Whole document restricted, see Access Instructions file below for details of how to access the print copy. / Aluminium smelters emit upwards of 6 kg of gaseous hydrogen fluoride per tonne of aluminium metal produced. Since the 1960's, many aluminium smelters have used the dry scrubbing process to capture the HF on the surface of smelter grade alumina. In this way, dispersion of the emitted HF is prevented and the fluoride is returned to the aluminium electrolysis cells. The surface adsorption reactions on which the dry scrubbing process relies have been studied by various researchers. It is common knowledge that there occurs a relatively strong bond between HF and alumina and that the quantity of water in the gas effects the maximum fluoride adsorption capacity of the alumina. It has also been considered that FIF adsorption is a combination of strong chemisorption and reversible physisorption at the temperatures at which the dry scrubbing process operates. Some researchers have postulated the formation of Al-F bonds at the alumina surface, while others have postulated the existence of hydrogen bonds between surface fluoride or hydroxyl ions and molecular H2O and HF. However, these models do not agree with the experimental data which was gathered during the course of researching this thesis, nor do they agree with much of the experimental data presented earlier. The major finding of this research was that hydrogen fluoride adsorption is irreversible under the temperature and gas composition conditions of the dry scrubbing process. The maximum fluoride adsorption capacity of smelter grade alumina depends on the relative humidity during adsorption, as well as the specific surface area of the alumina. Both factors indicate that HF adsorption is a surface process. The most likely product of reaction is a thin layer of crystalline aluminium hydroxyfluoride, AIFx(OH)3-x 6H2O, formed in an aqueous reaction at the alumina surface. The reaction mechanism involves the steps of: H2O adsorption to form an aqueous layer on the alumina surface; HF adsorption to acidify the surface water layer; dissolution of the alumina surface to form AlO2- and AlO2-; precipitation of AlFx(OH)3-x.nH2O. The overall adsorption rate appears to be controlled by the rate of the surface chemical reactions rather than by transport phenomena such as fluid phase mass transfer and intraparticle diffusion. At relative humidity greater than 35% the adsorption capacity of smelter grade alumina increases dramatically and small crystallites of AIFx(OH)3-x.6H2O and AIF3.3H2O are formed. Under these conditions the reaction mechanism is similar, except that water-filled pores provide an environment which is conducive to the formation of larger crystallites of product. At temperatures below 450°C the aluminium hydroxyfluoride hydrate phase dehydrates, and at temperatures above 450°C hydrolysis of aluminium hydroxyfluoride results in the release of HF. Samples which are produced under dry scrubbing conditions and aged under ambient conditions, are indefinitely stable. However, when aged at high humidity the product layer is transformed into distinct crystallites of aluminium hydroxyfluoride by a dissolution/re-precipitation mechanism involving water filled pores. Samples which are hydrofluorinated at greater than 35% humidity show continued growth of A1Fx(OH)3-x 6H2O and AlF3.3H2O under all storage conditions due to residual water condensed within the alumina pores.

Organometallic chemistry is concerned with the study of metal-carbon bonded species. A wide variety of bonding modes have been discovered ranging from simple σ- through to more complex π- and μ-interactions. This thesis deals with the synthesis and chemistry of just three classes of compound, those containing formal TM-C single, double and triple bonds. These species are normally referred to as transition metal alkyl (σ-aryl), carbene and carbyne complexes respectively. The material is divided into five chapters and each is introduced by a relevant review. In chapter 1 the syntheses of σ-alkyl and -aryl complexes of ruthenium and osmium are described. These species are produced from organomercury reagents either by oxidative addition to the zerovalent complex Ru(CO)₂(PPh₃) ₃ or by reaction with the hydrido complexes MClH(CO)(PPh₃) ₃ (M = Ru, Os). This latter reaction provides a new route to organotransition metal complexes and some possible mechanisms are discussed. The organo-complexes formed by this latter method are coordinatively unsaturated and the structure of RuCl(p-tolyl)(CO)(PPh₃)₂ has been obtained by X-ray crystallography. The migratory insertion and reductive elimination reactions of these new compounds are discussed in chapters 2 and 3. Predictably, the Lewis base CO rapidly adds to these 16 electron species and the expected octahedral derivatives are formed. In some cases these are in equilibrium in solution with the corresponding dihapto-acyl complexes. The positions of the equilibria, the rates of interconversion and the relative solubilities of the two forms