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A comparative kinetic study of the reaction between chromium nitrate solutions and the carboxyl groups of acetate and collage

  • Authors: Russell, Allan Edward
  • Date: 1962
  • Subjects: Chemical kinetics , Chromium , Spectrophotometry , Electrophoresis
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4493 , http://hdl.handle.net/10962/d1013101
  • Description: The kinetics of the coordination reaction between the carboxyl group of the acetate radical and the trivalent chromium ion has been examined by independent methods at a temperature selected to yield reasonably accurate rate data. The study has been extended to an examination of the rate of chromium "fixation" by the carboxyl groups of hide collagen in a series of miniature tannages carried out under similar conditions for comparative purposes. The effect of olation of the chromium ions in solution on the kinetics of t he coordination reaction has also been examined. The rate of coordination of the acetate radical was followed by solvent extraction and spectrophotometric techniques over a range of concentration and pH levels. The rate data revealed a reaction having typical mass-action characteristics, the rate of reaction depending on the concentration levels of the chromium ion and the ionised acetate radical. An attempt made to distinguish a differential reaction rate in the case of a parallel reaction series using boiled and aged chromium nitrate reactant solutions, failed to reveal any significant differences between the series. The reactant solutions gave absorption spectra characteristic of the trivalent chromium ion with maxima in the 420 mµ and 570 mµ wavelength regions. The changes in optical density occurring in the vicinity of the maxima were followed spectrophotometrically, the height of the 570 mµ being found to increase during the course of reaction, while the height of the 420 mµ peak decreased. The variation in optical density at the 570 mµ peak was found to be directly related to the increase in concentration of the product complex in solution in accordance with the Baer-Bougher law, while the decrease in the height of the 420 mµ peak was related to the properties of unolated OH groups associated with the chromium complex as governed by pH and olation changes during the course of reaction. Boiled and aged chromium nitrate solutions gave reactant solutions having initial optical densities greater than those of the correspending fresh reactant solutions at the 570 mµ peak, and less than those of the fresh solutions at the 420 mµ peak. During the course of reaction, however, the two series converged to the same values. The equilibrium reaction solutions were subjected to paper electrophoretic study which indicated that all tho chromium was present in the form of cationic species. This finding was in accordance with stoicheiometric indications in the solvent extraction studies where coordination in a l : 1 ratio was reflected, giving rise to positively charged complex ions only. Making due allowance for band spreading the numbers of species predicted from the kinetic studies correspond with the electrophoretic patterns found. Application of the classical second order kinetic expression to the solvent extraction rate data, yielded plots having two distinctly linear sections, apparently indicating consecutive second order processes occurring in solution, contrary to the findings of previous workers who assign a first order mechanism to the reaction. This finding was consistent with the view that in the case of both the fresh and aged series, reaction consisted of successive coordination of an acetate radical to each chromium atom of a diol complex. Second order rate "constants" were calculated for each step and their dependency on pH level demonstrated. The findings of Hamm et al that these were first order reactions independent of acetate co'ncentration are believed to be due to their use of a large excess of acetate in their experiments. The kinetic study was further extended to an examination of the rate of "fixation"of trivalent chromium by the carboxyl groups of hide collagen under comparable conditions in a series of miniaturv tanning experiments in which the tannage substrate was provided in each of two physical forms:- (a) As hide powder where surface development was large, and (b) as prepared pelt pieces in which the fibrous weave pattern was retained. In view of the heterogeneity of the tannage systems, remarkable similarity was observed in the reaction course when compared with that of the acetate coordination studies, particularly in the case of the hide powder tannages. The dependency of the tannage rate data upon concentration and pH conditions was also found to be the same as in the case of the pure chemical system. The exact correlation between the rate data for the tannage and pure chemical systems was demonstrated by means of correlation plots. Close correlation was revealed in the case of hide powder tannage while the smaller degree of correlation observed in the case of the pelt tannage systems was attributed to the modifying effects of diffusion, particularly on the initial reaction velocity. The effect of using boiled and aged chromium solutions in the tannages was to increase the initial rate of chroniill!l "fixation" apparently due to tho coordination of a dial species at each coordination site. After the initial reaction period, the two series showed a tendency to converge as in the case of the spectrophotometric studies on the acetate reaction. The convergence trend was regarded as indicative of the tendency for the chromium in fresh solutions to under go rapid olation to the ame level as in the boiled and aged solutions. The experimental observations made on the various systems lead to the following conclusions:- (a) The mechanism of coordination of the acetate radical ttrivalent chromium appears to involve the successive coordination of ligand to each of the chromium atoms of a diol complex, both coordination steps proceeding by second order reaction mechanisms. (b) At the pH levels at which the reaction is carried out, the formation of elated bodios is rapid so that reaction in the case of both fresh and aged solutions essentially occurs between an elated species and the ionised acetate radical. (c) Modificati0ns in the absorption spectrum of the reactant solution at the 570 mµ peak are directly related to coordination, while changes at the 420 mµ peak are related to the formation of loosely-bound hydroxo chromium compounds, the concentrations of which depend on the pH level. (d) The mechanism of chromium fixation in hide is essentially similar to that operating in the case of coordination of the acetate radical to chromium, involving attachment of chromium to the side chain acid r sidues of collagen. (e ) The effect of olation is to enhance the rate of chromium fixation by hide protein during the initial reaction stages and to render possible bridge formation between adjacent side chains by secondary coordination during the latter reaction stages. (f) Where pelt pieces are used instead of hide powder, the initial rate of chromium fixation is dominated by the rate of diffusion of chromium into the fibrous structure. It should be stressed that the observations made on the various reaction systems cannot be regarded as exhaustive and the conclusions are subject to further confirmation. Consequently, the present study is essentially of a preliminary nature, but it is felt that the need for further investigation along similar lines has been demonstrated.
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  • Date Issued: 1962

