Richard T. Taylor

Structural confirmation of polyurethane dendritic wedges and dendrimers using post source decay matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

‘Post source decay’ analysis was utilized in structural confirmation of first, second and third generation polyurethane dendritic wedges as well as first generation porphyrin dendrimers. The samples were prepared by using α-cyano-4-hydroxycinnamic acid and acetone as the matrix and the solvent, respectively. The cleavages take place at both inner and outer layers of the dendritic compounds. Sodium ion adducts from the cleavage at the ester or amide bond (or a combination of both) are observed. The results obtained are in good agreement with the proposed structures of all analyzed compounds. Copyright

Detection of ozone gas using gold nanoislands and surface plasmon resonance

Gold nanoislands interact with gaseous ozone to produce a surface plasmon resonance shift, similarly to the interaction of ozone and gold nanoparticles in water. Gold nanoislands are produced by sputtering, which significantly simplifies the synthesis and produces controlled size for the gold nanoislands. The shift of surface plasmon resonance peak was monitored while gold nanoislands were exposed to variable concentration of gaseous ozone. The shift was then correlated with ozone concentration. Our current results indicate sensing gaseous ozone at concentration of as low as 20 microg/L is achievable. Gold nanoislands were reversed to their original wavelength and were able to cycle between the wavelengths as ozone was introduced and removed. Potentially, this system can be useful as a sensor that identifies the presence of ozone at low part-per-billion concentrations of ozone in gaseous media.

Characterization and monitoring reaction of polyurethane dendritic wedges and dendrimers using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

The purity of polyurethane dendritic wedges from first generation through fourth generation was verified by employing matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). First and third generation polyurethane porphyrin dendrimers, and tri-core dendrimers obtained by attachment of the corresponding dendritic wedges to a porphyrin and to 1,3,5-benzenetricarboxylic acid, were also mass analyzed by MALDI measurements. The spectra were acquired in both reflectron and linear mode. Due to the ease and speed of the analysis, MALDI-TOF also proved to be a powerful tool in monitoring the progress of the reaction which can provide significant informative results that can be useful in designing and optimizing the synthesis. Copyright

Polyurethane dendrimers via Curtius reaction

Abstract Reaction of 5-(t-butyldiphenylsiloxy)propyloxyisophthalic acid with dodecanol and diphenylphosphoryl azide (DPPA) affords the diurethane via Curtius reaction. Removal of the silyl group affords an alcohol which undergoes similar reaction with the isophthalic acid. Iteration of the process affords dendritic wedges through generation four, which can be attached to 1,3,5-benzenetricarboxylic acid in the same fashion. Materials are characterized by NMR and MALDI-TOF mass spectrometry.

Addition of trimethylsilylmethylmagnesium chloride to α, β-unsaturated carbonyls

Abstract Reactions of α,β-unsaturated carbonyl compounds with Me 3 SiCH 2 MgCl, prepared from chloromethyltrimethylsilane [1], were examined. Unlike its lithium counterpart (Me 3 SiCH 2 Li), which adds to α,β-unsaturatedketones in the 1,2-sense, the Grignard reagent afforts γ silanes via a 1,4-addition sequence. This tendency is accentuated by the addition of Cu 2 Br 2 . Addition of the Grignard reagent to α,β-unsaturated aldehydes gives the simple 1,2-addition products.

Mercury mediated synthesis of bis(carboxy)iodobenzenes

Abstract Iodobenzene dibenzoates and acetoxylates can be conveniently prepared from iodobenzene dichloride and the corresponding mercuric carboxylate generated in situ . Especially noteworthy is the high yield preparation of bis(trifluoro-acetoxy) iodobenzene.

Removal of transition metals from motor oil using ion exchange resins

A variety of polystyrene-divinylbenzene resins functionalized with such groups as SO3H, N(CH2COOH)2, and SH were tested in the slurry batch mode for the removal of transition metals from used motor oil. Naturally occurring materials such as coal and clay were also tested. The N(CH2COOH)2 resin (Chelex 100) and the SH resin (Duolite GT-73) were found effective removing on the average 70 and 78% of metals such as Fe, Pb, Zn, Cu, Ni, and Mn, respectively. About 700 mLs of hot oil when pumped through a 37 × 0.9 cm column packed with the Duolite resin could be demetalized to the extent of about 80% if the column was first washed with hexane.

The serendipitous synthesis of an oxabicyclo [3.2.0] heptadiene

Abstract 5,6-Dihalobicyclo [2.1.1]hexanes resist simple nucleophilic displacement in several ways. Least expected of these is the 2→1 rearrangement.

Syntheses of Oxazolidinone, Imidazolidinone and Thiazolidinone Derivatives Using a Polymer-supported Diphenylphosphoryl Azide

By using a polymer-supported diphenylphosphoryl azide (PS-DPPA), oxazolidinone, imidazolidinone and thiazolidinone derivatives were successfully prepared from carboxylic acids bearing different reactive functional groups in the β position, such as alcohols, thiols, primary or secondary amines. The desired compounds were obtained in good yields via Curtius rearrangement and subsequent intramolecular cyclization.

Total syntheses of microminutin and other coumarins through the key intermediate isomurralonginol

Abstract A straightforward route to isomurralonginol (1) from umbelliferone (4 steps, 59% yield) is described. Isomurralonginol is used as the key intermediate in the preparation of isomurralonginol acetate (2) (1 step, 94% yield), murralongin (3) (1 step, 75% yield) and microminutin (2 steps and 38% yield). The synthesis of microminutin involves the selenolactonization of α, β-substituted vinyl acetic acid (12) (50% yield) with spontaneous elimination of the selenyl moiety, without oxidation, to the unsaturated lactone.