p-Xylylenediamine and new polyimides derived from it

Article abstract of DOI:10.1023/B:RJAC.0000008307.50543.8b

p-Xylylenediamine was prepared by hydrogenation of terephthalodinitrile; the conditions ensuring high yield of this monomer were found. The influence exerted by the catalyst and solvent on the diamine yield was examined. Single-step polycondensation of p-xylylenediamine with tricyclodecenetetracarboxylic dianhydrides in the presence of catalytic amounts of isonicotinic acid gave a series of new polyimides consisting of aliphatic and aromatic fragments.

Full text of DOI:10.1023/B:RJAC.0000008307.50543.8b

Russian Journal of Applied Chemistry, Vol. 76, No. 8, 2003, pp. 1304 1309. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 8, 2003,
pp. 1341 1345.
Original Russian Text Copyright
2003 by K. Zhubanov, Abil’din, Bizhanova, B. Zhubanov, Kravtsova.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
p-Xylylenediamine and New Polyimides Derived from It
K. A. Zhubanov, T. S. Abil’din, N. B. Bizhanova, B. A. Zhubanov, and V. D. Kravtsova
Research Institute of New Chemical Technologies and Materials, Almaty, Kazakhstan
Bekturov Institute of Chemical Sciences, Ministry of Education and Science of the Republic of Kazakhstan,
Almaty, Kazakhstan
Received November 27, 2002; in final form, May 2003
Abstract p-Xylylenediamine was prepared by hydrogenation of terephthalodinitrile; the conditions ensur-
ing high yield of this monomer were found. The influence exerted by the catalyst and solvent on the diamine
yield was examined. Single-step polycondensation of p-xylylenediamine with tricyclodecenetetracarboxylic
dianhydrides in the presence of catalytic amounts of isonicotinic acid gave a series of new polyimides consist-
ing of aliphatic and aromatic fragments.
Polyalkanimides show promise as materials for
electrical and radio engineering [1, 2]. The interest in
these polymers is not occasional. Occupying an inter-
mediate position between aromatic and aliphatic de-
rivatives, they combine the advantages of both. In-
troduction of methylene units into the backbone de-
creases the melting point, enhances the resistance to
hydrolysis, and imparts to the polymers other valuable
properties allowing their processing with commercial-
ly available equipment [2].
It is known that the prospects for application of
polymeric materials are determined by numerous fac-
tors, with the availability of the starting monomers
being of major importance. We have developed a pro-
cedure for preparing p-XDA in quantitative yield,
which allowed us to begin studies of synthesis of new
PAIs derived from p-XDA and alicyclic dianhy-
drides.
Here we report the features of synthesis of p-XDA
and polyimides derived from it.
A series of polyalkanimides (PAIs) derived from
pyromellitic dianhydride and aliphatic diamines (deca-
and dodecamethylenediamines, and also their mix-
tures) have been prepared; these materials shown long
service life at temperatures of up to 200 C [2, 3].
At the same time, PAIs can also be prepared from
p-xylylenediamine ( p-XDA) and other anhydrides.
EXPERIMENTAL
The starting compounds and solvents were purified
by common procedures. The IR spectra were recorded
on a Specord IR-25 spectrometer. The monomer sam-
ples were prepared as KBr pellets, and the polymer
samples, as 3 5- m films. The reduced viscosities of
0.5% solutions of polyimides were measured with an
Ubbelohde viscometer at 25 C in DMSO. The TG
and DTA curves were recorded simultaneously on an
MOM derivatograph (Hungary) at a heating rate of
In this study, we prepared dianhydrides of cyclo-
decenetetracarboxylic acids: tricyclo[4.2.2.02,5]dec-
7-ene-3,4,9,10-tetracarboxylic dianhydride (product of
photochemical addition of maleic anhydride to ben-
zene, AB) and its 7-fluoro (AFB) and 7-chloro (ACB)
derivatives, which are starting compounds for prepar-
ing a wide set of heat-resistant polymers, including
polyimides [4, 5]:
1
8 deg min . From the TG curves, we calculated
the temperatures of the onset of weight loss and of
5, 10, and 50% weight loss (T0, T5, T10, and T50, re-
spectively).
O
C
O
C
The physicomechanical (tensile strength , relative
elongation l) and dielectric (dielectric loss tangent
tan , relative dielectric permittivity ) characteristics
were studied under standard conditions by published
procedures [6, 7].
O
O
C
O
C
O
R
where R = H (AB), F (AFB), Cl (ACB).
1070-4272/03/7608-1304 $25.00 2003 MAIK Nauka/Interperiodica

