US3071617A - Nitro plastic propellants - Google Patents

Description

United States Patent Ofiice 3,971,617 Patented Jan. 1, 1%63 3,671,617 NETRO PLASTIC PROPELLANTS Henry B. Hass, West Lafayette, lnd., assignor to Purdue Research Foundation, West Lafayette, End, a corporation of Indiana No Drawing. Fiied June 1, 1948, Ser. No. 30,512 14 Claims. (Cl. 250-553) The present invention relates to solid propellants.

.More particularly, the invention relates to smokeless propellants and to unique nitro plastics which may be employed as the sole or major thrust-producing component of such solid smokeless propellants of the type utilized in rocket and other similar jet-propulsion type motors demandin g great power.

Following upon the rapid' development of jet-type motors, a great demand has arisen for solid propellants which are useful as fuel therein. Because of the many exacting specifications which such a solid propellant must fulfill, very few, if any, solid propellants having suitable characteristics have been available up to the present time.

The ideal solid propellant would exhibit the following characteristics. It should:

(1) Be solid and stable over the entire range of ambient temperatures of 40 to +60 degrees centigrade and under pressures between about 300 and 1500 pounds per square inch.

(2) Burn uniformly and have a low temperature coefiicient, i.e., its burning rate increase with temperature should be as small as possible.

(3) Be composed of large grains and preferably of large molecules.

(4) Have a low pressure exponent, i.e., its increase in burning rate with pressure increase should be as small as possible.

(5) Be substantially smokeless.

(6) Have a satisfactory oxygen balance, i.e., it should preferably possess enough oxygen to burn all carbon to carbon dioxide and all hydrogen to Water.

(7) Not undergo deterioration upon storage.

(8) Possess a minimum of susceptibility to detonation under conditions of employment and be stable upon heating.

(9) Not be hygroscopic.

(10) Have a high specific impulse.

Still other specifications are desirable, but these may be considered sub-specifications of those enumerated above.

It has previously been proposed to use as solid fuels compositions embodying cellulose nitrate, but with such compositions the temperature coetficient is undesirably high so that the rate of burning of the fuel is relatively slow when cold and quite rapid when hot. While the rate at intermediate temperatures is satisfactory, it is impossible to maintain such desirable temperatures for any extended period. Further, cellulose nitrate is inherently unstable, and thus fails to fulfill another very important requirement.

These disadvantages have been partially overcome with the provision of compositions embodying ethyl cellulosecastor oil, neoprene casting cements, cross-linked maleic anhydride-styrene resins, or other styrene-linear polyester resins or peptized gums, in admixture with perchlorate powders. However, with perchlorates, shorting of electrical equipment and corrosion is commonly experienced, and the white potassium chloride smoke which comprises approximately 57 percent of the exit gases when potassium perchlorate is used limits visibility to an undesirable and hazardous extent. Likewise, when ammonium perchlorate is employed, the mist-forming hydrogen chloride present in the exhaust gases is objectionable for the same reasons.

It is an object of the present invention to provide novel solid propellants which are more suitable than previously known propellants. A further object of the invention is the provision of novel solid propellants which are substantially smokeless. Another object of the invention is the provision of novel solid propellants comprising a nitro plastic having a minimum oxygen balance of minus 80. Other objects of the invention will become apparent hereinafter.

The novel nitro plastic propellants of the present invention are generally more satisfactory than any known solid propellant composition. They are, for example, substantially smokeless, by virtue of their desirable oxygen balance. Moreover, these propellants exhibit a very high thrust potential due to their high specific impulse and the fact that substantially none of their potential energy is wasted in incomplete combustion to smoke. Likewise, since any effluent gases from combustion of these propellants are substantially non-corrosive and innocuous, detcrioration of wiring and other equipment is avoided. As substantially all of the oxygen needed for complete combustion is present in the nitro plastic itself, the propellants do not depend upon atmospheric oxygen for their combustion and are therefore to be distinguished from other propellants which are unlike in this respect. The temperature coefiicient of nitro plastic propellants, as indicated in some of the examples, is usually a very desirable low number in contrast to the more undesirable higher coeflicients of previously known propellants. Other advantages accruing to the use of nitro plastic propellants will be apparent to one familiar with the art, and, as important among these advantages may be mentioned the relative stability of the N0 groups which are characteristic of nitro plastics as compared to the more unstable ONO groups present in many commonly employed explosives or combustible materials.

Oxygen balance of the combustible nitro plastics of the present invention may be calculated readily. When it contains suflicient oxygen to burn all the carbon to carbon dioxide and all the hydrogen to water, the compound is considered to be in perfect oxygen balance. It is then said that the compound has an oxygen balance of zero, the value being determined by inserting the values in the formula:

A compound having a minimum oxygen balance of approximately 50 is considerable entirely suitable. This calculation is based on the assumption that a compound containing sutficient oxygen to burn all the carbon to carbon monoxide and one-third of the hydrogen to water will be productive of substantially no smoke. Likewise, it is considered that a propellant having a minimum oxygen balance of minus is suitable for all practical purposes, and experimental tests with compounds having such a minimum oxygen balance of minus 80 have proved the 3 correctness of this assumption. At any greater negative value, the smoke produced and decreased thrust per weight of fuel makes use of the propellant undesirable.

Procedure for calculating burning-law exponents or temperature coefiicients is also known (Crawford and Huggett, O.S.R.D. Report 4009; see also O.S.R.D. Report 5577, p. 52). This procedure allows the indirect evaluation of the temperature coetiicient of a fuel by the experimental measurement of burning-rate change with respect to pressure. Assuming that the Paul Vielle equation proposed by the French Physicist in 1893, holds,

where: r is the linear burning rate of a powder, and n are constants for a certain composition, and P is gas pressure.

It follows that:

d log 1' d log P (rilogP 1 dlogr) dT p rlT K where T equals absolute temperature and area of burning surface of propellant cross-sectional area of throat Experimental burning rate measurements in a Crawford bomb compare very favorably with actual combustion data obtained by the use of the propellant in midget motors. The compositions of the present invention generally exhibit very low temperature coeflicients.

The propellants of the present invention comprise a nitro plastic having a specific oxygen balance. The requisites of such a nitro plastic may be further elucidated as follows:

(a) nitro-: it must contain NO groups, in contrast to other groups sometimes called by the misnomer nitro which are not N0 groups.

(b) -plastic: it must be of high molecular weight, i.e., a polymer; soft, moldable, or pliable.

(c) It must have a minimum oxygen balance of minus 80, calculated according to the equation given previously.

Such suitable nitro plastics may be of various types. These may be, for example, as follows:

(a) Condensation products of nitro aldehydes, nitro acids, nitro acid chlorides, nitro alcohols, nitro aromatic chlorides, with preformed polymers. Representative of this type of nitro plastics are the condensation products of 2,3,3-trinitropropanol, 2,4,6-trinitrobenzaldehyde, nitrofurfurals or poly-(2',2',2 trinitroethyl) benzaldehydes with polyvinyl alcohol or polyvinylamine, such products being nitro acetals and nitro imides, respectively; the condensation product of picryl chloride with polyvinylamine; the condensation products of 2,4,6-trinitrobenzoyl chloride with polyvinylamine, i.e., the polyvinyl amide of trinitrobenzoic acid; the condensation product of phenylisocyanate and polyvinylamine after nitration to introduce N0 groups; and the like.

(b) Condenstaion products of nitro compounds, e.g., nitro prafiins, with polyvinylaminc, such as the condensation products therewith of dinitromethane, nitroform, 1,1- dinitroethane, tetranitroethane, hexanitroethane, 2,3,3-trinitropropanal, and the like.

(c) Polymers of diisocyanates and diamines, with subsequent nitration of the product where necessary. This class includes the nitration products of m-phenylene diisocyanate, toluene diisocyanate, ethylene diisocyanate and 7 known.

(g) Polymers of 1,3-dichloro-2,4,6-trinitrobenzene with hydrazines, with further nitration where practical if desired. Representative hydrazines are hydrazine itself and oxalyl dihydrazide.

(11) Polymers of 1,3-dichloro-2,4,6-trinitrobenzene with itself by the use of a powdered copper polymerization agent.

(i) Polymers of polynitromethanes, formaldehyde, and ammonia through use of a Mannich-type reaction.

The nitration of polymers, where required, may be conducted according to conventional procedure. Thus, for example, nitration may be accomplished with fuming nitric acid or with mixed concentrated sulfuric and concentrated nitric acid. Mild conditions are generally advisable to preclude disintegration of the formed polymer, and nitration of polymers already containing highly nitrated groups is generally not advisable.

