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Complete Structure Verification

ALL ABOUT SOLVING PROTON-NMR What
is
1 H‐NMR? 1 H‐NMR
is
NMR
(Nuclear
Magnetic
Resonance)
spectroscopy
in
which
the
proton
nuclear
spin
is
 manipulated.

It
revolves
around
the
idea
that
the
energy
required
to
cause
nuclear
spin
flip
is
a
 function
of
the
magnetic
environment
of
an
atom’s
nucleus. How
can
we
find
structure
from
NMR? We
find
structure
through
the
information
NMR
relays
to
us.

These
pieces
of
information
 include: ‐ Number
of
signals
[which
is
the
number
of
nonequivalent
proton
sets
in
a
molecule] ‐ Position
of
signals
[also
known
as
chemical
shift,
which
is
the
magnetic
environment
 in
which
protons
are
in] ‐ Relative
intensity
of
signals
[also
known
as
integration,
which
is
the
ratio
of
 equivalent
proton
types] ‐ Splitting
of
signals
[also
known
as
spin‐spin
coupling,
which
is
the
amount
of
proton
 neighbors
present] How
to
solve
for
number
of
signals
present The
number
of
signals
depends
on
the
equivalency
of
protons.

Protons
are
equivalent
if
they
 have
nuclei
with
the
same
magnetic
environment.

In
other
words,
they
have
to
be
the
same
in
 every
possible
way.

It
is
easier
to
find
nonequivalent
protons. http://www.chem.ucla.edu/harding/index.html Within
the
molecule
depicted
above,
there
are
three
different
signals
present,
in
that
there
are
 three
different
sets
of
protons
with
different
equivalencies.

Ha,
Hb
and
Hc
are
all
nonequivalent
 to
one
another,
thus
producing
three
separate
signals
on
the
NMR
spectrum. How
to
solve
for
the
position
of
signals/chemical
shift Chemical
shift
is
defined
as
the
position
of
a
signal
in
an
NMR
spectrum.

It
is
dependent
on
 different
influences,
such
as
the
ΔE
of
the
spin
state
energy
(which
is
controlled
by
the
 magnetic
field
at
the
nucleus),
and
electronegativity
(as
chemical
shift increases,
 electronegativity
of
atoms
near
the
proton
increases).

The
posi