p-XYLYLENEDIAMINE AND NEW POLYIMIDES DERIVED FROM IT
1305
p-Xylylenediamine was prepared by catalytic re-
duction of terephthalodinitrile (TDN)1 in a high-
pressure kinetic unit [8] allowing monitoring of the
hydrogen uptake in unit time [9]. As catalysts we used
promoted catalytic alloys whose base component was
Raney nickel; the catalysts were prepared by leaching
of the corresponding alloys with Ni : Al 1 : 1. A 0.5-l
long-necked stainless steel vessel was shaken at a fre-
quency of 600 700 one-side rockings per minute. A
0.5-g portion of the catalyst was loaded under the layer
of the solvent (50 ml of methanol preliminarily sat-
urated with ammonia under cooling; nitrile : ammonia
ratio 1 : 3). Then 1.43 g of TDN was added. Hydro-
genation was performed until the H2 uptake stopped.
Table 1. Conditions of TDN hydrogenation on Raney
nickel catalysts (H2 pressure 4.0 MPa; 60 C)
Composition of starting alloy
before leaching (weight ratio)
p-XDA
yield, wt %
, min
Ni : Al = 50 : 50
140
50
73 75
90 92
Ni : Ti : Al commercial
(TU*-59-83 75), prescribed
content: Al, 50 53.5;
Ni, 44 46.5; Ti, 2.2 2.8
N-5 catalyst
Ni : M : Al:
47.5 : 2.5 : 50.0
45.0 : 5.0 : 50.0
41
32
94 95
97 98
p-XDA was identified by elemental analysis, melt-
ing point, and IR spectra.
*
Technical Specifications.
Table 2. Conditions of TDN hydrogenation in various
solvents (H2 pressure 4.0 MPa; 60 C)
Found, %: C 70.26, H 8.84, N 19.92.
C8H12N2.
Calculated, %: C 70.60, H 8.09, N 20.57.
Ni Ti catalyst
N-5 catalyst
( 3% Ti)
Solvent
1
IR spectrum, , cm : 1500 (benzene ring); 1670,
(saturated
p-XDA
yield,
wt %
p-XDA
yield,
wt %
3420 ( NH2 groups); 2920 ( CH in CH2 group); mp
34.5 35 C (published data [8]: 35 C).
with NH3)
,
,
min
min
AB, AFB, and ACB were prepared by published
procedures [10, 11] and purified by three- or fourfold
1.5 2.0-h treatment with hot acetone under stirring.
The precipitate of the monomers was filtered off and
vacuum-dried in an oven to constant weight at 80
90 C.
Methanol
Ethanol
Propanol
Butanol
50
62
69
71
90 92
89 91
90 91
90 91
32
41
48
53
97 98
96 97
96 97
96 97
AB: equivalent weight 68.5 (calculated 68.5), mp
250 252 C; AFB: equivalent weight 73.04 (calcu-
lated 73.04), mp 312 314 C; ACB: equivalent weight
77.12 (calculated 77.12), mp 302 304 C. The ele-
mental analyses were consistent; the melting points
agreed with published data [10, 11]. The solvents
[dimethylformamide, DMF; dimethylacetamide, DMA;
N-methyl-2-pyrrolidone, MP; dimethyl sulfoxide,
DMSO] were dried over 4- molecular sieves.
the temperature was raised to 110 C over a period
of 20 min, and the mixture was stirred for additional
2 h. After cooling to room temperature, the polyimide
was precipitated with chemically pure acetone, and
the precipitate was washed with two portions of ac-
etone and vacuum-dried in an oven at 80 90 C to
constant weight.
The elemental composition of the precipitated poly-
mer corresponds to the theoretical value. Polyimide
films were prepared by casting 25% solutions of the
polyimides in DMA on glass plates. To remove the
solvent, the films were predried by vacuum heating
in an oven at 80 C for 0.3 h, after which they were
heated to constant weight at 150 C for 1 h.
The polyimide derived from AB and p-xylylene-
diamine was prepared as follows. A three-necked flask
equipped with a stirrer and an inlet tube for inert gas
was charged with 13.71 g (0.05 mol) of AB, 5.20 g
(0.05 mol) of p-XDA, 0.09 g (5 wt % relative to
the sum of the monomers) of isonicotinic acid, and
56.9 ml of DMA. The mixture was heated on an oil
bath (50 C) for 15 min with stirring, after which
Polyimides derived from p-XDA and halogenated
dianhydrides were prepared similarly. Yield 98.5
99.0%, degree of imidization about 100%.
1
Terephthalodinitrile was kindly submitted by P.B. Vorob’ev
Catalytic hydrogenation of nitriles involves a set
of parallel-consecutive reactions [8, 12 14]. The re-
duction of TDN was performed on the catalysts listed
in Table 1. The results are given in Tables 1 and 2.
and L.F. Gabdullina (Bekturov Institute of Chemical Sciences,
Ministry of Education and Science of the Republic of Ka-
zakhstan).
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 8 2003

