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Патент USA US3073741

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Jan. 15, 1963
3,073,731
J. COHEN ETAL
PLASTICIZING AGENTS FOR NITROCELLULOSE
2 Sheets-Sheet 1
Filed March 29, 1956
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INVENTORS
RONALD A. HENRY
WILLIAM G_ FINNEGAN
JOSEPH COHEN
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ATTORNEYS
Jan. 15, 1963
3,073,731
J- COHEN ETAL
PLASTICIZING AGENTS FOIR NITROCELLULOSE
Filed March 29, 1956
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INVENTORS
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RONALD A HENRY
WILLIAM G. FINNEGAN
JOSEPH COHEN
o
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ATT'oRNEYsH
T
ice
.
3,®73,73i
Patented Jan. 15, 1963
2
content of 80 percent.
3,073,731
PLASTICTZING AGENTS FOR NITRGCELLULOSE
Joseph Cohen, Arcadia, and William G. Finnegan and
Ronald A. Henry, China Lake, €alif., assignors to the
United States of America as represented by the Secre
tary of the Navy
Filed Mar. 29, 1956, Ser. No. 574,939
11 Claims. {CL 149—92)
(Granted under Title 35, US. Code (1952), see. 266)
This is contrasted with the 10.4
percent of nitrogen in ethyl centralite and 18.5 percent
of nitrogen in nitroglycerin. Further some of these de
rivatives have the property of absorbing oxides of nitro
gen released from propellants on standing. An advan
tage of the derivatives of tetrazole over prior non-explo
sive plasticizers for propellent compositions for jet actu
ated devices is the superior degree of gelation or colloid
ing of nitrocellulose produced by them. When they are
10 mixed’ with nitrocellulose they produce a gel of varying
degree, dependent upon the particular derivative which is
The invention described herein may be manufactured
used and on the relative percentages of the derivative and
and used by or for the Government of the United States
the nitrocellulose. When a complete propellent compo
of America for governmental purposes without the pay
sition is processed to contain nitrocellulose, the tetrazole
ment of any royalties thereon or therefor.
This invention relates to improved propellent compo 15 derivative, nitroglycerin, and the various other conven
tional additives to propellants for jet actuated devices,
sitions for jet actuated devices, more particularly, it re
such as ballistic modi?ers, stabilizers, and others, the col
lates to propellent compositions incorporating improved
plasticizers.
loiding effect on the nitrocellulose is so effective that a
uniformly distributed matrix incorporating the other in
In the art of compounding propellent compositions for
jet actuated devices it is well known that plasticizers are 20 gredients of the composition is formed. Furthermore,
the absorption by nitrocellulose of other ingredients of
essential to the compositions for providing the required
the composition which are ordinarily physically compati
plasticity to permit homogeneous mixing of the raw ma
ble with nitrocellulose, is not inhibited by the presence of
terials and to provide a ?nished propellent grain which
the tetrazole derivatives. Illustrative of the superior plas
is well plasticized and not subject to cracking or break
ing. A suitable plasticizer, in addition to being capable 25 ticizing effect of the tetrazole derivatives is the fact that,
whereas it is common practice to include approximately
of imparting plasticity to the propellent composition and
equal weights of nitrocellulose and total plasticizer in
to the ?nished propellent grain, must possess a number of
double base propellent compositions it has been found
other well de?ned properties. Its presence in the com
that the ratio of nitrocellulose to the total amount of plas
position should not undesirably affect the highly sensitive
ticizer, when one of the tetrazole derivatives is included,
ballistic properties of the propellant, such as, the mesa
can be as high as 2 to 1 and still give a properly colloided
and plateau effect of propellants for jet actuated devices.
composition. This is illustrated by a comparison of the
Further, incorporation of the plasticizer in the propellent
plasticizing effects produced in a conventional propellent
composition should not undesirably affect the surveillance
‘composition by a standard plasticizer, ethyl centralite,
characteristics and thermochemical properties of the com
and by a representative member of the tretrazole deriva
position. Additionally, the plasticizing agent should pref
tives, 1-ethyl-S-ethylaminotetrazole, the compositions
erably have a high nitrogen content, thus assuring a low
being as follows:
~average molecular weight for the combustion products.
Representative plasticizers ordinarily incorporated in
double base propellent powders are dialkyl phthalates
such as dimethyl and diethyl phthalate, ethyl centralite, 40
dibutyl sebacate and nitroglycerin, the latter being an
explosive plasticizer. None of these plasticizers, with the
exception of ethyl centralite, function to remove certain
oxides of nitrogen generated in propellants during storage
I (weight
percent)
Nitrocellulose (12.6% N) __________________ __
19. 1
II (weight
percent)
29. 84
Nitraglycerin _____________ ._
.
18. 6
Nitroguauidlne. .__
-
54. 8
64. 8
Ethyl centralite _____________ __
_
7. 5
0.0
7. 86
l-eth yl-?-ethyla ninotetrazole _____ __
0. 0
7. 5
which shorten the storage life of the propellants. Fur 45 Ratio of nitrocellulose to p1asticizer_____ _ 0. 73 to 1.0 1. 94 to 1.0
ther, of the named compounds only nitroglycerin con
tains an appreciable percentage of nitrogen.