A comparative study of the catechin components in the barks of wattle species related to Acacia Mernsii

  • Authors: Maihs, Edwin Alfred
  • Date: 1962
  • Subjects: Wattles (Plants) Acacia mearnsii Acacia
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4482 , http://hdl.handle.net/10962/d1012793
  • Description: The distribution of flavonoid constituents in the barks of Acacia mearnsii De Wild.(black wattle) , A· decurens Willd. (green wattle), A. dealbata Link.(silver wattle) and A. pycnantha Benth.(golden wattle) has been studied. Bark extracts of the four wattle species have been fractionated into low molecular weight fractions containing mainly catechins and other low molecular weight constituents, and high molecular weight fractions containing the bulk of the polymerized tannins. The low molecular weight fractions have been further fractionated by "preparative paper chromatography". (-)-Robinetinidol, (-)-7:3': 4': 5'-tetrahydroxy flavan- 3-ol, a new naturally occurring catechin, (+)-catechin and (+)-gallocatechin have been isolated from the barks of A. mearnsii, A. dealbata and A. pycnantha. (-)-Epicatechin and (-)-epigallocatechin have been identified in the bark extracts of A. dealbata and A. pycnantha, but appeared to be absent in the barks of A. mearnsii and A. decurrens. (-)-Epicatechin has been isolated fron A. dealbata, and both (-}-epicatechin and (-)-epigallocatechin were isolated from A. pycnantha. (-)-Epicatechin gallate, (-)-epigallocatechin gallate and gallic acid were isolated from A. pycnantha only. These three constituents appeared to be absent in the barks of the three other wattle species. (-)-Epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate which were not available for direct comparison, were subsequently isolated from green tea where they are present as major phenolic constituents. A method for the quantitative estimation of polyphenolic substances on two dimensional paper chromatograms has been developed, and a photoelectric densitometer constructed. Two spray reagents, ammoniacal silver nitrate and bisdiazotised benzidine, were found to give straight line relationships of instrument deflection against log concentration for flavonoid substances. This estimation method for the first time supplied means for a detailed study of the concentration of catechin constituents in the bark extracts of A. mearnsii, A. decurrens, A. dealbata, A. pycnantha and of A. mearnsii x A. decurrens hybrids. The concentration of catechin constituents has been shown to vary considerably between species whereas variation within species was small. In the latter respect silver wattle is an exception. Taxonomic significance may possibly be attached to the distribution of catechin constituents in the bark of the four Acacia species. The concentration of (-)-robinetinidol, which appears to be the characteristic compound of these Acacias, progressively decreases in the sequence black-, black x green hybrid, green-, silver- and golden wattle, while the number of catechin constituents of the "phloroglucinol series" increases in the same sequence. It thus appears, that by the examination of their bark components, a differentiation between species of a subgenera may be possible. Two tannins, constituents D and B, which are related to the leuco-anthocyanidins (flavan-3:4-diols) have been found in the barks of the four wattle species. One of the two, constituent D, was isolated in a pure form from the barks of A. mearnsii and A. pycnantha. Constituent D was found to generate robinetinidin and an orange pigment, the structure of which has not yet been fully identified. Compound D and its acetyl- and methoxyl derivatives did not crystallize. From the results of alkaline-, acidic- and enzymatic degradations, colour reactions and light-absorption studies, combustion analysis of the compound and its derivatives and molecular weight estimations, constituent D is surmised to be a dimer of 7:3': 4': 5'-tetrahydroxyflavan-3:4-diol (leuco-robinetinidin), The isolation of this complex leuco-anthocyanidin tannin represents the first isolation of a flavonoid tannin from commercial vegetable tannin sources. The second tannin obtained from the bark of A.mearnsii, "constituent B" appears to consist of two overlapping substances, which have not yet been separated. The tannin (B) was found to have an average molecular weight of 676 and it is considered likely that both substances may be dimolecular. On heating with mineral acid robinetinidin, fisetinidin and an orange pigment are generated, the pigment being identical with the pigment generated from constituent D. It may therefore be assumed that "Constituent B" consists of a mixture of complex leuco-robinetinidins and leucofisetinidins. The distribution of complex leuco-anthocyanidins in the bark extracts of Acacia mearnsii, A. decurrens, A. dealbata and A. pycnantha has been examined. A correlation between the distribution of leuco-anthocyanidins in the bark of the four wattle species, and accepted systematics, does not, apparently, exist.
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  • Date Issued: 1962

