T. Grindley - Academia.edu (original) (raw)
Papers by T. Grindley
Journal of Colloid and Interface Science, 2014
The surface properties of some families of cationic two-headed surfactants based on a pentaerythr... more The surface properties of some families of cationic two-headed surfactants based on a pentaerythritol backbone are described. The compounds have the following general structure (1), where R' are head groups and R are linear alkyl groups ranging from octyl to tetradecyl. The syntheses of these compounds has been published in detail previously. Critical micelle concentrations (cmc values) of these two-headed surfactants have been determined and compared to conventional ionic surfactants and gemini surfactants of similar structure. In addition, the surface activity of these two-headed surfactants, expressed as the C20 value and the surface tension at the cmc, have been determined. Transmission electron microscopy has been used to examine the morphology of the aggregates formed by these amphiphiles. In general, when compared to conventional ionic and two-headed surfactants, these new two-headed surfactants exhibit a remarkable efficiency in the tendency to self-assemble and are significantly more surface active than their conventional counterparts [structure: see text].
The Journal of Organic Chemistry, 2015
The most common method for achieving the regioselective monoalkylation of diols involves formatio... more The most common method for achieving the regioselective monoalkylation of diols involves formation of dialkylstannylene acetals as intermediates. Reactions of dialkylstannylene acetals with alkyl halides are slow but rates are enhanced by addition of fluoride or other nucleophiles. The mechanism of the fluorideaccelerated alkylation of dialkylstannylene acetals was studied at several levels of theory in the gas phase, in DMF solution, and in DMF solution in the presence of tetramethylammonium ions. The reactive species were adducts involving addition of fluoride to tin. Under the conditions that most closely simulated experiment, reactions from fluoridated monomers and monofluoridated dimers were calculated to have similar activation energies. In the transition states in the rate-determining steps for the two pathways, carbon-oxygen bond formation was between 60 and 75% complete while tin-oxygen bond cleavage was much less advanced, between 6 and 16% complete. A test of Sn-O bond dissociation indicated the "Sn-O bond cleavage first" mechanism is not a minimum energy pathway.
Journal of Carbohydrate Chemistry, 1985
The H and C NMR spectra of ethylidene derivatives of simple diols and of carbohydrates were measu... more The H and C NMR spectra of ethylidene derivatives of simple diols and of carbohydrates were measured to determine whether NMR parameters could be found which could be related to structure. Four NMR parameters were considered; the chemical shifts of the acetal proton and carbon, the JC,H value between the acetal proton and methyl carbon and the JC,H value of the acetal carbon. The values,.of these parameters were all somewhat related to ring-size; the JC,H value was most closely related. The sign of JC,H was shown to be positive for 2-methy l-l,3-dioxolane and Z-methy l-l,3-dioxane by means of selective population transfer experiments. Comparison of the C NMR chemical shifts of the acetal with the parent diol was found to give information about acetal location.
Chemischer Informationsdienst, 1981
Canadian Journal of Chemistry, 2003
Canadian Journal of Chemistry, 2003
J Carbohyd Chem, 1999
ABSTRACT The variable temperature H NMR spectra of the signals of the C-6 protons of 2-hydroxy-3-... more ABSTRACT The variable temperature H NMR spectra of the signals of the C-6 protons of 2-hydroxy-3-methylphenyl β-D-glucopyranoside (9a) and its 2,3,4,6-tetra-O-acetyl derivative (2a) had previously been interpreted as indicating that there was slow rotation around the C5-C6 bond in 2a and for 9a, that the tg rotamer was significantly populated while the gt rotamer had a negligible population. The data was reanalysed to demonstrate that neither conclusion was valid.
Journal of the Chemical Society, Chemical Communications, 1978
ABSTRACT D-Idose at equilibrium in aqueous solution at 37 °C contains 1·6% of a septanose anomer ... more ABSTRACT D-Idose at equilibrium in aqueous solution at 37 °C contains 1·6% of a septanose anomer in addition to the furanose and pyranose anomers.
Tetrahedron Letters, 1972
Despite widespread use and investigation, sigma constants have remained essentially empirical pro... more Despite widespread use and investigation, sigma constants have remained essentially empirical proportionality constants, providing measures of the difference in stabilisation, for example of the product and reactant, by the substituent in question. We now show that the resonance crRo constants may be directly related to the energy scale using rotational barriers.
Journal of the Chemical Society, Perkin Transactions 2, 1975
New J. Chem., 2015
The user has requested enhancement of the downloaded file.
