DTIC ADA419990: Solid State Thermochemical Decomposition of Neat 1,3,5,5-Tetranitrohexahydropyrimidine (DNNC) and Its DNNC-d6 Perdeuterio-Labeled Analogue

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Sotid State Thermochemical Decompasition of Neat
1,3,5,3-Tetranitrobexahydropyrimidine (DNNC) and
Its DNNC-d, Perdeuterio-Labeled Analogue

Scott A. Hendrickson"

Department of Chetvisry, Pl. Lame Nazaccoc University. San Diego, CA, 92106-2899 (USA)

Sentt A. Shacketfora*™™?

‘Al Force Roscarch Jatksralory, AFRTIPRSP, Bdviards AFB, CA. ¥3524 7680 (088)

Abstract

‘The solid state exorhermic thermochemical decomposition kmelica oF neat 1,3,55-
\etsanitcohexahydro-pytimidine (DANC: ant its pordcuteria INC, deuterium labeled analogue were
‘obcaived hy inothecmal ditferontiat seanming calorimctrs (IDSC) st 142, 165, and 148 °C. Rate constants
subyected to kinelic deuterian isotope effec (DIL) ecitecia saggost tant C-H bond rezunne in either one
‘or both eypos ofthe ckemivally imeguivalsnt alternating -Clly- methylene groupe of ths DIC: ring
stmtetnre constitutes the exoihermie ra-caminilling step. Ad eaergy of at.vation oqual 10115 kIiranle
ae detecmino¢ For the-exechemmie NISC? lacsmnpwsiion, acl Inn which 106 klfmiol was calculates
Jor whvteled DNNC. The akethesmic DNNC deoonapesition follows an extended endemic
‘induction pezind witha higher 122 k1/mole activation enatgy dong whuch # oxalylie apecies my Fora
bya eifferentrale-Smiciny step prior lo iiliaging the exoghernsie desoraposition and sesullam energy
selense,

Kegwands: 1.355-Tranirchesabyropsimiin, DNC, Set

te Seromusin,Ta.c Toki et

1. Introduction

‘The hetergcystie DNNC molecnle ik comprised of a unique hybuid chemical stature that
Incorpocares features thet define both high energy gexninal dinitraalkane and cyclic nitvaminc
‘compounds. As suck, i¢ contains fo typos of merhylene groups (CTT. On2 non-equivalent -CH>-
nu is saudichod betvroen ewe N NOzstructual groups, ancl iso chemically equivalent -Cls- grotps
‘each Mank the geminal -CONO.de-sereteral feature. Fins aynthesived in 1982," this DNNC™ hybrid

*Camexponding euthor: ¢-mal: srottshackelfore @edwards.af sil

pprovel for Puble Relace: dlsotbatlon witovted
GEM. DINTrRO.
‘coMPOUND

DNNC

igre 1. titramntocolr hybrid structure of the DNC assets

strncture provides u high energy pseude-sitvamine heteresyele watt wy empact censitivty significantly
lower than thet exhibited by Lt sinuctorally seared six eenibczed cyelic RDX nitran'ne (Figure 1). The
explosive imtistion sonasivily of DNC eesemBles that of tho more stable mirvaromatie TNT mialecule,
but wen immated, re detonation energy autpat is significantly higher thon (NT snl ives the RDX.
niteaanine:2 hos, the BNNC! prude nilsamine exhibits encegy and sensi:ivly properties associated
wich hath nlttamine ané ntrenecmnatie compourds

‘The BNC theemockemica stall ty also is sirmler w TNT Like TNT, DNNC mates witha!
rieeable or significant deconspasition ar default TDSC semmitiviny seluings. A stedy to determ:ne the
heat of Susie of DNC using stendacd diffrcatial soorning slorimelyy (DSC at its 154.8 to 156.2°C
snckinng pain revenle rs significant DNC sample decomzosition Prewiting the melwsd DNNC
sample to re-solicify, then ennenating nm TDSC Fquid thertsookemical decomposition at 176 °C wave
‘virtually tae same thermograsn nd Fel sf decimation enecey ourput as did a fresh DNNC sammie
under the same condicions, Comveescly, the symmetrical, cyclic six-membored IDX nittarmne an ils
tiyht-membered HME Romelague wiley Iberraovbernical decom gostion dutiag meting ar
Tiquetaction so sapidly ths their heat of usm carmat be determined.”