Despite the substantially larger ratio of total plasticizer
It is, therefore, an object of this invention to provide
to nitrocellulose in the composition of Example I, strands
propellent compositions for jet actuated devices possess
produced from the composition of Example 11 were found
50
ing a high degree of plasticization.
to be less brittle and more ?exible than those produced
It is another object of this invention to provide highly
from the composition of Example I.
plasticized propellent compositions for jet actuated de
The invention is best understood by reference to the
vices which have good ballistic and thermochemical prop‘
description which follows, taken in connection with the
erties as well as good surveillance properties.
drawings, which form a part of this speci?cation and in
It is still another object of this invention to provide 55 which the FIGS. 1-4, inclusive, are graphs of the pressure
homogeneous propellent formulations in which the plas
iburning rate relationship of propellent compositions of
ticizer, in addition to its plasticizing effect, also functions
the invention.
as a coolant by providing a large percentage of nitrogen.
Table I below contains 24 examples of propellent com
It is a further object of this invention to provide pro
positions of the invention which were selected as repre
pellent compositions for jet actuated devices which pro 60 sentative from among those prepared and tested. The
duce combustion products having a low average molecu
examples include a sampling of compositions containing
lar weight.
13 representative tetrazoles as plasticizers, some tetrazoles
It has been found that the above and other objects are
being used in more than one composition. Examples
accomplished by homogeneously incorporating deriva
1-7, inclusive, 9-13, inclusive, and 15-20, inclusive, and
tives of tetrazole into propellent compositions in amounts 65 24 are examples of propellants made by incorporating the
varying from about 5 percent to about 50 percent, depend
tetrazole plasticizers in conventional double base propel
ing upon the particular derivative and the compositions
lants, the propellent composition being set forth in the
into which it is incorporated.
table. Examples 22, 23, 25, 26 and 27 are of propellent
The derivatives of tetrazole disclosed herein as plas
compositions made by incorporating tetrazole plasticizers‘
ticizers have a high nitrogen content, generally over 30 70 in cool gun propellent formulations. Examples 8 and
14 are blanks using conventional double base components,
percent, the parent compound itself having a nitrogen
3,073,731
which were made for comparative purposes.
4
Example
The following compounds were tested as plasticizers
with nitrocellulose and found to be compatible and excel
lent plasticizers at the percentage level indicated.
21 is a blank of a conventional cool gun propellent com
position, cordite-N. All of the formulations were made
by the solvent process, a conventional manufacturing
method used for double base and cool gun propellants.
V
Percent
Other processes may be used, the only requirement being 5 Compound
Ethyl
that a'process be used which insures that the plasticizer
out the propellant in its ?nished state.
compound
(l-methyl-S-tetraZolyl)acetate ________ __ 20
Ethyl’ (2-rnethyl-5-tetrazolyl)acetate ________ __ 40
is uniformly and homogeneously incorporated through
This can only be
insured by a thorough mixing and incorporating of the
plasticizer in'the form of small particles in the raw pro
propellant mix, such as'is done in the solvent or solvent
.
?-(l-tetrazolynethyl acetate ________________ __ 40 >
10
?-(Z-tetrazolyDethyl acetate ________________ __ 40
Ethyl (2-tetrazolyl)acetate ________________ __ 210
Mixture of 1,4-bis (1, and Z-methyI-S-tetrazolyl)
less process mentioned above.
butanes ______________ -L ______________ __ 20
TABLE I
[Weight percent]
Example ___________ _.123
4
5
67
8
9
1011
12
13
14
15
1617
18
19
20
21
22
23
24
25
26
27
INGREDIENT
60. 66
20. 92 40. 17 29. 84 29. 84
1 Passed through 200 on 270 mesh.
Key to Table I:
-OAT—5-octy1amin0tetrazole
-DA‘I'—5-decylaminotetrazole
-5-AT—1-methyl—5-arninotetrazole
-E-5-AT—1-erhy1-5~an1inotetrazole
NC—Nitrocellulose (12.6%)
NG—Nitroglyc-e1in
DEP-——Diethy1 phthalate
-
DBS—Dibuty; sebacate
EC-Eethyl eentralite
2-NDPA—-2-nitrodiphenylamine
PbSal—Lead salicylate
.
CW-—Candeli1la Wax
1-B-5-BAT--1~ hutyl~5~butylaminotetrazole.
5WIAT-—5-methylaminotetrazole
5-EAT—-5-ethy1aminotetrazole
E
A—Ethyl (I-tetrazolyl ) acetate
2G—Nit_roguanidine
'
1- ( 5-T ) -2-N—1— t 5-tetrazolyl) ~2-nitroguanidine
G—'Guanidinium
The tetrazole plasticizers were found to be compatible with 50 The ?nished product in the above cases was highly plasti
the propellent compositions over wide percentage ranges.
cized and ?exible, and the plasticizer was uniformly and
All of the compositions were well plasticized. Com
homogenously blended in, the nitro cellulose.
patibility tests, heat stability and other surveilance tests,
?ex tests, temperature of explosion tests, second order
' The following flex tests. performed on compositions of
nitrocellulose and representative tetrazoles are included.
transitions tests, burning rate tests, and other tests showed 5-5 The tests were made by folding the product back on itself
that the compositions were satisfactorily plasticized, that
and counting the number. of folds before breaking. The
they had good surveilance characteristics, had no dele
tests were performed at 25.5 ‘’ C.
terious effects on required ballistic characteristics of pro
pellants and even increased the burning rate of double base
and cool gun propellent- compositions.
