U.S. patent application number 09/803235 was filed with the patent office on 2003-05-15 for method of synthesizing diglycerol tetranitrate, and solid rocket motor propellant containing the same.
Invention is credited to Martins, Laura J., Sanderson, Andrew J..
Application Number | 20030089435 09/803235 |
Document ID | / |
Family ID | 26887156 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030089435 |
Kind Code |
A1 |
Sanderson, Andrew J. ; et
al. |
May 15, 2003 |
Method of synthesizing diglycerol tetranitrate, and solid rocket
motor propellant containing the same
Abstract
Diglyercol tetranitrate is an energetic nitrate ester
plasticizer having no freezing point, making the nitrate ester
plasticizer especially suited for use in solid rocket motor
propellants that are subjected to low temperature storage and
operational environments, which can reach as low as -54.degree. C.
in temperature. In order to avoid problems associated with fume-off
that characterize the conventional synthesis method of making
diglycerol tetranitrate, synthesis is performed in a medium
including a mixed acid phase and an inert organic phase. The mixed
acid phase contains, as ingredients, at least one nitronium ion
source and at least one acid having sufficient strength to generate
nitronium ions from the nitronium ion source. The nitronium ions in
the mixed acid nitrate diglycerol to form diglycerol tetranitrate,
which is then received into the organic liquid. The organic liquid,
which preferably is a chlorocarbon such as dichloromethane, is
insoluble with diglycerol but soluble with diglycerol tetranitrate.
The inert organic phase is then treated to neutralize any acid
contained in the inert organic phase, and the diglycerol
tetranitrate is separated from the inert organic phase.
Inventors: |
Sanderson, Andrew J.; (North
Ogden, UT) ; Martins, Laura J.; (Ogden, UT) |
Correspondence
Address: |
SULLIVAN LAW GROUP
1850 NORTH CENTRAL AVENUE
SUITE 1140
PHOENIX
AZ
85004
US
|
Family ID: |
26887156 |
Appl. No.: |
09/803235 |
Filed: |
March 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60191548 |
Mar 23, 2000 |
|
|
|
Current U.S.
Class: |
149/19.1 |
Current CPC
Class: |
C07C 201/02 20130101;
C07C 203/04 20130101; C06B 45/105 20130101; C07C 201/02
20130101 |
Class at
Publication: |
149/19.1 |
International
Class: |
C06B 045/10 |
Claims
What is claimed is:
1. A method of synthesizing diglycerol tetranitrate, comprising:
forming a nitrating medium comprising a mixed acid phase and an
inert organic phase, the mixed acid phase comprising, as
ingredients, at least one nitronium ion source and at least one
acid having sufficient strength to generate nitronium ions from the
nitronium ion source, the inert organic phase comprising at least
one organic liquid in which diglycerol is insoluble yet in which
diglycerol tetranitrate is soluble; combining the nitrating medium
with diglycerol and nitrating the diglycerol in the mixed acid
phase to form diglycerol tetranitrate, which is received into the
inert organic phase; separating the inert organic phase having the
diglycerol tetranitrate dissolved therein from the mixed acid
phase; and recovering the diglycerol tetranitrate from the inert
organic phase.
2. The method of claim 1, further comprising neutralizing any of
the acid or nitronium ion source present in the inert organic phase
subsequent to said separating of the inert organic phase from the
mixed acid phase.
3. The method of claim 1, wherein the nitronium ion source
comprises nitric acid and further wherein the acid comprises
sulfuric acid.
4. The method of claim 3, wherein a molar ratio of the nitronium
ion source to the diglycerol is at least 4:1 and not greater than
about 8:1.
5. The method of claim 3, wherein a weight ratio of the nitric and
sulfuric acids to water in the mixed acid phase is from about 100:0
to about 80:20.
6. The method of claim 3, wherein the organic liquid comprises at
least one organic chlorocarbon.
7. The method of claim 6, wherein the chlorocarbon is
dichloromethane.
8. The method of claim 3, wherein a weight ratio of the inert
organic phase to the diglycerol tetranitrate is preferably at least
1:1.
9. The method of claim 3, wherein said nitrating of the diglycerol
further comprises maintaining the nitrating medium in a range of
from about 5.degree. C. to about 20.degree. C.
10. The method of claim 3, further comprising neutralizing any of
the acid or nitronium ion source present in the inert organic phase
subsequent to said separating of the inert organic phase from the
mixed acid phase.