1306
ZHUBANOV et al.
Table 1 shows that Ni Ti and N-5 catalysts are
Table 2 shows that the most favorable ratio of the
reactants on the catalyst surface in alcohol is attained
at the nitrile : ammonia ratio of 1 : 3.
more active, compared to straight Raney nickel. The
yield of the target product is 90 92% on Ni Ti and
as high as 97 98% on N-5. Therefore, the subsequent
experiments were performed with N-5 catalyst.
It is known that the products of hydrogenation of
phthalonitriles contain amino nitriles [14, 16, 17].
This fact suggests consecutive reduction of the nitrile
groups. The hydrogenation rate on N-5 catalyst de-
creases with time; the hydrogen uptake corresponds
to the reaction stoichiometry [18]. Hydrogenation
starts and proceeds at a high rate until 2 mol of H2
is taken up per mole of the dinitrile; after that,
the rate of hydrogen uptake somewhat decreases, and
the remaining 2 mol of H2 is added at a lower rate
[17, 18].
Published data on hydrogenation of aromatic dini-
triles demonstrate a significant solvent effect on the
process; the best results are attained in alcohols [14].
In this study, we examined the influence exerted by
the nature of a solvent on hydrogenation of TDN on
N-5 catalyst in the presence of ammonia. The results
are listed in Table 2. It is known that the highest rate
of formation and highest yield of the product are at-
tained at the stoichiometric ratio of the reactants on
the catalyst surface [15]; this fact was taken into
account in our experiments.
Hydrogenation of TDN can be described by the fol-
lowing scheme:
C N
CH=NH
CH2
NH2
+ H2
+ H2
C N
C N
C N
p-TDN
Aldimine
4-Cyanobenzylamine
+NH3
NH2
CH
NH2
+H2
NH3
C N
CH2
CH2
NH2
CH2
NH2
+ H2
NH2
+ H2
CH2
NH2
p-XDA
C N
4-Cyanobenzylamine
CH=NH
Aldimine
+NH3
CH2
NH2
+H2
NH3
NH2
CH
NH2
This scheme suggests that, initially, one of the ni-
trile groups is hydrogenated to give the amino nitrile
(cyanobenzylamine), and only after that p-XDA is
formed.
and the reaction rate depend on both the synthesis
conditions and the catalyst used. The activity and
selectivity of N-5 catalyst may be due to its high en-
richment in firmly bound adsorbed hydrogen; its
amount is 2 3 times higher than that on straight
Raney nickel [19].
Bizhanov [19] believes that the growth of activ-
ity of Raney nickel catalysts is associated with an in-
crease in the content of the NiAl3 phase relative to
the Ni2Al3 phase. Thus, the yield of the target product
Tricyclodecenetetracarboxylic dianhydries are the
starting monomers for preparing various heat-resistant
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 8 2003