60
Typical results of tests performed on representative
compositions shown in Table I are included in the fol
Plasticizer
Average
Z-ethyltetrazole and 1,5-dimethyltetrazole were tested
as plasticizers for nitrocellulose by the sorption method 65
with the following results: The Weight of nitrocellulose
in the presence of 2-ethyltetrazole was increased by 182%
after 3 hours at. 40° C., indicating that this tetrazole sol~
vates nitrocellulose strongly. The weight of nitrocellu
lose in the presence of l,5-dimethyltetrazole was in 70
creased 45.5% after 75‘ minutes at 40° C. indicating
satisfactory compatibility. 1-ethyl-5-ethylaminotetrazole
Average
?lm
Number of
thickness,
folds to
lowing paragraphs.
inches
None ____________________________ _ -
0. 00175
break
34.4
l-ethyl-Sethylaminotetrazole .
0. 00177
380
l-methyl-5ethylaruinotetrazole
0. 00207
292
-
0. 00196
454
l-methyl-5-methylaminotetra-zole ____________ _ _
0. 00177
511
1-allyl-5-ally1arninotetrazole_ _ _ _ _
‘Comparison of the results obtained from the plasticized'.
compositions With that obtained on the blank graphically
about the 30% level indicating the versatility of the tetra
illustrates the general effectiveness of the tetrazole plasti~
zoles as plasticizers.
75 cizers.
was found to be compatible with cellulose acetate up to
3,073,731
5
members from Table I are included below.
Example
of the plasticizer. While some of this e?ect for Exam
ples 25, 26 and 27 of FIG. 4 must be attributed to the
use of the new cool gun base compounds, it is quite 0b
vious that some of the effect is due to the plasticizers.
Tables Ill and IV below present results of heat sta
bility tests performed on propellent compositions con
Results
No.
7 _______ _. No peak in the dielectric power loss curve occurred from
—50 to —14° 0. Films were tough and ?exible.
16 ______ __
6
4 with the graphs'for the other compositions shows that
the burning rate is appreciably increased by the presence
Second order transition temperatures for representative
Peaked at —8° 0.
‘Peaked at —20° C.
Peaked at —18° 0. The ?lm was tough and ?exible at room
taining varying amounts of tetrazole plasticizers.
For
10 making the tests the weighed ingredients were dissolved
in acetone by tumbling in sealed bottles for 24 hours
. The ?lm was tough and ?exible at room temperature.
Peal-zed at -—21° 0. Films were tough and ?exible.
and the resulting solutions cast into ?lms on glass and
dried for 2.5 days.
The above results illustrate the effectiveness of the plasti
TABLE III
cizers at lower temperatures.
15 [The compositions consisted of 37% nitrocellulose (12.6%
Representative results of conventional temperature of
N), 30% nitroglycerin, and 33% of the tetrazole deriva
tive—-tests performed at 136° (3.]
explosion tests for typical compositions of Table I are
temperature.
No peak in dielectric power loss curve from —63° C. to —10°
as follows:
First
salmon
TABLE 11
Example
[Average time in seconds for explosion at
298°
330°
372°
C.
C.
C.
397
412°
428°
C.
C.
458°
.
color on
20
temperatures shown]
Example
Compound
485°
De?nite
Explosion
salmon
or decom
color, min.
position
min.
510°
O.
13
53-56
__________ .1
1.49
1. 19
1. l8
0. 83
39-42
8
1. 41
1.33
1. 03
8-16
8-10
32
26
33
135
____ _
10-13
The extended time of explosion at the temperatures
shown further indicates the stability of the compositions.
To supplement the heat stability tests given below for
double base propellent formulations incorporating the
150-180
28-29
29-39
(1)
210
(1)
plasticizers, heat stability test results obtained on Exam
13
ples 22 and 25, cool gun propellent compositions, are in
l-M-?-DMAT _____ __
(3)
25
cluded as follows: The compositions darkened in heat 35
1 Melted but no explosion.
stability tests at 136° C. but did not explode during 8
2 Melted after 10 minutes, frothed after 55 minutes.
hours. Oxides of nitrogen were not evolved, as indicated
. 3 Melted after 7 minutes. frothed after 20 minutes.
Key to Table III excluding those terms used in Table I:
by the fact that the methyl violet paper used for indicat
5~DMAT—5~dimethylaminotetrazole
ing stability did not develop a pink or salmon color.
