Studies on energetic compounds Part 9: Preparation and...
5
Indian Journal of Engineering & Materials Sciences Vol. 5, June 1998, pp. 140-144 Studies on energetic compounds Part 9: Preparation and thermal decomposition of 1- and 2-naphthylammonium nitrates and perchlorates Gurdip Singh", Inder Pal Singh Kapoor & Smiju Jacob Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, India Received 17 December 1997; accepted 27 April 1998. 1- and 2-naphthylammonium nitrates and perchlorates have been prepared and characterised. Thermal and explosive characteristics of these salts are studied by TG, DSC and ignition delay measurements. Suitable decomposition pathways have also been proposed. The preparation, characterisation and thermal decomposition of alkyll.2 and aryl 3-8 ammonium nitrates and perchlorates have been extensively studied because of the technological use of these compounds, especially in pyrotechnics, explosives and solid propellants. As a part of the ongoing research programmes on thermolysis of energetic materials, studies on the nitrates and perchlorates of l+and 2-naphthylamines have been carried out and results are reported in the present com- munication. Experimental Procedure Preparation and characterisation of naphthyl- ammonium nitrates and perchlorates-l- and 2- naphthylammonium nitrates (NAN) were prepared by the reaction of 20% HN0 3 with 1- and 2- naphthylamines (I: I) respectively at 0 - 5 °C (Scheme 1). 1- and 2- naphthylammonium perchlo- rates (NAP) were prepared by reacting 20% HCI0 4 with 1- and 2- naphthylamines (1: 1) respectively at room temperature (Scheme I). The mixture was concentrated at 60°C under rotary vacuum evaporator and cooled to obtain crystalline solid. All the four salts were recrystallised from absolute alcohol, crystals were vacuum dried and purity was checked by TLC. Moreover these are characterised by gravimetric (using nitron reagent)", IR and UV spectra'?' II (Table 1). Thermal decomposition studies on NAN and NAP-Thennal decomposition of NAN and NAP was carried out using following techniques: ·For correspondence Non-isothermal TG-TG studies on nitrates and perchlorates (wt. 10 mg, 100-200 mesh) were undertaken in static air at a heating rate of 5°C/min using indigenously fabricated TG apparatus'< fitted with temperature indicator cum controller (Model CT 808T Century) and bucket type gold crucible 20% HNO, + - C,oH,NH,NO, I· & 2· naphathylanunonium nitrates 0-5°C CIOH,NH, I· & 2· naphalhylamine ,--2_00/._0.".HC"::-IO-,-,,,--. RT + - C,oH7NH,ClO. I· & 2· naphalhylammonium pcrchlorates Scheme 1 (height = 8 mm, diameter = 8 mm). Fraction decomposed (a) versus temperature (OC) plot is given in Fig. 1. DSC-DSC thermograms on NAN and NAP were obtained on a Mettler TA 4000 in nitrogen atmosphere (flow rate 40 em' Imm.). Weighed samples (Sartorius-Werke Type 2405 electro balance, Germany) were sealed with sample sealer. A pin hole was made at the top of the lid so that the product gases could escape during decomposition. The sample and the reference pans were positioned at the centre of the holder cells and were covered with aluminium domes. The thennograms (Fig. 2) were recorded at a heating rate of 10°C/min using Hewlett Packard 7475A plotter. Ignition delay and ignition temperature measurements-30 mg of the sample was taken in an ignition tube (height = 5 em and diameter = 0.4 ern) and the time between the insertion of the
Transcript of Studies on energetic compounds Part 9: Preparation and...
Indian Journal of Engineering & Materials SciencesVol. 5, June 1998, pp. 140-144
Studies on energetic compoundsPart 9: Preparation and thermal decomposition of
1- and 2-naphthylammonium nitrates and perchlorates
Gurdip Singh", Inder Pal Singh Kapoor & Smiju Jacob
Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, India
Received 17 December 1997; accepted 27 April 1998.
1- and 2-naphthylammonium nitrates and perchlorates have been prepared and characterised. Thermaland explosive characteristics of these salts are studied by TG, DSC and ignition delay measurements.Suitable decomposition pathways have also been proposed.