11. A rocket motor assembly comprising a rocket motor case, a solid
propellant grain loaded in the rocket motor case, and a nozzle in
operative association with the rocket motor case to receive and
discharge combustion products generated upon ignition of the solid
propellant grain, the solid propellant grain comprising diglycerol
tetranitrate plasticizer.
12. The rocket motor assembly of claim 11, wherein the diglycerol
tetranitrate plasticizer is synthesizing by a method comprising:
forming a nitrating medium comprising a mixed acid phase and an
inert organic phase, the mixed acid phase comprising, as
ingredients, at least one nitronium ion source and at least one
acid having sufficient strength to generate nitronium ions from the
nitronium ion source, the inert organic phase comprising at least
one organic liquid in which diglycerol is insoluble yet in which
diglycerol tetranitrate is soluble; combining the nitrating medium
with diglycerol and nitrating the diglycerol in the mixed acid
phase to form diglycerol tetranitrate, which is received into the
inert organic phase; separating the inert organic phase having the
diglycerol tetranitrate dissolved therein from the mixed acid
phase; and recovering the diglycerol tetranitrate from the inert
organic phase.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The benefit of priority is claimed based on U.S. Provisional
Application No. 60/191,548 filed in the U.S. Patent & Trademark
Office on Mar. 23, 2000, the complete disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a method of synthesizing
diglycerol tetranitrate, which is an excellent plasticizer for
energetic materials such as rocket motor propellants, explosives,
and pyrotechnics. This invention is also directed to a solid rocket
motor propellant comprising diglycerol tetranitrate as the
plasticizer.
[0004] 2. Description of the Related Art
[0005] Energetic materials used in solid rocket motor propellants,
explosives, and pyrotechnics comprise an energetic material that,
when ignited, releases sufficient amounts of energy to provide, in
the case of a propellant, the interior pressures needed to attain
rocket motor flight or, in the case of an explosive, sufficient
energy to demolish an intended target. Generally, energetic
materials comprise, among other ingredients, a fuel and oxidizing
agent immobilized in a polymeric binder. Selection of an
appropriate binder can enhance the mechanical properties of the
energetic material. Enhanced mechanical properties are important
for maintaining the structural integrity of the energetic materials
during operation and storage, especially when the energetic
materials are subjected to operation and storage conditions
characterized by extremely low and high temperatures. Other
ingredients are added to the composite solid propellant, as are
needed or desired, to provide additional energy performance,
improve the mechanical properties of the propellant, and/or
simplify processing.
[0006] Among the additional ingredients commonly found in energetic
materials are plasticizers. In particular, nitrate ester
plasticizers have found wide acceptance as energetic plasticizers
due to the ability of nitrate ester plasticizers to enhance
energetic performance. Nitrate ester plasticizers provide the added
benefits of improving rheological properties during processing,
preventing crystallization of the binder, and enhancing mechanical
properties of the energetic material.
[0007] Due to the low temperatures at which energetic materials are
sometimes stored, as well as the low temperatures that energetic
materials existing as rocket motor propellants experience during
high altitude operation, military specifications sometimes require
that energetic materials be resistant to prolonged exposure to
temperatures as low as -54.degree. C. Inferior low temperature
mechanical properties, such as poor tensile strength and low strain
capability, can generate mechanical strain in the energetic
material at low temperatures and can promote the likelihood of
fracture to the energetic material. For instance, in the case of a
solid propellant grain, fractures in the propellant grain can, if
widespread, significantly increase the propellant grain surface
area available for combustion reaction. As a consequence, the
chamber pressure created during combustion of a propellant grain
can be increased to unanticipated levels, leading in extreme cases
to catastrophic failure of the rocket motor in which the propellant
grain is loaded upon ignition.
[0008] The most commonly used conventional nitrate ester
plasticizers reach their freezing points well above the military
design specification of -54.degree. C. In particular, nitroglycerin
has a freezing point of about -13.degree. C. Butanetrioltrinitrate
(BTTN) has a freezing point of -27.degree. C. The freezing point of
trimethylolethanetrinitrate (TMETN) is about -15.degree. C. Upon
freezing, these common nitrate ester plasticizers tend to
crystallize and migrate into agglomerations, disrupting the
homogeneity of the energetic material and increasing the risk of
fracture to the energetic material.
