In an industrial application a GFAAS method for monitoring the Rh concentration in process streams is being used. Matrix effects are known to exist with the application of this technique; in fact, it was observed that different solvents lead to different results. Therefore, standard additions have to be employed for quantitative determinations, resulting in high costs and long analysis times. In an attempt to understand these interfering effects, fractional factorial designs were proposed to determine whether any GFAAS parameter was responsible for, or related to, the matrix effects. Seven GFAAS parameters were investigated: final temperature, ramp time and hold time of the transitions step (from the dry step); final temperature, ramp time and hold time of the ashing/pyrolysis step; ramp time of the atomisation step. The results showed that the matrix effects were not related to any specific parameter. A complete factorial design was implemented to demonstrate the fundamental role of the atomisation temperature. SEM analysis showed that the surface of the graphite tubes might be affected in different ways by different solvents. A Principal Component Analysis demonstrated that the matrix effects may be related to the viscosity and melting point of the solvents and may be independent of their molar mass. To identify the origins of these effects, an investigation on the link between the tube surface-sample matrix interactions and the physical properties of the matrices is recommended. Since GFAAS parameters cannot compensate for the matrix effects, standard additions remain the preferred mode of operation as it accounts for the effects in-situ. / Chemistry / M.Sc. (Chemistry)

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published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

Alkoxy alkyl groups migrate to benzylic carbon when alkyl alkylphenyl ethers are treated with n-butyllithium and potassium t-butoxide. For alkyl 2,6-dialkylphenyl ethers, yields of the rearrangement products range from 45-70%. Rearrangement products are obtained in 10-30% yield from other dimethylanisoles and methylanisoles. The reactions appear to proceed by homolytic cleavage of the alkoxy alkyl group of alkoxybenzyl anions followed by recombination of the resulting radical pair in a different way. The reaction is useful for preparing 2,6-dialkylphenols and their corresponding ethers. The rearrangement can be avoided by using methyl ethers and working at or below room temperature. This was shown by reacting the dianion from methyl 2,6-dimathylanisole with dialkyl sulfates to give methyl 2,6-dialkylanisoles, with a,ω-dihalides to give methoxy[n]metacyclophanes (n = 8-15), dimethoxy[n.n]metacyclophanes (n = 5-10) and trimethoxy[S.S.S]metacyclophane, and with oxidizing agents to yield dimethoxy[2.2]metacyclophane.

One new dianion was prepared and many alkylation and oxidation reactions of this new dianion and several known dianions were carried out. These reactions provide the best synthetic routes to most of the compounds prepared. More specifically, many oxidation products were obtained when 3-methyl-1,4-pentadiene dianion was treated with alkyl bromides. A quantitative yield of substitution product was obtained by reacting this dianion with trimethylsilyl chloride. New compounds obtained by treating this dianion with 1,2-dichloroethane are shown below: The dianion shown below was prepared from 2,5-dimethyl-1,5-hexadiene and Lochmann's base. Many different 2,5-disubstituted 1,5-hexadienes and related compounds were made by treating this dianion with alkyl halides, sulfates and alkyl (alpha),(omega)-dihalides. Attempts to make a cyclic hexapyridyl by treating 2-methyleneallyl dianion with 6,6'-dicyano-2,2'-dipyridyl (see below) apparently failed.

This work involved synthetic approaches to the anti-tumor agent deoxybouvardin. Numerous reactions were explored in an attempt to build an amino acid from an aromatic aldehyde under mild conditions. From these reactions new and useful synthetic methods have been discovered for making α-acylamino alcohols and unsymmetrical imides. Some dehydroamino acids were successfully prepared from aromatic aldehydes and an N-acylphosphorylglycine ester. Progress towards a synthesis of 5- η-thiodeoxybouvardin will also be discussed.

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