Resin acids. I. An improved method of isolation of resin acids the isolation of a new abietic-type acid, neoabietic acid


Harris, G.C.; Sanderson, T.F.

Journal of the American Chemical Society 70(1): 334-339

1948


An improved method, based on the amine salt technique, for the isolation of abietic acid from acid-isomerized wood rosin and levopimaric acid from the gum oleoresin of Pinus palustris is described. The isolation of a new, abietic-type acid, termed neoabietic acid, from heat-isomerized abietic acid, the gum oleoresin of Pinus palustris and gum rosin is described. The ultraviolet absorption spectra, utilizing speciuc absorption coefficients, a, have been determined for each of the three abietic-type acids.

334
GEORGE
C.
HARRIS
AND
THOMAS
F%
SANDERSON
A
sample
of
the
diene
(VIII)
in
absolute
alcohol
was
subjected
to
hydrogenation
over
Raney
nickel
at
50°
and
160
atmospheres.
The
product
after
one
recrystallization
from
methanol
was
pure
IXb,
m.
p.
104-105°.
7,7
cDimethozy-1,1
'-binaphthyl
(X)
.—A
mixture
of
the
diene
(VIII)
with
about
2.5%
of
its
weight
of
palladized
charcoal,"
when
heated
at
290-300°
for
fi
fteen
minutes,
gave
a
practically
quantitative
yield
of
X
which,
after
recrystallization
from
ethanol,
formed
colorless
rectangu-
lar
plates,
m.
p.
110.5-111.5°.
Anal.
Calcd.
for
C22111802:
C,
84.08;
H,
5.77.
Found:
C,
83.73;
H,
5.64.
Similar
treatment
of
the
bitetralyl
(IXa
and
IXb)
gave
in
each
case
the
same
compound,
identified
by
mixed
m.
p.
7,7
'-Dihydroxy-1,1
'-binaphthyl
(XI)
.—The
methyl
ether
(X)
was
smoothly
demethylated
in
practically
quantitative
yield
by
the
method
of
Prey."
A
mixture
of
X
with
three
times
its
weight
of
pyridine
hydrochloride
was
heated
at
200°
for
six
hours,
then
poured
into
water.
For
analysis,
the
compound
was
converted
to
its
diacetate
by
standard
methods,
because
the
free
phenol
was
dif-
fi
cult
to
purify.
The
diacetate
formed
white
crystals
from
ethanol,
m.
p.
173.5-174.5
°.
After
three
recrystallizations
the
compound
gave
the
following
analytical
values.
Anal.
Calcd.
for
C24111804:
C,
77.82;
H,
4.90.
Found:
C,
77.38;
H,
4.66.
Perylene
(XII)
.—A
mixture
of
the
binaphthol
(XI)
with
fi
ve
times
its
weight
of
zinc
dust
was
heated
in
a
dis-
(19)
Linstead
and
Thomas,
J.
Chem.
Soc.,
1130
(1940).
(20)
Prey,
Ber.,
74B,
1219
(1941).
Vol.
70
tilling
fl
ask
with
a
free
fl
ame.
A
yellow
oil
distilled
out
of
the
mixture
and
solidified
in
the
cooler
parts
of
the
apparatus.
This
was
removed
and
recrystallized
from
benzene;
it
formed
yellow
leaflets
with
a
bronze
luster,
melting
at
267-268°.
This
was
identified
as
perylene
by
comparison
with
an
authentic
specimen
prepared
by
heating
2,2
'-dihydroxy-1,1
'-binaphthyl
(XIII
)
21
with
zinc,
zinc
chloride
and
water."
A
mixture
of
the
two
samples
melted
at
267-268°.
The
picrate
formed
dark
violet
needles
from
benzene,
m.
p.
220°
(reported"
m.
p.
221
°).
The
sample
of
perylene
obtained
from
XI
gave
the
following
analytical
results.
Anal.
Calcd.
for
C01112:
C,
95.21;
H,
4.80.
Found
:
C,
94.90;
H,
4.65.
Summary
1.
A
procedure
for
the
preparation
of
6-meth-
oxy-l-tetralone
in
40-45%
yields
from
anisole
is
described.
2.
A
by-product
from
the
catalytic
hydrogen-
ation
of
7-methoxy-l-tetralone
or
7-methoxy-1-
tetralol
has
been
shown
to
be
7,7'-dimethoxy-
1,1',2,2',3,3',4,4'-octahydro-1,1'-binaphthyl.
KALAMAZOO,
MICHIGAN
RECEIVED"
AUGUST
27,
1947
(21)
Julius,
Chem.
Ind.,
10,
98
(1887).
(22)
Brass
and
Tengler,
Ber.,
64B,
1650
(1931).
(23)
Original
manuscript
received
November
29,1946.
[CONTRIBUTION
FROM
THE
HERCULES
EXPERIMENT
STATION,
HERCULES
POWDER
COMPANY]
Resin
Acids.
I.
An
Improved
Method
of
Isolation
of
Resin
Acids;
The
Isolation
of
a
New
Abietic-Type
1
Acid,
Neoabietic
Acid
BY
GEORGE
C.
HARRIS
AND
THOMAS
F.
SANDERsoN
This
is
the
fi
rst
in
a
series
of
papers
presenting
recent
developments
made
in
these
laboratories
on
the
isolation
and
proof
of
structure
of
pure
resin
acids.