[0009] As reported in Seymour M. Kaye, The Encyclopedia of
Explosives and Related Items (U.S. Army Armament Research &
Development Command 1983), between 1920 and World War II a
currently less used nitrate ester plasticizer, diglycerol
tetranitrate, was used in combination with nitroglycerin as a
nitrate ester plasticizer for nitrocellulose-based explosives.
Unlike nitroglycerin, BTTN, and TMETN, diglycerol tetranitrate does
not have a freezing point, much less a freezing point below
-54.degree. C. However, to the knowledge of the inventors, use of
diglycerol tetranitrate has ceased and publications discussing
diglycerol tetranitrate have been few since approximately the end
of World War II. The cessation of activity relating to diglycerol
tetranitrate is believed by the inventors to be attributable to
drawbacks associated with the conventional synthesis method for
making diglycerol tetranitrate. Conventional synthesis calls for
the nitration of diglycerol in a mixed acid comprising nitric acid
to make diglycerol tetranitrate, followed by quenching of the mixed
acid in water to recovery the diglycerol tetranitrate. However, a
significant portion of the diglycerol tetranitrate formed in the
mixed acid is not recovered by quenching the mixed acid. The
difficulty in recovering diglycerol tetranitrate by quenching of a
mixed acid is responsible not only for relatively low yields of
about 80 molar percent, as reported in the art, but also for
fume-off problems. Residual nitric acid remaining in the spent
mixed acid reacts with unrecovered diglycerol tetranitrate in an
exothermic reaction that is autocatalytic. This exothermic reaction
generates large amounts of nitrogen oxide and water in a process
known as a fume-off. Due to the autocatalytic nature of this
reaction and the formation of large amount of nitrogen oxide, if
left uncontrolled the fume-off can lead to violent explosion and
other problems. Accordingly, great care in the handling and
disposal of the waste acid is required to avoid unintentional
explosion. Another problem of the conventional synthesis method
stems from the solubility of the diglycerol tetranitrate in the
mixed acid. During quenching an emulsion tends to form in the spent
mixed acid. The emulsion is difficult and slow to separate from the
spent mixed acid, thus increasing process time and the likelihood
for fume-off.
[0010] It would, therefore, be a significant improvement in the art
to provide a method of synthesizing diglycerol tetranitrate in
which the risk of fume-off is significantly reduced and which
provides much higher, almost quantitative yields.
SUMMARY OF THE INVENTION
[0011] An object of this invention is to fulfill a long-felt need
in the art by providing a method of synthesizing diglycerol
tetranitrate that attains the above-discussed improvement.
[0012] In accordance with the principles of this invention, the
above and other objects are attained by nitrating diglycerol in a
nitrating (or reaction) medium comprising a mixed acid phase and an
inert organic phase. The mixed acid phase comprises, as
ingredients, at least one nitronium ion source capable of nitrating
each of the four hydroxyl groups of diglycerol and at least one
acid having sufficient strength to generate nitronium ions from the
nitronium ion source. The inert organic phase comprises at least
one organic liquid that is immiscible with the mixed acid phase, so
that the inert organic phase and mixed acid phase are stratified.
The organic liquid should neither dissolve nor nitrate the
diglycerol. In practice, the inert organic phase provides a liquid
medium for receiving from the mixed acid phase the diglycerol
tetranitrate generated by nitration of the diglycerol.
[0013] There are several advantages that are derived from
practicing the inventive process. For example, the diglycerol
tetranitrate has greater solubility in the inert organic phase than
the mixed acid phase, and upon synthesis migrates from the mixed
acid phase to the inert organic phase. As a consequence, heat and
diglycerol tetranitrate generated during the exothermic nitration
reaction migrate from the mixed acid phase and into the inert
organic phase, thereby reducing the likelihood of fume-off and
degradation of diglycerol tetranitrate in the mixed acid phase.
Additionally, the migration of the diglycerol tetranitrate into the
inert organic phase simplifies and improves the efficiency of
diglycerol tetranitrate recovery, thereby providing improved yields
compared to the conventional synthesis route. For example,
diglycerol tetranitrate yields are routinely on the order of 95%
molar or greater according to the inventive method, and often
approach or attain quantitative maximum yields. The spent mixed
acid phase can then be neutralized and disposed of with lesser
concerns over fume off and other safety issues.
