• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 212
  • 93
  • 36
  • 15
  • 15
  • 15
  • 15
  • 15
  • 15
  • 11
  • 9
  • 7
  • 6
  • 5
  • 4
  • Tagged with
  • 459
  • 74
  • 57
  • 47
  • 33
  • 32
  • 31
  • 30
  • 28
  • 25
  • 25
  • 24
  • 24
  • 23
  • 22
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The chemistry of phenoxocopper complexes /

Van Gheluwe, Patrick January 1978 (has links)
No description available.
2

A qualitative test for phenols

Johnson, Gordon Barker, 1920- January 1947 (has links)
No description available.
3

Kinetic study of the mechanism of the iodination of phenol

Kilby, Donald Charles 08 1900 (has links)
No description available.
4

The kinetics of iodination and bromination of 2,6-dibromophenol and 2,6-dibromophenol-4-d

Bryan, Coleman Jennings 08 1900 (has links)
No description available.
5

The chemistry of phenoxocopper complexes /

Van Gheluwe, Patrick January 1978 (has links)
No description available.
6

Synthetic studies in substituted phenols, involving electrophilic side-chain and ring substitutions /

Warote, Bussakorn. January 1983 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 1983. / Typescript. Includes bibliographical references (leaves 119-121).
7

De l'action du phénylsénévol sur les phénols et les naphtols

Kunz, Susanne. January 1931 (has links)
Thesis (D. Sc.)--Neuchatel, 1931. / Paper.
8

Polyphenols from tree barks : I. Syntheses of diarylheptanoids. II. Characterization of some Douglas-fir tannins /

Charleson, Dan Alexander. January 1981 (has links)
Thesis (M.S.)--Oregon State University, 1982. / Typescript (photocopy). Includes bibliographical references (leaves 80-87). Also available on the World Wide Web.
9

A study of manganese (III) oxidation of hindered phenols

Poh, Bo Long January 1972 (has links)
The complex of manganese(Ill) with trans-1,2-diaminocyclohexane-tetraacetic acid was prepared and its formula shown to be KMnIII CyDTA(H₂O), where CyDTA is an abbreviation for trans-1,2-diaminocyclohexanetetraacetic acid anion. A mechanistic study of the oxidation of 2,4,6-tri-t-butylphenol with this complex was carried out in methanol under three conditions: (1) in the presence of acid; (2) in the presence of base; (3) in the absence of acid and base. Under acidic conditions, the oxidant is HMnIIICyDTA(H₂O) and the rate-determining step of the reaction involves a hydrogen atom abstraction from the O-H group of 2,4,6-tri-t-butylphenol by the oxidant. A kinetic isotope effect of 4.8 was obtained at 25°. The activation parameters are ΔH* =15.7 Kcal.mole-¹ and ΔS* = -10.4 e.u. The small effect observed for substitution in the para position is consistent with the radical character of the reaction. A ℓ value of 0.39 was obtained from a Hammett plot of log k₃/k₃H versus σp. Under basic conditions, the oxidant is MnIIICyDTA(OH)²- and there are two competitive reactions: one that involves electron-transfer from 2,4,6-trl-t-butylphenoxy anion to MnIIICyDTA(OH)²- and another that involves hydrogen atom abstraction from 2,4,6-tri-t-butylphenol by MnIIICyDTA(OH)²-. The activation parameters are ΔH* = 10.2 Kcal.mole-¹, ΔH* = -23 e.u. for the former reaction; ΔH* =10.2 Kcal.mole-¹ , ΔH* = -29 e.u. for the latter reaction. A kinetic isotope effect of 1.9 was obtained for the latter reaction at 25°. The rate of electron-transfer from 2,4,6-tri-t-butylphenoxy anion to MnIIICyDTA(OH)²- is 104 times faster than the rate of hydrogen atom abstraction from 2,4,6-tri-t-butyl- phenol by MnIII CyDTA(OH)²-. The effect on reaction rate for substitution in the para position is large, a ℓ value of 2.3 being obtained from a Hammett plot of log k₉/k₉H versus σ-p (k₉ is the rate constant for the reaction between 2,4,6-tri-t-butylphenol and MnIIICyDTAC(OH)²-). Under neutral conditions, the oxidant is MnIIICyDTA(H₂0)- and the rate-determining step of the reaction involves hydrogen atom abstraction from the O-H group of 2,4,6-tri-t-butylphenol by the oxidant. A kinetic isotope effect of 5.9 was obtained at 25°. The activation parameters are ΔH* =10.9 Kcal.mole-¹ and ΔH* = -39 e.u. The small effect observed for substitution in the para position is consistent with the radical character of the reaction, a ℓ value of -0.07 being obtained from a Hammett plot of log k₃a/k₃aH versus σp. The compound 3,5-di-t-butyl-4-hydroxybenzaldehyde, however, has an anomalously high rate. This anomaly is also observed under acidic conditions. The oxidising power of MnIIICyDTA(OH)²- is 360 times greater than that of MnIIICyDTA(H₂0)-with respect to hydrogen atom abstraction from 2,4,6-tri-t-butylphenol. This difference in oxidising strength suggests that an 'inner-sphere'-type mechanism.is involved in the reactions. The difference in oxidising strength between MnIIICyDTA(OH)²- and MnIIICyDTA(H₂0) is even greater in 95% dimethyl sulfoxide solvent -5.4 x 107. Oxidation of 2,4,6-tri-t-butylphenol with potassium ferrlcyanide in methanol in the presence of hydrochloric acid is shown to be a reversible reaction. The lack of data on the ionization constants of H₄Fe(CN)₆ and H₃Fe(CN)₆ prevented a detailed study of the equilibria involved. / Science, Faculty of / Chemistry, Department of / Graduate
10