This
paper
deals
with
improved
methods
of
isolation
of
abietic
acid
(1)
2
and
levopimaric
CH,
COOH
CH
s
COOH
/\/C X/\
2
10a
9
I
III
3
4a
N/N
8a
CH,
ab
8
II
/
CH,
5
7
—CH
03
/ /
CH
s
I
II
/
CH
s
\
,T
cH3
(1)
We
wish
to
desi
g
nate
by
this
term
that
type
of
resin
acid
that
yields
retene,
1-methyl-7-isopropylphenanthrene,
upon
complete
dehydrogenation
and
has
an
isopropyl
or
isopropylidene
group
at
C-7.
(2)
L.
Ruzicka,
L.
Sternbach
and
0.
Jeger,
Rely.
Chim.
Acta,
24,
504
(1941).
(3)
This
word
has
purposely
been
written
as
one
word
since
the
compound
is
not
stereoi.omeric
with
dextropimaric
acid
as
the
pre-
fi
xes
leyo-
and
dextro-
would
imply.
(4)
L.
Ruzicka
and
S.
Kaufman,
Hely.
Chim.
Acts,
23,
1346
(1940);
according
to
Ruzicka
and
Kaufman
the
double
bonds
may
be
at
the
positions
indicated
in
Formula
II
or
at
positions
5-6
and
7-8,
the
former
being
preferred.
acid
(II)
8,4
the
most
familiar
abietic-type
acids;
they
isolation
of
neoabietic
acid
(III),'
a
new
primary
acid
of
this
type,
is
also
described.
CH,
COOH
\"C
CHe
\CH
I
,
III
Abietic
Acid
The
difficulty
in
separating
abietic
acid
from
isomeromorphic
resin
acids
has
made
its
isolation
from
rosin
a
difficult
problem.
However,
Palkin
and
Harris'
were
able
to
obtain
a
pure
abietic
acid
according
to
the
following
procedure:
(1)
isomerizing
rosin
by
boiling
in
glacial
acetic
acid
to
increase
the
abietic
acid
content,
(2)
concen-
(5)
G.
C.
Harris
and
T.
F.
Sanderson,
Resin
Acids.
II.,
THIS
JOURNAL,
69,
339
(1947).
(6)
S.
Palkin
and
T.
H.
Harris,
ibid.,
56,
1335
(1934).
Jan.,
1948
ISOLATION
OF
RESIN
ACIDS
AND
NEOABIETIC
ACID
trating
the
abietic
acid
in
the
form
of
"Steele's"
acid
7
by
crystallizing
the
isomerized
rosin
from
glacial
acetic
acid,
(3)
further
concentrating
the
abietic
acid
by
the
preparation
and
recrystalliza-
tion
of
the
acid
sodium
salts
(Ci
9
H2
9
COONa•
3C2
0
1
-
I3002),
and
(4)
fractionating
the
regenerated
acids
by
the
preparation
and
recrystallization
of
the
diamylamine
salts,
a
method
fi
rst
employed
by
Balas.'
This
procedure
is
effective
but
somewhat
tedious
and
gives
a
relatively
low
recovery
(ca.
12%)
of
the
pure
acid
compared
with
the
total
abietic
acid
which
can
be
shown
to
be
present
by
ultraviolt
absorption
spectra.
We
have
now
found
that
diamylamine,
the
amine
used
by
Ba.lass
and
Palkin
and
Harris,
6
not
only
offers
a
means
of
puri-
fi
cation
of
abietic
acid,
[a]
24
D
—98
°
,
but
is
spe-
cific
for
the
separation
of
abietic
acid
from
the
com-
plex
mixture
of
resin
acids
in
rosin.
Addition
of
a
molar
quantity
of
diamylamine
to
an
acetone
solu-
tion
of
isomerized
rosin
precipitates
the
crystalline
amine
salts
high
in
abietic
acid
content
from
which
the
salt
of
abietic
acid
is
readily
separated
by
[a
]24D
fractional
crystallization.
The
pure
acid,
[a]
24D
106°,
m.
p.
172-175
°
,
was
obtained
by
decom-
position
of
the
salt
with
a
weak
acid
such
as
ace-
tic
or
phosphoric
to
minimize
isomerization
of
the
regenerated
acid.
The
yield
amounted
to
40%
of
the
weight
of
the
isomerized
rosin
which
is
in
fair
agreement
with
that
indicated
by
the
absorp-
tion
spectra.
Ultraviolet
absorption
curves
are
of
great
value
in
determining
the
amount
of
abietic
acid
present
in
modified
or
unmodified
rosins.
Figure
1
shows
the
ultraviolet
absorption
spectra
of
pure
abietic
acid
(curve
1)
and
isomerized
rosin
(curve
2)
The
difference,
Oa,
in
specific
absorption
coeffi-
cient
between
the
maximum
at
241
my
and
the
inflection
point
at
248.5
mil
is
a
constant
value
characteristic
of
pure
abietic
acid
and
can
well
be
used
as
a
measure
of
the
abietic
acid
content
of
a
rosin.
The
ratio
of
this
difference
for
isomerized
rosin
to
that
for
the
pure
acid
is
a
measure
of
the
amount
of
pure
acid
in
the
isomerized
rosin.
On
the
basis
of
these
ratios,
isomerized
rosin
con-
tains
47
2%
of
abietic
acid.
This
precision
does
not
hold
for
a
non-isomerized
rosin
which
contains
neoabietic
acid
whose
most
intense
band
of
ab-
sorption
is
at
250
mkt.
