being reported by a team led by Michel Couturier of Canadian custom chemicals firm
OmegaChem (J. Org. Chem., DOI: 10.1021/
jo100504x). XtalFluor-E and XtalFluor-M,
which have [R2N=SF2]+ as the key structural
feature, are founding members of a new
generation of deoxofluorination reagents.
They join Fluolead, a crystalline phenyl-sulfur trifluoride compound introduced
last fall by Denver-based IM&T Research
(C&EN, Oct. 12, 2009, page 45). Deoxofluorination is a key reaction for converting the
COURTESY OF MICHEL COUTURIER
XtalFluor-E BF4– SF2 N+
B. Zimmermann of the Swiss Federal Institute of Technology, Zurich, and coworkers added nanopowders of poorly soluble
phosphates and oxides containing both iron
and zinc to rat food, including two oxides
doped with either calcium or magnesium.
When rats ate the food, the bioavailability of
the iron was comparable with that of FeSO4,
a highly soluble compound used to fortify
human food. The magnesium in particular
lightened the dark-brown color of the oxide
and improved the bioavailability of the iron.
Iron didn’t accumulate in the gastrointestinal tract or other tissues of the rats, and
histological analyses revealed no significant
structural changes in most tissues, the
researchers report. They note that further
research is still needed to rule out potential
toxicity of the nanomaterials.—CHA
be recovered by filtering, which can drive up
solvent use. Still, Taarning says, “this paves
the way for designing more economical processes for the production of chemicals from
biomass.”—EKW
NANORUTHENIUM READILY REDUCES AROMATICS
By stabilizing ruthenium(0) nanoclusters
within a nanozeolite framework, chemists
at Middle East Technical University, in Ankara, Turkey, have made a heterogeneous
catalyst that exhibits remarkable activity,
selectivity, and lifetime in the hydrogenation of aromatics under mild conditions—25 °C and roughly 3 atm of H2 (J.
Am. Chem. Soc., DOI: 10.1021/ja101602d).
METHYL LACTATE FROM SUGAR, CATALYTICALLY
C–O in hydroxyl and carbonyl groups to
C–F derivatives. Currently, (CH3CH2)2NSF3
(DAST) and (CH3OCH2CH2)2NSF3 (
Deoxo-Fluor) are the reagents of choice for these
transformations. But as liquids, DAST and
Deoxo-Fluor react vigorously with water
and are thermally unstable, which precludes
using them in larger scale processes. Like
Fluolead, the XtalFluor reagents are crystalline solids that don’t fume in air, don’t react
violently with water, and have enhanced
thermal stability. Couturier and coworkers
have hit a “grand slam” for deoxofluorinations with their XtalFluor reagents,
comments Robert P. Discordia, Bristol-Myers Squibb’s group director of process
R&D. “These compounds have properties that discovery and process chemists
desire, including ease of isolation, good
yields, and selectivity.”—SR
HO
A catalytic process that converts plant
sugars to the industrially useful compound
methyl lactate offers a potential alternative
to fermentation processing. It also adds
to the strategies being developed to use
biomass rather than petroleum to produce
commodity chemicals (Science 2010, 328,
602). Fermentation currently dominates the
processes used to derivatize carbohydrates
from plants, in part because carbohydrates’
thermal instability usually requires low processing temperatures. On the other hand,
J. AM. CHEM. SOC.
OH OH
OH
OH
OCH3
This TEM image
shows nanozeolite
crystals that
house ruthenium
nanoclusters.
OH O
O
Fructose
Methyl lactate
NANOPOWDERS IMPROVE IRON BIOAVAILABILITY
Nanostructured iron- and zinc-containing
compounds are highly bioavailable in rats
but don’t accumulate in their tissues, mak-
ing the nanomaterials a promising means of
fortifying foods, according to a study (Nat.
Nanotechnol., DOI: 10.1038/nnano.2010.79).
Iron fortification of foods is difficult be-
cause easily absorbed water-soluble com-
pounds can change the color or taste of
foods, whereas poorly water-soluble com-
pounds have limited bioavailability. Michael
catalytic processes are more tolerant of
temperature and concentration extremes.
Esben Taarning, Martin Spangsberg Holm,
and Shunmugavel Saravanamurugan at the
Technical University of Denmark report
that the Lewis acid zeolite catalyst Sn-beta
suspended in methanol readily converts
fructose, glucose, and sucrose into methyl
lactate. Sucrose conversion reached 68%,
the researchers report, and the catalyst can
be reused multiple times. But the process
has some drawbacks, cautions Michael E.
Himmel of the Department of Energy’s
National Renewable Energy Laboratory,
including the need for relatively high tem-
peratures (160 °C), which can increase
energy costs. Additionally, the catalyst must
Because the catalyst
works on neat aromat-
ics, it offers a greener
hydrogenation than
catalysts that require
solvents, say Mehmet
Zahmakiran, Yalçin Tonbul, and Saim Özkar,
who did the research. The team prepared
the catalyst via borohydride reduction of a
colloidal solution of nanozeolites that have
undergone ion exchange with Ru(III). Upon
investigating the catalyst’s properties, they
discovered that during benzene hydrogena-
tion to cyclohexane the catalyst will undergo
177,200 turnovers during the course of 105
hours before becoming deactivated. That’s
the highest total turnover ever reported for
this reaction and is 70 times greater than
the previous record. In addition to benzene,
the catalyst works well with substituted
aromatics, such as toluene, o-xylene, and
mesitylene. Furthermore, the catalysts are
isolable, bottleable, and reusable, making
them “superior” to many other hydrogena-
tion catalysts, the researchers note.—BH