Procedure for preparing the compositions of group (a) above may conveniently be such as known in the art and further elucidated by the examples. The starting aldehydes and methods for their preparation are already Trinitrobenzaldehyde has been prepared by Sachs and Evcrding, Berichte 35, 1236 (1902), ibid. 36, 999 (1903) and by Secareanu, Berichte 64, 836 (1931). 2,3,3-trinitropropanal dipotassium salt may be prepared from mucubromic acid (from bromine and furoic acid of furfural, Hill, A. Chem. Jour. 3,4 (1881)) according to the procedure of Torrey, Am. Chem. Jour. 24, 457 (1900). Nitrofurfural may be prepared by the procedure of R. Marquis (Comp. rend. 132, -142 (1901); ibid. 134, 776-777 (1902); Br. Chem. Ab. 80, I, 222 (1901); ibid. 82, I, 483 (1902) or Gilman and Wright, J. Am. Chem. Soc. 52, 2550-2554, 4165-4166 (1930). Aromatic nitro aldehydes may also be prepared by the oxidation of corresponding methylated hydrocarbon derivatives according to the procedure of Thiele and Winter, Annalen 311, 353 (1900). The method of Organic Synthesis, Coll. vol. II, p. 442, is also applicable to the preparation of nitro aldehydes in general. Methods for synthesis of the alcohols are known and in some cases the alcohols are commercially available. Polyvinylamine may be prepared as indicated by Reynolds and Kenyon, J. Am. Chem. Soc. 69, 911 1947 The preparation of group (b) polymers is fully described in the examples, the starting material being known.

The preparation of group (a) polymers is also disclosed in the examples, the starting materials being known. Diisocyanates may be prepared from hydrazides by the Curtius reaction (Curtius and Hechtenberg, J.

Praet. Chem. 105, 289-318 (1923)).

The remaining types of nitro plastics may be prepared according to the method given in the examples, the starting materials being known.

While nitro plastics of prescribed oxygen balance are themselves suited for use as the propellant without. additaments, it may in some cases be desirable to in clude in the propellant a combustible additament, such as a plasticizer, filler, or the like. The nitro plastics may, for example, be plasticized with compounds which are also in satisfactory oxygen balance so that the plasticized product falls within the prescribed range. Compounds which may be incorporated with the nitro plastics,

as plasticizers or additives are o-nitrotoluene, 1,1,2,2- tetranitroethane, 2,2-dinitropro-panol acetate, nitromethane, nitroform, tetranitromethane, methyl nitroacetate, ethyl nitroacetate, glycol dinitrate, glyceryl trinitrate, mannitol hexanitrate, 2,2,3,3-tetranitrobutane, 2,3,3-trinitroisopentane, 2-methyl-2,3,3-trinitropentane, 2,3,3-trinitroisohexane, nitroguanidine, and the like. For optimum stability of the composition, it is considered somewhat less desirable to employ -ONO2 containing compounds than to-employ --NO containing compounds, as the former. are usually relatively unstable, although otherwise satisfactory.

Organic plasticizers or additives other than those mentioned above, such as guanidine or urea derivatives, dibutyl phthalate, etc., may also be employed, providing that the relative quantities of nitro plastic and plasticizer are chosen= for suitable compatibility and so that the plasticized composition is-stillin proper oxygen balance.

When the nitro plastics are plasticized with the above or similar plasticizers, determinations on the polymer indicate a very low burning rate exponent. This is very important as indicative of a low pressure and temperature sensitivity, which, as mentioned above, is highly desirable in a solid propellant of the type here concerned.

Moreover, it has been found that, if desired, a minor proportion of a solid inorganic oxidizer such as ammonium nitrate, potassium nitrate, ammonium picrate, or potassium perchlorate may be incorporated into the nitro plastic and plasticization accomplished subsequently thereto. When such procedure is followed, the composite plasticized nitro plastic and oxidizer composition still is of a very desirable nature, exhibiting a burning rate exponent only slightly higher than that of the plasticized polymer itself. By incorporation of such an inorganic oxidizer into the nitro plastic, it is possible to use as plasticizer compounds other than the nitro com pounds listed above, if desired, making up the lack of oxygen balance in the composition through employment of a selected inorganic oxidizer. It is, of course, to be understood that perchlorates and other corrosive or smoke-producing compounds are to be avoided for optimum utility and smokelessness.

The following examples are illustrative only and are in no way to be construed as limiting.

EXAMPLE 1 Polyvinyl-Acetal of Trinitrobenzaldehyde (a) To a suspension of 0.870 mole (70.4 grams) of high viscosity polyvinyl alcohol in 600 milliliters of glacial acetic acid there was added one mole (241 grams) of 2,4,6-trinitrobenzaldehyde dissolved in 1000 milliliters of glacial acetic acid. An acid catalyst, consisting of 20 milliliters of concentrated hydrochloric acid diluted with twenty milliliters of water, was added with stirring and the reaction continued for 65 hours at a temperature of about 60 degrees centigrade. The transparent solution was then dropped into about ten gallons of water with vigorous stirring. The precipitated fibrous nitro acetal was filtered, washed with one percent solution of sodium carbonate and then with water. The nitro acetal resin was obtained in a yield of about 80 percent and found to be yellow in color, combustible, and to have, a softening point of 85 degrees centigrade.

The polynitro acetal plasticized readily with tetranitromethane, methyl nitroacetate, nitromethane, and onitrotoluene.

(b) One-tenth of a mole (24.1 grams) of 2,4,6-trinitrobenzaldehyde was dissolved in 50 milliliters of glacial acetic acid (or other solvent). To milliliters of the same solvent there was added 7.0 grams of polyvinyl alcohol and stirring employed until the alcohol was dissolved or dispersed. This represented a molar ratio of the aldehyde to the alcohol of 1.25, where a mole of polyvinyl alcohol is considered as The two solutions were transferred to a 300-rnilliliter wide-mouth Florence flask equipped with a stirrer and placed in a 55 degree centigrade thermostat. After the desired amount of dilute hydrochloric acid (equal parts by volume of water and concentrated dilute hydrochloric acid) was added, the mixture was allowed to react with stirring for the desired period of time (see table below).

t the end of the reaction time, the contents of the flask were added dropwise to four liters of water with very vigorous agitation at room temperature. The plastic formed immediately and was separated from the aqueous solution by filtration. The product was washed with dilute sodium bicarbonate and then with water until the pink color due to the action of sodium bicarbonate had disappeared. The white plastic mass was finally dried at 60 degrees centigrade. Conditions under which the While the runs employing glacial acetic acid as solvent resulted in a clear, brown solution, complete solution of the reactants was not obtained in run 3 where methanol was used as a solvent.

EXAMPLE 2 Polyvinyl A cetal of S-Nitrofurfural (a). To. a suspension of 0.2 mole (17.6 grams) of high viscosity (45-55 centipoises) polyvinyl alcohol in 200 milliliter of glacial acetic acid there was added 0.2 mole (48.6 gram) of S-nitrofurfural diacetate and eight milliliters of six-N hydrochloric acid. The mixture was stirred mechanically for hours at 60 degrees centigrade. The clear brown solution was then added dropwise to about two gallons of water with vigorous stirring. The precipitate was washed with a two percent sodium carbonate solution and then with water. The dried, white polymer burned readily in air and had a softening point of about degrees centigrade.

'(b) In a SOD-milliliter round-bottom three-neck flask equipped with a stirrer was placed 200 milliliters of glacial acetic acid containing 0.2 mole (48.6 grams) of S-nitrofural diacetate. After adding eight milliliters of six-N hydrochloric acid and 0.2 mole of high Viscosity polyvinyl alcohol which had been emulsified in 150 milliliters of glacial acetic acid, the contents of the flask were maintained at 57 degrees centigrade for 23 hours. At the end of this time, the polyvinyl alcohol had completely dissolved. The solution was added dropwise into about ten liters of water with vigorous stirring. The solid product, which immediately formed, consisted of small white balls. The precipitate was Washed with two percent sodium carbonate solution, then with water, and dried in an oven at 65 degrees centigrade. The dried product burned readily in air. The apparent density, determined by pouring a weighed quantity of the polymer into a graduated cylinder, was 0.12. The product weighed 34 grams, representing about 81 percent of the theoretical yield. The polymer did not liquefy under 200 degrees centigrade with slow rise in temperature.

The nitro acetal polymer plasticized readily with onitrotoluene or methyl nitroacetate.

EXAMPLE 3 Polyvinyl Acetal of 2,3,3-Trinitropropanal Twenty grams of the dipotassium salt of 2,3,3-t1initropropanal was added slowly to 100 milliliters of glacial acetic acid. A definite decrease in the acidity of the acid was noted upon addition. The mixture was placed in a round-bottom three-neck flask fitted with a thermometer and a stirrer and 4.4 grams of polyvinyl alcohol suspended in 100 milliliters of glacial acetic acid added thereto The solution was heated to 90 degrees centigrade and refluxed for 48 hours, whereupon the mixture became viscous and was poured into cold water, washed and separated. The nitro acetal which was obtained in this manner burned with an almost smokeless flame, and plasticized or formed intimate admixtures with tetranitromethane, 2,2-dinitropropane and methyl nitroacetate.