The
ultraviolet
absorption
spectrum
of
pure
abietic
acid
was
found
to
demonstrate
its
most
intense
band
at
241
nip,
a
(specific
absorption
coefficient)"
=
77.0.
This
value
is
in
good
ac-
cord
with
that
reported
by
Sandermann
9
(240
my)
and
that
calculated
(242
my)
according
to
a
method
postulated
by
Woodward'°
and
in
dis-
agreement
with
the
value
of
237.5
my
reported
by
Kraft."
(12)
L.
Ruzicka
and
R.
G.
R.
Bacon,
Hely.
Chim.
ACia,
20,
1542
(7)
L. L.
Steele,
THIS
JOURNAL,
44,
1333
(1922).
(1937).
(8)
Fr.
Balas,
easopis
Ceskoslovenskeho
Likarniciva,
7,
320
(1927).
(13)
S.
Palkin
and
T.
H.
Harris,
THIS
JOURNAL,
35,
3677
(1933).
(8a)
Defined
in
the
experimental
section.
(13a)
"Galipot"
is
a
term
used
to
describe
the
crystalline
acids
(9)
W.
Sanderniann,
Ber.,
74,
154
(1941).
which
settle
out
of
the
oleoresin,
which,
in
turn,
is
a
solution
of
resin
(10)
R.
B.
Woodward,
THIS
JOURNAL,
64,
72
(1942).
acids
in
turpentine.
(11)
K.
Kraft,
Ann.,
520,
133
(1935).
(14)
G.
C.
Harris,
U.
S.
Patent
2,419,211,
April
22,
1947.
80
70
6
60
EE
50
.9.
40
H
H
30
U
U
tg
20
10
0
335
220
240
Wave
length
in
mg.
Fig.
1.
—Ultraviolet
absorption
spectra:
1,
abietic
acid;
2,
isomerized
rosin.
Levopimaric
Acid
Although
levopimaric
acid
is
the
major
con-
stituent
of
the
gum
oleoresin
of
several
conifers,
its
isolation
has
always
been
difficult
with
yields
of
the
order
of
1%
having
been
obtained
by
Ruz-
icka,
et
al.,"
and
Palkin
and
Harris"
from
the
"galipot"'"
of
Pinus
maritima
and
Pinus
palus-
Eris,
respectively.
The
method
employed
was
based
on
the
fractional
crystallization
of
the
so-
dium
salts.
The
application
of
the
amine
salt
technique
in
this
instance
resulted
in
the
much
increased
yield
of
20%
of
pure
levopimaric
acid
[a]
24
D
—276
°
,
from
the
"galipot"
of
Pinus
palustris.
The
pro-
cedure
is
similar
to
that
used
for
the
isolation
of
abietic
acid
from
rosin
with
the
exception
that
butanolamine
(2
-
amino
-
2
-
methyl
-
1
-
propanol,
Commercial
Solvents,
Inc.)
was
used
since
it
was
found
to
be
more
specific
for
the
precipitation
of
levopimaric
acid
than
any
other
amine
tried.
In
the
event
that
the
whole
oleoresin
of
Pinus
palustris
is
used
as
the
source
of
levopimaric
acid,
the
total
acids
can
be
first
separated
from
the
turpentine
by
precipitation
as
amine
salts.
Cyclo-
hexylamine
was
found
most
suitable
for
this
pur-
pose,
since
it
results
in
a
nearly
quantitative
pre-
cipitation
of
resin
acids
as
the
very
insoluble
cyclohexylamine
salts
from
any
medium
in
which
they
exist
with
non
-resin
acid
material,
e.
g.,
gum
oleoresin
or
tall
oil."
Formation
of
the
butanol-
260
336
GEORGE
C.
HARRIS
AND
THOMAS
F.
SANDERSON
Vol.
70
amine
salt
and
regeneration
of
the
acid
as
in
the
previous
instance
gave
a
yield
of
15%
based
on
the
total
acids
or
approximately
50%
of
the
amount
reported
to
be
present.
Recently,
Fleck
and
Palkin"
reported
a
value
of
36%
of
levopim-
aric
acid
in
the
acids
fraction
of
the
oleoresin
of
Pinus
palustris
determined
by
the
quantitative
addition
of
maleic
anhydride
to
levopimaric
acid.
The
ultraviolet
absorption
spectrum
of
pure
levopimaric
acid
was
found
to
demonstrate
its
most
intense
band
at
272
ni,u,
a
=
19.2
(Fig.
2),
in
good
agreement
with
that
reported
by
Kraft."
sr
8
0
20
15
10
5
310
230
270
Wave
length
in in
A
i.
Fig.
2.
—Ultraviolet
absorption
spectrum
of
levopimaric
acid.
Neoabietic
Acid
The
presence
of
a
dextrorotatory
abietic-type
acid
in
gum
oleoresin
has
often
been
alluded
to
in
the
extensive
literature
on
resin
acids.
The
first
serious
attempt
to
isolate
it
was
made
by
Kraft,"
who
was
able
to
obtain
only
a
mixture
of
acids
with
a
positive
rotation,
[a]
24
D
11°."
R.
F.
Cox,
of
this
Laboratory,
also
isolated
a
resin
acid
with
positive
rotation,
[
a
]
24D
+83°.