A critical investigation into the methods of determining sulphur in plant material

  • Authors: Smith, Anthony John Hibbert
  • Date: 1962
  • Subjects: Plants -- Effect of sulfur on , Plants -- Nutrition , Sulfur
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4520 , http://hdl.handle.net/10962/d1014526
  • Description: Although sulphur is one of the more abundant elements present in plants, its importance as a plant nutrient has been underestimated until comparatively recently. Scientific literature over the past few years, however, shows that interest in the determination of sulphur in natural waters, soil and plant materials has been renewed. Perhaps the main reason for the non-recognition of the importance of sulphur as a plant nutrient is the fact that sulphur-deficiency seldom occurs since sufficient sulphur is usually added to the soil in rainfall (particularly near industrial towns) to supply all the sulphur requirements of plants. In addition, sulphur is frequently present in fertilizers added to soils to counteract deficiency in other elements, especially phosphorus. Superphosphates, for example contain up to 60%, gypsum. Sulphur is also added to the soil in some instances in order to reduce the soil pH, the elemental sulphur being fairly readily oxidised in the soil to sulphuric acid. The organic fraction in the soil also contains sulphur. , [From Introduction]. Although sulphur is one of the more abundant elements present in plants, its importance as a plant nutrient has been underestimated until comparatively recently. Scientific literature over the past few years, however, shows that interest in the determination of sulphur in natural waters, soil and plant materials has been renewed. Perhaps the main reason for the non-recognition of the importance of sulphur as a plant nutrient is the fact that sulphur-deficiency seldom occurs since sufficient sulphur is usually added to the soil in rainfall (particularly near industrial towns) to supply all the sulphur requirements of plants. In addition, sulphur is frequently present in fertilizers added to soils to counteract deficiency in other elements, especially phosphorus. Superphosphates, for example contain up to 60%, gypsum. Sulphur is also added to the soil in some instances in order to reduce the soil pH, the elemental sulphur being fairly readily oxidised in the soil to sulphuric acid. The organic fraction in the soil also contains sulphur.
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  • Date Issued: 1962

