The purpose of this investigation was to determine the nature of the
chemical constituents of incense cedar bark with the hope that such an endeavor
would spur future research, development and use of a now neglected
natural raw material.
The bark from nine trees, which were separated into three age...
The variable length, six-electrode plasma source for atomic
emission spectroscopy described here is operated from three
compact, simple, and inexpensive direct current power supplies. The
vertical arcs formed between the three electrode pairs completely
entrain the sample and are typically operated at 40 V and 20 A.
Three concentric quartz...
A critical study of the cold vapor atomic absorption and fluorescence instrumentation for the analysis of mercury is described. Some of the important modifications involve the reduction vessel, absorption cell, fluorescence cell, and radiation source. The new modified systems have much greater calibration sensitivities and lower detection limits than those...
An oscillating plasma glow discharge detector for gas
chromatography is used to obtain fingerprint information
about an analyte by combining both the average cell
current and oscillation frequency signals. Five homologs
each of the n-alkanes, 1-alkenes, 1-alkynes, 2-ketones and
aldehydes are studied. Although triplicate determinations
had some scatter due to...
Four strategies which involve synthetic elaboration of
the shikimate nucleus are discussed. Methyl shikimate was
differentially protected as the 3,4-0-cyclopentylidene ketal
and as the 5- 0- tert- butyldiphenylsilyl ether. The methyl
ester was then reduced with diisobutylaluminum hydride and
the resulting allylic alcohol was oxidized to aldehyde 47
with pyridinium...
In recent years nuclear reduction of pyrimidines by catalytic hydrogenation in acid media has been considered a possible synthetic method for the preparation of substituted tetrahydropyrimidines. This technique has the advantage of simplicity over the older condensation methods and is limited only by the preparation of the appropriately substituted pyrimidines....
An automated multielement flame atomic fluorescence (AF) spectrometer based on microcomputer control was constructed to determine four elements simultaneously. The instrument employs a multiple exit slit monochromator where the light from various exit slits is directed to a single detector with a mirrored funnel. Each element is excited to fluoresce...
Two approaches to the tricyclic core of the furanoeremophilane sesquiterpenoids are described. The first approach entails a projected Diels-Alder/retro Diels-Alder reaction of an acetylenic oxazole 64. Construction of the pivotal aldehyde 67 commenced from ketone 68. The acetyenic moiety was then introduced via a Felkin-Ahn addition of lithiopropyne to aldehyde...