The preparation, characterisation and thermaldecomposition of alkyll.2 and aryl 3-8 ammoniumnitrates and perchlorates have been extensivelystudied because of the technological use of thesecompounds, especially in pyrotechnics, explosivesand solid propellants. As a part of the ongoingresearch programmes on thermolysis of energeticmaterials, studies on the nitrates and perchloratesof l+and 2-naphthylamines have been carried outand results are reported in the present com-munication.
Experimental ProcedurePreparation and characterisation of naphthyl-
ammonium nitrates and perchlorates-l- and 2-naphthylammonium nitrates (NAN) were preparedby the reaction of 20% HN03 with 1- and 2-naphthylamines (I: I) respectively at 0 - 5 °C(Scheme 1). 1- and 2- naphthylammonium perchlo-rates (NAP) were prepared by reacting 20% HCI04with 1- and 2- naphthylamines (1: 1) respectively atroom temperature (Scheme I). The mixture wasconcentrated at 60°C under rotary vacuumevaporator and cooled to obtain crystalline solid.All the four salts were recrystallised from absolutealcohol, crystals were vacuum dried and purity waschecked by TLC. Moreover these are characterisedby gravimetric (using nitron reagent)", IR and UVspectra'?' II (Table 1).
Thermal decomposition studies on NAN andNAP-Thennal decomposition of NAN and NAPwas carried out using following techniques:
·For correspondence
Non-isothermal TG-TG studies on nitrates andperchlorates (wt. 10 mg, 100-200 mesh) wereundertaken in static air at a heating rate of 5°C/minusing indigenously fabricated TG apparatus'< fittedwith temperature indicator cum controller (ModelCT 808T Century) and bucket type gold crucible
20% HNO, + -C,oH,NH,NO,
I· & 2· naphathylanunonium nitrates0-5°C
CIOH,NH,I· & 2· naphalhylamine ,--2_00/._0.".HC"::-IO-,-,,,--.
RT+ -
C,oH7NH,ClO.I· & 2· naphalhylammonium pcrchlorates
Scheme 1
(height = 8 mm, diameter = 8 mm). Fractiondecomposed (a) versus temperature (OC) plot isgiven in Fig. 1.
DSC-DSC thermograms on NAN and NAPwere obtained on a Mettler TA 4000 in nitrogenatmosphere (flow rate 40 em'Imm.). Weighedsamples (Sartorius-Werke Type 2405 electrobalance, Germany) were sealed with sample sealer.A pin hole was made at the top of the lid so thatthe product gases could escape duringdecomposition. The sample and the reference panswere positioned at the centre of the holder cellsand were covered with aluminium domes. Thethennograms (Fig. 2) were recorded at a heatingrate of 10°C/min using Hewlett Packard 7475Aplotter.
Ignition delay and ignition temperaturemeasurements-30 mg of the sample was taken inan ignition tube (height = 5 em and diameter = 0.4ern) and the time between the insertion of the
----
._--
--
Tabl
eI-
Phys
ical
para
met
ers,
TLC
anal
ytic
al(u
sing
nitro
nre
agen
t)an
dsp
ectra
lda
taon
naph
thyl
amm
oniu
mni
trate
san
dpe
rchl
orat
es
Com
poun
dC
ryst
als
m.p
/TL
CRr
pK.
Ana
lytic
alIR
®U
V·
dec.