This
was
ob-
tained
by
the
heat
isomerization
of
abietic
acid,
—105
°
,
at
180°
in
accordance
with
a
postu-
lation
by
Ruzicka
18
that
dextrorotatory
acids
are
formed
in
equilibrium
with
levorotatory
acids
when
the
latter
are
isomerized
at
elevated
tem-
peratures.
Cox's
method
of
isolation
of
the
dex-
tro
acid
consisted
of
crystallizing
the
unaltered
(15)
E.
E.
Fleck
and
S.
Palkin,
Ind.
Eng.
Chem.,
Anal.
Ed.,
14,
146
(1942).
(16)
K.
Kraft,
Ann.,
524,
1
(1936).
(17)
The
composition
of
Kraft's
proabietic
acid
is
the
subject
of
a
future
publication;
G.
C.
Harris
and
T.
F.
Sanderson,
Resin
Acids,
VI.
(18)
L.
Ruzica
and
J.
Meyer,
Hely.
Chim.
Acta,
5,
338,
342
(1922).
abietic
acid
from
the
mixture
to
concentrate
the
former
in
the
residue
from
which
it
was
fraction-
ally
crystallized.
It
is
not
surprising
that
further
purification
of
the
dextro
acid
was
not
obtained
because
fractional
crystallization
of
mixtures
of
resin
acids,
as
pointed
out
by
Duffour,"
always
results
in
the
isolation
of
mixed
crystals
rather
than
pure
compounds.
It
was
apparent,
then,
from
the
two
instances
cited
above,
that
the
lack
of
a
workable
technique
for
the
isolation
of
pure
resin
acids
from
mixtures
impeded
progress
in
this
direction.
Before
employing
the
amine
salt
technique
for
the
isolation
of
the
dextrorotatory
acid
from
the
gum
oleoresin
of
Pinus
palustris,
it
was
considered
best
to
attempt
its
isolation
from
the
simpler
mixture
of
acids
obtained
in
heat-isomerized
abie-
tic
acid.
Abietic
acid,
for
this
purpose,
was
heated"
at
300°
for
twenty
minutes,
and
the
unreacted
abietic
acid
(76%)
separated
from
the
mixture
as
its
insoluble
diamylamine
salt.
In
this
manner,
a
highly
dextrorotatory
residue
was
ob-
tained
which
was
treated
with
butanolamine
in
acetone
to
obtain
two
crops
of
crystalline
salts.
The
fi
rst
with
rotation
[a]
24
D
+24
°
was
discarded,
the
second
with
rotation
[a]
+100
°
was
recrys-
tallized
from
acetone
to
a
constant rotation,
[a]
24
D
+102°.
The
salt
was
decomposed
with
boric
acid
to
obtain
a
new
resin
acid,
termed
neoabietic
acid,
with
rotation
[a]24D
+1590
,
and
melting
point
167-169
°
.
Neoabietic
acid,
like
levopimaric
acid,
was
found
to
be
highly
susceptible
to
mineral
acid
and
isotnerizes
almost
completely
to
abietic
acid
in
the
presence
of
a
trace
of
strong
acid.
This
acid
was
isolated
in
5%
yield
from
the
resin
acids
of
gum
oleoresin
by
alternate
fractional
crystallization
of
the
diethylamine
and
butanol-
amine
salts.
Neoabietic
acid
can
also
be
prepared
from
commercial
gum
rosin
of
any
color
grade
by
using
the
diethylamine
salt
to
obtain
initial
concentration
and
butanolamine
to
effect
fi
nal
purification.
The
homogeneity
of
neoabietic
acid
was
es-
tablished
by
preparation
and
recrystallization
of
the
methy
ester,
m.
p.
61.5-62
°
,
and
also
of
the
butanolamine
salt,
[a]
24
D
+
102
°
,
and
regenera-
tion
in
each
case
of
acid
identical
with
the
original
in
optical
rotation
and
ultraviolet
absorption.
The
ultraviolet
absorption
spectrum
of
pure
neoa-
bietic
acid
demonstrates
its
most
intense
band
at
250
imt,
a
=
80.0
(Fig.
3).
Experimentalmn
Abietic
Acid
Acid
Isomerization
of
Wood
Rosin.
—The
extent
to
which
rosin
was
isomerized
to
produce
the
maximum
amount
of
abietic
acid
was
determined
as
follows:
A
sample
of
rosin
was
heated
under
reflux
in
alcohol
with
concentrated
hydrochloric
acid.
Samples
were
taken
at
intervals
and
the
ultraviolet
absorption
characteristics
and
specific
rotation
of
each
determined.
As
shown
in
(19)
M.
A.
Duffour,
Compi.
rend..
175,
109
(1922).
(20)
All
melting
points
are
corrected.
(21)
All
rotations
are
of
1%
solutions
in
absolute
ethanol.
Jan.,
1948
80
70
.r;
60
CJ
50
2
6
40
ce
ce
30
it.
20
10
0
ISOLATION
OF
RESIN
ACIDS
AND
NEOABIETIC
ACID
230 250
270
Wave
length
in
nip.
Fig.
3.
—Ultraviolet
absorption
spectrum
of
neoabietic
acid.
Fig.
4,
the
absorption
curves
of
samples
taken
at
one
hour
or
after
were
the
same
and
attained
the
highest
value
for
specific
absorption
coefficient,
a,
at
241
ma,
indicating
the
production
of
the
maximum
amount
of
abietic
acid,
47
th
2%,
at
the
end
of
one
hour.