are such that in each case either essentially pure dicarbonyl or essentially pure dihapto-acyl can be isolated from solution. The dihapto-mode of bonding has been confirmed by X-ray crystallography for two of the derivatives. CNp-tolyl also adds to the 16 electron organo-compounds in an analogous fashion and equilibrium with the corresponding dihapto-iminoacyl compounds is attained in some cases. The dihapto-iminoacyl formulation has been confirmed by X-ray crystallography. Factors affecting the positions of all these equilibria are discussed and the possible relevance of these dihapto-acyl and -iminoacyl complexes as models for the proposed intermediates in the CO and CNR insertion reactions is noted. Compounds containing cis-H,R ligands are rarely stable since reductive elimination of R-H usually occurs very readily. Species of this type, therefore, appear to be ideal precursors for reactive, low valent complexes which are unobtainable by other means. A synthetic route has been developed by which an hydrido ligand can be incorporated into the coordination sphere of the new organo-derivatives described in chapter 1. The key step involves the thermal decarboxylation of a dihapto-formate ligand. In this way remarkably stable cis-H, tolyl complexes of osmium have been prepared. Toluene is eliminated from these derivatives only under forcing conditions. In contrast, reductive elimination from the analogous ruthenium complexes proceeds much more rapidly and in only one case has a stable hydrido, aryl complex been isolated. Other compounds that have been formed by this route are the zerovalent complex Ru(CO)(dppe)₂ and the ortho-metallated complex Ru(C6H₄PPh₂)H(CO)(PPh₃)₂. Factors affecting the rates of all these reactions are discussed. Some reactions of Ru(C₆H₄PPh₂)H(CO)(PPh₃)₂ have been investigated, and most notably a methyl, formate complex is produced with formaldehyde and a small amount of a dichlorocarbene complex with CCl₄. The reactions of this ortho-metallated compound may proceed via the intermediate "Ru(CO)(PPh₃)₃". Extension of the synthetic procedure described in chapter 1 has led to the production of the dichlorocarbene complex OsCl₂ (CO)(CCl₂)(PPh₃)₂, the structure of which has been determined by X-ray crystallography. This compound, which formally contains an Os-Ccarbene double bond, provides the subject matter for chapter 4. The carbene carbon atom is attacked by nucleophiles and the chloride substituents are easily displaced. This species therefore behaves as a remarkably versatile synthetic intermediate. Reaction with the chalcogen hydrides HX⁻ (or H₂X) leads to the corresponding chalcocarbonyl derivatives and OsCl₂ (CO)(CTe)(PPh₃)₂ is the first tellurocarbonyl complex to be isolated. Characterization of this complex includes an X-ray crystallographic analysis. Primary mines react with OsCl₂ (CO)(CCl₂)(PPh₃)₂ to form the corresponding coordinated isocyanides and reactions with other nucleophiles are also discussed. The most important of these, however, is the reaction with Li(p-tolyl). This produces the monomeric carbyne complex, Os(Cp-tolyl)Cl(CO)(PPh₃)₂, the structure of which has been determined by X-ray crystallography. This compound has an extremely short Os-Ccarbyne bond length and this is consistent with a triple bond formulation. The synthesis and chemistry of this compound is discussed in chapter 5. Although other carbyne complexes have been isolated previously this is a relatively new area of organometallic chemistry and reports of the chemistry of these species are restricted mainly to compounds of the GpVIa and VIIa metals. Os(Cp-tolyl)Cl(CO)(PPh₃)₂ displays a rather different chemistry from these compounds and some new reactions have been observed. Electrophiles such as H₊ and Cl₂ readily attack Ccarbyne and the corresponding carbene complexes are formed. This suggests that Ccarbyne is nucleophilic. The elements S, Se and Te add to the Os-Ccarbyne triple bond under ambient conditions to give the corresponding dihapto-chalcoacyl complexes. Adducts of the Os-Ccarbyne triple bond are also formed with the GpIb metals and the structure of Os(C{p-tolyl}AgCl)Cl(CO)(PPh₃)₂ has been determined by X-ray crystallography. Analogues of all these reactions are to be found in acetylene chemistry. In contrast to the cationic carbyne complexes of the GpVIa and VIIa metals, Ccarbyne in [Os(Cp-tolyl)(CO)₂ (PPh₃)₂]ClO₄ is not attacked by nucleophiles. Instead LiBHEt₃ preferentially attacks the para-carbon atom of the Ccarbyne p-tolyl substituent and an Os(O) vinylidene complex is formed. The structure of this compound has been confirmed by X-ray crystallography. Although the aromatic ring is destroyed in this reaction it is replaced by an extensively conjugated system which reaches through to the osmium atom. Further reactions of this species and the cationic carbyne complex [Os(Cp-tolyl)(CO)(CNp-tolyl)(PPh₃)₂]ClO₄ are also discussed. / Note: Whole document restricted due to copyright restrictions, but available by individual request use the feedback form to request access.