(d)
Elue
ntN
data
,g
tem
p,O
CSp
otC
olou
rEx
perim
enta
l(T
heor
etic
al)
en Z1-
Nap
hthy
lam
mon
ium
Bro
wni
sh-
grey
88a:
bG
rey
0.82
3.92
0.08
9434
1O,1
339(
N-H
),37
6o ::t::
nitra
te(I
-NA
N)
amor
phou
s(1
0:2)
(0.0
910)
1663
,159
2,76
7(1
.375
)~
(u-n
apht
hyla
rnin
e),
I:l :-
1382
,82
7(N
OJ-
),12
977"
(C-N
),16
24,
1926
;I>(N
HJ+
).Z 0
2-N
apht
hyla
rnm
oniu
mR
eddi
sh-
brow
nd
152
a:b
Bro
wn
0.83
4.11
0.08
9934
03,
1298
(N-H
),37
8N I
nitra
te(2
-N
AN
)sh
inin
gfla
t(9
:3)
(0.0
910)
2918
,161
9,75
1(1
.389
)Z
(l3-n
apht
hyla
min
e),
;I> -e<
,13
85,8
17(N
OJ-
),::t::
511,
167
(NH
J),
1037
,~ -<
960,
887
(C-N
).r >
1-N
apht
hyla
rnm
oniu
mV
iole
td2
14a:
bG
reen
ish
0.81
3.92
0.08
3134
31,1
267
(N-H
),34
7a;::
perc
hlor
ate
(1-
NA
P)ne
edle
s(1
1:3
)br
own
(0.0
847)
3069
,16
38,
766
(1.7
89)
a;:: 0(a
-na
phth
ylam
ine)
,Z
627
(CI0
4-),
1608
,15
07~
(NH
J+).
2-N
apht
hyla
rnm
oniu
mW
hite
-si
lver
d215
a:b
Bro
wni
sh0.
834.
110.
0824
3419
,144
8,13
7534
7Z =i
perc
hlor
ate
(2-
NA
P)sh
inin
g(9
:3)
blac
k(0
.084
7)(N
-H),
3112
,15
72,
(1.7
93)
~fla
t81
3(l3
-nap
hthy
lam
ine)
,....
j./
1251
,12
11(C
-N),
626
rn en(C
I04)
,16
11,
;I>
1508
(NH
J+)
.Z 0
#a=
chlo
rofo
rm,
b=
met
hano
l,lo
catin
gre
agen
t-
iodi
ne;
*=in
DM
F;0
=in
KB
r-e rr
l;:Q o
Tabl
e2-
Igni
tion
dela
y(ti
d)ig
nitio
nte
mpe
ratu
re(I
T)an
dA
ctiv
atio
nen
ergy
for
igni
tion
(P)
for
NA
Nan
dN
AP
::t:: r 0C
ompo
und
tid(s
ee)
atIT
for
P~
125°
C15
0°C
175°
C20
0°C
225°
C25
0°C
275°
C30
0°C
325°
C35
0°C
25se
e(K
Cal
/mol
)....
jrr
l enI-
NA
ND
NI
DN
ID
NI
DN
ID
NI
31.6
±2.4
28.6
HI
27±0
.624
.6±0
.423
±o.o
313
2.08
2-N
AN
DN
I64
.6±2
.249
.3±
1.1
34±2
.829
.3±2
.422
±1.3
16.3
±0.4
14.3
±0.4
13.3
±0.4
8.6
±0.4
235
5.53
I-N
AP
DN
ID
NI
127.
6±
1.5
75±3
.347
.3±1
.738
.6±2
.425
±221
.3±0
.815
.6±0
.414
±O.O
275
7.39
2-N
AP
DN
I15
8±1
.388
.6±
3.7
55.3
+2.
234
±2.
630
.3±1
.I17
.6±0
.416
±0.6
12.6
±0.2
\0±0
.625
86.
63
- ~ -
142 INDIAN J. ENG. MATER. SCI., JUNE 1998
Table 3-- Thermal analytical data on naphthylammonium nitrates and perchlorates
CompoundTG data
Starting dec. Final dec.temp, °C temp, °C
Endothermic°C
I-NAN2-NANI-NAP2-NAP
46434042
268316386234
93.7
6HJig
269.1
DSC dataExothermic
°C6HJig
114.3543.92241.42508.8
115.7177.8283.1275.7
0.'
0.4
0.2
0.&
0.4
t 0.2
11
0.70.&
0.4
0.2
2S0 ]00 350 380
Fig.I-Non-isothermal TG of NAN and NAP in static air.
'-NAN 1-NAPJ~"!~I ~~. Jo. ~. 50. t<»o. Jm. s:
f ~b. lIiO. JIi.