Journal of Colloid and Interface Science, 2014
The surface properties of some families of cationic two-headed surfactants based on a pentaerythr... more The surface properties of some families of cationic two-headed surfactants based on a pentaerythritol backbone are described. The compounds have the following general structure (1), where R' are head groups and R are linear alkyl groups ranging from octyl to tetradecyl. The syntheses of these compounds has been published in detail previously. Critical micelle concentrations (cmc values) of these two-headed surfactants have been determined and compared to conventional ionic surfactants and gemini surfactants of similar structure. In addition, the surface activity of these two-headed surfactants, expressed as the C20 value and the surface tension at the cmc, have been determined. Transmission electron microscopy has been used to examine the morphology of the aggregates formed by these amphiphiles. In general, when compared to conventional ionic and two-headed surfactants, these new two-headed surfactants exhibit a remarkable efficiency in the tendency to self-assemble and are significantly more surface active than their conventional counterparts [structure: see text].
The Journal of Organic Chemistry, 2015
The most common method for achieving the regioselective monoalkylation of diols involves formatio... more The most common method for achieving the regioselective monoalkylation of diols involves formation of dialkylstannylene acetals as intermediates. Reactions of dialkylstannylene acetals with alkyl halides are slow but rates are enhanced by addition of fluoride or other nucleophiles. The mechanism of the fluorideaccelerated alkylation of dialkylstannylene acetals was studied at several levels of theory in the gas phase, in DMF solution, and in DMF solution in the presence of tetramethylammonium ions. The reactive species were adducts involving addition of fluoride to tin. Under the conditions that most closely simulated experiment, reactions from fluoridated monomers and monofluoridated dimers were calculated to have similar activation energies. In the transition states in the rate-determining steps for the two pathways, carbon-oxygen bond formation was between 60 and 75% complete while tin-oxygen bond cleavage was much less advanced, between 6 and 16% complete. A test of Sn-O bond dissociation indicated the "Sn-O bond cleavage first" mechanism is not a minimum energy pathway.
Journal of Carbohydrate Chemistry, 1985
The H and C NMR spectra of ethylidene derivatives of simple diols and of carbohydrates were measu... more The H and C NMR spectra of ethylidene derivatives of simple diols and of carbohydrates were measured to determine whether NMR parameters could be found which could be related to structure. Four NMR parameters were considered; the chemical shifts of the acetal proton and carbon, the JC,H value between the acetal proton and methyl carbon and the JC,H value of the acetal carbon. The values,.of these parameters were all somewhat related to ring-size; the JC,H value was most closely related. The sign of JC,H was shown to be positive for 2-methy l-l,3-dioxolane and Z-methy l-l,3-dioxane by means of selective population transfer experiments. Comparison of the C NMR chemical shifts of the acetal with the parent diol was found to give information about acetal location.
Chemischer Informationsdienst, 1981
Canadian Journal of Chemistry, 2003
Canadian Journal of Chemistry, 2003
J Carbohyd Chem, 1999
ABSTRACT The variable temperature H NMR spectra of the signals of the C-6 protons of 2-hydroxy-3-... more ABSTRACT The variable temperature H NMR spectra of the signals of the C-6 protons of 2-hydroxy-3-methylphenyl β-D-glucopyranoside (9a) and its 2,3,4,6-tetra-O-acetyl derivative (2a) had previously been interpreted as indicating that there was slow rotation around the C5-C6 bond in 2a and for 9a, that the tg rotamer was significantly populated while the gt rotamer had a negligible population. The data was reanalysed to demonstrate that neither conclusion was valid.
Journal of the Chemical Society, Chemical Communications, 1978
ABSTRACT D-Idose at equilibrium in aqueous solution at 37 °C contains 1·6% of a septanose anomer ... more ABSTRACT D-Idose at equilibrium in aqueous solution at 37 °C contains 1·6% of a septanose anomer in addition to the furanose and pyranose anomers.
Tetrahedron Letters, 1972
Despite widespread use and investigation, sigma constants have remained essentially empirical pro... more Despite widespread use and investigation, sigma constants have remained essentially empirical proportionality constants, providing measures of the difference in stabilisation, for example of the product and reactant, by the substituent in question. We now show that the resonance crRo constants may be directly related to the energy scale using rotational barriers.
Journal of the Chemical Society, Perkin Transactions 2, 1975
New J. Chem., 2015
The user has requested enhancement of the downloaded file.