5-DAAT-5-diallylamin0tetrazole
Graphs of representative results of standard burning 40
35
5-HAT—5-heptylaminotetrazole
5-PAT-—5-phenylaminotetrazole
1-(m-CP)-5-AT—-1-(rn-chlorophenyl) -5-aminotetrazole
2-E-5-AT—2-ethyl-5~arninotetrazole
2-M-5-MAT-—2-1netl1y1—5-methylaminotetrazole
2-M-5-NT—2-methyl-5-nitrotetrazole
1-M-5-DMAT—1~inethyl~5-dimethylaminotetrazole
rate tests performed on typical compositions of Table I
are included as FIGS. 1, 2, 3 and 4. The graphs are
logarithmic plots in which the burning rate of the propel
lant is plotted against pressure, the divisions on the ab
In order to illustrate the heat stability of different per
scissa representing multiples of 100. Inspection of the 45
centage compositions of propellants as well as the com
graphs shows that ballistic properties of the propellants
patibility of the tetrazole plasticizers with a conventional
are actually enhanced by incorporation of the plasticizers
stabilizer, Z-nitrodiphenylamine, the results of Table IV
therein. For example, comparison of the graphs for the
are included.
blanks 8 and 14 of FIG. 2 and the blank 21. of FIG.
TABLE IV
Example __________________ __
45
46
47
48
50
49
51
52
53
54
55
56
57
58
Ingredient:
N C (12.6%) ____________ s _
NG
2-M-5-MAT ___________ ._
Heat stability. 106° 0.:
First salmon color on
methyl violet paper,
minutes _____________ __
None
270
43
None
47
None
______________________________ _ .
None
______________________________________________________________ _ _
107
110
None
______________________________ _ _
De?nite salmon color,
minutes _____________ __
Explosion or extensive
decomposition, minutes.
Heat stability, 136° 0.:
First salmon color, min
utes _________________ __
None
______ __
53
None
______ __
None
None
None
None
None
27
27-46
______ __
53
28
_____ __
35
______ _.
71
44
_____________________ __
None
40-49
38
28-38
14-35
9-17
16-42
11-22
135
28-33
None
None
None
______ r_
7. 9
10-15
10
10
16
50
43-68
52
._.. _ _ _ _
De?nite salmon color,
minutes _____________________ __
Explosion or extensive
decompositiomminutes.
64
None
12
9. 5
58
None
>
7
3,073,731
As is illustrated by the examples in Tables I, III and
I -Buty lr-5-Butylaminotez‘razole '
IV the tetrazole plasticizing agents are effective within a
range of 5 to 50 percent by weight of the compositions.
The compound was made in a similar fashion from 1,3
dibutylthiourea with a yield of 86%. Two recrystalliza
tions from ethyl acetate-petroleum ether (1:10) gave a
Numerous tests performed on S-aminotetrazole showed
that it was not the equivalent of the other tetrazoles as a
product melting between 74-76“ C.
plasticizer. For example, it showed no compatibility
with either double base or cool gun propellants, and did
Analysis
not have any plasticizing etfect on these propellants. This
compound forms a heretrogeneous rather than a homo
geneous system with the propellant, and as a result the
’ Carbon Hydrogen Nitrogen
Calculated (CgI-I19N5) ___________ _.
54. 79
Found;________________________ __ 54.. 92-54. 86
composite propellant formulation has poorer physical
properties than the homogeneous system formed by this
invention. Further, the fact that ‘this compound is hygro
9. 71
9. 22-9. 23
35. 51
35. 66
Ethyl (1- ‘and 2-Tetraz0lyl)Acetates
scopic seriously detracts from its value as a component of
Tetrazole (41.9 g., 0.599 mole) was suspended in 100 g
ml. of absolute ethanol in a one liter, three necked, round
propellent formulations. As respects solvating and plas
ticizing power this compound is not the equivalent of the
bottom ?ask, equipped with a mechanical stirrer, addi
tetrazole plasticizers set forth above.
tional funnel, and a re?ux condensed.
The tetrazole was
neutralized to the phe-nophthalein end point by the addi
A number of the tetrazole derivatives and the cool ,
gun propellants disclosed above arenew or relatively un
, tion of a solution of 39.6 g. (0.599 mole) of 85% potas
known, so that it is believed expedient to cite references 20 sium hydroxide in 100 ml. of 95% ethanol, and the solu
to methods of preparation for those which have been'
tion was heated to boiling on a steam bath. Ethyl bromo
previously preparedand to give the method of prepara
acetate (100 g., 0.599 mole) was then added as rapidly as
the re?ux permitted and the resulting homogeneous solu
tion for those which are‘new. The method of prepara
tion of the following compounds is given in “Preparation
tion was heated and stirred for two hours. Potassium
and Isomerization of S-Alkylaminotetrazoles,”‘ by Wil 25 bromide precipitated as thereaction proceeded. The re
liam G. Finnegan, Ronald A. Henry, and Eugene Lieber,
action mixture was then cooled to room temperature, the
potassium bromide removed by ?ltration and the ?ltrate
published in volume 18, No. 7, of The Journal of Organic
Chemistry, July 1953: S-methylaminotetrazole, S-dimeth
ylaminotetrazole, S-ethylarninotetrazole, S-phenylamino
tetrazole, 1-methyl-S-aminotetrazole, l-ethyl-S-aminotet
razole, 1-methyl-5-methylaminotetrazole, 1-methyl-5
evaporated to dryness in vacuo on a steam bath.