A study of South African aquatic Hyphomycetes

  • Authors: Greathead, Sarah Kathleen
  • Date: 1962
  • Subjects: Hyphomycetes -- South Africa , Aquatic fungi -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4269 , http://hdl.handle.net/10962/d1014992
  • Description: 1, Eighteen species of aquatic Hyphomycetes are recorded from South Africa for the first time. All except two of these can be assigned to described species. The other two are new species of Articulospora and Anguillospora and are described in this thesis. Three unidentified spore types, an "Articulospora" type and "Anguillospora" type and a Y-shaped spore are also described. 2. Spore development in ten species is described. 3. A key to the fungi described in this thesis is given. 4. General notes on the ecology of these fungi and a table recording the fungi found in the Eastern Cape Province of South Africa, their distribution within the localities and the nature of the material on which they are growing are given. 5. The gross characteristics of plate cultures of six species, five growing on malt agar, Czapek agar, plain agar and maize agar and one on malt agar only are described. 6. Growth of four species in liquid culture using the Czapek-Dox medium is reported. 7. The results of an investigation into the effect of variations in temperature and medium on the growth of plate cultures of five species are analysed, discussed and conclusions are drawn. 8. Growth of certain isolates of four species on twigs is described.
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  • Date Issued: 1962

A theoretical investigation of the effects of solar eclipses on the ionosphere

  • Authors: Walker, Anthony David Mortimer
  • Date: 1962
  • Subjects: Solar eclipses , Ionosphere , Solar activity
  • Language: English
  • Type: Thesis , MSc , Masters
  • Identifier: vital:5550 , http://hdl.handle.net/10962/d1013467
  • Description: The behaviour of the ionosphere during a solar eclipse is of great interest because radiation from the sun is the cause of ionization in the upper atmosphere and it is useful to be able to conduct experiments where this radiation is cut off and restored in a known manner. Experimental results, especially those dealing with the F2 layer, have proved puzzling. Cusps which cannot be explained appear on the records obtained from ionosphere sounders and in the F2 region the electron density at a given height shows a maximum after the eclipse where one would expect it simply to rise to a steady value. An attempt is made in this thesis to explain some of the anomalies in terms of tilts in the ionospheric layers and minima of electron density or "valleys" between the ionospheric layers. The problem is attacked theoretically. Part I deals with the theoretical background to ionospheric physics in general and to this problem in particular. Standard methods of dealing with radio propagation in the ionosphere as well as some methods developed by the author are discussed. Part II deals directly with the effects of a solar eclipse on a theoretical ionosphere. Ionograms which would be obtained in the theoretical ionosphere are constructed. These are scaled by standard methods to show where errors may arise . It appears that tilts in the layers have only a small effect. The effect of the valley is, however, extremely important, giving rise to the apparent maximum of electron density in the F2 layer at a given height after the eclipse. This maximum does not in fact exist but arises from an error in the scaling method which ignores the possibility of a valley. Some records taken during the solar eclipse of 25 December, 1954 have been scaled. They support the conclusion reached theoretically.
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  • Date Issued: 1962

All Saints Church and school bell, 1962

An investigation into the effects of ant control on scale insect populations (Homoptera, Coccoidea) of citrus trees in the Eastern Cape Province, South Africa

  • Authors: Brettell, J H
  • Date: 1962
  • Subjects: Scale insects -- South Africa Insect pests -- Biological control
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5838 , http://hdl.handle.net/10962/d1009700
  • Description: In order that the citrus industry in South Africa may be commercially developed to the greatest possible extent it is of importance that certain basic ecological problems should be investigated. Until the complex relationships between the host plant, the insect pests and their parasites and predators are known, the results of applications of either chemical or biological control must be largely a matter of chance. A certain amount of rather generalised work in this connection has already been done in South Africa, principally by Carnegie (1955), Smithers (1953) and Whitehead (1948) in the Eastern Cape Province and by Steyn (1954) in the Transvaal. The first three of these workers were content to determine which species of insects occurred in citrus orchards and made some attempts to study the biology of certain predators. Steyn went a little further when he correlated ant activity with scale insect infestations. Without doubt the most economically important insect pests of citrus are the scale insects (Homoptera: Coccoidea). Introduction, p. 1.
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  • Date Issued: 1962

An investigation of the orientation of certain long-chain fatty acids at the air-water interface