Fig.2-DSC thermograms of NAN and NAP in nitrogenatmosphere.
/
u
Z.Z
2.0
1.1
:2
J' H
14
·-'-NAN1.2 &- Z-NAN
.- '-NAP• - Z-fjAP
'.0
Fig.3--Plots of log (tid) vs IITi (K) for NAN and NAP.
100
130
liO
310
4 i '0 12
ActiYOtion .nergy, I( Co, mati' --..
Fig.4-Plot of Td vs E* for NAN and NAP.
\
-SINGH et al.: 1- AND 2-NAPHTHYLAMMONIUM NITRATES AND PERCHLORATES 143
[~HO~J ;:;rOO"HN~lAaMIaI c:ompIe:x Condooood ,.... k
~,NO, ~NH-OH19J.gJ --2!........0 ~ + NO,t 2. ) Ignition ~ HCN+HCHO+H,o+COtCO,
2- NAN +N,+NH,+N,O + C
NH,CIO. d' ~CI
% lo % Jb CO+CO,+H,+H,OLSJ..8) ---=--+ ~ +NH,t + o.t ) Ignition -++HCI+NH,+O"idesi of mtrogen + Oxide.sI-NAP I of chloride + C + ..
~~~t:,.~·c",~@@"'coo, 'NH,~~~C;NN"_'_2-NAP
NH,NO,~ 1..-19J.gJ ==-
I-NAN
Fig.5---Schematic representation of thermal decompositionpathways for NAN and NAP.
sample tube in the tube fumance" and appearanceof the smoky flame was taken to be the ignitiondelay and data are given in Table 2. The activationenergy (Table 2) for ignition was calculated usingthe following equationl4
-15 and plots are given in
Fig. 3.lid = B exp (E*IRn
where lid is the ignition delay, B is a constant, Tisabsolute temperature and E* is the activationenergy. The ignition temperature (In at 25 s wasnoted and data are reported in Table 2.
Results and DiscussionTG analysis (Table 3, Fig. 1) clearly suggest
that all salts decompose in the temperature range40-380°C. 2-Naphthylammonium perchlorate wasfound to ignite at 234°C. An endotherm wasobserved for I-NAN (Table 3, Fig. 2) which maybe due to melting. The exotherm may be due todecomposition of this salts. Other salts showedonly exotherms, proving thereby that thesedecompose without melting. Very high values oft1H(JTg) were obtained for NAP as compared toNAN, which shows that perchlorate salts are moreenergetic than nitrates.
Although NAN and NAP are stable at roomtemperature, they get ignited when subjected tosudden higher temperatures. Thus, ignition delaydata measured in the range 150-350°C are pre-sented in Table 2. It has been observed (Table 2)that 2-NAP and 2-NAN get ignited at 150°C andI-NAP and I-NAN at 175°C and 250°Crespectively. It seems that l+substituted salts are
thermally more stable as compared to 2-substi-tuted salts. The activation energy for I-NAP isquite high than that of I-NAN (Table 2). HoweverE* showed a linear relationship with DSC peaktemperature (Td) Fig. 4.
The reaction pathways of the thermolysis ofthese salts have been proposed (Fig. 5). It seemsthat I-NAN decompose (steps la-c) by protontransfer (NH bond heterolysis )3-8 via activatedcomplex to form I-naphthylamine and HN03
molecules in condensed phase prior to ignition.N02 may be the decomposition product of 2-NAN(steps 2a-c) and chloroperoxonaphthalene as anintermediate for I-NAP (steps 3a-c) as given inFig. 5. 2-NAP decompose by C-N bond hetero-lysis" and ammonia may be evolved (steps 4a-c).All these salts undergo ignition at highertemperature forming gaseous products leaving asmall amont of carbonaceous residue.
AcknowledgementsThe authors are thankful to the Head,
Department of Chemistry, DDU GorakhpurUniversity, Gorakhpur for providing library andlaboratory facilities, RSIC, Nagpur for IR, DSCand ISRO, Bangalore for financial assistance.
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