EXAMPLE 4 Percent Nitroacetal 52.25 Ammonium nitrate 34.83 Methyl nitroacetate 12.92

The strand was placed on a glass plate at room temperature (27 degrees centigrade) to determine weight increase (hygroscopicity) or weight loss (volatility of methyl nitroacetate) The weight of the sample and the uniform texture thereof did not change over a period of one month.

EXAMPLE 5 Forty grams of ball-milled polyvinyl acetal of 2,4,6-trinitrobenzaldehyde and sixteen grams of dried ammonium nitrate (0.1 percent calcium phosphate added) were tumbled in the ball mill of Example 4. After 24- hours of blending, the powdered mixture was mixed with tetranitromethane (20.6 grams) of which 6.7 grams volatilized Initial Peak Burning Pressure, Pressure, Rate,

p.s.l. p.s.l. Inches/ Second When graphed, the value of the slope n, using the method of least squares, was found to be 0.57, which is a very low burning-law exponent.

EXAMPLE 6 Suflicient tetranitromethane is added to the desired quantity of pulverized nitro acetal to yield a mixture containing 28 percent thereof. If the mixing is done by hand with a steel spatula, about 40 grams of the nitro acetal worked on a 10 x 10 inch glass plate is convenient. This amount requires 16 grams of tetranitromethane, which is quickly absorbed by the plastic, and the mixture may be finally kneaded with the fingers. A stifi, brown, doughy mass results, which is shaped by rolling on a plate to form strands of whatever length and diameter may be desired.

Burning rate determinations were conducted with strands of (a) polyvinyl acetal of 2,4,6trinitrobenzaldehyde plasticized with 28 percent tetranitromethane and (b) 75 percent potassium perchlorate-25 percent peptized rubber. The strands were coated with glyptal enamel before determinations in a Crawford bomb. The results were as follows:

COMPOSITION (a) Initial Peak Burning Pressure, Pressure, Rate,

p.s.i. p.s.l. Inches] Second The burning-law exponent n for this composition was 0.36, a very low value.

COMPOSITION (b) Initial Peak Burning Pressure, Pressure, Rate,

p.s.i. p.s.i. Inches/ Second The burning-law exponent for composition (b) was n=0.74.

H2O (NOz)a 20H20 NR3 plastics in the same manner are l,1,4,4-tetranitrobutane, 1,1,3,3 tetranitropropane, 1,3 dinitropropane, tetranitropentane and bis-beta,beta-dinitrodiethyl ether.

EZN

EXAMPLE 7 In a burning-rate experiment similar to that of Example 6, a strand of 72 percent polyvinyl acetal of 2,4,6-trinitrobenzaldehyde and 28 percenttetranitromethanecomposition, coated with glyptal enamel, exhibited a burninglaw exponent of 0.32.

EXAMPLE 8 Conversion of Dinitromethane Into a Plastic 10 N02 ]-OH2NHCH2.

l lo: n

(a) Eleven and four-tenths grams of 37 percent formalin (0.141 mole formaldehyde) and 2.8 grams of 28 percent amrnonia-solution (0.047 mole of ammonia) were mixed together and placed in a three-neck flask provided with reflux condenser, stirrer, and thermometer. contents of the flask were cooled to five degrees centigrade and five grams of dinitromethane (0.047 mole) dissolved in 6.6 grams of benzene added dropwise. required about 30 minutes. 21 hours at room temperature (25 degrees centigrade) and for an additional hour at about 50 degrees centigrade. The reaction mixture was then poured into water and an amorphous substance separated and dried in a vacuum desiccator. burned readily and plasticized with cellulose nitrate and methyl nitroacetate.

The

The addition The mixture was stirred for The product was a brown powder which (5) Five and two-tenths grams of 37 percent formalin solution (0.063 mole formaldehyde) and 1.4 grams of 28 percent ammonia solution (0.021 mole of ammonia) weremixed together and placed in a ZOO-milliliter roundbottom three-neck flask provided with stirrer, thermometer, and reflux condenser. cooled down to 3 degrees centigrade and 2.3 grams (0.021 mole) of CH (N0 dissolved in 15 milliliters ofbenzene added dropwise thereto. minutes, during which the temperature rose from 3 degrees centigrade to +3 degrees centigrade. continued for 48 hours while the reaction mixture was allowed to warm to room temperature (25 degrees centigrade). water to yield a plastic material which could be pulverized to a brown powder after drying in a vacuum desiccator over drierite.

The contents of the flask were 40 Additlon required ten Stirring was The contents of the flask were then diluted with Other polynitro compounds which may be converted to EXAMPLE 9 Condensation of m-Phenylenediamine With Ethylene Bromide and Subsequent Nitration 6O NHz BICHtCHzBl OgN N02 (a) A-solution of freshly rectified m-phenylenediamine 75.

(40.8 grams) in 30 milliliters of ethylene glycol was placed in a-250-rnilliliter three-neck flask equipped with thermometer, stirrer, and reflux condenser. Ethylene bromide (16.4 milliliters) was added from a burette, and the mixture slowly heated. When the temperature reached degrees centigrade, a vigorous exothermicv reaction occurred and the temperature rose rapidly to 150 degrees centigrade. After this first reaction had subsided, the resulting dark red solution was refluxed at 190 degrees centigrade for minutes. The viscous reaction mixture at 150 degrees centigrade was poured into 1750 milliliters of cold water, and the aqueous mixture neutralized with dilute sodium hydroxide solution. A dark red plastic material precipitated as a ball, was removed, washed thoroughly with hot water, and dried in an oven at 110 degrees centigrade. The dried material was cooled and pulverized, yielding 31.3 grams of an orange powder.

For nitration of this material, 100 milliliters of fuming nitric acid (specific gravity 1.5) Was cooled'to zero degrees centigrade and 0.1 gram of urea added. Eight gramsof the orange powder was then added in approximately 01 gram portions, while holding the temperature below five degrees centigrade. The addition required one hour, whereafter the resulting brown solution was allowed to-warm to 20-degrees centigrade, andwas then heated to 40 degrees centigrade for 15 minutes. The solu tion was cooled to roomtemperature and poured into one liter of distilled water. A tan precipitate formed and was filtered off, washed with water, dilute Na CO solution and then more water,. and finally dried. A yield of 12.04 grams of tan powder containing 20.55 percent nitrogen -was obtained. This material burned well, leaving only some residue. Therefore 10.0 grams were added slowly to 100 milliliters of fuming nitric acid at 20 degrees centigrade, and the resulting solution heated for fifteen minutes at 92 degrees centigrade. Vigorous evolution of N0 occurred. The reaction mixture was then cooled to 20 degrees centigrade and poured into one liter of water. The yellow precipitate which formed was fil tered off, washed with Na CO solution, water, and dried on the filter. A yield of 8.3 grams of tan powder containing 20.00 percent nitrogen was obtained. The burning. properties of this material were somewhat better than those of the once nitrated material.

([2) A solution of 31.0 grams of freshly rectified m-phenylenediamine in 30 milliliters of dioxan was placed in a 250-milliliter three-neck flask equipped with thermometer, stirrer, and reflux condenser.v Ethylene bromide (12.42 milliliters) was added from a burette, and the solution slowly heated. An exothermic reaction began at 65 degrees centigrade, the temperature rising rapidly to 110 degrees Centigrade. At this point'a gummy mass precipitated from solution. This mixture was refluxed for one hour and then poured into one liter of water. The resulting slurry was neutralized and the greenishyellow plastic which separated removed as a ball. This was washed thoroughly with several portions of Na CO solution followed by several portions of water. The washed product was dried in a vacuum desiccator and a yield of 16.73 grams of greenish-yellow powder containing 16.12 percent nitrogen obtained. This material softened at -135 degrees centigrade. The starting materials can also be condensed in nitromethane or without a solvent.

For nitration, 10.0 grams of this material were added in approximately 0.1 gram portions to milliliters of fuming nitric acid cooled to zero degrees centigrade. The brown solution which resulted was allowed to warm to 20 degrees Centigrade, stand for one hour, and then poured into one liter of distilled water. The brown solid which precipitated was filtered 01f, washed and dried. A yield of 13t25 grams of tan powder containing 19.95 percent nitrogen was obtained. This material burned very vigorously and could be plasticized with methyl nitroacetate.

1 1 EXAMPLE 10 Condensation of m-Phenylenea'iamine With Trimethylene Bromide and Subsequent Nitration H N NH: BrCHzCHzCHzBr NO: N N02 OzN N01 The procedure described in Example 9 was repeated using 26.5 grams of m-phenylenediamine, 12.50 milliliters of trimethylene bromide and 30 milliliters of dioxan. A yield of 17.0 grams of greenish-yellow powder containing 15.92 percent nitrogen was obtained.

Nitration of the product according to the procedure of Example 9 gives a plasticizable resin which burns very well.