The
specific
rotation
40
30
8
0
0
Q.
20
0
220
240
260
Wave
length
in
ma.
Fig.
4.
—Ultraviolet
absorption
spectra:
1,
N
wood
rosin;
2,
rosin
isomerized
for
half
an
hour;
3,
rosin
isomer-
ized
for
one,
two
and
three
hours.
of
the
samples,
Fig.
5,
also
reached
a
constant
value,
[0/1
24
o
—35
,
after
one
hour
of
heating,
again
indicating
the
formation
of
the
equilibrium
mixture
at
the
end
of
this
time.
a
m
—10
40
—30
20
9
9
50
0
40
t
a
20
10
0.
30
337
E
cf.
ci
CS
1
2
3
Time,
hours.
Fig.
5.—e,
Rate
of
change
of
specific
absorption
coef-
fi
cient
of
isomerized
rosin:
0,
rate
of
change
of
specific
rotation
of
isomerized
rosin.
The
sample
used
was
prepared
in
the
following
manner.
To
a
hot
solution
of
250
g.
of
wood
rosin
(color
grades
N
to
X,
acid
number
166)
in
740
cc.
of
95%
ethanol
was
added
42
cc.
of
concentrated
hydrochloric
acid
and
the
resulting
solution
boiled
under
reflux
for
one
and
one-half
hours.
A
stream
of
carbon
dioxide
was
passed
over
the
surface
of
the
solution
during
the
reflux
period
and
when
the
solution
was
being
cooled
to
avoid
discoloration
due
to
atmospheric
oxidation.
At
the
end
of
the
reaction
time,
the
alcohol
and
acid
were
steam
distilled,
the
water
de-
canted,
and
the
residue
dissolved
in
ether.
The
ether
solution
was
washed
free
of
acid
with
water,
dried
over
sodium
sulfate,
and
the
ether
evaporated.
The
last
traces
of
solvent
were
removed
by
melting
the
rosin
in
an
oil
-bath
at
180
to
200°
under
water
-pump
vacuum.
The
molten
rosin,
blanketed
continuously
with
carbon
dioxide,
was
poured
into
a
paper
boat
for
ease
of
handling,
to
obtain
245
g.
of
material
with
rotation
ja]ido
—35°.
Preparation
and
Purification
of
the
Diamylamine
Salt.
To
a
solution
of
the
isomerized
rosin
(245
g.)
in
375
cc.
of
acetone
at
incipient
boiling
was
added
127
g.
of
di-
amylamine
(Sharpies
Company,
Philadelphia,
Pennsyl-
vania)
slowly
with
vigorous
agitation.
On
cooling
to
room
temperature,
crystals
appeared
in
the
form
of
rosets.
The
mass
was
agitated,
cooled
in
ice
and
fi
ltered
to
obtain
a
cake
of
salts
that
was
washed
with
150
cc.
of
acetone.
The
latter
was
dried
in
a
vacuum
oven
at
50°
to
obtain
material
with
rotation
[
a
]
24D
—18°.
After
four
crystal-
lizations,
using
a
sufficient
amount
of
acetone
(ca.
4
liters
for
200
g.
of
salt)
to
obtain
an
almost
clear
solution
and
evaporating
to
incipient
precipitation
(ca.
2
liters
of
solution),
118
g.
of
the
pure
amine
salt
of
abietic
acid
was
obtaineil
with
rotation
[a]
"D
60°
.
On
recovery
and
recrystallization
of
the
back
crops
to
material
with
rota-
tion
[a]
24
D
—60°,
an
additional
29
g.
of
pure
salt
was
obtained,
making
a
total
of
147
g.
In
obtaining
the
later
crops
of
salt
by
concentration
of
the
mother
liquors,
some
amine
is
lost
by
evaporation
that
should
be
replaced
by
the
addition
of
a
few
drops
to
the
concentrated
solution.
Isolation
of
Abietic
Acid.
—To
a
cooled
solution
of
the
amine
salt
of
abietic
acid
(147
g.)
in
one
liter
of
95%
ethanol
was
added
39
g.
of
glacial
acetic
acid
at
once
with
stirring
and
900
cc.
of
water
slowly
at
first
with
vigorous
agitation
to
incipient
precipitation
and
then
more
freely.
The
crystals
were
fi
ltered
at
once
and
washed
with
a
liter
of
water
to
free
them
of
traces
of
acetic
acid.
The
acid
was
recrystallized
from
750
cc.
of
95%
ethanol
by
the
slow
addition
of
600
cc.
of
water
as
above
and
dried
in
a
vacuum
desiccator
at
room
temperature
over
sodium
hy-
droxide
in
an
oxygen
-free
atmosphere.
Undue
exposure
to
higher
temperatures
will
result
in
isomerization,
and
contact
with
air
will
result
in
the
oxidation
of
the
material.
In
this
manner,
98
g.
(40%
by
weight
of
isomerized
rosin;
theoretical
47%)
of
abietic
acid
was
obtained
with
rota-
338
GEORGE
C.
HARRIS
AND
THOMAS
F.
SANDERSON
Vol.
70
tion
[a]
21
D
—106
°
.
For
storage
purposes,
the
acid
should
be
kept
in
vials
under
good
vacuum.
Absorption
Spectra.
—The
absorption
spectrum
data
were
obtained
from
measurements
made
with
a
Beckman
ultraviolet
spectrophotometer.