This thesis describes synthetic work directed towards the synthesis of the dimeric pyranonaphthoquinone antibiotic crisamicin A 1.46 and its regioisomer 2.77. The synthetic strategy adopted is based on a double furofuran annulation/oxidative rearrangement strategy that has been successfully used by this research group to prepare a related dimeric pyranonaphthoquinone based on the actinorhodin skeleton. The retrosynthesis that was adopted (see Scheme 1.47, page 59) required the initial preparation of a key bis-naphthoquinone 1.267 which in turn is available from bisnaphthalene 1.268 that bears acetyl groups at C-7 and C-7’. Initial work concentrated on the construction of the biaryl linkage of bis-7- acetylnaphthalene 1.268 using a palladium(0)-mediated Suzuki-Miyaura homocoupling of the key triflate 1.269 (prepared in 10 steps from vanillin 1.271) using bis(pinacolato)diboron 1.179. This coupling method successfully afforded binaphthyls 2.8b and 2.8d which were subjected to attempts to effect either double bromination, double acetylation or double Fries rearrangement to a more functionalised biaryl system. Disappointingly, none of these methods allowed introduction of the key acetyl group at C-7 and C-7’ onto the initial biaryls 2.8b and 2.8d. Attention then turned to the synthesis of the bis-7-acetylnaphthalene 1,268 that was required for the ensuing furofuran annulation reaction starting from triflate 2.7 that already contained an acetyl group at C-7, then effecting formation of the key biaryl linkage. Attempts to prepare 7-acetyltriflate 2.7 via either Fries rearrangement of acetates 2.33a or 2.9a, or via bromination of acetate 2.33a, naphthol 2.56 or benzyl ether 2.6 were unsuccessful. An alternative approach for the preparation of 7-acetyltriflate 2.7 involved the preparation of 2-acetylcarbamate 2.74 from carbamate 2.64 via a directed ortho-metalation, followed by reaction of the derived ortho-lithiated species with N-methoxy-N-methylacetamide 2.71. However, this strategy resulted only in low yields of the desired 2-acetylcarbamate 2.74, although initial model work did provide methodology for the successful conversion of carbamate 2.68 to 2-acetyl-l-naphthol 2.73. The synthetic target of this thesis shifted to the regioisomer of crisamicin A 2.77 when attempts to introduce an acetyl group atC-7 of triflate 2.9 failed. However formation of the 6-acetyltriflate 2.81b was successful from triflate 2.9b. A subsequent one-pot in situ Suzuki-Miyaura homocoupling of triflate 2.81b with boronate 2.89 furnished dimmer 2.76b. Oxidation of dimer 2.76b to bis-naphthoquinone 2.80 was then accomplished using silver(II) oxide and 6 M nitric acid. With the key bis-6-acetylnaphthoquinone 2.80 in hand, an efficient double furofuran annulation reaction was carried out using 2-trimethylsilyloxyfuran 1.88 affording the desired bis-furonaphthofuran adduct 2.79 as an inseparable l:l mixture of diastereomers 2.79a and 2.79b. However, initial experiments to effect the double oxidative rearrangement of bis-furonaphthofuran adducts 2.79 using either silver(Il) oxide and 6 M nitric acid or with ceric ammonium nitrate in aqueous acetonitrile to the bisfuronaphthopyran 2.7 8 were unsuccessful. Attention then turned to the preparation of bis-furonaphthopyran 2.78 from the 6-acetyltriflate 2.81b via initial oxidation of triflate 2.81b to naphthoquinone 3.3 followed by furofuran annulation and then oxidative rearrangement. Attempts to effect the key Suzuki-Miyaura homocoupling of furonaphthofuran 3.2 to bis-furonaphthofuran 2.79, or of furonaphthopyran 3.1 to bis-furonaphthopyran 2.78, using catalyst PdCl2(dppf) and ligand dppf were unsuccessful. The work achieved herein constitutes the synthesis of an advanced intermediate for the synthesis of the crisamicin analogue 2.79. The final synthesis of the regioisomer of crisamicin A 2.77 can be completed by preparing bis-furonaphthopyran bis-lactol 2.78 using more powerful palladium(0) catalysts and ligands for the Suzuki-Miyaura homocoupling of the monomeric furonaphthopyran 3.1. Subsequent reduction af 2.78 using triethylsilane and trifluoroacetic acid will then afford the bis-cyclic ether 3.15, which can undergo deprotection of the methyl ether and epimerisation at C-5 upon treatment with excess boron tribromide to finally furnish the regioisomer of crisamicin A 2.77. An investigation into the double oxidative rearangement of bis-furonaphthofuran 2.79 to the bis-lactol 2.78 could also be carried out by the use of several alternative oxidising agents, such as phenyliodine(III) bis(trifluoroacetate) (PIFA), phenyliodine(III) diacetate (PIDA), polymer-supported (diacetoxyiodo)benzene (PSDIB), Fremy's salt, iron trichloride or CrO3.