EXAMPLE 11 Condensation of Ethylene Diisocyanate With Ethylene Diamine and Subsequent Nitration 0=C=NCH2CH2N=C=O+HgNCH2CHzNHI v [-CH CHzNHCONH-]n+HNOa N02 N 02 --CH2GH2NC ON 111 A solution of 1.12 grams (0.01 mole) of ethylene diisocyanate in milliliters of dioxan was added dropwise to a solution of 0.60 gram (0.01 mole) of ethylene diamine in 10 milliliters of dioxan. A white precipitate formed immediately and was filtered oil. The yield was 1.4 grams.

Nitration of this product was eifected by adding 1.0 gram of the material in small portions to 10 milliliters of fuming nitric acid at room temperature. The resulting solution was poured into cold water, to give the white nitrated product, which burned well.

EXAMPLE 12 Condensation of m-Phenylenediamine With Phosgene and Subsequent Nitration HnN NHz NO: IITO: N01

Oz N02 A solution of 10.8 grams (0.10 mole) of purified mphenylenediamine in 50 milliliters of chloroform was placed in a large test tube and 9.9 grams (0.10 mole) of phosgene bubbled in over a period of 30 minutes. A black tacky material precipitated, and on further treatment the precipitate turned to a white powder. This material was filtered 01f, washed with chloroform, and dried, yielding 13.9 grams of white powder.

Five grams of this material was added in small portions to 25 milliliters of fuming nitric acid at zero degrees centigrade. A deep brown solution formed, and was allowed to stand for ten minutes. This solution was added 12 to 500 milliliters of cold water, whereupon a tan precipitate formed. This was filtered off and dried, yielding 5.7 grams of material which burned vigorously and was plasticized with methyl nitroacetate.

EXAMPLE 13 Condensation of m-Phenylenediamine With Ethylene Diisocyanate and Subsequent Nilration HzN NHg+0=C=NCHzCHz-N=C=O 11 NO; $01 N02 N02 N01 -N-O O-N-CHzCHzNC ON- On N0 A solution of 1.55 grams of ethylene diisocyanate in 10 milliliters of o-dichlorobenzene was added dropwise to a hot solution of 1.5 grams of m-phenylenediamine in 10 milliliters of o-dichlorobenzene. A gummy white product precipitated and hardened on cooling. This was filtered oh? and dried, yielding 2.8 grams of product.

This product (2.0 grams) was nitrated by addition in small portions to 20 milliliters of fuming nitric acid at room temperature. The resulting solution was heated to 70 degrees centigrade for 15 minutes, then cooled, and poured into water. A tan material precipitated, was filtered off and dried. This material burned fairly well, leaving only a small amount of residue.

Renitration under similar conditions, but with hot mixed acids apparently did not improve the burning qualities by any appreciable amount.

EXAMPLE 14 Condensation of m-Phenylenediamine With Ethylene Oxide, Polymerization, and Subsequent Nitration an NHz-CHzCHzOH H250 N01 N01 NO:

OzN N02 (a) Liquid ethylene oxide (18.6 grams) was poured into a solution of 45.6 grams of freshly distilled m-phenylenediamine in 200 milliliters of methanol, and the resulting mixture was rectified at reduced pressure, and the following fractions collected:

(1) Bl. 30 at 150 mm.l ml.--methanol (2) B.P. 127-185 at 2.5 mm.-m-phenylenediamine (3) BF. 188 at 3.5 mm.21.6 g. Fraction 3 solidified on standing, and recrystallization from chloroform gave White crystals melting at 62-63 degrees centigrade and containing 18.65 percent nitrogen. (18.42 calculated for N-(fi-hydroxyethyl)-mphenylenediamine.)

(b) A solution of 74.7 grams of freshly rectified m- (2) HP. 191 at 3 rnm.-1.0 g.

phenylenediamine in 250 milliliters of water was heated to boiling, and 20.4 grams of ethylene oxide was bubbled through the solution. The effluent gas was passed through a water-cooled reflux condenser and into a Dry-Ice trap. When all of the ethylene oxide had been added, the contents of the Dry-Ice trap were allowed to vaporize and pass through the solution.

The resulting solution Was then rectified at reduced pressure, and, after the water had been removed, the following fractions were collected:

The resulting solution was then rectified at reduced pressure, and, after the water had been removed, the following fractions were collected:

(1) HP. 130-133" at 3 mm.--38.0 g.-m-phenylenediamine 3 B.P. 192494 at 3 mm.28.6.-M.P. 61-62 0.

Fraction 3 was the desired N-(B-hydroxyethyD-mphenylenediamine.

(c) Five grams of molten N-(fi-hydroxyethyl)-m-phenylenediamine was added to 25 milliliters of concentrated sulfuric acid, and the mixture carefully warmed until solution was complete. The resulting clear, colorless solution was cooled to five degrees centigrade and concentrated nitric acid (20 milliliters) added dropwise thereto at 5-10 degrees centigrade. The solution turned to a deep brown color, but no fumes were evolved. The solution Was allowed to warm up to 40 degrees centigrade and was held at this temperature with cooling until reaction ceased. The mixture was then poured over crushed ice, and the resulting slurry boiled to coagulate the solid product into a plastic ball. This was washed thoroughly with hot water and dried in a desiccator to yield a reddish-brown material which burned with extreme vigor. This material melted at 6070 degrees centigrated with some decomposition.

EXAMPLE 15 Condensation of m-Phenylenediamine with Ethylene Oxide and Subsequent Nitration HQN NH; 0112-0112 O N N02 A solution of 169.8 grams of freshly rectified rn-phenylenediamine in 500 milliliters of methanol was placed in a one-liter flask equipped with a vapor inlet tube, a thermometer, and a Dry Ice-cooled reflux condenser. The solution was cooled to five degrees Centigrade and 72.5 grams of ethylene oxide bubbled in over a period of three hours. An exothermic reaction occurred, and the solution turned blue. This solution was allowed to warm to room temperature and stand for two hours, whereafter the methanol was removed by distillation under reduced pressure. A viscous red residue, weighing 219 grams, remained in the flask.

Fuming nitric acid (100 milliliters) was cooled to zero degrees centigrade in a 250-milliliter three-neck flask and 15.6 grams of viscous reaction product added dropwise over a period of four hours at 0-5 degrees Centigrade. The dark red resulting solution was allowed to warm up to 20 degrees centigrade and stand for one hour, and was then added dropwise to 1100 milliliters of percent acetic acid. A tan material precipitated, was filtered off, and placed in 200 milliliters of hot water. A

EXAMPLE 16 (CrHsO CO-NHCHzCHzNHhCO 2 C (I. A

Hm ONH A HzN-NH: 2 I

("l-NH O (e) Condensation of N,N'-his-(beta-arninoethyl)-urea with diisocyanate.

(f) Subsequent nitration.

(a) Reaction of Ethylene Diamine With Diethyl Carbonate Ethylene diamine (92 grams, 1.53 mole) was heated to reflux temperature in a 250-milliliter, three-neck flask equipped with a stirrer, reflux condenser, and dropping funnel. Diethyl carbonate (60 grams, 0.5 mole) was added dropwise over a period of six hours, and the resulting solution was refluxed for an additional 18 hours. The solution was then transferred to a distilling flask and two fractions distilled at reduced pressure. The first fraction, boiling below 146 degrees centigrade at 35 millimeters of mercury pressure consisted of ethanol, unreacted ethylene diamine, and diethyl carbonate. The second fraction, boiling at 146-161 degrees centigrade at 35 millimeters of mercury pressure was rectified under reduced pressure, and 33.4 grams of material boiling at 1065-1072 degrees Centigrade at 4 millimeters of mercury pressure obtained. This was the monourethan of ethylene diamine. The residue from the distillation solidified on cooling, and recrystallization of a portion of this material showed it to be the diurethan of ethylene diamine, MP. 112-113 degrees Centigrade.

(17) Reaction 0 the Monourethan of Ethylene Diamine With Phosgene A solution of 6.6 grams of the monourethan of ethylene diamine in aqueous potassium hydroxide (20 milliliters H O+2.8 grams of KOH) was placed in a small flask and 2.5 grams of phosgene bubbled into the solution. An exothermic reaction occurred, and, when the solution was cooled, a white crystalline material precipitated. This was filtered off and recrystallized from water, giving 2.65 grams of a white crystalline solid melting at 166-168 degrees centigrade. A nitrogen analysis showed 19.64 percent nitrogen in the compound, as compared to a theoretical value of 19.3 percent for N,l l'-bis-(beta-carbethoxyamino ethyl) -urea.

15 (c) Reaction of N,N-Bis-(Beta-Curbetlzoxyamin'oethyl)- Urea With Phthalie Anhydride A mixture of 1.45 grams (0.05 mole) of the diurethan from (b) and 1.49 grams (0.10 mole) of phthalic anhydride was heated in a test tube until gas evolution from the molten mass ceased. The melt was then cooled and dissolved in boiling ethanol. When this solution was cooled, 1.8 grams of white crystals melting at 155-156 degrees centigrade precipitated. This material was N,N- bis-(beta-phthalimidoethyl)-urea.