  • Authors: Saayman, Henry Martin
  • Date: 1962
  • Subjects: Fatty acids , Surface chemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4496 , http://hdl.handle.net/10962/d1013117
  • Description: The results obtained for the cross-sectional areas of the series of long-chain fatty acids may best be summarized with the aid of Graph 9. This graphical representation of the molecular areas, in Ų , against the chain length (n), of the fatty acid molecules, illustrates variation of the areas with chain length for the series in recrystallized form, and also for selected samples in the zone purified and vacuum distilled forms. On the graph, the limits of variation of the molecular areas have been represented as lines of a length corresponding to twice the standard deviation (2S). This is to give representation that the standard deviation may be positive or negative in relation to the mean. For molecules with n odd and lying between 15 and 19, the molecular area decreases. This may be due to the effect of 3 factorsg (1) A general decrease in lateral translation because of the increasing molecular mass (translational kinetic energy per molecule = ½ mc ⁻²), resulting in closer spacing of molecules. (2) A general, but steady decrease in the angle of tilt of the molecules which thus tend to be held more erect in the condensed film. (3) A general decrease in the precessional motion of the hydrophobic chain groups. For molecules with n odd and between 19 and 23, the molecular areas increase probably due to the steady increase in molecular mass causing the long chains to commence to buckle, tilt or topple in their upper regions. This tilting becomes greater because of the increasing gravitational effect on the heavier molecules which tends to make them assume a flatter posture in relation to the surface. The lower values observed for margaric and nonadecanoic acids, may be due to increasing symmetry in the chain, with corresponding economy in packing in condensed monolayers. This effect may be connected with increasing cylindrical symmetry of the hydrocarbon chain for even values of n. The results of this investigution, incomplete as it is, - serve to indicate what might reasonably be expected to happen in the orientation of these fatty acids in monolayers. Further work, especially on a greater range of acids with even n, is clearly necessary in order to establish the tentative ideas which have been suggested. However, in the present research, work was limited to those acids in the series which were obtainable without undue difficulty or delay, those which would spread readily under the conditions of experiments carried out at 20°C, and those which could be purified relatively easily. The acids below n = 15 in the series were found to be too soluble in aqueous substrates, at operating temperatures of 20°C, to yield reliable evidence with the Langmuir trough technique. The acids above n = 23 were unobtainable commercially and the synthesis of those acids from the lower members in the series presented problems of isolating the required specimens and difficulty in purifying these, which were considered b be beyond the scope of the present research. Summary and conclusion, p. 122.
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  • Date Issued: 1962

Baya ndi Nemeza

Bush recession - Dubu Drift, Keiskamma River

Conversation piece : Nkondlo, 1962

Death, immortality & the biblical doctrine of resurrection : a study in the theology of renewal

  • Authors: Bank, Louis
  • Date: 1962
  • Subjects: Jesus Christ -- Resurrection , Resurrection -- Biblical teaching , Church renewal
  • Language: English
  • Type: Thesis , Bachelor , BDiv
  • Identifier: vital:1280 , http://hdl.handle.net/10962/d1013448
  • Description: From Introduction: The fact of the resurrection of Jesus Christ, the Son of God, from the dead is the central fact of Christian faith and teaching. This centrality is certainly accorded it in the Bible, but has often been forgotten in the thinking, practice and worship of the Christian Church. (The paucity of available contemporary literature on the subject is one fact which may serve to illustrate this.) The subject of the first Christian sermon preached on the Day of Pentecost was on the Resurrection. The Jesus whom they had crucified, God had made both Lord and Christ. (Acts 2. 37.) The Gospels would belie their name if they had left us with an account of the life and tragic death of a man who claimed to know and reveal God in a special way. The news is good news precisely because of the Resurrection of our Lord from the dead.
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  • Date Issued: 1962

Elderly whites in Grahamstown: a survey of their socio-economic characteristics, housing needs and preferences

  • Authors: Watts, H L
  • Date: 1962
  • Subjects: Older people -- South Africa -- Grahamstown
  • Language: English
  • Type: Book , Text
  • Identifier: http://hdl.handle.net/10962/2518 , vital:20300
  • Description: During 1960 a survey was made of the elderly White population of Grahamstown, and its characteristics. In particular, housing needs and preferences were investigated with a view to uncovering problems. Housing meets the basic need of man for shelter. Satisfactory housing provides not merely shelter alone, but meets important social, psychological and physical needs of the inhabitants. The situation in regard to the housing of the elderly must not be ignored, for as Tunbridge has pointed out, 'the need for adequate housing of the elderly is vital, because the added strain of living in unsuitable accommodation may precipitate disability and dependency'. The survey was undertaken by the Department of Sociology of Rhodes University. Structured interviews were conducted with a probability cluster sample of elderly Whites. The fieldwork was carried out on a part-time basis by twenty- five second-year Sociology students after an initial period of training. Generally people were most co-operative, and the elderly appreciated an interest being taken in their needs and preferences. Response was obtained from a total of 102, or 86.5 per cent of the persons aged 60+ years in the sample. Fuller details of the sampling design are given for the technical reader in Appendix B. The sample is considered to be free from major biases, and provides an estimate of the position prevailing in the total population of elderly Whites in Grahamstown. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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  • Date Issued: 1962