PART I A general introduction is given to the mechanisms of olefin-forming β-elimination. The development of mechanistic criteria and their application to the various reactions is discussed. Conflicting theories concerning the nature of the transition states of E2H reactions in protic solvents as well as the Winstein-Parker E2C-like transitions states for elimination by weak bases in dipolar aprotic solvents are described. PART II The use of primary deuterium isotope effects: structure-reactivity relationships, and rate-acidity correlations as mechanistic criteria for the E2 mechanism and the variants of the E1cB mechanism is reviewed. These criteria have been applied to the dehydrochlorination of the 1,1-diaryl-2, 2, 2-trichloroethanes (DDT-type compounds) with methoxide-methanol and t-butoxide-t-butanol. Literature comparisons indicate that the kinetic evidence for these two systems is in accord with an "irreversible" E1cB elimination pathway. PART III Characteristics of weak base-promoted eliminations in dipolar aprotic advents are reviewed. The evidence is not entirely consistent with either E2C or the E2H mechanism. Deuterium isotope effects and equilibrium constants are reported for the chloride ion-promoted elimination of the 1, 1-diary1-2,2,2-trichloroethanes in dimethylformamide and acetone respectively. The results are in accord with an E2H mechanism.

The results to be described and discussed in this thesis concern synthesis and reactivity of iridium(I) and (III) complexes containing thiocarbonyl or selenocarbonyl ligands. Chapter 1 comprises: a review of Vaska's compound, IrCl(CO) (PPh3)2 and related species, covering syntheses, structure and bonding and reactions of this very widely studied moiety; and brief reviews of metal-thiocarbonyl syntheses and reactions and metal-selenocarbonyl chemistry. These three reviews background the themes developed in this work; of preparations and reactions, particularly ligand reactions, of thiocarbonyl and selenocarbonyl analogues of Vaska's compound and species derived from IrCl(CE)(PPh3)2, E = S, Se. A new synthesis of IrCl(CS)(PPh3)2 is described in Chapter 2. The route employed involves preparation of dithioester complexes and facets of the reactivity of these species have been considered and a number of metallocycle derivatives prepared. Reductions of coordinated-thiocarbonyl groups have been considered; IrH(CS)(PPh3)3 was transformed into IrH2(SMe)(PPh3)3 by treatment with hydrogen, while the thiocarbonyl cation complexes [IrClX(CO)(CS)-(PPh3)2]+ were treated with borohydride to afford thioformyl species. Iridium alkyl, thiocarbonyl complexes have been prepared, and transformed by reaction with dithiocarbamate ion to yield monohapto-thioacetyl derivatives. The preparation of IrCl(CSe)(PPh3)2, the selenocarbonyl analogue of Vaska's compound is reported in Chapter 3. The synthesis utilizes carbon diselenide as the selenocarbonyl source, and involves a four-step conversion of a dihapto-carbon diselenide adduct complex to the iridium(I) selenocarbonyl species. Reactions of a range of iridium(I) complexes with carbon diselenide are described, including the preparation of a complex including three CSe2 groups. Reactions of IrCl(CSe)(PPh3)2 have been studied and several iridium(I) and (III) selenocarbonyl compounds prepared. The ready reduction of IrCl(CSe)(PPh3)2 (in the presence of phosphine) by borohydride to give IrH2(SeMe)(PPh3)3 is described and comparisons are drawn between the relative reactivities of iridium thiocarbonyl and selenocarbonyl groups, in analogous species, with nucleophiles. It is concluded the Ir-CSe system is more reactive under similar conditions. Metallocycle derivatives of iridium selenocarbonyl, diselenomethylester complexes have been characterised.