(d) Reaction of N,N'-Bis-(Beta-Phthalimidoethyl)-Urea With Hydrazine Hydrate To a solution of 0.52 gram of 85 percent hydrazine hydrate in 10 milliliters of ethanol was added 1.8 grams of N,N'-bis-(beta-phthalimidoethyl)-urea. The resulting solution was heated until a white, gelatinous precipitate formed. Hydrochloric acid (2.6 milliliters) was then added and the mixture filtered to remove phthalyl hydrazide. The filtrate was concentrated to remove ethanol, and the resulting aqueous solution was neutralized with aqueous potassium hydroxide. The solution was then saturated with potassium carbonate to salt out the free amine which was taken up with ether. The ether solution was dried over solid KOH, and then saturated with anhydrous HCl to precipitate 0.27 gram of a white crystalline substance melting at 113-115 degrees centigrade. This material is the dihydrochloride of N,N'-bis-(betaaminoethyl) -urea.

(e and f) Condensation of the N,N'-bis-(beta-aminoethyl)-urea with diisocyanates, e.g., m-phenylenediisocyanate, ethylene diisocyanate, and subsequent nitration according to the procedure of the preceding examples gives nitro plastics having very desirable burning characteristics.

Copper N02 O N NO; OzN N02 (a) A solution of 7.05 grams (0.025 mole) of 1,3-dichloro-2,4,6-trinitrobenzene [Sudborough and Picton, J. Chem. Soc. 89, 591 (1906)] in 75 milliliters of nitrobenzene was heated to boiling, and 17.5 grams (0.27 mole) of copper powder added in small portions to the refluxing solution. The resulting brown suspension was refluxed for one hour; then cooled and poured into 500 milliliters of ether. The resulting slurry was filtered and the filter cake extracted successively, with ether, dilute hydrochloric acid, dilute nitric acid, and water. The remaining solid was dried to yield 4.5 grams of brown powder. This material burned readily leaving little residue. The product was chlorine-free and could be plasticized with methyl nitroacetate.

(b) A second experiment was carried out in the same manner as above, but the solution was refluxed for sixteen hours instead of one hour. A yield of 3.5 grams of chlorine-free product was obtained.

EXAMPLE 18 Reaction of 1,3-DichZora-2,4,6-Trinitrobenzene With Ethylene Glycol Cl Cl +110 CHzCHzOH O: N01

0 CH2CH2O- OgN NO:

To 25 milliliters of pyridine was added 1.0 gram of l,3-dichloro-2,4,6-trinitrobenzene, whereupon a dark brown solution containing a reddish brown precipitate was formed. The mixture was heated to reflux temperature, five drops of ethylene glycol added, and, after refluxing for six hours, cooled to zero degrees centigrade and filtered. A small amount of tan crystalline material which did not melt below 250 degrees centigrade and which exploded when heated in an open flame was obtained. This material gave a negative Beilstein test for halogen. The filtrate was poured over approximately grams of ice and acidified with concentrated HCl, forming a brown amorphous precipitate. This material was filtered off, dried, and found not to melt below 250 degrees centigrade; to burn rapidly when ignited leaving little residue; and to give a positive Beilstein test for halogen. It apparently was not readily plasticized with tetranitromethane or dibutyl phthalate.

EXAMPLE 19 Reaction of 1,3-Dichl0ro-2,4,6-Trinitrobenzene With Hydrazine N0, No,

01 or -NIINH HzN-NH: OzN N O, OgN N 0:

(a) Five moles of hydrazine per mole of dichlorotrinitrobenzene.

A solution of 7.05 grams (0.025 mole) of 1,3-dichloro- 2,4,6-trinitrobenzene in 300 milliliters of methanol was prepared and 40 milliliters of absolute ethyl alcohol containing 0.10 gram of hydrazine per milliliter (0.125 mole total) added dropwise thereto with vigorous stirring. The addition required three hours, during which time the temperature rose from 20 degrees centigrade to 33 degrees centigrade. T he resulting slurry was stirred for 48 hours and then filtered, yielding a black solid and black filtrate. The solid was washed free of hydrazine hydrochloride, and 2.2 grams of chlorine-free material melting at 175- 95 degrees centigrade obtained. This product burned vigorously.

The filtrate was added to water and the resulting emulsion broken by addition of sodium chloride. The solid was filtered off, and 1.3 grams of brown solid, melting at 77-95 degrees centigrade, obtained. This material plasticized with methyl nitroacetate and was chlorine-free.

(b) Three moles hydrazine per mole of dichlorotrinitrobenzene.

A solution of 7.05 grams (0.025 mole) of dichlorotrinitrobenze-ne in 300 milliliters of methanol was prepared and 24 milliliters (0.075 mole) of the alcoholic hydrazine solution added dropwise with stirring and cooling. The addition was carried out at 18-20 degrees centigrade over a period of two and one-half hours, the resulting solution being stirred for 48 hours.

The solution was added dropwise in a steam distillation apparatus to one liter of boiling water through which steam was being passed. Methanol was stripped 011?, and an aqueous slurry of brown powder which remained in the distillation flask filtered to give 3.0 grams of brown powder. This material could be plasticized with methyl nitroacetate.

(c) A solution of 7.05 grams (0.025 mole) of 1,3- dichloro-2,4,6-trinitrobenzene in 75 milliliters of ethanol was prepared, and a solution of 2.94 grams (0.050 mole) of 85 percent hydrazine hydrate in 24 milliliters of ethanol added dropwise thereto with stirring. The mixture was stirred for hours at room temperature and filtered to yield a brown precipitate and a black filtrate.

The precipitate was washed free of hydrazine hydrochloride with successive portions of distilled water and yielded 3.2 grams of brown powder melting at 108-115 degrees centigrade. This material burned vigorously and could be plasticized with methyl nitroacetate.

tered ofi and dried, yielding 2.7 grams of a black solid' which melted at approximately 60 degrees centigrade.

(d) This experiment was similar to (c) except that 5.88 grams (0.10 mole) of hydrazine hydrate and 7.05 grams (0.025 mole) of 1,3-dichloro-2,4,6-trinitrobenzene were used. When the reaction mixture wasfiltered after 122 hours, a brown filter cake and black filtrate were obtained. The filter cake was washed free of hydrazine hydrochloride and extracted with benzene. The brown powder (3.3 grams) which was obtained burned with extreme vigor and could be plasticized with the product from the reaction of potassium nitroform and acrylonitrile. When the filtrate was added to water containing Na SO a black gummy precipitate was obtained which burned well.

(e) Experiment was repeated at a temperature of 40 degrees centigrade instead of room temperature. The solid product obtained by filtration weighed 3.86 grams. This was washed free of hydrazine hydrochloride and extracted with benzene to yield a reddish brown powder which could be plasticized with methyl nitroacetate.

(f) A solution of 5.5 grams of hydrazine sulfate in aqueous ethanol was prepared and added rapidly with stirring and cooling to a solution of 10.0 grams of 1,3-dichloro-2,4,6-trinitrobenzene in 90 milliliters of dioxan. The resulting deep red solution was stirred for two hours at room temperature, filtered to remove potassium sulfate, and added dropwise to one liter of water. The stable emulsion which formed was broken by addition of sodium chloride. A dark brown solid precipitated and was tiltered oflf and dried to yield 7.5 grams of a material which melted at 53-83 degrees centigrade. This product burned vigorously, contained some chlorine, and could be plasticized with methyl nitroacetate to give a firm, semi-elastic product.

In an attempt to form a higher polymer, 6.0 grams of this material was dissolved in 25 milliliters of dioxan and one milliliter of 85 percent hydrazine hydrate solution added thereto. A vigorous reaction ensued, whereafter the solution was heated for 48 hours to 85 degrees centigrade. The products isolated from the reaction mixture contained less chlorine, but did not seem to be much higher polymers as indicated by the product obtained on plasticization with methyl nitroacetate.

(g) A solution of 10.0 grams of 1,3-dichloro-2,4,6-trinitrobenzene in 100 milliliters of dioxan was prepared and a solution of 2.1 grams of 85 percent hydrazine hydrate in 20 milliliters ofdioxan added dropwise thereto with vigorous stirring. A white precipitate and a small amount of black tar was formed. The mixture was transferred to a flask equipped with a reflux condenser, heated at 85 degrees centigrade for 48 hours, cooled to room temperature, filtered to remove hydrazine dihydrochloride, and added dropwise to ice-water. The black tarry product was dried in a vacuum desiccator to yield a black, pitchlike substance melting at approximately 60 degrees centigrade.

(h) A solution of 2.94 grams (0.05 mole) of hydrazine hydrate in 20 milliliters of glacial acetic acid was added to a solution of 14.1 grams (0.05 mole) of 1,3-dichloro-2,4,6-trinitrobenzene and 7.7 grams (0.10 mole) of ammonium acetate in 100 milliliters of glacial acetic acid. The resulting red solution was heated for 65 hours at 70-80 degrees centigrade. On cooling and filtering, 3.4 grams of ammonium chloride was obtained. The filtrate was added dropwise to water, whereupon 2.0 grams of brown powder precipitated. This material contained some chlorine, burned readily, and could be plasticized with methyl nitroacetate to yield a plastic-like material of low tensile strength.

