ARL-TN-0750 ● APR 2016

US Army Research Laboratory

A New Solid/Liquid Hypergolic System:

3-amino-1,2,4-triazine and Nitric Acid

by William M Sherrill, William M Sickels, Eric J Bukowski, 

Eric C Johnson, and Joseph E Banning

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ARL-TN-0750 ● APR 2016

US Army Research Laboratory

A New Solid/Liquid Hypergolic System:

3-amino-1,2,4-triazine and Nitric Acid

by William M Sherrill, Eric J Bukowski, and Joseph E Banning

Weapons and Materials Research Directorate

William M Sickels

Bowhead Science and Technology

Eric C Johnson

TKC Global

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4. TITLE AND SUBTITLE

A New Solid/Liquid Hypergolic System: 3-amino-1,2,4-triazine and Nitric Acid

5a. CONTRACT NUMBER

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5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

William M Sherrill, William M Sickels, Eric J Bukowski, Eric C Johnson, and 

Joseph E Banning

5d. PROJECT NUMBER

H43

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

US Army Research Laboratory

ATTN: RDRL-WML-C

Aberdeen Proving Ground, MD 21005-5066

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ARL-TN-0750

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12. DISTRIBUTION/AVAILABILITY STATEMENT

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

Two new hypergolic systems have been discovered based on 3-amino-1,2,4-triazine as the fuel source. The compound was 

synthesized and found to be hypergolic with 100% nitric acid under ambient conditions and with solution of hydroxyl 

ammonium nitrate at elevated temperatures. Based on the exothermicity of these reactions, the material was selected as a 

candidate for further study as a possible base for a hybrid hypergolic system. The ignition delay of the nitric acid system and

its predicted performance is discussed. The ignition temperature of the hydroxylamine nitrate system was determined through 

the use of differential scanning calorimetry at both a standard heating rate of 10 °C/min and a maximum heating rate of 

40 °C/min.

15. SUBJECT TERMS

triazine, white fuming nitric acid, WFNA, amino, hypergol, motor, rocket, HAN

16. SECURITY CLASSIFICATION OF:

17. LIMITATION

OF ABSTRACT

UU

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OF PAGES

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19a. NAME OF RESPONSIBLE PERSON

William M Sherrill

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Unclassified

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410-278-8608

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Contents

List of Figures iv

List of Tables iv

Acknowledgments v

1. Introduction 1

2. Theoretical Property Measurements 1

3. Ignition Delay of 3-amino-1,2,4-triazine and HNO3 2

4. Propellant Mixture with HAN 3

5. Experimental 6

5.1 General Information 6

5.2 Synthesis of 3-amino-1,2,4-triazine 7

5.3 3-amino-1,2,4-triazine and HNO3 Determination of Ignition Delay 7

5.4 Preparation of HAN 8

5.5 Preparation of HAN and 3-amino-1,2,4-triazine Mixture 8

6. Conclusions 8

7. References 9

Appendix. Spectral Data 11

List of Symbols, Abbreviations, and Acronyms 17

Distribution List 18
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List of Figures

Fig. 1 Structure of 3-amino-1,2,4-triazine...........................................................1

Fig. 2 Hypergolic reaction between 3-amino-1,2,4-triazine and HNO3..............2

Fig. 3 HAN and 3-amino-1,2,4-triazine dropped onto preheated plate...............3

Fig. 4 DSC of HAN and 3-amino-1,2,4-triazine at maximum heating rate ........4

Fig. 5 DSC of HAN and 3-amino-1,2,4-triazine at 10 °C/min ...........................5

List of Tables

Table Summarized results of optimization screening.........................................5
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Acknowledgments

The authors wish to thank Mr Eric Johnson, Terry Piatt, and Ms Lori Pridgeon for 

general equipment assistance and supply management. The authors also wish to 

thank Drs Jesse Sabatini, Brian Roos, Thuvan Piehler, Eric Bukowski, and 

Mr Stephen Aubert for procedural input and technical review. The authors also wish 

to express their gratitude to Drs Edward Byrd and Betsy Rice for making available 

their computer codes and related scripts and their assistance with the computational 

modeling of 3-amino-1,2,4-triazine. The authors are also indebted to Dr Michael 

McQuaid for discussions related to the use of hydroxyl ammonium nitrate as an 

oxidizer source.
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1. Introduction

Materials that when mixed together generate enough heat to spontaneously ignite 

are known as hypergolic materials. These mixtures are useful in a variety of 

aviation applications such as space travel, where they are used to ignite rocket 

motors, or used as the propellant in the motors themselves, and in aviation where 

they have been used to ignite jet engines. While there are a number of materials that 

are known to be hypergolic, for these materials to be useful, it is important that they 

have short ignition times and be controllable. Interest has been developing in the 

Army for hypergolic materials that are solid/liquid or solid/gel type systems.

