α-Δ3-octalin have been determined. The results indicate that when a coplanar arrangement of the allylic C—O bond can be attained, it is preferred, leading to a favored conformation of the allylic alcohol or ether.

Electronic interactions in vinylamines can be divided into nN − π conjugation, and effects arising as a consequence of the electron-withdrawing abilities (−I) of both the nitrogen and π-system. Dehydroquinuclidine represents an ideal model which minimizes nN − π conjugation, and exhibits a pe spectrum which indicates that both the nN and π-orbitals are stabilized by about 0.4 eV relative to quinuclidine and bicyclooctene respectively. This stabilization is proposed to be a consequence of −I effects of each group and/or rehybridization of the nitrogen. Similar inductive effects are assumed to operate in enamines which do not prohibit nN − π interaction. In these cases, strong conjugative effects are operative in addition to the −I effects.

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The photoelectron spectra of 2-hydroxycyclohexanone and 2-methoxycyclohexanone, show that the ionization assigned to removal of the carbonyl n-electron is 0.6 eV higher in the former, presumably due to the intramolecular hydrogen bond. The ultraviolet spectra of these molecules also exhibit a marked blue shift of the n → π* transition in the former of roughly 0.5 eV. A discussion of the observations includes consideration of the effect of the intramolecular hydrogen bond on the ground and excited or ion state.