(i) A solution of 5.88 grams (0.10 mole) of 85 percent hydrazine hydrate in 20 milliliters of glacial acetic acid was added to a solution of 14.1 grams (0.05 mole) of 1,3-dichloro-2,4,6-trinitrobenzene in 100 milliliters of glacial acetic acid, and the resulting mixture heated for 65 hours at 70-75 degrees Centigrade. It was then cooled, filtered, and 1.8 grams of impure hydrazine dihydrochloride separated therefrom. The filtrate was added dropwise to ice water, whereupon 9.0 grams of a red-brown powder precipitated. This material contained chlorine, melted at 105160 degrees centigrade, burned vigorously and plasticized readily with methyl nitroacetate to give a firm material with low tensile strength.

(j) To 13.7 grams of hydrazine sulfate suspended in 50 milliliters of hot water was added 3.5 grams of po tassium acetate. The mixture was boiled for five minutes, cooled to 70 degrees centigrade, diluted with 30 milliliters of ethanol, and filtered to remove potassium sulfate. The filter cake was washed with 30 milliliters of hot ethanol, and the combined filtrate and wash solution set aside for use in the reaction with 1,3-dichloro-2,4,6-trinitrobenzene.

In a 500-milliliter three-neck flask equipped with reflux condenser and stirrer was placed 12.3 grams of 1,3-dichloro-2,4,6-trinitrobenzene and 100 milliliters of ethanol. The mixture was heated to boiling and the previously prepared hydrazine solution added dropwise thereto. The resulting black solution was refluxed for 16 hours, cooled, and filtered to give 11.5 grams of a black powder. After washing with hot water to remove potassium salts, 10.0 grams of potassium-free black powder was obtained. This material burned rapidly leaving a moderate amount of residue, did not contain chlorine, and did not melt below 275 degrees centigrade. On heating to 375 degrees centigrade, slow decomposition was observed but there was no evidence of melting. It was insoluble in water, acetone, alcohol and pyridine, and slightly soluble in benzene. With pyridine the product gave a tacky material which changed back to powder when the pyridine was evaporated.

(k) A hot solution of 8.8 grams (0.15 mole) of percent hydrazine hydrate in 25 milliliters of glacial acetic acid was added rapidly to a refluxing solution of 14.1 grams (0.05 mole) of 1,3-dichloro-2,4,6-trinitrobenzene in 25 milliliters of glacial acetic acid. The mixture was deep red in color. The temperature was then lowered to degrees centigrade, the mixture stirred for 24 hours, and the resulting black suspension added to 750 milliliters of water. A brown precipitate was formed, filtered off and dried, yielding 5.4 grams of a brown powder which burned readily and could be plasticized with methyl nitroacetate.

EXAMPLE 20 Condensation of 1,3-DichZora-2,4,6-Trinitrobenzene With Oxalyl Dihydrazide Preparation of oxalyl dihydrazide, (CONHNH according to Schoefer and Schwan (J. Prakt. Chem. 51, 194). Yield: 85 percent of theory.

(a) A solution of 7.05 grams of 1,3-dich1oro-2,4,6-trinitrobenzene in 50 milliliters of hot ethylene glycol was added slowly to a boiling solution of 2.70 grams of oxalyl dihydrazide in 50 milliliters of ethylene glycol. The mixture turned deep red in color and was refluxed for two hours, cooled to room temperature, and added dropwise to one liter of water. A brown solid precipitated and was filtered off. Drying at 55 degrees centigrade resulted 19 in a black pitch-like substance which, when dry, weighed 29 grams.

(b) A mixture of 7.05 grams of 1,3-dichloro-2,4,6- trinitrobenzene, 2.80 grams of oxalyl dihydrazide, and 12 milliliters of ethylene glycol was placed in a twelve-inch Pyrex test tube equipped with stirrer, thermometer, and gas inlet and outlet tubes for operation under nitrogen atmosphere. The tube was heated slowly while nitrogen circulated through the system. At 80 degrees centigrade an exothermic reaction began, and the mixture turned to a viscous orange mass. When this reaction had subsided, the temperature was slowly raised to 127 degrees centigrade, where a second more vigorous reaction started. The mass became dark brown in color, HCl was evolved, and the temperature rose to 150 degrees centigrade. This temperature was maintained for one hour by applying heat as the reaction became less vigorous, whereafter the hot fluid mixture was poured into one liter of cold water. Five grams of a red-brown powder precipitated, was filtered olf, and was dried for 36 hours in a vacuum desiccator. This product melted at 80-110 degrees centigrade, was readily plasticized with methyl nitroacetate, and burned well.

(c) This experiment was conducted in the same manner as (b), except that, after heating for one hourat 134 degrees centigrade, a vacuum of 70-80 millimeters of mercury was applied to the system and heating continued for four hours at 110-120 degrees centigrade. The product (4.0 grams) was a brown powder which melted at 135-65 degrees centigrade, plasticized readily with methyl nitroacetate, and burned well.

(a) Five-tenths gram of solid polyvinylamine was added to approximately two grams of nitroform dissolved in ether. A yellow gummy precipitate was formed which, upon drying, burned vigorously and left no ash.

(b) Twenty-seven milliliters of methanol containing .6 gram of polyvinylamine was placed in a 400-milliliter beaker and the solution cooled to between zero and five degrees centigrade. Thirty-five milliliters of ether containing 2.20 grams of nitroform was added to this solution with stirring. A yellow precipitate was formed immediately. The mixture was stirred for one hour, methanol decanted off, and the residue washed with methanol and dried in a vacuum desiccator. The product burned very well.

(c) Approximately one gram of nitroform dissolved in ether was placed in a beaker and approximately three grams of polyvinylamine dissolved in alcohol added dropwise thereto. A yellow precipitate was formed. This was rubber-like when wet but burned well after drying. (d) Six-tenths gram of polyvinylamine was added to approximately two grams of nitroform. The solution was shaken vigorously and allowed to stand at room temperature for several days. A yellow gummy precipitate was obtained which burned well on drying and analyzed for 24.4 percent nitrogen as compared to 35.5 percent calculated.

(e) One hundred milliliters of alcohol containing .5 gram of sodium hydroxide Was placed in a 500-milliliter round-bottom three-neck flask and one gram of polyvinylamine hydrochloride added in a nitrogen atmosphere. The solution was heated to 40 degrees centigrade and 1.8 grams of nitroform dissolved in 50 milliliters of alcohol added dropwise with stirring. Stirring and heating were continued for three hours, whereafter the yellow precipitate which formed was isolated, washed with water, and dried in a vacuum desiccator.

(f) Polyvinylamine hydrochloride (.5 gram) was dis- 20 solved in water and added dropwise to a water solution of potassium nitroform (2 grams) which was placed in a three-neck round-bottom flask equipped with a stirrer. The yellow precipitate which was formed burned very well upon drying leaving very little ash. The mole ratio of polyvinylamine hydrochloride and potassium nitroform was 1 to 2.

(g) An experiment similar to (f) was carried out but with 1 to 3 ratio. The product burned well, leaving very little ash.

(11) An experiment similar to (1) was carried out but with 1 to 4 mole ratio. The product burned about the same.

(1) One gram of polyvinylamine hydrochloride was placed in 250 milliliters of freshly distilled ethanol contained in a separatory funnel. Nitrogen was bubbled through the alcohol solution and 0.5 gram of solid sodium hydroxide added. The solution was agitated for eight hours while nitrogen was introduced into the solution, after which the nitrogen inlet tube was lifted to just above the surface of the alcohol solution. The NaCl formed was allowed to settle out and the alcohol solution was syphoned over to a sintered glass disc funnel which was connected to a ground glass three-neck round-bottom flask equipped with stirrer, dropping funnel, and two two-way stopcocks. for a nitrogen inlet and a vacuum connection. The purpose of the filter was to remove any traces of NaCl remaining in the solution. After the solution had filtered through, the stirrer was started and 3.72 grams of nitroform dissolved in milliliters of ether added dropwise. A yellow precipitate was formed immediately. The solution was stirred for six hours and the gummy precipitate was removed along with the mother liquor to a round-bottom flask. The flask was stoppered and allowed to stand for several days with frequent shaking. The precipitate was then removed and dried in a vacuum desiccator. It burned very well.

(i) Identical with (i). Used 11.6 grams of HC(NO to one gram of polyvinylamine (3 to 1 ratio). The reaction time was 15 hours. A greenish precipitate was obtained which burned well.

(k) Identical with (i). Used four grams of solid HC(NO of the highest purity to 0.5 grams of polyvinylamine (2 to 1 ratio). The reaction time was ten hours. A yellow brown product was obtained which burned well.

'(I) In this experiment freshly distilled water was used as solvent. Sodium nitroform was used in place of nitroform and polyvinylamine hydrochloride was used instead of polyvinylamine. The reaction time was 16 hours and the ratio was 2 to 1. A greenish precipitate was obtained which burned well.