The
formulas
employed
in
making
the
calculations
use
the
term
a,
specific
absorp-
tion
coefficient.
a
=
log
in
/
0
///c/
/
0
=
intensity
of
radiation
transmitted
by
the
solvent
(95%
ethanol)
I
=
intensity
of
radiation
transmitted
by
the
solution
c
=
concentration
of
solute
in
grams
per
liter
/
=
length
in
centimeters
of
solution
through
which
the
radiation
passes
Levopimaric
Acid
Preparation
and
Purification
of
the
Butanolamine
Salt.
—To
a
solution
of
125
g.
of
"galipot"
in
250
g.
of
acetone
was
added
37
g.
of
butanolamine
(2-amino-2-methyl-l-
propanol)
in
37
g.
of
acetone.
22
The
suspension
was
cooled,
the
salt
fi
ltered,
and
a
second
crop
taken
by
con-
centrating
the
solution
to
half
its
volume.
The
salt
was
fractionally
crystallized
from
methyl
acetate
to
obtain
31
g.
of
material
with
rotation
(«IN:,
-218°.
Isolation
of
Levopimaric
Acid.
—The
decomposition
of
the
amine
salt
of
levopimaric
acid
was
carried
out
with
boric
acid.
23
The
salt
was
suspended
in
ether
and
shaken
vigorously
with
a
saturated
boric
acid
solution
until
the
amine
salt
crystals
had
disappeared.
To
assure
complete
decomposition
of
the
salt,
the
ether
solution
was
washed
twice
more
with
boric
acid.
The
ether
solution
containing
the
resin
acid
was
washed
free
of
boric
acid
with
water,
dried
and
the
ether
evaporated."
The
acid
was
crystal-
lized
by
dissolving
it
in
warm
ethanol
and
adding
water
to
incipient
turbidity,
to
obtain,
upon
cooling
to
room
tem-
perature,
24
g.
of
levopimaric
acid
(20%
of
the
"galipot")
with
rotation
[a]
34
D
-276°.
Isolation
of
Primary
Resin
Acids
from
Gum
Oleoresin.
When
the
oleoresin
is
to
be
used
as
the
source
of
levo-
pimaric
acid,
the
resin
acids
are
separated
from
the
tur-
pentine
according
to
the
following
procedure
and
used
as
in
the
following
section.
To
a
solution
of
200
g.
of
the
gum
oleoresin
of
Pinus
palustris
in
600
g.
of
narrow
-range
gasoline
(boiling
range
90-400°)
at
40°
was
added
41
g.
of
cyclohexylamine
(Monsanto
Chemical
Co.)
in
41
g.
of
gasoline.
22
The
mass
of
crystalline
salts
was
agitated
and
the
suspension
cooled
in
ice
before
the
salts
were
fi
ltered
and
washed
with
200
g.
of
fresh
solvent.
The
salts
were
fi
rst
air-dried
overnight
to
remove
the
solvent
and
then
decomposed
in
the
same
manner
as
the
butanolamine
salts
taking
the
usual
precautions
for
com-
plete
decomposition
and
rise
in
temperature
of
the
concen-
trated
solutions.
The
last
traces
of
ether
were
evaporated
by
puffing
the
residue
to
a
powder
under
water
-pump
vacuum.
In
this
way
was
obtained
124
g.
of
resin
acids
(62%
of
the
total
oleoresin)
with
acid
number
185
and
neutral
equivalent
302.
Preparation
and
Purification
of
Amine
Salt
and
Isolation
of
Levopimaric
Acid.
—The
butanolamine
salts
of
the
resin
acids
fraction
(124
g.)
were
prepared
as
in
the
case
of
"galipot"
using
the
same
ratio
of
amine
and
solvent.
The
decomposition
of
the
salts
was
carried
out
with
the
same
precautions
and
the
regenerated
acid
crystallized
from
ethanol
and
water
to
obtain
18.6
g.
of
pure
levo-
pimaric
acid
(15%
of
the
total
oleoresin
acids)
with
rota-
tion
[a1
24
o
-276°.
(22)
The
formation
of
the
amine
salts
is
an
exothermic
reaction
and
great
care
must
be
taken
that
the
temperature
does
not
rise
above
50
°
to
alter
the
levopimaric
acid
(this
applies
to
neoabietic
acid
as
well)
which
is
highly
susceptible
to
isomerization
by
heat.
(23)
Levopimaric
acid
(this
applies
to
neoabietic
acid
as
well)
is
highly
susceptible
to
mineral
acid
and
isomerizes
almost
completely
to
abietic
acid
in
the
presence
of
a
trace
of
strong
acid.
Such
precautions
against
acid
isomerization
must
be
taken
in
regenerating
the
resin
acid
from
its
amine
salt.
Boric
acid,
therefore,
the
weakest
acid
that
can
effect
the
decomposition
of
the
amine
salts,
is
always
employed.
Neoabietic
Acid
Heat
Isomerization
of
Abietic
Acid;
Isolation
of
Amine
Salt
of
Neoabietic
Acid.
—A
50.0-g.
sample
of
abietic
acid,
[a]
84
D
-106°,
prepared
according
to
the
method
described
in
this
paper,
was
heated
at
300
°
for
twenty
minutes
under
a
stream
of
carbon
dioxide
gas.
At
the
end
of
this
time
the
molten
material
was
poured
in
a
paper
boat
to
cool,
chipped
and
dissolved
in
100
cc.
of
acetone.