Studies of simple phenols in plants : 1. Phenolic acids in ferns. 2. The uptake of phenolic compounds by Pityrogramma calomelanos and Hordeum vulgare. 3. The phenol Glucosylation reaction in higher plants

Glass, Anthony David Melville January 1970 (has links)
I. Systematic studies of the distribution of phenolic acids have been largely restricted to angiosperm families. This survey of forty-six species of ferns extended the work begun by Bohm and Tryon, and brought the total number of species examined to ninety-two. p-Coumaric acid, caffeic acid, ferulic acid, p-hydroxybenzoic acid, protocatechuic acid, and vanillic acid were found to be widespread. A time study of the concentrations of these compounds in Pteridium aquilinum and Athyrlum fellx-femina suggests that certain of these acids undergo considerable turnover during the growing season. II. Kinetic studies of the uptake of hydroquinone glucoside by roots of Hordeum vulgare and by gametophytes of Pityrogramma calomelanos showed that this compound is actively transported, and suggested that catechol glucoside is absorbed by a similar mechanism. Hydroquinone exhibited a different pattern of uptake which possessed some of the features of an active system. The latter compound is absorbed by passive diffusion. A concentration gradient favouring diffusion is maintained by the conversion of this phenol to its corresponding glucoside. III. A survey of twenty-nine species of ferns showed that these plants, like flowering plants, are capable of glucosylating administered phenols. Certain acidic compounds, identified by J.B. Pridham as phenolic glucoside-6-sulphates, are formed when simple phenols such as hydroquinone, catechol, resorcinol, etc., are administered to germinating seeds of Vicia faba. The present studies indicate that these compounds are commonly formed when simple phenols are administered to higher plants. Since Pridham’s identification was based upon the identification of hydrolysis products, without reference to authentic compounds, and since several of the properties of the supposed sulphates were inconsistent with the known properties of sugar sulphates, arbutin-6-sulphate was chemically synthesized. Comparisons of the properties of this authentic compound with the natural product showed that the two compounds were quite dissimilar and therefore suggest that Pridham’s identification was incorrect. / Science, Faculty of / Botany, Department of / Graduate

Page generated in 0.0322 seconds