EXAMPLE 22 Preparation of Polyvinylimide From Polyvinyl-Amine and 2,3,3-Trinitr0propanal Polyvinylamine hydrochloride was prepared according to procedure of D. D. Reynolds and W. C. Kenyon, J. Am. Chem. Soc. 69, 911 (1947).

| NO: NO: NH: 11

,to in small amounts. An orange-yellow precipitate formed immediately. The reaction was continued for one-half hour, the mixture filtered, and the residue washed with copious amounts of water, 10 percent acetic acid, and

again with. water. The, reactionproduct was. dried in a The polynitroimide' vacuum desiccator for. 24 hours; burned rapidly with very little smoke, analyzed 19,88 per cent nitrogen, as compared to.23.?, percent calculated, and appeared to be stableat a temperature of 65 degrees c'entigrade.

(b) Ten grams of the dipotassinm salt of 2,3,3-trinitropropanal was dissolved in" ammonia and one gram of polyvinylamine hydrochloride dissolved in water added dropwise thereto. The solution was allowed to stand overnight at room temperature. The ammonia solution was neutralized, by dropping into a dilute HCl solution, whereupon a' yellow precipitate wasobtained. The prodnot turned brown, upon drying and burned well.

Threeand three-tenths grams of the dipotassium salt of 2,3,3-trinitropropanal was dissolved in Water and placed in a round-bottom three-neck flask equipped with a stirrer and a dropping funnel. Five-tenths gram of polyvinylamine hydrochloride was dissolved in water and added dropwise to the solution of the dipotassium salt. Ayellow precipitate Was formed immediately. The product burned well leaving some ash. The mole ratio ihthis experiment was one mole of polyvinylamine hydrochloride to two moles of the, dipotassium salt.

(d) Experiment similar to (0), only a one to three mole ratio was used. The product burned about the same as that obtained from (c).

(e) Experiment similar, to (c), only a one to four mole ratio was used. The product burned about the same as that obtained from (c).

The product obtained from the experiment using a one to two mole ratio showed the highest percentage of nitrogen (Found 20.22 percent; 20.42 percent N; calculated 23.30 percent N).

EXAMPLE 23 Preparation of Poly-N-Vinyl-Nitrobenzamide Q E (a) Three grams of polyvinylamine was dissolved in water in a 300-milliliter round-bottom flask equipped with stirrer and dropping funnel, and ten grams of benzoyl chloride added dropwise thereto. A white precipitate' formed, was washed with water, and dried. The precipitated poly-N-vinyl-benzamide was then redissolved in methanol, reprecipitated with water, and finally dried at 70 degrees centigrade.

(b) Five-tenths gram of the polyvinyl benzamide from (a).was added in Small amounts to 40 milliliters of fuming HNO at room temperature. The solution was allowed to stand for two hours and was then heated on a steam cone (60 degrees centigrade) for two hours. The nitration solution was poured into cold water with stirring to give a White precipitate which burned well. (c) Two grams of polyvinyl benzamide from (a) was added to 80 milliliters of mixed acid (85 percent concenrated H 80 15 percent HNOg), and the soluti'onheated for six hours at 85-90 degrees Centigrade. The mixture was then filtered, cooled, and poured into ice-water. The yellow precipitate which was obtained analyzed for 13.08 percent N as compared to 25.90 percent calculated.

Five-tenths gram of polyvinylamine hydrochloride was dissolved in freshly-distilledWater contained in a roundbottom three-neck flask equipped with a stirrer and nitrogen inlet. To this solution Was added 3.3 gram of the dipotassium' salt of 2,3,3-trinitropropanal in small amounts. A strean i of nitrogen was passed through the solution for four hours, whereafter stirring Was stopped and the solution filtered. A yellow precipitate was obtained, washed, with water, 10 percent acetic acid and. It burned very well after drying in a;

again with water. vacuum desiccator.

EXAMPLEZS Condensation of Polyvinylamine With 1,1-Dinitroethane (a) Fifty milliliters of methanol containing 1.1 grams polyvinylamine was cooled to between zero and five degrees centigrade and 3.06 grams of 1,1-dinitroethane dis solved in 30 milliliters of methanol decanted off, and the residue washedwith methanol and dried in a vacuum desiccator for 30 hours. The product burned well leaving little ash. I

(b) Seven-tenths gram of polyvinylamine was dissolved in ethanol, the solution placed in a beaker, and 0.5 gram of 1,1-dinitromethane added dropwise with stirring. The alcohol was allowed to evaporate off and a dark brown plastic material obtained. It analyzed for 22.1 percent N as compared to 25.5 percent calculated.

(c) The conditions were the same as in Example 20 (i). Two grams of 1.1-dinitroethane was reacted with 0.5 gram of polyvinylamine. The yellow precipitate obtained burned with an almost smokeless flame.

EXAMPLE 26 Condensation ofRolyvinylamine With Dinitl omethane (a) Fifty milliliters of methanol containing 1.1 grams of polyvinylamine was placed in a 400-rnilliliter beaker and'the solution cooled to between zero and five degrees centigrade. To this solution was added 250 milliliters of ether containing approximately 2.46 grams of dinitromethane. A white precipitate formed, was filtered as, and the residue washed with ether and methanol and finally dried for 24 hours in a vacuum desiccator. The product burned Well, leaving very little ash.

(b) In this experiment the same experimental conditions as in Example 20 (i) were used. Five-tenths gram of polyvinylarnine was reacted with two grams of dinitromethane. A light yellow product was obtained which burned very well and left only a little ash.

EXAMPLE 27 Preparation of Poly-N-Vinyl- -Nitraphenylurea CH2--CH- CieHsNCO 11111: n

otmNnooNn-en HNO: OH:

' in a' glass-stoppered bottle and eight grams of phenyl isocyanate added thereto. The bottle was stoppered and shaken vigorously. A white precipitate was formed, washed with ether, then with water, and dried. This method is preferred to (a) since the time for the leaching process is shortened.

(c) Twenty-five milliliters of fuming nitric acid was placed in a 250-milliliter Erlenmeyer flask and cooled to zero degrees centrigrade. Eight-tenths gram phenylurea derivative from (a) or (b) was added in small amounts while maintaining the temperature between zero and five degrees centigrade. After addition was complete, the solution was allowed to warm to room temperature and stand overnight. The nitration solution was then poured into cold water with stirring. A tan precipitate was obtained, washed with distilled water, and dried in a vacuum desiccator. The product analyzed for 21.35 percent N as compared with 25.59 percent N calculated.

(d) Two grams of poly-N-vinyl-N'-phenylurea was added to 40 milliliters of fuming HNO at room temperature. The mixture was maintained at 70 degrees centigrade for 20 minutes, the'solution then filtered, cooled, and poured into ice-water. A yellow product was obtained which burned fairly well. Nitrogen analysis gave 21.90 percent as compared to 25.32 percent calculate-d.

(e) One gram of nitrated product from (d) was added to 80 milliliters of mixed acid (85 percent concentrated H 80 percent concentrated HNO The mixture was heated for one hour at 85-90 degrees centigrade, the solution filtered, cooled, and poured into ice-water. A light tan precipitate was obtained which analyzed for 21.88 percent N as compared to 25.32 percent calculated. This product burned well.

(f) One gram of the poly-N-vinyl-N'-phenylurea was added in small amounts to 50 milliliters of fuming HNO at room temperature. The mixture was allowed to stand for several hours at this temperature and was then heated .on a steam bath for four hours at 50-60 degrees centigrade.

The solution was filtered and poured onto ice, whereupon a brown precipitate formed. It was washed vwell with water, dried in a vacuum desiccator, and found to burn well.

(g) Five-tenths gram of the phenylurea was dissolved in concentrated H 80 and 30 milliliters of fuming nitric acid added dropwise to the solution. The temperature rose to 35 degrees centigrade. It was then filtered and poured on ice. A yellow precipitate of the poly-N-vinyl- N'-nitrophenylurea was obtained.

was added dropwise while the temperature was kept below zero degrees centigrade. The solution was kept at this temperature for four hours and then allowed to warm to room temperature overnight. The solution was filtered and poured on ice. A yellow gummy precipitate of the poly-N-viny1-N'-nitrophenylurea was obtained.

The propellants of the present invention are, as previously stated, useful in the production of the impelling force for jet propulsion motors. The invention thus provides novel solids combining fuel and all the elements required for its combustion which can be used without exploding but with the production of great power.

These propellants are especially suited for use in rocket jet engines, which ordinarily comprise a combustion chamber where the fuel is combusted and one or more exhaust nozzles leading from the chamber to the atmosphere. Use of the self-combustible compositions of the present invention as charges in such motors is advantageous in that storage and feed systems for an oxidizing element are eliminated, with subsequent reduction of weight, a matter of great importance in aircraft. As a consequence of the saving in weight, a great gain in the ratio of total impulse to total weight is also realized. The substances are moreover relatively stable under a variety of conditions and hence safer than many compositions heretofore proposed, while at the same time being capable of generating great power upon decomposition.

