Custom-designed
additives
play
a
crucial
role
in
achieving
desired
transformations
under
aqueous
conditions
modern
organic
synthesis.
In
micellar
catalysis,
designer
amphiphilic
molecules
create
dynamic
supramolecular
structures
that
can
dissolve
reactants
and
catalysts
conditions.
This
enables
the
to
occur
mild
without
need
for
hazardous
solvents.
Additionally,
such
as
tetra
-butyl
ammonium
chloride
or
bromides
facilitate
reactions
through
efficient
transfer
of
reactive
species
between
non-miscible
biphasic
systems.
method,
known
phase-transfer
has
been
instrumental
challenging
asymmetric
chapter
overviews
recent
advancements
these
respective
fields,
outlining
fundamental
principles
underlying
their
operational
mechanisms.
The Journal of Organic Chemistry,
Год журнала:
2024,
Номер
89(11), С. 8267 - 8271
Опубликована: Май 16, 2024
A
fluorescence
lifetime
imaging
microscopy
(FLIM)
technique
characterizes
surfactant-dependent
partitioning
of
organics
in
a
system
that
mimics
Negishi-like
cross-coupling
reaction
water,
under
synthetic
concentrations,
with
emulsion
droplets.
Experimental
data
were
not
predictable
from
simple
hydrophilic–lipophilic
balances.
The
ionic
surfactant
cetrimonium
chloride
suppressed
the
reactivity
metallic
zinc
surface,
presumably
through
competitive
binding
and
concurrent
coating,
finding
may
contribute
to
reduced
performance
surfactants
bench-scale
coupling
reaction.
The Journal of Organic Chemistry,
Год журнала:
2024,
Номер
89(15), С. 10684 - 10692
Опубликована: Июль 17, 2024
Fluorescence
lifetime
imaging
microscopy
(FLIM)
provides
spatiotemporal
resolution
of
the
changing
composition
emulsion
droplets
during
aqueous-surfactant
Suzuki
coupling.
In
contrast
to
previous
investigations,
present
experiments
characterize
full
course
a
catalytic
chemical
reaction,
addressing
key
questions
about
reaction
species
buildup
and
correlating
these
microscale
behaviors
with
bench-scale
product
yields.
At
low
concentrations
(active)
catalyst,
droplet
environments
are
stable;
however,
at
higher
concentrations,
change
markedly.
These
changes
consistent
consumption
inside
droplets.
A
combination
FLIM
bright-field
pinpoints
limitations
in
catalyst
solubility
as
controlling
rate
degree
also
identified
cause
induction
period
an
origin
rate-and-reproducibility
advantage
obtained
by
adding
THF
cosolvent.
The
subsequent
mechanistic
model
from
data
led
optimization,
wherein
premixing
components
bypasses
period,
resulting
faster
reaction.
understanding
generated
thus
early
example
how
visualizing
compositions
on
ongoing
aqueous-organic
reactions
can
be
leveraged
for
enhancing
efficiencies
reactions.
ACS Catalysis,
Год журнала:
2024,
Номер
14(22), С. 17132 - 17147
Опубликована: Ноя. 6, 2024
Fluorescence
lifetime
imaging
microscopy
(FLIM)
is
an
emerging
tool
to
characterize
ongoing
chemical
reactions
in
synthetic
chemistry
and
catalysis.
Initially
applied
biological
systems,
FLIM
now
reveals
spatially
resolved
reaction
species
system-wide
physiochemical
changes
that
accompany
reactions.
combines
the
advantage
of
environmental
sensitivity
with
high
signal
(as
sensitive
as
single
molecules)
has
key
ability
operate
under
conditions
(e.g.,
concentrations
reagents,
organic
solvents,
ambient
temperature
pressure,
opaque
mixtures,
multiphasic
systems).
Chemical
inherently
induce
medium,
neighboring
compounds,
surface
compositions,
and/or
bonding
structure
compounds
involved,
resulting
changes.
The
methods
recently
developed
harness
interpret
these
ways
lead
characterizing
enhancing
a
mechanistic
understanding.
Here,
current
advantages
limitations
are
considered,
common
factors
influencing
fluorescence
systems
discussed
tutorial
format,
seven
research
case
studies
strategically
analyzed,
chosen
highlight
how
provided
complementary
information
understand
mechanisms,
intermediates,
product
distributions,
partitioning,
roles
catalyst
behaviors.
These
data
insights
obtained
from
assist
rational
design
optimization
catalytic
methods.
