Pressure DSC for energetic materials. Part 2. Switching between evaporation and thermal decomposition of 3,5-dinitropyrazole

Pressure DSC for energetic materials. Part 2. Switching between evaporation and thermal decomposition of 3,5-dinitropyrazole Full article

Journal

Thermochimica Acta
ISSN: 1872-762X , E-ISSN: 0040-6031

Output data

Year: 2020, Volume: 690, Article number : 178697, Pages count : DOI: 10.1016/j.tca.2020.178697

Authors

Gorn Margarita V. ^1,2 , Monogarov Konstantin A. ³ , Dalinger Igor L. ⁴ , Melnikov Igor N. ³ , Kiselev Vitaly G. ^1,2 , Muravyev Nikita V. ³

Affiliations

1	Institute of Chemical Kinetics and Combustion SB RAS, 3 Institutskaya Str., 630090 Novosibirsk, Russia
2	Novosibirsk State University, 1 Pirogova Str., 630090 Novosibirsk, Russia
3	Semenov Federal Research Center for Chemical Physics RAS, 4 Kosygina Str., 119991 Moscow, Russia
4	Zelinsky Institute of Organic Chemistry RAS, 47 Leninsky Ave., 119991 Moscow, Russia

Differential scanning calorimetry at an elevated external pressure (Pressure DSC) allows for shifting the vaporization of a sample to higher temperatures, thus often facilitating the direct observation of its thermal decomposition. In the present work, the thermolysis of a promising energetic material 3,5-dinitropyrazole was studied under pressures up to 10 MPa. The thermokinetic analysis of the datasets acquired at 2 and 5 MPa exhibited a pronounced kinetic compensation, thus allowing to build the joint formal kinetic model. The final kinetic scheme is comprised of the two parallel reactions, viz., the first-order process (Ea = 198 kJ mol−1) along with a first-order autocatalysis (Ea = 127 kJ mol−1). The experiment was complemented with the highly accurate CCSD(T)-F12 quantum chemical calculations. Theory revealed an unusual primary decomposition channel, viz., a sigmatropic [1,5]H-shift followed by the pyrazole ring opening yielding a molecular nitrogen and a nitro radical as simple primary products. Apart from this, the comparative thermogravimetry at a normal pressure yielded the vapor pressure of 3,5-dinitropyrazole along with the internally consistent set of phase change enthalpies. In general, the pressure DSC is a facile technique to study the true decomposition kinetics of the compounds that vaporize/sublime in conventional DSC experiments.

Gorn M.V. , Monogarov K.A. , Dalinger I.L. , Melnikov I.N. , Kiselev V.G. , Muravyev N.V.
Pressure DSC for energetic materials. Part 2. Switching between evaporation and thermal decomposition of 3,5-dinitropyrazole
Thermochimica Acta. 2020. V.690. 178697 . DOI: 10.1016/j.tca.2020.178697 WOS Scopus OpenAlex

≡ Web of science:	WOS:000568901900041
≡ Scopus:	2-s2.0-85087336233
≡ OpenAlex:	W3037634069