1,2

Recently, it was discovered that 3-amino-1,2,4-triazine (also referred to in this 

report as 1), (see Fig. 1) a solid material, is hypergolic when mixed with 100% 

nitric acid (HNO3) and in solution of hydroxylamine nitrate (HAN) when dropped 

onto a preheated plate. The hypergolic reaction between 1 and HNO3 varies rapidly 

under ambient temperature and pressure, and is highly exothermic while the 

reaction of the solution of HAN requires heating. Based on observance of this 

phenomenon, it was determined this system should be examined to determine its 

properties and performance.

N N

N

NH2

1

Fig. 1 Structure of 3-amino-1,2,4-triazine

2. Theoretical Property Measurements

The predicted performance characteristics of the system were obtained through first 

using quantum mechanical modeling to determine the heat of formation (ΔHf) and 

the density of 1. From these data, it is possible to use the CHEETAH 7.03 code to 

obtain calculated performance values. The ΔHf and density measurements were 

obtained using the methods detailed by Rice and Byrd.

4–8 Using their methodology, 

1 is predicted to have a density of 1.439 g/cm3 and a ΔHf of 53.851 kilocalorie per 

mole (kcal/mol). The calculated density is in good agreement with the 

experimentally determined 1.473 g/cm3 measured through X-ray diffraction.9

Using CHEETAH 7.0, a formulation of 100% HNO3 and 1 were optimized to 

generate the highest specific impulse (ISP). Using the formulation optimization 

tool, CHEETAH predicts the formulation should consist of 33.82% of 1 and 
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66.18% HNO3 by weight. This optimized formulation is predicted to generate an

ISP of 259.82 s. 

CHEETAH was also used to optimize formulation of compound 1 and HAN. From 

these calculations, it was determined the optimum ratio of HAN to 1 would be 

79.72% to 20.28% by weight. From the optimized formulation, CHEETAH predicts 

the performance of this system to be 243.7 s.

3. Ignition Delay of 3-amino-1,2,4-triazine and HNO3

The ignition delay of the system was determined both through the analysis of a 

standard video camera shooting 24 frames per second (fps) and through analysis of 

high-speed video obtained from a photron camera system. Based on the analysis of 

the standard definition video, the ignition time of the system was calculated to be 

294 ms. Photron analysis of the event filmed at 500 fps gave an average ignition 

time over 5 runs of 588 ms (Fig. 2).

Fig. 2 Hypergolic reaction between 3-amino-1,2,4-triazine and HNO3
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4. Propellant Mixture with HAN

Compound 1 was investigated as a potential hypergol with HAN. A solution of 

HAN was prepared and mixed with 1. Under ambient conditions, no reaction 

occurred. Slight heating was required for all of the 1 to dissolve in the HAN 

solution. No bubbles or other signs of decomposition were observed in the mixture. 

When the mixture is slowly heated in a test tube to approximately 

300 °C, after all of the water has boiled out of the mixture, there is a large volume 

of nitrogen oxide (NO2) gas that is liberated. This is accompanied with charring of 

the residual sample. However, when the solution is dropped on a plate that has been 

preheated to approximately 300 °C, large flames appear from the mixture and very 

little residue is left on the plate after the event has completed (Fig. 3). Both a 

solution of HAN and solid 1 were dropped onto the same preheated plate, and 

neither sample exhibited the same decomposition behavior as was seen with the 

solution of HAN and 1.

Fig. 3 HAN and 3-amino-1,2,4-triazine dropped onto preheated plate
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The differential scanning calorimetry (DSC) analysis of the solution in a hermetic 

pan at the maximum heating rate of the instrument shows an ignition temperature 

of 190 °C (Fig. 4). 

Fig. 4 DSC of HAN and 3-amino-1,2,4-triazine at maximum heating rate

Running the DSC on the solution at a heating rate of 10 °C gives a slightly different 

ignition temperature of 156 °C (Fig. 5).

190.06°C

184.22°C

443.3J/g

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Fig. 5 DSC of HAN and 3-amino-1,2,4-triazine at 10 °C/min

Standard definition video of the event recorded at 24 fps gives an ignition delay of 

the system of between 500 and 1,000 ms.

A brief optimization of the fuel to oxidizer ratio was run starting at the CHEETAHdefined optimum 80% HAN to 20% 1. At the 80% HAN mixture, the material was 

unable to be ignited even when the plate was heated to near 400 °C. However, by 

decreasing the amount of HAN to 76% the material was readily ignited. The 

material was still capable of being ignited until the amount of HAN dropped below 

65% at which point there was not enough oxidizer present to allow for any 

combustion and the mixtures simply charred on the heated plate. The results are 

summarized in the following Table.