Diamylamine
(27
g.)
was
added
to
precipitate
the
un-
reacted
abietic
acid
as
its
insoluble
salt.
Two
successive
crops
of
salts
were
obtained,
totalling
58.1
g.
and
cor-
responding
to
76%
of
unaltered
abietic
acid.
The
mother
liquor
was
diluted
with
50
cc.
of
acetone
and
treated
with
3.6
g.
of
butanolamine
to
form
the
butanol-
amine
salts
of
the
residual
resin
acids
combined
as
di-
amylamine
salts.
A
first
crop
with
rotation
[a]24D
+24°
was
discarded,
and
the
second,
with
rotation
l a
j
24
+100°,
obtained
by
concentrating
the
mother
liquor
to
half
the
volume,
was
recrystallized
from
acetone
to
a
constant
rotation,
[a]
24
D
+102
° .
Isolation
of
the
New
Abietic-Type
Acid,
Neoabietic
Acid.
—The
butanolamine
salt
was
suspended
in
ether
and
decomposed
with
a
saturated
solution
of
boric
acid
in
the
usual
manner."
The
ether
solution
containing
the
resin
acid
was
washed
free
of
boric
acid
with
water,
dried
over
sodium
sulfate,
and
the
ether
evaporated."
The
residue
was
crystallized
from
alcohol
and
water
to
obtain
the
pure
neoabietic
acid
with
rotaticn
[a]
24
D
+159°,
melting
point
167-169°,
neutral
equivalent
302,
calcd.
302,
in
about
1%
yield.
Anal.
Calcd.
for
C20113002:
C,
79.39;
H,
10.00.
Found:
C,
79.46,
79.40;
H,
9.97,
9.97.
Isolation
of
Neoabietic
Acid
from
the
GumOleoresin.—
The
resin
acids
of
the
gum
oleoresin
of
Pinus
palustris
were
separated
from
the
turpentine
according
to
the
method
described
in
the
previous
section
on
levopimaric
acid
and
used
in
the
following
manner
for
the
isolation
of
neoabietic
acid.
To
a
solution
of
the
total
acids,
124
g.,
in
248
g.
of
acetone
was
added
37
g.
of
butanolamine
in
37
g.
of
ace-
tone.
The
first
three
crops
of
salt,
with
rotations
[a]
24
n
-218,
-210
and
-60°,
highly
concentrated
with
the
salt
of
levopimaric
acid,
were
isolated.
Further
concen-
tration
of
the
mother
liquor,
with
intermittent
addition
of
small
amounts
(2
g.)
of
butanolamine
to
replace
that
lost
by
evaporation,
resulted
in
the
isolation
of
the
two
dextrorotatory
crops,
with
rotations
[a]
94
D
+12
and
+15°.
Since
no
further
increase
in
dextrorotation
could
be
realized,
these
salts
were
combined
and
decomposed
with
boric
acid
in
the
usual
manner.
The
more
specific
diethylamine
was
used
to
prepare
the
salts
of
the
regener-
ated
acids.
Four
recrystallizations
from
acetone
resulted
in
the
isolation
of
salts
with
rotation
[a]
24
n
+70°,
which
again
could
not
be
increased
by
further
fractionation.
These
salts
were
then
decomposed
with
boric
acid,
the
butanolamine
salts
prepared,
and
the
latter
recrystallized
from
acetone
to
the
top
rotation
of
[a]
24
D
+102°.
The
pure
salt
of
neoabietic
acid
(8.2
g.)
was
decomposed
with
boric
acid
to
obtain
6.1
g.
(5%
of
the
total
oleoresin
acids)
of
pure
acid
with
rotation,
(«]
84
n
+159°.
Preparation
of
the
Methyl
Ester
of
Neoabietic
Acid.
Five
grams
of
neoabietic
acid,
[a]
24
o
+159°,
was
dissolved
in
50
cc.
of
ether;
the
resulting
water
-white
solution
was
treated
with
an
excess
of
an
ether
solution
of
diazomethane
as
evidenced
by
a
permanent
yellow,
coloration.
After
standing
for
twenty
minutes,
the
solution
was
evaporated
to
dryness."
The
seed
crystal
was
obtained
by
cooling
a
methanol
solution
of
one
drop
of
li
quid
ester
to
-30
in
an
acetone
-Dry
Ice
-bath.
The
ester,
then,
was
readily
crystallized
from
methanol
with
the
aid
of
the
seed
crystal
in
excellent
yield
(5.0
g.)
with
a
constant
melting
point,
61.5-62°.
Anal.
Calcd.
for
C
34
l-1
32
0
2
:
C,
79.69;
H,
10.19.
Found:
C,
79.70,
79.65;
H,
10.07,
10.17.
The
purity
and
homogeneity
of
neoabietic
acid
was
established
in
the
following
manner.
Material
with
rotation
[
a
]
24,
+159°
was
used
to
prepare
the
butanol-
Jan.,
1948
THE
STRUCTURE
OF
NEOABIETIC
ACID
339
amine
salt
which
was
recrystallized
several
times
to
obtain
the
constant
rotating
salt
(same
as
that
from
which
the
acid
was
isolated),
[a]
44
D
+102
°
.
The
resin
acid
was
regenerated
in
the
usual
manner
with
the
same
rotation,
[
a
]
24D
+159°,
and
the
'same
ultraviolet
absorption
char-
acteristics,
particularly
the
height
of
the
most
intense
band,
250
mil,
at
a
=
80.0.