In
recent
years,
methodologies
that
rely
on
water
as
the
reaction
medium
have
gained
considerable
attention.
The
unique
properties
of
micellar
solutions
were
shown
to
improve
regio-,
stereo-,
and
chemoselectivity
different
transformations.
Herein,
we
demonstrate
aqueous
environment
is
a
suitable
for
visible
light
driven
cobalt-catalyzed
involving
radical
species.
this
system,
reduced
vitamin
B12
reacts
with
alkyl
halides,
gen-erating
radicals
are
trapped
by
lipophilic
olefin
present
in
Stern
layer.
A
series
NMR
measurements
theoretical
studies
revealed
location
components
system.
Performing
organic
reactions
in
water
provides
environmental
and
toxicity
advantages
compared
to
solvents,
but
such
strategies
are
still
evolving,
limited
by
current
understanding
of
these
multiphasic
systems.
Here,
a
fluorescence
lifetime
imaging
microscopy
(FLIM)
technique
characterizes
surfactant-dependent
partitioning
organics
system
that
mimics
the
early,
zinc-related
steps
Negishi-like
cross-coupling
reaction
water,
under
synthetically
relevant
high
concentrations
substrate
(0.18
M),
where
large
emulsion
droplets
(5–20
um)
form
an
phase.
Brij-30
resulted
highest
degree
aqueous
phase,
which
was
not
predictable
from
simple
hydrophilic–lipophilic
balances
(HLB).
The
ionic
surfactant
CTAC
suppressed
reactivity
metallic
zinc
surface
with
both
neutral
(TMEDA)
anionic
(carboxylate)
reactants,
presumably
through
competitive
chloride
binding
concurrent
cetrimonium
coating,
finding
may
contribute
reduced
performance
bench-scale
coupling
reaction.
Fluorescence
lifetime
imaging
microscopy
(FLIM)
provides
spatiotemporal
resolution
of
the
changing
composition
emulsion
droplets
during
an
aqueous–surfactant
Suzuki
coupling.
In
contrast
to
previous
investigations,
present
experiments
characterize
full
course
a
catalytic
chemical
reaction,
addressing
key
questions
about
if
and
where
reaction
species
build
up,
correlating
these
microscale
behaviors
with
bench-scale
product
yields.
At
low
concentrations
(active)
catalyst,
droplet
environments
are
stable;
however,
at
higher
concentrations,
change
markedly,
as
indi-cated
by
rise
fall
fluorescence
lifetimes.
These
changes
consistent
buildup
consumption
inside
droplets.
A
combination
FLIM
brightfield
pinpoint
limitations
in
catalyst
solubility
controlling
rate
degree
also
identified
cause
induction
period,
origin
rate-and-reproducibility
advantage
obtained
adding
THF
cosolvent.
The
subsequent
mechanistic
model
from
data
led
optimization,
wherein
premixing
components
bypasses
resulting
faster
otherwise
constant
load-ing.
understanding
generated
thus
early
example
how
compo-sitions
on
ongoing
aqueous–organic
reactions
can
be
leveraged
for
enhancing
efficiencies
reactions.
Chemistry - A European Journal,
Год журнала:
2023,
Номер
30(14)
Опубликована: Дек. 18, 2023
Commercial
zinc
metal
powder
requires
activation
for
consistent
and
reliable
use
as
a
reductant
in
the
formation
of
organozinc
reagents
from
organohalides,
avoidance
supplier
batch-to-batch
variability.
However,
impact
methods
on
reaction
environments
subsequent
intermediates
has
been
unknown.
Herein,
fluorescence
lifetime
imaging
microscopy
(FLIM)
method
is
developed
to
bridge
this
knowledge
gap,
by
examining
that
activated
pretreatment
through
different
common
(i.
e.,
chemical
with
TMSCl,
dibromoethane,
or
HCl;
mechanical
activation).
The
group
activating
agents,
previously
thought
act
similarly
removing
oxide
layers,
are
here
shown
produce
markedly
experienced
oxidative-addition
organohalides
-
data
uniquely
available
FLIM's
ability
detect
small
quantities
situ
coupled
its
microenvironmental
sensitivity.
These
microenvironments
potentially
give
rise
rates
formation,
solubilization,
reactivity,
despite
shared
"[RZnX]"
molecular
structure
these
intermediates.
This
information
revises
models
development
oxidative
addition
currently
sluggish
metals
beyond
establishing
diverse
outcomes
were
considered
similar.