The crystal structure of the bromo derivative of a cyclic diterpene has been determined. The crystals are of orthorhombic symmetry with a = 9.00Å, b = 31.46Å, c = 7.31Å. The structure was solved by the normal heavy atom procedure, and refined by least-squares to a residual of R = 0.064. The molecule is shown to be phyllocladan-15-yl bromoacetate, rather than to be a neo-atisirane derivative, as had been expected.

The ketoester, 3-ethoxycarbonyl-12-methoxy-5βH-18,19-bisnor-podocarpa-8,11,13-trien-4-one(80). The numbering used throughout this thesis is that proposed by J.W. Rowe (personal communication to Dr. R. C. Cambie) in 'The Common and Systematic Nomenclature of Cyclic Diterpenes', 3rd Revision, Oct. 1968, to be submitted to the IUPAC Commission on Organic Nomenclature has been prepared from 12-hydroxypodocarpa-8,11,13-trien-19-oic acid (1), via the C4 ketones (76) and (77). Both of these isomers were obtained from the methoxyalkene (11), which was isolated in a pure form during selective epoxidation of the methoxyalkene mixture (11 - 13) obtained from the decarboxylation of 12-methoxypodocarpa-8,11,13-trien-19-oic acid (2) with lead tetraacetate. This reaction has been investigated, and a mechanism accounting for the formation of nondecarboxylation products is proposed. The unsaturated ketoester (102) was prepared in low yield via the saturated C12 ketone (24), obtained from 12-hydroxypodocarpa-8,11,13-trien-19-oic acid (1) by Birch reduction of the aromatic ring. A number of ring A epoxide derivatives of the acid(1) were prepared and cleaved by a variety of reagents to give the 3-oxygenated derivatives (145), (146), and (152), together with compounds possessing a contracted ring A. Some ring B lactone derivatives of the acid (1) were prepared, and their stereochemistry and conformation were determined by n.m.r. spectroscopy. The conformation of some ring B-substituted derivatives was also determined by n.m.r. methods. The bromination of some 7-ketopodocarpa-8,11,13-triene derivatives was investigated, and reasons are advanced for the non-stereospecific reactions observed in some cases.

The first part of this thesis describes the use of several diterpenoids which are readily available in New Zealand for the synthesis of compounds possessing ambergris-type odours. Homologues and analogues of known odorants have been prepared with a view to correlating their odour properties with molecular structure. A new series of 1,3-dioxa-compounds has been found to exhibit odour properties characteristic of this class of odorants. In the second part a simple procedure for the conversion of totarol into a C-12 oxygenated derivative is reported. This derivative has been oxidatively degraded using ozone, and the degradation product has been converted into a possible intermediate for the synthesis of a ring-C system found in naturally occurring nagilactones. The rearrangement of several aryl phosphates under the action of n-butyllithium is reported.