The
methyl
ester,
prepared
with
diazomethane
as
above,
was
obtained
with
the
same
constant
melting
point
61.5-62
°
.
Saponification
in
alcoholic
alkali
with
alkali
in
a
sealed
tube
at
50°
for
ninety-six
hours
with
subsequent
acidification
with
carbon
dioxide
and
boric
acid
resulted
in
the
quantitative
isolation
of
neoabietic
acid
with
unchanged
rotation,
[a]
24
D
+159
°
.
Isolation
of
Neoabietic
Acid
from
Gum
Rosin.
—A
200-g.
sample
of
gum
rosin
was
dissolved
in
400
g.
of
acetone
and
treated,
at
50°,
with
45
g.
of
diethylamine
in
an
equal
weight
of
acetone.
The
complete
precipitation
of
salts
was
allowed
to
take
place
over
a
long
period
of
time
(twenty-four
hours)
at
room
temperature.
No
at-
tempt
was
made
to
hasten
the
crystallization
by
cooling
because
the
necessary
fractionation
was
not
obtained
in
this
manner.
The
salts
were
fractionated
from
acetone
to
a
rotation
[,]240
+70°
and
converted
to
the
butanol-
amine
salts
by
dissolving
in
acetone
and
adding
the
necessary
amount
of
butanolamine.
The
latter
were,
in
turn,
crystallized
to
a
rotation
[a]
24
D
+102°
and
the
pure
neoabietic
acid
isolated
in
5%
yield
(10.0
g.)
with
rotation
[c]24D
+159°.
Summary
1.
An
improved
method,
based
on
the
amine
salt
technique,
for
the
isolation
of
abietic
acid
from
acid-isomerized
wood
rosin
and
levopimaric
acid
from
the
gum
oleoresin
of
Pinus
palustris
is
described.
2.
The
isolation
of
a
new,
abietic-type
acid,
termed
neoabietic
acid,
from
heat-isomerized
abietic
acid,
the
gum
oleoresin
of
Pinus
palustris
and
gum
rosin
is
described.
3.
The
ultraviolet
absorption
spectra,
utilizing
speciuc
absorption
coefficients,
a,
have
been
de-
termined
for
each
of
the
three
abietic-type
acids.
WILMINGTON,
DELAWARE
RECEIVED"
AUGUST
12,
1947
(24)
Ori
g
inal
manuscript
received
August
9,
1948.
[CONTRIBUTION
FROM
THE
HERCULES
EXPERIMENT
STATION,
HERCULES
POWDER
COMPANY]
Resin
Acids.
II.
The
Structure
of
Neoabietic
Acid
BY
GEORGE
C.
HARRIS
AND
THOMAS
F.
SANDERSON
Neoabietic
acid'
has
been
isolated
from
the
oleoresin
and
rosin
of
Pinus
palustris.
It
has
now
been
proved
that
this
acid
is
an
abietic-type
acid
since
upon
dehydrogenation
with
palladium
—car-
bon
catalyst
retene,
1-methyl-7-isopropylphenan-
threne,
was
isolated.
The
presence
of
two
double
bonds
was
shown
by
catalytic
hydrogenation
to
the
tetrahydro
acids
and.
by
absorption
in
the
ultraviolet
region.'
The
intense
band
(Fig.
1,
Curve
1)
at
250
mg,
indicated
also
that
the
two
double
bonds
are
conjugated
between
two
rings
or
that
one
is
exocyclic
with
respect
to
the
other
in
analogy
with
the
absorption
of
abietic
acid
at
241
mg
and
in
contrast
with
that
of
levopimaric
acid
at
272
mg.
With
this
information,
the
structures
I
—V
came
into
consideration.
From
the
work
of
R.
B.
Woodward'
predictions
can
be
made
concerning
the
wave
length
of
the
most
intense
band
of
absorption
of
this
type
of
CHs
COOH
></\
I
III
CH
II
CH
C(11
NCH,
242
iniA
I
CH3 COOH
CH3
/CH3
CH
\
CH3
247
nus
II
(1)
G.
C.
Harris
and
T.
F.
Sanderson,
Resin
Acids.
I.
THIS
JOURNAL,
70,
334
(1948).
(2)
The
ultraviolet
absorption
data
were
determined
by
Dr.
Evelyn
V.
Cook
of
this
Laboratory.
(8)
R.
B.
Woodward,
THIS
JOURNAL,
64,
72
(1942).
CH3 COOH
CH3
237
mil
III
/
CH:
—CH
\
•C113
CH3
COOH
></\
CH3
CH3 COOH
></\
\./
CH3
/
CHI
C
\./
\CHs
252
mg
IV
/CH3
=C
\
CH3
242
mg
V
conjugated
system.
These
predictions
are
based
on
the
degree
of
substitution
of
the
double
-bond
carbon
atoms;
they
are
given
below
each
form-
ula.
Since
neoabietic
acid
demonstrates
its
most
intense
band
at
250
mg
and
since
the
predicted
value
for
abietic
acid,
I,
was
so
close
to
that
found,
241
mg,
formula
IV
was
at
once
suspected
as
that
for
neoabietic
acid.
If
formula
IV
were
that
for
neoabietic
acid,
ozonization
and
decomposition
of
the
ozonide
with
water
would
result
in
the
formation
of
ace-
tone,
as
one
of
the
products.
The
experiment
was
carried
out
and
acetone
was
isolated
as
its
2,4-