The
residue was extracted with three 100' ml. portions of
30 methylene chloride. The methylene chloride solution was
dried over magnesium sulfate and evaporated to' dryness,
leaving 86.2 g. (92.2% yield) of impure ethyl tetrazolyl
dimethylaminotetrazole and 1-ethyl-S-ethylaminotetrazole.
Methods of preparing the following compounds are found
acetates as a viscous oil. Distillation at 1 mm. pressure
in the article. “Preparation and Hydrogenation of Azo
yielded 23.2 g. (24.8% yield) of ethyl (2-tetrazolyl)
methines Derived From S-Aminotetrazole,” by Ronald A. 35 acetate, B.P. 83.5-84° C., M.P. 51-52" C.
Henry and William G. Finnegan, published in The Jour
nal of the American Chemical Society, 76, 926 (1954) :1 5
Analysis '
‘ Carbon Hydrogen Nitrogen
heptylaminotetrazole, 5-octylaminotetrazole and S-decyl
aminotetrazole. The preparation of 1-(m-chlorophenyl)
Calculated (C5HsOzN4) _________ __
38. 46
5.16
35. 89
S-aminotetrazole is given in the article “Thermal Isom 40
erization of Substituted S-Aminotetrazoles,” by Ronald
Found __________________________ ._
38. 10
4. 50 -
35. 71
A. Henry, William G. Finnegan, and Eugene Lieber, pub
The residue of ethyl ( l-tetrazolyDacetate (42.1 g., yield——
lished in The Journal of the American Chemical Society,
45%) was distilled in a Hickman still at 10-4 mm. pres
sure and 90-100‘0 C. pot temperature.
76, 88 (1954). The method of preparing the following
compounds is given in the article, “Mono-Alkylation of
Sodium S-Aminotetrazole in Aqueous Medium,” by Ron
ald A. Henry and William G. Finnegan, published in The
Journal of the American Chemical Society, 76, 923
(1954): 2-methyl-5-aminotetrazole, 2-ethyl-5-aminotetra
45
Analysis
Carbon
Calculated (CgI‘IsOzNJ) _________ __
Found __________________________ __
38. 46
38. 99
Hydrogen
5.16
4. 69
Nitrogen
35. 89
35. 06
zole, 2-methyl-5-methylaminotetrazole and 2-methyl-5
nitrotetrazole.
The methods for preparing tetrazole, 5
dimethyltetrazole, 5-diallylaminotetrazole and Z-ethyltet
razole are Well known in the art.
The following are new
compounds for which the methods of preparation are
given below: 1-butyl-5-butylaminotetrazole, 1-allyl-5-allyl—
aminotetrazole, ethyl (1-tetrazolyl)acetate, ethyl (2-tet
raz0lyl)acetate, B-(1~tetrazolyl)ethyl acetate, ?~(2-tetraz
olyl)ethyl acetate, ethyl (l-methyl-S-tetrazolyl)acetate,
ethyl (2-methyl-5-tetrazolyl)acetate, 1,4-bis (l-methyl-S
tetrazolyl)butane, 1,4-bis (2-methyl-5-tetrazolyl)butane,
I-(S-tetrazolyl)-2-nitroguanidine and the guanidinium salt
of 1-( S-tetrazolyl ) -2-nitroguanidine.
B-(J- and 2—Tetraz0lyl)Ethyl Acetates
The compounds were prepared from l- and 2-(2-hy
droxyethyl)tetrazoles which were prepared as follows:
A suspension of 70 g. (1.0 mole) of recrystallized tetrazole
in 150 ml. of water in a two liter round bottom ?ask was
neutralized to the phenolphthalein end point with a solu
tion of 4125 g. (1.0‘ mole) of 97% sodium hydroxide in
150 ml. of water.
A re?ux condenser was attached to the
. ?ask and the solution was heated to re?ux.
2-chloro~
ethanol (101 g., 1.25 moles) was then added through the
condenser as rapidly as the rate of re?ux permitted.
After the solution had been re?uxed overnight, the Water
J -A llyl-5-A llylaminotetrazo‘le
was removed by vacuum evaporation on- a steam bath.
The hydroxyethyltetrazoles in the residue were separated
The compound Was prepared in 82% yield from 1,3-di- ' 65 from the sodium chloride by extraction with one 300 ml.
allylthiourea by the method of Finnegan, Henry, and Lie
and three 100' ml. portions, of boiling acetone. The ace
ber. (Journal of Organic Chemistry, 18, 779 (1953) .)
After three recrystallizations from diethyl ether, the melt
ing point of the product was found to be 48.5—49.5° C.
Analysis
Carbon
Hydrogen
Nitrogen
tone solution Was vacuum evaporated to leave 113.3 g.
(99.34%) of mixed hydroxyethyltetrazoles. This mix
ture was dehydrated by azeotropic distillation with ben
70 zene and the excess benzene removed by vacuum evapora
tion. Acetylation of the hydroxyethyltetrazoles was ac
complished by heating the mixture with a large excess of
Calculated (C1HHN5) ___________ _-
51. 44
6. 69
41. 89
acetic anhydride for 2 hours on a steam bath.