This thesis describes the chemical, physico-chemical and structural studies of two types of copper compounds which interact with molecular oxygen in their formation. The first type is an intensely coloured species based on the ligand oxalyldihydrazide. The divalent metal and the ligand react together with simple carbonyl compounds and molecular oxygen in basic conditions to form blue species the nature of which has been the subject of conjecture for many years. This work shows that the metal is trivalent in the highly coloured states and that it acts as an oxidative catalyst with ascorbic acid. The copper (III)/copper (II) potential has been established as +0.244V by polarography. Compounds including acetaldehyde and acetone as the carbonyl component have been crystallized in monoclinic space groups. In both instances X-ray diffraction studies show that the metal is co-ordinated to a 6-5-6-5 macrocycle formed by a condensation reaction between two oxalyldihydrazide molecules and two carbonyl moieties. The co-ordination is via four deprotonated 'amide' nitrogen atoms and is of square-planar geometry. A structural study of oxalyldihydrazide has also been undertaken and comparisons are made with the co-ordinated species. The second type of compound studied is a Cu4OX6L4 cluster. It was made from a copper(I) precursor and studies with oxygen-18 gas show that formation requires oxidation to copper(II) followed by hydrolysis. Infrared evidence based on the Cu-O stretch (500-580 cm-1) is presented. Attempts to include both fluorine and iodine as the halogen component suggest that only chlorine and bromine may fill such a role.

Formaldehyde is an important industrial chemical due to its unique properties, coupled with its low cost and the basic availability of the raw materials from which it is produced. It is generated principally by the catalytic oxidation of methanol using a heated stationary catalyst at approximately atmospheric pressure. Formaldehyde is used in the manufacture of a wide variety of commercial products, the most significant of which in New Zealand, are the urea-formaldehyde resins. Such resins are used in the production of reconstituted wood products such as: particleboard; medium density fibreboard; plywood; laminated and finger jointed wood products; and in the modification of textiles and papers. Insulating building foams have also been formulated using urea-formaldehyde resins. Formaldehyde release from products containing urea-formaldehyde adhesives has been well documented in the literature over recent years. It has been shown that in some instances the levels of airborne formaldehyde inside dwellings and commercial premises may exceed various industrial threshold limit values for an eight hour working day. In New Zealand the current industrial permissible time weighted average value for formaldehyde in air is set at a maximum level of 2 ppm (2.4 mg of formaldehyde per metre3 of air). Natural levels of formaldehyde in air do exist and have been measured as being in the vicinity of 0.12 to 0.39 parts per billion. In terms of being a health hazard, formaldehyde was found to be a primary irritant of the respiratory airways and a skin sensitizer in some individuals. Some suggestion has been made that formaldehyde can also be carcinogenic. This suggestion should be treated with caution as it derives from preliminary experiments on rats and mice exposed to very high formaldehyde levels. Over the years a variety of test methods have been applied to the measurement of formaldehyde which is released from formaldehyde-bearing materials. A dynamic testing method, in the form of a wind-tunnel was adopted in this study for measuring the emission rate of formaldehyde directly from the surfaces of urea-formaldehyde bonded particleboard. Emissions were quantified in terms of the weight of formaldehyde emitted in mg from one square metre of panel surface over one hour, under the prevailing climatic conditions. It was observed that formaldehyde emissions were as great as about 12 mg h-1 m-2 from panels tested soon after manufacture. After five years of storage of the particleboard panels in ventilated conditions, the formaldehyde emission rates were measured as being between 0.1 and 1.1 mg h-1 m-2. It was apparent that formaldehyde emissions from particleboard bonded with a urea-formaldehyde resin with a urea to formaldehyde molar ratio of 1 to 1.5, reached a basal level approximately 12 months from the time of manufacture. The formaldehyde emitted over the initial 12 month period was equated to the formaldehyde which was originally present dissolved in the resin solution and the formaldehyde which was cleaved from the urea-formaldehyde polymer network during high temperature pressing. Formaldehyde lost from the particleboard after the initial 12 month storage phase was probably due to hydrolysis of the resin under ambient conditions. The latter was termed "evaporable" formaldehyde as opposed to "free" formaldehyde which was emitted in the first 12 month period. The fluctuations in the basal emission rates of formaldehyde from particleboard were attributed to changes in the microclimate