Erythrina caffra

Fishes of the family Gaterinidae of the Western Indian Ocean and the Red Sea with a resume of all known Indo Pacific species

  • Authors: Smith, J.L.B. (James Leonard Brierley), 1897-1968
  • Date: 1962
  • Subjects: Grunts (FIshes) , Fishes -- Classification , Fishes -- Indian Ocean , Fishes -- Red Sea
  • Language: English
  • Type: Text
  • Identifier: vital:14993 , http://hdl.handle.net/10962/d1019670 , Ichthyological Bulletin; No. 25
  • Description: Family Gaterinidae - Fairly robust usually deeply ovoid body, moderately compressed, covered with moderate to small strong adherent ctenoid scales, mostly only front of muzzle naked. Vertical fins partly scaly. Lateral line complete, concurrent with dorsal profile, but in adults not very distinct, tubules oblique, fewer than series of scales. Snout not pointed, moderately to markedly blunt. Mouth moderate, little protractile, maxilla slips below preorbital for most of its length. Lips well developed, often greatly swollen with age. Feeble cardiform teeth in bands in each jaw, outer series often enlarged, no teeth on palate or tongue. Chin with distinct pores, no central groove behind symphysis. Preopercle coarsely serrate in young, finer w ith age, obsolescent in very large fishes. Gill membranes free from isthmus. Gillrakers well developed, stout, spiny behind, 20-40 on whole outer arch. Dorsal continuous, of (9)10-14 spines and 15-26 rays, total 27-35, spines well developed, moderate to powerful, fewer than soft rays, but spinous part mostly with longer base, fin of almost uniform height to deeply notched, usually less so with age. Anal short, height exceeds base, III (6)7-8(9), 2nd spine mostly longer and stouter than 3rd. Caudal rounded in juveniles, feebly emarginate or truncate with age. Pectoral distinctly shorter than head. Juveniles up to about 40mm differ from the adults in certain features. They show some Pomadasyid characters i.a. the lateral line is continuous, the tubular scales adjacent; no pores are visible on the chin and the maxilla reaches to below the eye. Also the predorsal scaling ends in mid interorbital, and the scale rows above the lateral line are fewer. With growth the scale rows increase in number, but not the tubular L .l. scales, which become separated, the predorsal scales extend to the nostrils, while the snout extends, the maxilla not reaching to eye. , Rhodes University Libraries (Digitisation)
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  • Date Issued: 1962

Forest recession - Crapkloof, King William's Town

Forest recession - Cwengcwe

Fort Beaufort 3226DC

  • Authors: South Africa. Surveyor General
  • Date: 1962
  • Subjects: 1 : 50000 30.5595° S, 22.9375° E , Fort Beaufort (South Africa) Maps , South Africa History 1910-1961 Maps
  • Language: English
  • Type: maps , digital maps , cartographic
  • Identifier: http://hdl.handle.net/10962/114692 , vital:34014 , Cory Library for Humanities Research, Rhodes University Library, Grahamstown, South Africa , MP597
  • Description: 3226 Fort Beaufort, South Africa 1:50000 topo-cadastral sheet, Suid Afrika 1 : 50000 topo-kadastrale vel, Kadastrale informasie verskaf deur die Landmeter-Generaal, Kaap. TSO 200/1737. Air photography 1949. Surveyed in 1961 and drawn in 1962 by the Trigonometrical Survey Office. Lugfotografie 1949. Opgemeet 1961 en geteken in 1962 deur die Driehoeksmeting Kantoor. First edition.
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  • Date Issued: 1962

Guibourtacacidin: a new Leuco-anthocyanidin from Rhodesian copalwood; (Guibourtia coleosperma)