[0014] Synthesis by the method of this invention is particularly
useful for making diglycerol tetranitrate for solid rocket motor
propellants, especially tactical propellants designed for enduring
storage and operating temperatures as low as -54.degree. C.
Additionally, propellants comprising diglycerol tetranitrate have
significantly better safety handling properties compared to other
energetic plasticizers, such as BTTN. In this regard, diglycerol
tetranitrate exhibits a surprisingly low sensitivity to ignition
and detonation from accidental impact and shock stimuli. Diglycerol
tetranitrate is also characterized by high viscosity and low vapor
pressures, improving the handleability and processability of
diglycerol tetranitrate in the production of solid rocket motor
propellants.
[0015] Other objects, aspects, and advantages of this invention
will become more apparent to those skilled in the art upon reading
the specification and appended claims which, when taken in
conjunction with the accompany drawing, explain the principles of
this invention.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The accompanying drawing serves to elucidate the principles
of this invention by illustrating a rocket motor assembly in which
a solid propellant comprising diglycerol tetranitrate plasticizer
made in accordance with the method of this invention may be
loaded.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Diglycerol is a tetraol ether usually found as a mixture of
three isomers: 3,3'-oxy-di(1,2-propanediol),
2,2'-oxy-di(1,3-propanediol), and
2-(hydroxymethyl)-3-oxyhexane-1,5,6-triol. As referred to herein,
diglycerol includes one or a combination of more than one of these
isomers.
[0018] Among nitronium ion sources that can be used in accordance
with the present invention to nitrate the diglycerol are nitric
acid and nitronium salts, such as nitronium nitrate and nitronium
tetrafluoroborate. The generation of nitronium ions from the
nitronium ion source is performed with a strong acid. Although
sulfuric acid is preferred, other strong acids and anhydrides
capable of generating nitronium ions from the nitronium ion source,
while being substantially inert with the nitronium ions, may be
used as the strong acid in addition to or as an alternative for
sulfuric acid. Other acids that can be used to generate nitronium
ions from the nitronium ion source include methane sulfonic acid
(CH.sub.3SO.sub.2OH), acetic anhydride, acetic acid, and phosphoric
acid, as well as combinations thereof.
[0019] The molar ratio of nitronium ion source (e.g., nitric acid)
to diglycerol is at least a stoichiometric amount of 4:1 (four
nitronium ions for the four hydroxyl groups of each diglycerol),
but preferably is not greater than about 10:1, more preferably 8:1,
for economic reasons.
[0020] For practical reasons relating to availability and
handleability, preferably nitric acid is used in combination with
sulfuric acid to form a mixed acid phase. Various grades of nitric
acid and sulfuric acid can be used to make the mixed acid phase,
the proportions of mixed acid (nitronium ion source and strong
acid) to water in the mixed acid phase can be from about 100:0 to
about 80:20 by weight.
[0021] Prior to the addition of diglycerol to the mixed acid phase,
the mixed acid phase is combined with at least one organic liquid,
which is immiscible with the mixed acid and stratifies the mixed
acid phase to form a separate inert organic phase. The inert
organic phase preferably comprises dichloromethane (also known as
methylene chloride), although other chlorocarbons such as
chloroform and dichloroethane may be used alone or in combination
with dichloromethane to provide the inert organic phase. Further,
the chlorocarbons of the inert organic phase should be inert and
non-solvents with respect to the diglycerol reagent, yet should be
capable of dissolving the diglycerol tetranitrate into solution
without degrading (or solvolyzing) the diglycerol tetranitrate. One
of the advantages associated with the presence of the inert organic
phase is that upon synthesis, the diglycerol tetranitrate product
is removed from the mixed acid phase as the product is received
into the inert organic phase, thus eliminating the risks and
hazards of fume-off that would otherwise be associated with
retention of the diglycerol tetranitrate in the mixed acid
phase.
[0022] A sufficient volume of inert organic phase should be present
to permit all of the diglycerol tetranitrate product to be received
into the inert organic phase. On the other hand, there is no upper
limit on the amount of inert organic phase, except as dictated by
economic inefficiencies and waste management. The weight ratio of
inert organic phase to diglycerol tetranitrate is preferably at
least 1:1.
[0023] During the addition of the diglycerol to the nitrating
medium, the temperature of the nitrating medium is preferably
maintained in a range of from about 5.degree. C. to about
20.degree. C., more preferably 10.degree. C. to 15.degree. C. This
may be accomplished, for example, by conducting the nitration
reaction in a jacketed reactor.