Found __________________________ __
51.08
6. 31
42. 63
cess anhydride and the acetic acid produced were removed
75 by vacuum distillation.
The ex~
Fractionations of the residue
3,073,731
9
(1950)). The product was isolated by dissolving the re
action mixture in 100 ml. of ice water and acidifying the
solution with 20 ml. of concentrated hydrochloric acid.
tetrazo1yl)ethyl acetate, B.P. 81-840 C. at ca. 1 mm, and
47.6 g. (30.5% yield) of ?-(l-tetrazolyDethyl acetate
which was distilled in a Hickman still at 10'4 mm. pres
sure and 95° C. pot temperature.
Analysis
Carbon
Hydrogen
Or The precipitated 1,4-bis (5-tetrazolyl)butane was removed
by ?ltration, washed on the ?lter'with three, 50 ml. por
tions of ice water and air dried to give 16.18 g. of prod
uct. Recrystallization from water yielded 14.04 g. of pure
product having a melting point of 204—205° C.
Nitrogen
B—(2~tetrazolyl) ethyl acetate:
Calculated (CsHsOzNl) _____ __
Found ______________________ -_
38. 46
37. 74
5.16
3. 93
35.89
87. 71
38. ~16
40. 46
5.16
3. 29
35. 89
38. 21
10
Herbert (Journal of Organic Chemistry, vol. 15, 1082
yielded 43.6 g. (27.94% based on tetrazole) of B-(2
Analysis
?-(l-tetrazolyl) ethyl acetate‘
Calculated (C5HsOzN4) _____ __
Found ______________________ __
Carbon
Calculated (CtHmNa) ___________ __
Found __________________________ _.
37. 10
37. 15
Hydrogen
5. 19
4. 83
Nitrogen
56. 71
68. 12
15
Ethyl (1- and Z-Methyl-S-Tetrazolyl) Ace‘tates
For the preparation of the 1,4-bis (1- and Z-methyl-S
The compounds were made from ethyl (S-tetrazolyl)
tetrazolyl)butanes, 1,4~bis (5-tetrazolyl)butane (12.19 g.,
acetate. Ethyl (S-tetrazolyl) acetate was synthesized
0.063 mole) was suspended in 50 ml. of water, neu
from ethyl cyanoacetate by the alternate procedure of
tralized to a phenophthalein end-point with 50% sodium
Mihina and Herbst (Journal of Organic Chemistry, vol. 20 hydroxide solution and the solution diluted to a total vol
15, 1082 (1950)). A one mole scale reaction yielded
ume of 100 ml. After the solution was warmed to 70° C.,
52.5 g. (33.7%) ethyl (S-tetrazolyl) acetate; 14.0 g.
17.5 g. (0.1386 mole) of dimethyl sulfate was added drop
(12.4%) of ethyl cyanoacetate and 21.2 g. of (24.9%) of
wise with stirring; 50% sodium hydroxide was added as
cyanoacetic acid were recovered.
necessary to maintain the phenolphthalein endpoint. The
25 addition of dimethyl sulfate was complete in 30 minutes
Analysis
Calculated (C5HEO2N4) _________ __
Found __________________________ _-
Carbon
38. 46
38. 30
Hydrogen
5.16
4. 46
and the solution was stirred at 70° C. for an additional
two hours. The solution was then concentrated in vacuo
on a steam bath to about 25 ml. and extracted with three
Nitrogen
35.89
35- 83
For the preparation of ethyl (1- and 2-methyl-5
tetrazolyl)-acetates, ethyl-(S-tetrazolyl) acetate (62.4 g.,
50 ml. portions of ethylene chloride. The ethylene chlo
30 ride solution was evaporated to dryness leaving 10.18 g.
(72.8%) of methylated products as a semi-solid residue.
This residue was slurried with 100 ml. of cold acetone and
0.4 mole) in 200 ml. of 95% ethanol was neutralized to
2.03 g. (14.5%) of solid having a melting point of 139—
a phenolphthalein end point with a 50 percent solution of
140° C. were removed by ?ltration. Recrystallization
sodium hydroxide. The solution contained in the two liter 35 from ethanol did not raise the melting point.
round bottom flask equipped with a condenser was then
Analysis:
heated to reflux and 62.5 g. (0.44 mole) of methyl iodide
Nitrogen
Calculated
was added ‘through the condenser as fast as the rate of re
(CEHMNB) ____________ __
50.43
Found _________________________ __ 50.40-50.25
flux permitted. After a total of 17 hours re?ux, the solu
tion was stripped to dryness in vacuo on a steam bath and 40 This material was probably 1,4-bis (l-rnethyl-S-tetra
the residue extracted with three 100 ml. portions of meth
ylene chloride. The methylene chloride solution was
dried over magnesium sulfate, ?ltered and evaporated.
The residue from the methylene chloride solution was dis
solved in 200 ml. of isopropanol. Chilling this solution 45
butane and 1-(l-methyl-S-tetrazolyl)-4-(2-methyl-5-tetra—
zolyl) butane.
acetate having a melting point of 67—68° C.