Table Summarized results of optimization screening

HANa

(wt %)

1b

(wt %) Result Predicted ISPc(s)d

80 20 No ignition 250.94

76 24 Ignited 247.74

70 30 Ignited 239.63

67 33 Ignited 235.01

65 35 No ignition charring 231.73 a Hydroxylamine nitrate. bReference to 3-amino-1,2,4-triazine. c Specific impulse. d Chamber pressure held to 70 atm.

156.36°C

1213J/g

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40 60 80 100 120 140 160 180 200 220

Temperature (°C)

  

 

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5. Experimental

5.1 General Information

Nuclear magnetic resonance (NMR) spectra were recorded on an Anasazi

Instruments 90 MHz NMR. Dimethyl sulfoxide (DMSO)-D6 was obtained from 

Sigma-Aldrich and used as received. All NMR chemical shifts are reported in ppm 

and are relative to a 1

H (which is the proton designation referring to NMR) shift of 

2.50 ppm and 13C (which is the carbon designation referring to NMR) shift of 

39.54 ppm for DMSO-D6. All NMR spectra are available in the appendix to this 

report. Gas chromatograph mass spectrometer (GC/MS) analyses were performed 

on a Shimadzu GC-2010 gas chromatograph interfaced with a Shimadzu QP-2010S 

mass spectrometer, and equipped with an AOC-20i auto-injector with either a 6 or 

12 sample rack. The column was a 25 m × 0.25 mm × 0.25 μm Shimadzu designated 

SHR5XLB polydimethylsiloxane, 5% Ph capillary column. Helium (99.96%) was 

the carrier gas and it was pretreated by passing it through a VICI Metronics 

oxygen/moisture trap (P100-1). Fourier transform infrared (FTIR) spectra were 

recorded on a Brüker Alpha-T equipped with a platinum attenuated total reflectance 

(ATR) diamond cell and were sampled neat. DSC was conducted on a TA 

instruments Q10 or Q20 calorimeter and is available in the appendix of this report. 

High-speed videography was conducted using a Photron model SA-5 camera 

system shooting at 500 fps. Aminoguanidine bicarbonate and 40% aqueous glyoxal 

were obtained from Sigma-Aldrich and were used as received. 
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5.2 Synthesis of 3-amino-1,2,4-triazine

Compound 1 was prepared via a slight modification of the method described by 

Erickson in his patent10. Amino guanidine bicarbonate (29.2 g, 215 mmol) was 

suspended in 60 mL of water. To this was added 22.8 g (157 mmol) of 40% aqueous 

glyoxal and the mixture was allowed to stir for 18 h at 20–25 °C. The suspended 

solid was then filtered and the mother liquor was evaporated to dryness. The 

resulting residue was extracted with ice-cold methanol (3 × 50 mL) and the 

combined methanol rinses were then re-cooled, filtered, and the mother liquor was 

concentrated. The resulting solid was recrystallized from acetonitrile to yield 

11.23 g (117 mmol, 75%) of a slightly yellow solid, 3-amino-1,2,4-triazine.

DSC 10 °C/min melt at 177 °C is in good agreement with literature values. NMR 

data are in agreement with what has been previous published in the literature11. 1H 

NMR DMSO-d6 (90.420 MHz) δ 8.52 (d, J = 2.4 Hz, 1H), 8.19 (d, J = 2.4 Hz, 1 

H), 7.16 (br. s. 2H); 13C NMR DMSO-d6 (22.605 MHz) δ 163.4, 150.0, 140.7; 

FTIR (DATR),ν ̃ = 3292, 3098, 1557, 1532, 1516, 1489, 1113, 1076, 1044, 865, 

848, 794, 633, 593, 460; MS (EI) = 42, 68, 96 (M+).

5.3 3-amino-1,2,4-triazine and HNO3 Determination of Ignition 

Delay

Fifty milligrams of 1 was placed into a test tube. Using a 9-inch glass pipette, a 

single drop of 100% HNO3 was dropped onto 1, and the event was filmed at 

24 fps. The resulting video footage was placed into video editing software, and 

7 frames were counted from the time the drop of HNO3 touched 1 until the first 

emission of light. With each one of the frames equating to 24 ms, the ignition delay 

of the system under ambient conditions was determined to be 294 ms.