[0024] The inert organic phase containing the diglycerol
tetranitrate can be separated from the mixed acid phase by
liquid/liquid separation techniques known in the art, including
phase inversion, in which a sufficient amount of water is added to
the reaction medium to quench the mixed acid phase and cause the
inert organic phase to become denser than the mixed acid phase.
Separation funnels can be used to separate the inverted phases.
[0025] Any residual acid in the separated inert organic phase can
then be neutralized by addition of one or more suitable
neutralization agents, typically in the form of a weak base or weak
bases. Representative neutralization agents include: carbonates,
such as sodium carbonate and potassium carbonate, and calcium
carbonate; and bicarbonates, such as sodium bicarbonate, and
potassium bicarbonate.
[0026] The glycerol tetranitrate can then be separated from the
organic liquid (e.g., methylene chloride), for example, by
evaporation. In the case of the use of methylene chloride,
evaporation can be performed under reduced pressures at
temperatures of about 30.degree. C.
[0027] The diglycerol tetranitrate is especially useful as a
plasticizer for solid rocket motor propellants, including
elastomer-based composite propellants, modified composite
propellants, crosslinked double-base propellants, and other
plasticized propellants.
[0028] Representative nitrate ester plasticizers that optionally
can be used in combination with the diglycerol tetranitrate to
further plasticize the energetic composition include, by way of
example, nitroglycerine, trimethylolethanetrinitrate,
triethyleneglycoldinitrate, diethyleneglycol-dinitrate,
ethyleneglycol dinitrate, butanetrioltrinitrate, alkyl NENA's, or
combinations thereof. The propellant can also include one or more
inert plasticizers, such as triacetin (glycerol triacetate),
dioctyladipate, isodecylperlargonate, dioctylphthalate,
dioctylmaleate, dibutylphthalate, di-n-propyl adipate,
diethylphthalate, dipropylphthalate, CITROFLEX.RTM., diethyl
suberate, diethyl sebacate, diethyl pimelate, or combinations
thereof.
[0029] Solid rocket motor propellants also commonly include
inorganic oxidizers and metal fuels. Representative inorganic
oxidizers include, by way of example, ammonium perchlorate,
ammonium nitrate, hydroxylammonium nitrate, ammonium dinitramide,
potassium dinitramide, potassium perchlorate, or combinations
thereof. Representative fuels include metals, such as aluminum,
magnesium, boron, titanium, silicon, and alloys and/or mixtures
thereof. The fuel and oxidizer may be present as powder, or in
particulate or other forms. Other ingredients known in the art that
optionally can be included in the solid propellant in various
combinations include the following: bonding agents such as TEPANOL;
energetic fillers such as nitramines; thermal stabilizers such as
N-methyl-p-nitroaniline; ballistic modifiers such as titanium
dioxide, lead compounds, and bismuth compounds; reinforcing fibers;
and pressure oscillation stabilizers, such as zirconium carbide and
alumina. Methods of making and casting solid rocket motor
propellants, as well as acceptable combinations and concentrations
of ingredients, are within the purview of those skilled in the art
of rocket motor science.
[0030] An example of a rocket motor assembly comprising a solid
rocket motor propellant containing diglycerol tetranitrate is shown
in the FIGURE, in which the rocket motor assembly is generally
designated by reference numeral 10. The assembly 10 includes a
solid propellant grain 12 loaded within the interior surface of the
rocket motor case 14. Typically, insulation 16 and a liner 18 are
interposed between the case 14 and the solid propellant grain 12.
The insulation 16 and the liner 18 serve to protect the case from
the extreme conditions produced during combustion of the solid
propellant grain 12. Methods for loading a rocket motor case 14
with the insulation 16, the liner 18, and the solid propellant
grain 12 are known to those skilled in the art, and can be readily
adapted without undue experimentation to incorporate the propellant
of this invention. Liner compositions and methods for applying
liners into a rocket motor case are also well known in the art.
Also shown in the FIGURE is an igniter 20 attached to the forward
end of the case 14 for igniting the solid propellant grain 12 and a
nozzle assembly 22 attached at the aft end of the case 14 for
expelling at high velocities combustion products generated during
burning of the solid propellant grain 12.
[0031] The following examples are offered to further illustrate the
synthesis methods of the present invention. The examples are
intended to be exemplary and should not be viewed as exhaustive of
the scope of the invention.