  • Authors: De Bruyn, Guustaaf Cornelis
  • Date: 1962
  • Subjects: Phanerogams , Angiosperms , Flavonoids , Anthocyanidins
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4459 , http://hdl.handle.net/10962/d1011043
  • Description: A new leuco-anthocyanidin, (+)-7,4'dihydroxyflavan- 3:4-diol has been isolated from the heartwood of Guibourtia coleosperma. The heartwood extractives were fractionated by enrichment procedures involving fractional precipitation and Craig partitioning, to give a high RF (subscript) low molecular weight fraction containing the above leuco -anthocyanidin. This was further fractionated by "preparative" paper chromatography . The leuco-anthocyanidin was amorphous and present in low proportion (0.004%) in the wood. On boiling with alcoholic hydrochloric acid the compound gave an anthocyanidin which was identified as 3,7,4'-trihydroxyflavylium chloride. The degradation products formed by alkali fusion, on a micro-scale, were resorcinol and ♭-resorcylic acid, and also p (underscore)-hydroxybenzoic acid. This indicated resorcinol and phenol A and B nuclei respectively. The formation of amorphous dimethyl ether and tetra-acetoxy derivatives indicated two phenolic and two alcoholic hydroxyl groups. The above indicates that the compound was 7,4'-dihydroxyflavan- 3:4- diol and a molecular weight estimation showed it to be monomeric. Comparison of the infrared absorption spectra of the natural dimethyl ether with synthetic (±) dimethoxyflavan- 3:4-diol, to which a tentative 2:3- trans- 3:4-cis conformation had been assigned (Phatak and Kulkarni 94), showed close identity. Crystalline (±)-7, 4 '-dihydroxyflavan- 3:4 - diol was synthesised by catalytic hydrogenation over platinum oxide of the corresponoing (±) -7,4'-dihydroxyflavanonol. The flavanonol was synthesised by sodium hyposulphite reduction of the 7,4 ' -dihydroxyflavonol. The infrared absorption spectra of the natural and synthetic diols were similar but not identical. Chromatographic evidence showed the apparent identity of the synthetic and natural flavan- 3:4- diols, and two possible configurations were assigned for the natural flavan-3:4-diol. The new leuco-anthocyanidin was observed to form an O(underscore)-ethyl ether derivative on manipulation in ethanol. A monomeric leuco- fisetinidin from the heartwood was identified, by two dimensional paper chromatography, as (+) - mollisacacidin. The condensed tannins found also in the heartwood of G.(underscore)- coleosperma appear to be polymeric forms of leuco - fisetinidin and leuco - guibourtinidin. These polymeric tannins form a large proportion of the heartwood extractives and furnish high yields of fisetinidin and guibourtinidin chlorides on boiling with alcoholic hydrochloric acid. Examination of some other members of the Guibourtia spp . by paper chromatography showed that only G (underscore). coleosperma contained the new leuco - anthocyanidin as well as a leuco - fisetinidin. G. (underscore) tessmannii and G. (underscore) demeusii heartwoods contained only leuco-fisetinidin and the related polymers and a close chemical relationship to G.(underscore) coleosperma is thus apparent. G.(underscore) arnoldiana on the other hand is not chemically interrelated with the above members since it appeared to contain only leuco - cyanidin. (±) - 7,4 ' -Dihydroxyflavan- 4-ol was synthesised by hydrogenation of the corresponding flavanone over platinum oxide. Observations were made regarding its reddenig and ease of condensation.
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  • Date Issued: 1962

Kei Road 3227DA

  • Authors: Trigonometrical Survey (South Africa)
  • Date: 1962
  • Subjects: 1 : 50000 30.5595° S, 22.9375° E , Kei Road (South Africa) Maps , South Africa History 1910-1961 Maps
  • Language: English
  • Type: maps , digital maps , cartographic
  • Identifier: http://hdl.handle.net/10962/109858 , vital:33197 , Cory Library for Humanities Research, Rhodes University Library, Grahamstown, South Africa , MP476
  • Description: 3327 DA Kei Road, South Africa 1:50000 sheet, first edition. Air photography 1953, surveyed in 1960, drawn in 1962 by the Trigonometric Survey Office. T.S.O. 200/1635. (Lugfotografie 1953, opgemeet in 1960, en geteken in 1962 deur die Driehokesmatings Kantoor.) , 1st edition
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  • Date Issued: 1962
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