“The thermocheumen stbiliy of wlid stale BNNC was investigated using the meximun TDS
instnimeat sonsitvmy acuirgy seversl degrees below the DNNC aching point aly obtumed fro:n dese
stlies -evealed that ths eompoimel underwoes 8 very slow but slenificant exottarsmc tharmno-temieal
decomposition provess in the [12 lv 48 °C wemperatuve sange following a thee te tive hour
cendsthermic induction peiod ‘Using TDSC. analyses of DNNC and its DNINC-d, perdeutsrio belt
analogue, the kinetic deuterium isotope effect (KLE) approuch was spplied to this extended ambit
presste thermocheanical decompositoa ro enti the rate conerallong bond rupture thet governs the
sata at wich this solid sate exolbserinic pracess proceeds sac ta cersemine the cnoryy needed Tor ibs
activation,

2. Rxpertmnental

‘The TDSC: therrwchewnioal decomposition ovtes
instcument amd Perkin F-ver nainless steel asge votsene capac LV), part ne, O349-1
(0319-1525 (bottom) without Viten O-ring seals, part na. WS19 1333, DNNC and DNWC-d soragle nas

2

erenrined using Perkin Pliner
ranging from 4.40 ¢9 {1.54 mp, were weighed inta che LC capenlce ond thon sealed in she open
aiwasphece, Duviag the IDSC thenraechemical lecomposiiun tke scale capsules vee under c seem
‘of witroyen gas using che highest seustivity senting, flleving & contactor accomplishes! inaimamestal
calibrate amd Fine tuning service call. ‘Lae detailed synthesiv procedure and ebaracrertzation fort
DNC and DNNC-d, compounds have been reported To ensune wircost aoeusaey, the SCT
temaperitere was cn‘ with india {mp 156.60 °C) pur fe each TOSC sample run, A total of 32
IDSC rans were conduct, Six runs were condceted en DNC at 148°C mil 145 °C, shila ve rns
‘were conducted cash on DNC a 1424 wr DRNC-dy a¢ 148 °C. 145 °C, and 142°:

‘The thermochemical decorsposit.oa curves for bull DNC and DNNC-dy wets evahated wsny the
duit = 081-0) uatocalalytic rare plat where «isthe mole fractio.of decomposed DNC ac any given
tiane "The ¢ term is Fon as “he Sirepson's Mule arca at nay given lime (0 interval detined 35
AviAt Prpnasive surcnasion af “he Simpson's rule areas provide the partial area (a of decomposed
DNNC ander the TDSC curve afer t mines divided by ths total areu of decomposed DNIC under the
snlsre TDSC curve, ea = samnetion of partial cmrve ateas (@) al interval Limes Motel curve ava, a=
‘Ena

DSC pease the total heat evelved ducing the deceanposition proven, on because tals eat
evolution is progertional 1 une global vale at which the sample cheinically ents, dhe averall cate of
_docernpneitiom ix cescrdhel hy the loc kowing approximatioa: deldt = oigh! of the IDSC curve ab
{ts hosel al Line Ulntal area. A=: @ WA because h is properriona! ut the very small Sut segment."
"ls heights approx maton suocessfly has been wsod ithe auencuaye eae plots of IDSC
cenrves where the thermochemical decomposition occurs over # porind nf minaiss © Lowever, he
solid sate DNC pnd DNC thermachemieat decomposition proces necurred aver hou tong,
durations (eg. nevnly 14 hinat al 145 °C), Since the IDSC instrumentation software can only plot finite
number i dala points eegandless at the total docomposibon ime, u kmer decomposition precess give
Teger AGEAL values. Geeause of possibly large aroas dstine¢ by the-acinal AOSAR eas, this height based
4b) appomearmaiem wan no used. Rather, a moce e.goraus software program using amodifieaton of the
Simpsor.'s Rule summation orcs visite and develeped to calenlate tho wrea af specais partioas of the
decomposed comput