The nitro plastic propellants will not spontaneously ignite in a cool motor which allows a highly desirable safety factor. Accordingly, some means should be associated with the combustion chamber for ignition of the charge therein. Such suitable ignition or starting device may be a heating element located at the periphery of the combustion chamber, or some other ignition mechanism, such as an electric are, or an auxiliary flame introduced at a suitable place in the combustion chamber and caused to operate at the moment of starting. Such rocket jet engines are known in the art, as are suitable firing or ignition mechanisms valuable therein. The propellant is merely secured in place in the combustion chamber, the ignition mechanism actuated and the propelled vehicle launched and/or maintained in motion by development of thrust by decomposition of the propellant. Numerous other advantages of operation and result accrue to the use of these novel propellants, such as simplicity of construction and operation of the jet-motor, predetermined constancy of available energy, non-corrosive effects on equipment, higher specific impulse with relatively low combustion and exhaust temperatures, and the like, additional advantages being immediately apparent to one skilled in the art.

Various modifications may be made in the invention without departing from the spirit or scope thereof and it is to be understood that I limit myself only as defined by the appended claims.

I claim:

1. The method of producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: polymerizing together a phenylenediamine with an alkylene dibromide, and containing up to three carbon atoms, by contacting the reagents together at a temperature below degrees centigrade, but at least at that temperature at which reaction occurs, and thereafter nitrating the polymer thus-produced by contacting said polymer with fuming nitric acid in an amount and time sufficient to introduce enough nitro(NO groups into the molecule to afford sufncient oxygen present in the molecule to convert at least all of the carbon to carbon monoxide and one-third of the hydrogen to steam upon combustion of the polymer.

2. A method of producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: polymerizing together a phenylenediamine with phosgene by contacting the reagents together, and thereafter nitrating the polymer thus-produced with sufiicient fuming nitric acid for a period of time to introduce sufficient nitro(NO groups into the polymer molecule to afford sufficient oxygen present in the molecule to convert at least all of the carbon to carbon monoxide and one-third of the hydrogen to steam upon combustion of the polymer.

3. The method of producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: contacting a phenylenediamine, with ethylene oxide, thereby to cause a polymerization reaction and thereafter nitrating the polymer thus-produced by contact with fuming nitric acid in an amount and time suflicient to introduce enough nitro(NO groups into the polymer molecule to afiord suflicient oxygen present in the molecule to convert at least all of the carbon to carbon monoxide and one-third of the hydrogen to steam upon combustion of the polymer.

4. The process for producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: contacting ethylene diisocyanate with ethylenediamine, to produce a polymeric material, and subsequently contacting said polymeric material with fuming nitric acid inamonnt and time suflicient to introduce two nitro groups into each unit of said polymer, and separating the nitrated polymer thus-produced.

5. A method for producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: contacting meta-phenylenediamine with ethylene diisocyanate to produce a polymeric material, and subsequently contacting said polymeric material with nitric acid in an amount and time suflicient to introduce three nitro groups onto the phenyl ring and two nitro groups onto the nitrogen atoms of each unit of the polymeric material, and separating the polymer thus-produced.

6. The method of producing a substantially stable combustible nitro plastic adapted for use as the major thrust-producing component of a jet-type motor, which includes: nitrating a polymer selected from the group consisting of (A) an alkylene diamine containing from 2 to 6 carbon atoms in the molecule, polymerized with an alkylene diisocyanate, (B) a phenylenediamine polymerized with an alkylene diisocyanate, (C) a phenylenediamine, polymerized with an alkylene dibromide containing up to 3 carbon atoms, (D) a phenylenediamine polymerized with phosgene, and (E) a phenylenediamine polymerized with ethylene oxide, by contacting said polymer with fuming nitric acid in an amount and for a time suflicient to introduce into said polymer enough oxygen to convert at least all the oxygen to carbon monoxide and one third of the oxygen to steam upon combustion of the polymer.

7. The method of producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing compound of a jet-type motor, which includes: contacting an alkylene diamine containing from 2 to 6 carbon atoms in the molecule, with an alkylene diisocyanate, thereby to cause a polymerization reaction, and thereafter nitrating the polymer thus-produced by contact with fuming nitric acid in an amount and for a time sufficient to introduce enough nitro (N0 groups into the polymer molecule to afiord sufficient oxygen present in the molecule to convert at least all of the carbon to carbon monoxide and one-third of the hydrogen to steam upon combustion of the polymer.

8. The method of producing a substantially stable combustible nitro plastic adapted for use as the major thrustproducing component of a jet-type motor, which includes: contacting a phenylenediamine with an alkylene diisocyanate, thereby to cause a polymerization reaction, and thereafter nitrating the polymer thus-produced by contact with fuming nitric acid in an amount and time sufiicient to introduce enough nitro (N0 groups into the polymer molecule to afford suflicient oxygen present in the molecule to convert at least all of the carbon to carbon monoxide and one-third of the hydrogen to steam upon combustion of the polymer.

9. The nitration production produced by the process of claim 6.

10. The nitration product produced by the process of claim 7.

11. The nitration product produced by the process of claim 8.

12. The nitration product produced by the process of claim 1.

13. The nitration product produced by the process of claim 2.

14. The nitration product produced by the process of claim 3.

References Cited in the file of this patent UNITED STATES PATENTS 2,118,487 Burrows et al May 24, 1938 2,246,527 Melof June 24, 1941 2,275,923 Ross et al. Mar. 10, 1942 2,277,083 Dorough Mar. 24, 1942 2,310,943 Dorough Feb. 16, 1943 2,325,064 Lawrence July 27, 1943 2,384,049 Smith et al. Sept. 4, 1945 2,400,806 Bruson May 21, 1946 2,404,688 Bruson July 23, 1946 2,407,131 Bruson Sept. 3, 1946 2,408,252 De Ganahl Sept. 24, 1946 2,419,043 Urbanski Apr. 15, 1947 FOREIGN PATENTS 856,335 France Mar. 18, 1940 512,987 Great Britain Oct. 2, 1939 535,139 Great Britain Mar. 31, 1941 601,101 Great Britain Apr. 28, 1948 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,071,617 January 1, 1963 Henry B. Hass It is hereby certified that error appears in the above numbered patjent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 45 to' 47 the formula should appear as shown below instead of as in the patent:

lOO=oxygen balance O line 63, for "considerable" read considered column 13,

linesB to 10, strike out "The resulting solution was then rectified at reduced pressure, and, after the water had been removed, the following fractions were'collectedz"; line 49, strike out "-NO column 18, line 12, for "3.5 grams" read f 33.5 grams column 26, after line 43, insert the following:

2,287,093 Ellis June 23, 1942 Signed and sealed this 13th day of August 1963.

' (SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION .atent No. 3,071,617 January 1 1963 Henry Bo Hass It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 45 to 47 the formula should appear as shown below instead of as in the patent: Y

lOO=oxygen balance R line 63, for "considerable" read considered column 13,

lines 8 to 10, strike out "The resulting solution was then rectified at reduced pressure, and, after the water had been removed, the following fractions were'collectedz"; line 49,

strike out "-NO column 18, line l2, for "35 grams" read 33.5 grams column 26, after line 43, insert the following:

2,287,093 Ellis June 23, 1942 Signed and sealed this 13th day of August 1963,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Qfficer Commissioner of Patents

Claims (1)

1. 6. THE METHOD OF PRODUCING A SUBSTANTIALLY STABLE COMBUSTIBLE NITRO PLASTIC ADAPTED FOR USE AS THE MAJOR THRUST-PRODUCING COMPONENT OF A JET-TYPE MOTOR, WHICH INCLUDES: NITRATING A POLYMER SELECTED FROM THE GROUP CONSISTING OF (A) AN ALKYLENE DIAMINE CONTAINING FROM 2 TO 6 CARBON ATOMS IN THE MOLECULE, POLYMERIZED WITH AN ALKYLENE DIISOCYANATE, (B) A PHENYLENEDIAMINE POLYMERIZED WITH AN ALKYLENE DIISOCYANATE, (C) A PHENYLENEDIAMINE, POLYMERIZED WITH AN ALKYLENE DIBROMIDE CONTAINING UP TO 3 CARBON ATOMS, (D) A PHENYLENEDIAMINE POLYMERIZED WITH PHOSGENE, AND (E) A PHENYLENEDIAMINE POLYMERIZED WITH ETHYLENE OXIDE, BY CONTACTING SAID POLYMER WITH FUMING NITRIC ACID IN AN AMOUNT AND FOR A TIME SUFFICIENT TO INTRODUCE INTO SAID POLYMER ENOUGH OXYGEN TO CONVERT AT LEAST ALL THE OXYGEN TO CARBON MONOXIDE AND ONE THIRD OF THE OXYGEN TO STEAM UPON COMBUSTION OF THE POLYMER.