Analysis:
yielded 20.53 g. (30.2%) of ethyl (l-rnethyl-S-tetrazolyl)
zolyl)butane. The acetone ?ltrate was evaporated to
dryness, leaving 7.98 g. (52.0%) of soft solid which was
probably a mixture of 1,4-bis (2-methyl-5-tetrazolyl)
Nitrogen
Found
Calculated
_____________________
(C3H14Ng) ________ __ 51.6l—51.13—5l.5
Analysis
Carbon
Hydrogen
Nitrogen
50 The basic solution remaining after extraction of the meth
Calculated (otumotNi) . .-_
42. 35
5. 92
32. 93
ylated bis tetrazolyl butanes was acidi?ed with concen
Found ____________________ __
41.
5. 80
32. 77
trated hydrochloric acid and extracted with ethylene chlo
ride. Evaporation of the ethylene chloride left 2.92 g. of
The isopropanol ?ltrate was evaporated to dryness and
partially methylated products and starting material.
the residue was distilled, yielding 28.95 g. (42.6% yield) 55
of ethyl (Z-rnethyl-S-tetrazolyl) acetate having a boiling
A solution of 6.1 g. (0.072 mole) of anhydrous S-amino
point of 103°-—l04° C. at 0.8 mm. pressure.
Analysis
Carbon
Hydrogen
1-(S-Tetrazolyl)*-Z-Nizr0guanidine
Nitrogen
Calculated (C5H10N4) ___________ ._
42. 35
5. 92
32. 93
Found __________________________ -_
41. 79
5.35
33. 27
Recrystallization of the distillation residue yielded an
tetrazole in 150 ml. of water was adjusted to the phenol
phthalein endpoint with a 50% solution of sodium hy
60 droxide. S-methyl-N-nitroisothiourea (9.6 g., 0.072 mole)
was then added and the resulting solution was heated un—
der re?ux on a steam bath for 12 hours. The evolution
of methyl mercaptan began immediately and was essen—
tially complete at the end of the heating period. The solu
additional 7.13 g. (IO-5%) of ethyl (1—methyl-5-tetrazolyl) 65 tion was cooled, ?ltered from a small amount of insolu
ble material, adjusted ‘to pH 2 with concentrated hydro
acetate.
1,4-Bis (1- and Z-methyl-S-Tetrazolyl)Butanes
The compounds were made from 1,4-bis (5-tetrazolyl)
chloric acid, and cooled overnight at 5° C. The product
was removed by ?ltration, washed with two small vol
umes of cold water, and air dried. The yield was 6.35 g.
1,4-bis (5-tetrazolyl)butane was prepared in 70 (51.6%). From the aqueous mother liquors 1.5 g. (an
hydrous) of unreacted S-aminotetrazole was recovered.
(In a second experiment the yield wasl37.8%.) The
nitrile, 14.0 g. (0.215 mole) of sodium azide in 17.0 ml.
crude product was recrystallized once from water (about
of glacial acetic acid and 25 ml. of absolute ethanol at
10 ml./g.) to give a ?ne white-granular powder which
150° C. for 96 hours in a 180 ml. capacity high pressure
reactor following the procedure of J. S. Mihina and R. M. 75 did not melt below 250° C. when heated slowly, but which
butane.
80.5% yield by reacting 11.2 g. (0.1037 mole) of adipo
3,073,731
11
i2
decomposed vigorously at 240—245° C. when plunged into
sitions but also increasing the burning rate of the com
positions without detracting ifrom their surveillance and
a hot bath at this temperature.
Analysis
Carbon
Hydrogen
other requisite characteristics.
Obviously many modi?cations and variations of the
present invention are possible in the light of the above
Nitrogen
Calculated (CzHrNsOzHzO) __
12.63
3. 18
58. 94
Foun ______________________ __
13.56
3. 27
58. 0
13. 96
2. 34
6?. l1
l4. 1
2. 111
6a. 5
Calculated (C2H4Na02) _____ __
oun __________________________ __
Guanidinizim Salt of J-(S-Tctmzolyl)-2-Nitrogzmnidirze
teachings. It is therefore to be understood that within
the scope of the appended claims the invention may be
practiced otherwise than as speci?cally described.
What is claimed is:
of a ?rst component about 45 to about 90% of a ma
terial selected from the class consisting of nitrocellu
lose-nitroglycerin systems in which the components are
present in weight percents of about 30-60 and 25—45,
A slurry of, 17.0 g. of anhydrous S-aminotetra-zole in
v80 ml. of cold water was treated with 18.0 g. of guanidin
ium carbonate at such a rate that the evolution of car
bon dioxide was not excessive. When complete solu
tion of these reactants was attained, 120 ml. of 95% eth
1. Gas producing compositions consisting essentially
10
15 respectively; nitrocellulose - nitroglycerin-nitroguanidine
systems in which the components are present in weight
anol and 29.4 g. of l-methyl-1-nitroso-2-nitroguanidine
percents of about 19-30, 7-19 and 51—57.5, respective
were added. A slow evolution of gas began immediate
ly; after one week at room temperature the orange-yel
guanidine systems in which the components are present
ly;
nitrocellulose-nitroglycerin - l - (5 -tetrazoly1)-2-nitro
low methylnitrosoni-troguanidine had disappeared com 2.0 in weight per-cents of about 30, 7 and 55, respectively;
and nitrocellulose-nitroglycerin-guanidinium salt of 1-(5
pletely and had been replaced by a white granular solid.