‘The standard Simpwcm's Rue divides equally distsbutod saznzlos of a comtizuous curve into adjacent
pairs of gub intervals, Tach pair of aubsiagervals is dotined by terce data pints: (L) Ure start of the fst
subiaterva, (2) the ond of the socomil sahinterval, and (3) the poiat betssosa them, Simmpam’s Rule ses
ines fo create 4 polymonsial surve Lhal epprogienates the ouiginally sample lecummpenisina
Js arc mele the polyol eure aso ayprenionas the aoa under the
plecl desereposien cure “br the range spacited by hath eub-intorvals. Useng this
aypmiac, le aeea of a Laces portion of a sampled curve may be sopmosimeted by epplying the Sampson's
Rosle tn each adjacent pein of sub-ieervals i that sample and sgeregatng the apprerciraawarca of cach
por,

‘Sirkpscn's Rule uscs paits of sm>-amssevals for AO/AL arulysix which its the texibiise ofthis
appeich, heciuse il wequives az even amber of sub-intervals io be comdered. To tectty this.
Siropson’s Rule was mod lied ao that to sub-incervals were used 10 apprinximaty: che aviginal
decomposition curve at hefe, nt oly the scea wider che fist sub-iaterval wus approximuted frm this
foneve, Subsequent subintervals, such as dhe aocond age inthe pais, were approntmalsd in ysis
fashion by peng it with the next adjacent sub- interval, ‘This moditiee approach alse aliows adicanal
flexibility by making rome individual AnJAt suintecva.s avelable in cvitntiny linear weeression
vatnes. Such ovaluation is use! Ws delerrnine wpliniom linits of fines: portions inthe aulatalytic rare

oiginally sary
lor where» single coherect mechacist kinchs stop i¥ occurring 6 that its associared rae samsten (4p

‘81 be detenrined.

3 Reslis and Diseussion

IDSC measursmen's Laken wth mnaximam instrument scnsslivily 9C M42, 145, and 148 °C reveal chal»
very slow exethottae solid stale TINNC thermochemical decompos:tion praceous below its 155-156 °C
rrlling point, ‘kis exataernic docompauitinn process appears after a tare hots (184 mia, at 148 C)
tornsarly § hour (293 rain. at 142"C) endethermic induction period occurs. ‘Tae exothermic
thermochemical cexmpnsitioe ate data from che LDSC unlyeos curves for DNNC ata its DNNC-y
perdevterio labeted analogue chow a jwsitive Kinetic deuterium isotope effet (RDTE), DNNC predvecs

‘ornpasing the twa superimposed DNNG and

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Time (rants)

igre 2, Realtime LSC decungesiinu curve samparizon af DNAC and DNNC46 rons af 148°.

Role ta clvained frown the JOSC curves and the mugnitude GC the KDIE rate coastaar eatio. kk.
sigzea hit vashon-liydhogen (C-4) bond mprore in gne a hoth tyes of che-nicely uncquivalent
fnelhylent granpé af the DNNC molecule contre the row a unis exothenmae thermenicmicat
Accomposition process

Icletification ofthe chemice ned rupture that conttols tts ambien! pressure theninsichersical
decomposition rats proosst af hoth nitroarsate and pitcamive compounds hax proved to he ca
‘important mechanistic fouure which is mired in mare draetic mga aosceans civebuation and axplesion.

4
events:t©Indved, it also eppours his vate controling chemical hn pnt J @ Key mechanistic step
sm energetic compouné globo niaron and sensitivity properiea.™”

‘Te kil detesium ietoge eee (EDIT) has ee used ia conjmction wih amir ent pressure
TSC sb deity te ena maeeco ing bond niptoro the cans the thermochemical!
docomporition processes of goad TNT (2,4 6-tenitroteluonc)," wn sunequentty. sole LAT (UBS
tiaminn-2.6¢etrniubenzee)™ Fyuid und solid BMX (octayto-13,5.7tevantso-1 3.577
tecrzerone).? igs RDX (1 3S-nmilechoxahylro-L 3.5-iazine}$" on ther wenpeitve doucrnms
labeled TNT-ceds, TATB-de. HM, RDN makopues."Tosmal gravimetric enalysis (1GAY alse
fas bean use with TMIRITIMX cy aed RDSARDX-drisarines hic prodacs mails gaseous
rodsts during thie Figuid cn soli state therseckumical decompasitlon proces.