EXAMPLES
Example 1
[0032] Sulfuric acid (96%, 20 ml) was added to nitric acid (90%, 20
ml), then cooled to below 38.degree. C. before adding methylene
chloride (100 grams). This mixture was cooled to 0.degree. C. in an
ice bath and 8 grams of diglycerol were added dropwise over 0.5
hour. At this temperature of 0.degree. C., the diglycerol tended to
coagulate despite rapid agitation of the reaction mixture. After
another 0.5 hour the coagulated diglycerol had disappeared and the
reaction mixture was poured onto 40 ml of crushed ice, which
dissolved to form a dilute acid. The organic phase was separated
from the dilute acid with a separation funnel and was washed with
50 ml of saturated sodium bicarbonate solution. The organic phase
was then dried over 5 grams of magnesium sulfate, filtered, and the
volatiles were removed at 30.degree. C. under reduced pressure to
give diglycerol tetranitrate as a pale yellow oil in 95% yield.
Example 2
[0033] Sulfuric acid (96%, 30 ml) was added to nitric acid (90%, 30
ml), then cooled to below 38.degree. C. before adding 100 ml of
methylene chloride. This mixture was further cooled to 10.degree.
C. and 12 g of diglycerol were added by pouring in a steady thin
stream over 15 minutes. The rate of addition was such that with a
cooling bath at 0.degree. C. the reaction temperature stayed
between 10.degree. C. and 12.degree. C. Under these conditions the
diglycerol did not coagulate. After a further 15 minutes the
reaction mixture was poured onto 200 ml of crushed ice to dissolve
the ice and form a dilute acid. The organic phase was separated
from the dilute acid with a separation funnel and was washed with
50 ml of saturated sodium bicarbonate solution. The organic phase
was then dried over 5 grams of magnesium sulfate, filtered, and the
volatiles were removed at 30.degree. C. under reduced pressure to
give diglycerol tetranitrate as a pale yellow oil in 96% yield.
Example 3
[0034] Sulfuric acid (96%, 120 ml) was added to nitric acid (90%,
120 ml), then cooled to below 38.degree. C. before adding 400 ml of
methylene chloride. This mixture was cooled to 5.degree. C. and
48.4 grams of diglycerol were added by pouring in a steady thin
stream over 15 minutes. The rate of addition was such that with a
cooling bath at 0.degree. C. the reaction temperature stayed at
5.degree. C. Under these conditions the diglycerol did not
coagulate, but the diglycerol did tend to form a film on the
reactor sides and thermometer before it reacted and dissolved.
After a further 15 minutes the reaction mixture was poured onto 1
liter of crushed ice to form a dilute acid. The organic phase was
separated from the dilute acid with a separation funnel and was
washed twice with 500 ml of saturated sodium bicarbonate solution.
The organic phase was then dried over 5 grams of magnesium sulfate,
filtered, and the volatiles were removed at 30.degree. C. under
reduced pressure to give diglycerol tetranitrate as a pale yellow
oil in 96% yield.
Example 4
[0035] Sulfuric acid (96%, 1200 ml) was added to nitric acid (90%,
1200 ml), then cooled to below 38.degree. C. before adding 3000 ml
of methylene chloride. This mixture was cooled to 10.degree. C. and
460 g of diglycerol were added by pouring in a steady thin stream
over 65 minutes. The rate of addition was such that with a cooling
bath at 0.degree. C. the reaction temperature stayed between
10.degree. C. and 15.degree. C. Under these conditions the
diglycerol did not coagulate. After a further 30 minutes the
organic phase was separated from the acid phase without dilution.
The organic phase was washed twice with 500 ml of saturated sodium
bicarbonate solution. The organic phase was then dried over 5 grams
of magnesium sulfate, filtered, and the volatiles were removed at
30.degree. C. under reduced pressure to give diglycerol
tetranitrate as a pale yellow oil in 97.3% yield.
[0036] The foregoing detailed description of the invention has been
provided for the purpose of explaining the principles of the
invention and its practical application, thereby enabling others
skilled in the art to understand the invention for various
embodiments and with various modifications as are suited to the
particular use contemplated. This description is not intended to be
exhaustive or to limit the invention to the precise embodiments
disclosed. Modifications and equivalents will be apparent to
practitioners skilled in this art and are encompassed within the
spirit and scope of the appended claims.
* * * * *