tetrazolyl)-2-nitroguanidine systems in which the com
The mixture was heated to dissolve the solid phase, then
ponents are present in weight percents of about 30, 7
cooled overnight at 5° C. The solid was removed by ?l
and 55, respectively, and as a second component from
tration, washed with a small volume of cold water, and
air dried. The yield was 10.3 g. A second crop of 5.0 25 about 5 to about 50 weight percent of a material se
lected ‘from the class consisting of
g. was obtained ‘by evaporating the ?ltrate under reduced
pressure to 100 ml. and recooling ‘to 5° C. The total re
covery of guanidinium salt, melting point 236-240“ C.,
amounted to 33.1% of theory.
The impure salt can be
so
recrystallized from either water (10 mL/g.) or from
60% ethanol (20 mL/ g.) and is recovered as white, rather
:?uffy rosettes which decompose at 240—242° C. when
plunged into a hot bath.
35
Analysis
Carbon
Calculated (CaI‘IeNuOz) ________ _-
15. 58'
Found __________________________ __ 15. 55-15. 73
Hydrogen Nitrogen
3. 92
as. 65
' 4.03-4.24
67.1-64.5
N
Rte-Ill
40
The utility of I-(S-tetrazolyl)-2-nitroguanidine and its
I'l ’
wherein R is hydrogen, lower alkyl, lower alkylene, ni
tro, lower aminoalkyl, lower aminoalkylene, amino~
phenyl, lower carboalkoxyalkyl, and lower acyloxyalkyl;
and R1 and R2 are hydrogen, lower alkyl, lower alkyl
ene, phenyl, lower carboalkoxy-alkyl and lower acyloxy_
alkyl, with the limitation that'Rl and R2 are not hydro
guanidinium salt as substitutes for nitroguanidine in cool
gun propellants is well demonstrated by the burning
rate curves, Examples 26 and 27, respectively, of these
two compounds presented in FIG. 4, the increase in
burning rate being largely due to the presence of these
compounds. Stability tests demonstrated that they have
acceptable surveillance characteristics. In general, the
gen when R is hydrogen.
2.
said
3.
said
4.
use of I-(S-tetrazolyl)-2~nitroguanidine produces a two
to threefold increase in the burning rate over that shown
The gas producing
second component
The gas producing
second component
The gas producing
.
composition of claim 1 in which
is 1-ethyl-S-ethylaminotetrazole.
composition of claim 1 in which
is 1,5-dimethyltetrazole.
composition of claim 1 in which
said second component is 2 - methyl-S-methylamino
by comparable formulations with nitroguanidine, as 50 tetrazole.
shown in FIG. 4. The guanidiniurn salt of this com
pound in propellant compositions is seen to increase the
5. The gas producing composition of claim 1 in which
said second component is 2-methyl-S-nitrotetrazole.
6. The gas producing composition of claim 1 in which
Said second component is ethyl (l-tetrazOlyDacetate.
7. The gas producing composition of claim 1 in which
said ?rst component is a nitrocellulose-hitroglycerin-ni
troguanidine system and said second component is 1
burning rate appreciably over comparable formulations
containing nitroguanidine.
A distinct advantage of the invention, resulting from
the fact that the plasticizing agents contain a large per
centage of nitrogen, is the fact that the agents contribute
a smaller negative heat of explosion to the formula
tions, thus resulting in a more eliicient propellant in
that more nitrocellulose and less nitroglycerin can be
ethyl-S-ethylaminotetrazole.
used. For example, the conventional plasticizers, di
ethylphthalate and ethyl centralite have heats of ex
plosion of >—1761 and —2412, respectively, while the
heats of explosion
of 1-ethyl-5-ethylaminotetrazole,
ethyl (1-tetrazolyl)acetate and 1,5-dimethyl tetrazole are
—1225, —693 and —970.7 cal/gram, respectively.
A further advantage of the invention over the prior
art is the fact that it provides homogeneous, single phase,
cool propellent compositions.
From the above description it is seen that the inven
70 which said second component is ethyl (l-tetrazOlyDace
tate.
tion provides novel and effective propellent compositions,
'
References Cited in the ?le of this patent
UNITED STATES PATENTS
characterized by the addition thereto of tetrazole de
n'vatives, these derivatives serving not only as eifective
plasticizers ‘for the preparation of homogeneous compo
,
8. The gas producing composition of claim 1 in which
said ?rst component is a nitrocellulose-nitroglycerin sys
tem and said second component is l-ethyl-S-ethylamino
tetrazole.
9. The gas producing composition of claim 8 in which
said second component is 1,5-dimethyltetrazole.
10. The gas producing composition of claim 8 in
which said second component is 2~methyl-5-methylamino
tetrazole.
11. The gas producing composition of claim 8 in
75
2,480,852
Hale et al. ___________ __ Sept. 6, 1949
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