Tn every cee, the sara rle-coraoling bond muprure found inthe ambient press thenredenica!
dcrenpeition process 2 a given energetic comzound’* " "yfeo spears kv he the rat-contrlng
step for high ensure comustion™" ind explosive tiation ovonts, "2 With this face am ts
nate-contcoling stp in the sold stacs thermochemical deompention of INC! and DNINC-d 38
investigated by IDSC analysis using Ihe KDLE approseh,

3A. Physieocheruleal Characteristics

IDSC meesunenents taken at mgainnum inseunvent sensitivity revel thaw ery slow sols sete
NING theenocnemival desvmpasition process ours below is 155-156 °C meling print, TBSC
snypos of FONE ana 142, 145, ated 148 °C, olloving a Onee co acany fe ew andothernis
jnndetion ptioc, producn im exothexese theemechonaiculdocormposiion eur ose aulouatelyLe rate
‘lot displays three scginents Fem hich sate constat cata cam be ehlsived ¢Fignt.3). he time
Te\uired forthe sotid state decurepnsiion proces dts markeully Frm Ihe Tod sate process, Pet
example, Ju sare DNNC deeamposition asa 176°C over about 42 motes (0.7 hours) whic
‘ws entie sald stare decorponiion process at 188 °C requires nearly hous a7 20 tes lenge

Whi'e the thormochemical subi, thecnochemical decompositm rate, aed explosive milion
sonsilivily of DNNC more slosely wsetable dase of TNT, the cherice’ ect betaviar of he solid
slate DNNC therockemical decomposition praca als somewteae borwzen that of is exec RX ot
TMX sitremme rlel'ves sed the arowsace TINT compound. Over tho extended sai state
decomposition proce, bath DING and DNC se an overall average of 75 perce: sample mass
to gtscous product foontios and cvalution (Table #). Student ¢ stadstical nalyses he da in Table
‘eontizm tal wey ss values aro he same auinbe a 99.5 onnfidsnee costar. This average
weight Hoss, obtsined for 32 sannple runs, ews shat the DNC decorapostion proves, like thet of
RDX and HMX, predominantly generates small molecular woigh! paxeans produets. There is, however,
25 percent of the ocigmal NIC compound mass that romnms «is caved codeosee phase
byprodact(). The MX citrimne presices ply yaecus docompositon predicts leaving co condensed
peso maerial afier complete decomposition!” sehle TNT mainly proluces consensed phase
decomposition product”? 7

The prssence of ccnidensed decomneeitionprodts should instil some ceutian when ansgning the
rend mpnure thal serine sale oa givon thentochemial despmyosition process With condense
These odkce Zoumation, mochonniie consegenees cat be introduced hut potercllly dere. o wae

ped 1.35 experisintst minimum tx give an false secondary

fue primary IDLE valve below jis

ESB vata inthe 1.01 to 1.24 range
Table. Soba Sia

DANN and DNNC*ls Tharmovhemical Decennpeaion Mass Losses

Congpound ‘Temperature CC) ease Lass (6) Seandatd Devsstio
DNC 148 BS ESL
NN, 148 aT FAR
DNKC 145 +33
DNKC.dg 1465 +4
DNNG 142 B2 +18
DNNCs 142 3

Ave. Mass Lass

3.2 Kinetic Resets

‘The endothermus mdoction period (seen m Figure # can be exalted fora kmelie deuterium
fscinpe effect (KDIK) using aatio of the DNNC-d, and DNINC indacticn ts, ty. Won thas as
Fin demousuatec ith Squid TINT therragctenical decomposition a primary KDEB of 1.66 was
Jour, Tutte TPT investigation coma wih kis primary 1.6f KDUD value reveal! a all
concentration of eatalytic species Formod from the TNT iteolf by a rale sortrlling, C-F bun ruptane in
the IN penddan: mechy. group sshach requiret a pexivation energy equal o 104.6 Kmail. pon
seaching # tlueshold zancccirstin, tis catalytic species in:taced the exotbermie decomposition of THT
that showed an enegy of astivacion equal ta 123.0 klFmnole.

