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The application of experimental design to investigate the solvent matrix effects observed during the Determination of Rhodium (Rh) in organic media by Graphite Furnace Atomic Absorption Spectrometry (GFAAS)Baratta, Antonio 11 1900 (has links)
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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Chloro (ethoxycarbonye) methyleniminium salts : versatile electrophilic intermediates for heterocyclic synthesisBartholomew, David January 1979 (has links)
No description available.
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Enantioselective total synthesis of (-)-16-hydroxytriptolideLui, Bob., 呂思奇. January 2005 (has links)
published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy
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Development of a multipolymer reaction and polyfunctional polymeric catalysts鍾韻盈, Chung, Wan-ying, Cecilia. January 2008 (has links)
published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy
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Scope and mechanism of the rearrangement of alkoxybenzyl anions to alkylphenoxide ions; cyclophanes from 2,6-dimethylanisole.Suvannachut, Kessara. January 1989 (has links)
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.
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PREPARATION AND USE OF SOME HYDROCARBON DIANIONS IN SYNTHESIS (PENTADIENE, HEXADIENE, ALKYL, HALIDE, BROMIDE).HSU, HOWARD FU-JYA. January 1982 (has links)
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.
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PROGRESS TOWARDS A SYNTHESIS OF DEOXYBOUVARDIN AND ANALOGUES; NEW SYNTHETIC METHODS.JANDA, KIM DAVID. January 1984 (has links)
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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STEREOCHEMISTRY OF GLYCOLATE ENOLATES. STEREOSELECTIVE SYNTHESIS OF TRACHELANTHIC ACID AND VIRIDIFLORIC ACID.Shanklin, Michael Samuel. January 1982 (has links)
No description available.
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SYNTHESIS OF DIPHENYL ETHERS, AS RELATED TO DEOXYBOUVARDIN.Janda, Kim David. January 1983 (has links)
No description available.
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REACTIONS OF 2,3-BIS(METHYLENE)BUTADIENE DIANION.White, James J., 1957- January 1983 (has links)
No description available.
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