associated with the particleboard. Particleboard panels with a higher density surface layer of wood tended to have higher formaldehyde emission rates in the early period of storage compared with particleboard having a lower density of wood in the surface layer. Emissions of formaldehyde from the edges of freshly sawn particleboard tended to be as much as 30 to 60 times greater than emissions from the faces of the original panels. After extended storage, emissions from the edges of particleboard tended to approximate the levels of emissions from the faces of particleboard. It was demonstrated that the presence of an air boundary layer adjacent to the particleboard surface has a significant effect on the formaldehyde emission rate from the panel surface. Below air speeds of 5 cm s-1 over the panel surface, it appeared that the rate of diffusion of formaldehyde through the air boundary layer controlled the rate of diffusion of formaldehyde from the particleboard surface into the bulk air. At air velocities in excess of 5 am s-1 the effect of the air boundary layer diminished. It was estimated that within enclosed spaces, such as houses with a relatively low air-turnover rate, the diffusive resistance of air boundary layers to formaldehyde emissions from particleboard surfaces could be significant in lowering the formaldehyde levels inside the house. The use of paints, paint-coated wallpaper and polymer-coated wallpaper to cover particleboard surfaces tended to reduce the emission rate of formaldehyde to below the detection threshold of the method of measurement (0.01 mg h-1 m-2). Some building materials other than urea-formaldehyde bonded particleboard were shown to emit measureable quantities of formaldehyde. These materials were of cellulosic-origin and emitted as much as 0.3 mg of formaldehyde h-1 m-2. The latter were known to not contain urea-fonnal6ehyde bonding agents. The levels of formaldehyde inside a showhome containing urea-formaldehyde bonded particleboard as wall and floor cladding were measured as ranging from 1.2 to 7.2 mg m-3, but these air-borne concentrations of formaldehyde decreased to between 0.7 and 1.3 mg m-3. after an interval of three months. A mathematical model was derived for the prediction of the maximum expected steady state levels of formaldehyde inside dwellings containing formaldehyde-emitting materials. The model took into account such parameters as: the emission rate of formaldehyde from the emitting surface; the surface area of the exposed emitting material; and the volumetric air flow rate through the dwelling. The model in general tended to indicate higher formaldehyde levels when tested using the parameters derived from measurements taken in the showhome. This model could conceivably find use in the design of buildings in order to minimize the levels of formaldehyde in the indoor environment. The lack of sufficient information in the literature relating to the mass transfer of formaldehyde through polymers prompted the investigation into the permeability characteristics of polymeric materials to formaldehyde. The steady state transmission rates of formaldehyde through free polymer films, such as plastic films, free paint and free polyurethane varnish coatings, were measured using a diffusion cell operated at atmospheric pressure. The mass diffusion principle associated with this permeation testing device best paralleled the real-life situation where either polymer films (plastic films) or polymer coatings (paint or varnish coatings) may be in contact with formaldehyde and water vapour, at atmospheric pressure. As a source of penetrant in these studies a dilute aqueous solution of formaldehyde was used to yield molecular formaldehyde. It was calculated that an aqueous solution containing 69 mg L-1 of formaldehyde gave rise to a concentration in air of formaldehyde, above the solution, of 1 mg m-3 at 30°C. A solution with such a concentration of dissolved formaldehyde was chosen arbitrarily for permeation studies. Levels of air-borne formaldehyde inside enclosed airspaces such as in houses lined with urea-formaldehyde bonded particleboard, with a low air turn-over, could reasonably be expected to be in the region of 0.1 to 100 mg m-3. The use of carbon-14 formaldehyde was favoured in this research over the use of carbon-12 formaldehyde. This gave rise to the possibility of permeability isotope effects. Based on the information presented in this thesis and on the experimental variability in test results, it appeared that the effects of a permeability isotope effect were negligible in comparison. The transmission rates of formaldehyde through the following types of polymer films were measured: low density polyethylene; high density polyethylene; high density-low density polyethylene blended polymer; polypropylene; poly(ethy1ene terephthalate); poly(viny1idene dichloride)-coated Poly(ethy1ene terephthalate); "Paraform", a multi-layered food packaging polymer film based on cellophane; Poly(ethylene vinyl acetate), a multi-layered food packaging polymer film; plasticised poly(vinyl chloride); polystyrene; nylon-6; and cellophane. At 30°C transmission rates