_Asturing that long temperalire equ fibration Ses do cot occur daring the induetioa time of the
sol stale DING sanrple, and thal viher non-kimeti crys Taiz or physieachernical factors aren!
present that right diluke cr mvs rte primary RTDNE vue, thi fh naclan stow ai revel
DIT equal to 1.21 (Table 2. Because assignment of the terminntion point for induct-on periad of each
ecinepnsiticm carve olten was nn rune aceuvate than 1G rv'nules dhe slandard deviasions at 148 and
143 °C cam be srottcd 99 stalisteallysigniticam, Should 4 smal! concontranon af ealnlyic #pecies be
otening trom DINNC, whieh ther insias the exottiermic solid staze decomposition. this secondary
250.0 500.0 750.0 4000.0

Tine {rinutoo)

Figure 3, Tacuetion eriog (1) sale fv a DNC mun at 145°C

DIE valuc wovetd suggest the rale-iiting step acoutseltber by pendanc N-ND,, ring C-N Pond, or
pendent C-NQy bord clemenge, Presinus studies with the related RDX nitramine and larger TIM,
hitramine have redtessed tuieh powsile NNO» wad ring C-N Sand cleavage a8 poseibly occurring 'n the

Aecorapasition pronsss™*"" 22, ur mat auring the rale-contrulting step. Plotting In, versve UF yives
DNNG INDUCTION PERIOD ACTIVATION ENERGY

98 po = ~~ oop
po] |
ar -
97
sete !
vos : |
ast —
4 - -|
. = 18408 }
Eset = 128.3 kufmol
aad nk —— rl
i :
gat — — a
0.00287 00288 ones a.o0e40 o.ooet

aT Ky
Figure 4, Brergy af activation for inducsion period of DNNC decomposition eurve trom 11210 118°
(128.1 kifmole activation energy for dus DNC! metion period wath 0.990 Hiner regresaion data
‘oprelation shich is signficantly fewer than the 1946 kliniole cncrgy of ativetron founil durin the
Jnluction period of the Higeid state TNT thermochemical decomposition prccess.

‘Table 2. KDIT: Duta for Induction Period (t) Portion of the Thermochemical Decomposition Process

Compound vFerap. CC) Wwenin) Su. Dev DIE
DRNC A, 148 Zi rs

DNNC 148 184 ER

DNNC-4, né £31

DNNC 251 +19 1.26

DNWC. We 365
DNKC ve 203
Flowing the sndetherenie inuetcn period, che.seotherric decampesition 1 initiated. Ts
utncatel tie ate plots obtamed from these escthormic IDS thermachersical desompostinon eurves
reve three linear segments fo-the DINNC wnt DNNG- dat 145 anil M48 °C (Figure 5). “those Tear
segments cccur in the easly anccteratory partion [4], the fate aoccleratony pension [3], nar the
rant hear energy release peak, and in tho day partion [C] of ie decompositinn eneve. “Ths slope
of ese theee Lincs portions provide rate cosstar.t kj cata where és
process is nccumring during whica axe svaclion pathzay predominate
temperature, only eorky acuelecatory LA and decay puro: [C] of tac exuihermnic decompastion «im
show linerity. Tineurity in the later accolcratory pemtivm [B] cisappcars, ‘Fhe peraent of DINNC saree
tour that tndergoes thermachernical decomsosition during these three lucar syria cmained is
ute high, ranging from: 66 he 2 percent for DNC anc 76 1» 61 percant for DNC; within the 142 to
148°C emperame spzead