3 research outputs found
Environmentally friendly procedure for the aqueous oxidation of benzyl alcohols to aldehydes with dibromodimethylhydantoin (DBDMH) and cyclodextrin: Scope and mechanistic insights
<p>Reported herein is an environmentally friendly procedure for the oxidation of benzyl alcohols to aldehydes using an inexpensive, commercially available reagent, 1,3-dibromo-5,5-dimethylhydantoin (DBDMH), and a variety of cyclodextrin additives under fully aqueous solvent conditions. This reaction proceeds with moderate to good yields for a broad scope of benzyl alcohol substrates, with the cyclodextrin acting to enhance the desired reactivity and limit undesired aromatic bromination side products. The reported experiments provide substantial mechanistic insight that will drive further reaction optimization and have broad-reaching applications.</p
Impact of Nearly Water-Insoluble Additives on the Properties of Vesicular Suspensions
Nearly water-insoluble additives
are commonly used in surfactant-based
consumer products to enhance their appeal or performance. We used
viscosity measurements, time-resolved cryogenic transmission electron
microscopy, and NMR spectroscopy to investigate the effect of several
additives, linalyl acetate (LA), cyclohexanol, phenol, catechol, guaiacol,
and eugenol, that have extremely low water solubility, on the evolution
of microstructures in an aqueous multilamellar vesicle suspension
of diethylester dimethylammonium chloride (DEEDMAC), a major ingredient
in fabric softeners. LA and eugenol are used as fragrances in some
detergent-related consumer products. The other additives were chosen
to have degrees of aromaticity that are intermediate between LA and
eugenol. The viscosity of the DEEDMAC suspension increased only marginally
upon addition of LA, while it rose significantly upon addition of
eugenol. Cryo-TEM revealed no observable changes to the multilamellar
structures in the DEEDMAC suspension when LA was added. The addition
of eugenol triggers a transition from multilamellar vesicles to predominantly
unilamellar vesicles and bilayer fragments through exfoliation and
breakage. By examining NMR results from all the additives, we propose
that π electrons in aromatic rings interact strongly with the
cationic DEEDMAC head groups. Such interactions are strong in eugenol
but not present in LA
Cyclodextrin-Based Pseudorotaxanes: Easily Conjugatable Scaffolds for Synthesizing Hyperpolarized Xenon-129 Magnetic Resonance Imaging Agents
Hyperpolarized (HP)
xenon-129 (Xe) magnetic resonance (MR) imaging
has the potential to detect biological analytes with high sensitivity
and high resolution when coupled with xenon-encapsulating molecular
probes. Despite the development of numerous HP Xe probes, one of the
challenges that has hampered the translation of these agents from
in vitro demonstration to in vivo testing is the difficulty in synthesizing
the Xe-encapsulating cage molecule. In this study, we demonstrate
that a pseudorotaxane, based on a γ-cyclodextrin macrocycle,
is easily synthesized in one step and is detectable using HyperCEST-enhanced <sup>129</sup>Xe MR spectroscopy