of formaldehyde ranged from 1.2 x 10-7 μg cm-1 s-1 for cellophane to 1.2 x 10-l2 μg cm-1 s-1 for poly (ethylene vinyl acetate) polymer films, respectively. There was some indication that the transmission rate of formaldehyde through low density polyethylene decreased with increasing film thickness. It also appeared that an increase in the water contents of nylon-6 and cellophane films lead to an increase in the transmission rate of formaldehyde. With the exception of the poly(ethylene terephthalate)-types of polymer films and the polystyrene film, all other polymer film types exhibited typical Fickian behaviour, in that the permeation of formaldehyde through each polymer film was steady state. The permeation of formaldehyde through poly (ethylene terephtha1ate)-type films and polystyrene film appeared to be anomalous in that the mass transfer process did not appear to show Fickian-type behaviour. The transmission rates of formaldehyde through free alkyd-type paint films, free vinyl-based paint films and through free polyurethane varnish films, were measured at 30°C. The permeation of formaldehyde through free alkyd-type paint films and free polyurethane varnish films typified Fickian behaviour, in that after a short time-lag the steady state permeation of formaldehyde occurred. The transmission rates of formaldehyde through the free alkyd-types of paint film ranged from 1.8 x 10-9 μg cm-1s-1 to 3 2 x l0-9 μg cm-1 s-1 whereas transmission rates of formaldehyde through free polyurethane varnish films ranged from 4.1 x 10-10 μg cm-1 s-1 to 2.4 x 10-8 μg cm-1 s-1. It appeared that the "two-pack" or "catalytic-curing" type of polyurethane varnish film had a lower permeability to formaldehyde compared with either "one-pack" ("air-curing") or "one-pack" ("moisture-curing") varieties of polyurethane varnish. By contrast the transmission rates of formaldehyde through the vinyl-based types of paint films tended to range from 3.7 x 10-7 μg cm-1 s-1 to 6.2 x10-7 μg cm-1 s-1. A study of the temperature dependency of the permeation of formaldehyde through the following polymer film types was made: low density polyethylene; plasticised poly(vinyl chloride); polystyrene; polypropylene; high density polyethylene; cellophane; and nylon-6. The transmission rates of formaldehyde through each of these polymer film types increased with increasing temperature, over the temperature range of 30°C to 50°C, thus typifying Arrhenius behaviour. The energies of activation for the permeation of formaldehyde were calculated as ranging from 16 1 kcal mol-1 (67.4 kJ mol-1) for plasticised poly (vinyl chloride) to 33.1 kcal mol-1 (139 kJ mol-1 for cellophane, respectively. These activation energies were in general higher than the energies of activation for the permeation of other penetrants of similar molecular weight, through the same polymer types. The observed energies of activation for the permeation of formaldehyde through polymers were indicative of a strong interaction between formaldehyde and the various polymers. Desorption studies of formaldehyde from polymer films tested after permeability measurement, indicated that formaldehyde was irreversibly sorbed either onto or into the following polymer film types: low density polyethylene; poly(ethy1ene vinyl acetate); polypropylene; polystyrene; and plasticised poly(vinyl chloride). Formaldehyde was found to desorb from nylon-6 and cellophane polymer film types, indicating a different type of interaction between formaldehyde and these two polymer film types. The autoradiography of polymer films and free polymer coatings following permeability testing showed that the pattern of sorbed carbon-14 formaldehyde exhibited by each polymer film type or free polymer coating type, differed according to the type of polymer. Clustering of sorbed carbon-14 formaldehyde in polymer films containing polyethylene polymers may have been indicative of the formation of formaldehyde-formaldehyde polymers or perhaps could have been due to preferred pathways or sites for the diffusion of formaldehyde through the polymer film. The following types of polymer film tended to show a uniform sorption pattern of formaldehyde: nylon-6; cellophane; "Paraform"; free alkyd paint films; free vinyl-based paint films; and free polyurethane varnish films. The uniform appearance of the sorption pattern of carbon-14 formaldehyde may have been indicative of a higher solubility coefficient of permeation for formaldehyde in the latter polymer types. On the other hand, insufficient carbon-14 formaldehyde was sorbed by the poly(ethylene terephthalatel-type and polystyrene films in order to obtain autoradiographs. Both the poly(ethylene terephthalate)-types of films and the polystyrene film had a relatively low permeability to formaldehyde and appeared to also have a low solubilizing effect on formaldehyde. The data presented in this thesis are discussed in relation to the practical problem that initiated the study. Sufficient detailed information has been collected to enable informed decisions to be taken over the choice of formaldehyde-emitting materials used in the building and the food packaging industries.