To determine the ignition delay of the HAN solution of 1, a metal plate was heated 

to 350 °C using a heat gun. The temperature of the plate was measured using a 

thermocouple. Once the temperature of the plate had stabilized, a 9-inch pipette 

was used to drop a single drop of the HAN solution onto the heated plate. The event 

was filmed using a camera shooting at 24 fps. Using video editing software, 12 to 

35 frames were counted from the time the drop first hit the plate until the first 

emission of light. The large variability in these measurements can be attributed to 

inconsistent drop size as well as inconsistencies in the heating of the plate.
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5.4 Preparation of HAN

Using a volumetric pipette, 1 mL of a commercially available 50% by weight 

solution of hydroxylamine was added to a test tube and cooled to 0 °C in an ice 

bath. To this was slowly added 953 mg of 100% HNO3 and the mixture was stirred 

for 5 min and then allowed to warm to ambient temperature. This resulted in a 

solution that was 74% HAN by weight. 

5.5 Preparation of HAN and 3-amino-1,2,4-triazine Mixture

A sample of 340 mg of 1 was dissolved with slight heating into the 1-mL HAN 

solution prepared according to the method previously described. 

6. Conclusions

The compound 1 has been found to exhibit hypergolic properties with both HNO3

and HAN. In the case of HNO3, the hypergolic reaction takes place at ambient 

temperature and pressure; it has a measured ignition delay of 588 ms, and a 

predicted ISP of 259.82 s. With HAN, the reaction takes place at elevated 

temperatures with an ignition point between 150 and 190 °C depending on heating 

rate. The predicted ISP for this system is 243.7 s. The reaction between HAN and 

1 is promising based on the fact that the solution would behave as a monopropellant 

using water as the solvent. The solution of the 2 is nonviscous, making it possible 

to be pumped easily and ignites readily on exposure to a preheated surface. 
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7. References

1. McQuaid M, Chen C. BH3-amine and B(CH3)3-amine adducts as additives of 

liquid/gel hypergols and solid hybrid rocket motor fuels: property and 

performance predictions. Aberdeen Proving Ground (MD): Army Research 

Laboratory (US); 2013 Dec. Report No.: ARL-TR-6749.

2. McQuaid M, Chen C. AlH3-Amine and Al(CH3)3-Amine Adducts as Additives 

for Liquid/Gel Hypergols and Solid Hybrid Rocket Motor Fuels: A Literature 

Review and Property Predictions. Proceedings of the 7th JANNAF Liquid 

Propulsion Subcommittee Meeting, 2013-0002FV, JSC-CD-72, 2013.

3. Bastea S, Fired LE, Glaesemann KR, Howard WM, Kuo IW, Souers PC,

Vitello PA. CHEETAH 7.0 User’s Manual, LLNL-SM-599073, Lawrence 

Livermore National Laboratory, Livermore (CA) 2012.

4. Byrd EFC, Rice BM. Improved prediction of heats of formation of energetic 

materials using quantum mechanical calculations. J Phys Chem A.

2006;110:1005–1013.

5. Rice BM, Pai SV, Hare J. Predicting heats of formation of energetic materials 

using quantum mechanical calculations. Combust Flame. 1999; 118;445–

458.12.

6. Rice BM, Hare JJ, Byrd EFC. Accurate predictions of crystal densities using 

quantum mechanical molecular volumes. J Phys Chem A. 2007;111:10874.

7. Byrd EFC, Rice BM. A Comparison of methods to predict solid phase heats of

formation of molecular energetic salts. J Phys Chem A. 2009;113: 345.

8. Rice BM, Byrd EFC. Evaluation of electrostatic descriptors for predicting 

crystalline density. J Comput Chem. 2013;34:2146–2151.

9. Perpétuo GJ, Janczak J Acta Cryst. 2002;58:431–432.

10. Erickson JG; American Cyanamid Company, New York, NY. 

Aminoheterocycles. US Patent 2,653,933. 1953 Sep 29.

11. Radel RJ, Keen BT, Wong C, Paudler WW. J Org Chem. 1977;42:546–550.
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Appendix. Spectral Data 

 

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DSC of 1 at 10 °/min

GC-MS Data of 1

177.61°C

208.67°C

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53 78 91 110 122 138 158 177 191

205

150
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1

H NMR Data of 1
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13C NMR Data of 1
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FTIR Data of 1
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List of Symbols, Abbreviations, and Acronyms

1 reference to 3-amino-1,2,4-triazine

ATR attenuated total reflectance

DMSO dimethyl sulfoxide

DSC differential scanning calorimetry

fps frames per second

FTIR Fourier transform infrared

GC/MS gas chromatograph mass spectrometer

HAN hydroxylamine nitrate

HNO3 nitric acid

ISP specific impulse 

kcal/mol kilocalorie per mole

NMR nuclear magnetic resonance

ΔHf heat of formation
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