p-XYLYLENEDIAMINE AND NEW POLYIMIDES DERIVED FROM IT
Table 3. Optimal conditions for preparing polyalkanimides
1307
(0.5% solution
r
Polymer
no.
Dianhydride
cmon, wt % cINA, wt %
T,
C
, h
in DMSO, 25 C),
/
1
dl g
1
2
3
4
AFB
AB
ACB
AFB
40/2.0
40/2.5
40/2.5
20/0
120
2.2
2.5
2.5
2.5
1.23
1.10
0.94
0.32
120
110
25
Table 4. Thermal characteristics of PAI
Temperature of weight loss,
C
Polymer
Tg,
C
in air
under Ar
no.
T0
T15
T10
T50
T0
T15
T10
T50
1
2
3
270
280
265
340
325
335
380
350
365
420
400
415
530
500
510
380
360
355
440
415
435
470
450
460
580
545
560
polymers, including polyimides [20, 21]. No data are,
however, available on synthesis of high-performance
polyimides from p-XDA and the above dianhydrides,
because of the lack of efficient synthesis procedures.
In this study, we developed such procedures. The
polyimides were prepared by single-stage polyconden-
sation of the components in polar aprotic solvents
(amides) in the presence of catalytic amounts of iso-
nicotinic (pyridine-4-carboxylic, INA) acid, which is
known [5] to appreciably intensify polycondensation,
like other pyridinecarboxylic acids.
endocyclic double bond; as a result, the anhydride
groups become more electrophilic. AB and ACB are
less reactive [10].
It should be noted that PAIs with fairly good char-
acteristics, derived from an alicyclic dianhydride,
were prepared for the first time. The syntheses were
performed at 110 120 C for 2.0 2.5 h. All the reac-
tions occurred under homogeneous conditions and
gave PAIs in almost quantitative yields, with degrees
of imidization of about 100%. The viscosity of the po-
1
lymers was as high as 0.94 1.23 dl g .
It is known that polyheterocycles prepared in solu-
tion are more soluble than the same polymers pre-
pared by solid-phase imidization of polyamido acids.
Among the chosen solvents (DMF, DMA, MP,
DMSO), the best results were obtained with DMA;
the polyimides prepared in this solvent have the high-
The optimal conditions for preparing PAIs are
listed in Table 3; for comparison, we also give data
for the two-stage synthesis of the polyimide from
AFB and p-XDA (polymer no. 4). Table 3 shows that
the single-stage procedure ensures higher
polyimide.
of the
r
est viscosity. For example,
of 0.5% solution of
r
The compositions and structures of the polyimides
were confirmed by elemental analysis and IR spec-
troscopy. The IR spectra of the polyimides contain
absorption bands at 1775 and 1715 (carbonyl groups
the fluorinated polyimide prepared in various solvents
1
under the optimal conditions is as follows (dl g ):
0.45 in DMF, 0.53 in MP, 0.75 in DMSO, and 1.23 in
DMA. Therefore, all the subsequent syntheses were
performed in DMA.
1
of imide rings), 1365 1370 (>N ), and 715 725 cm
(imide ring); the PAI derived from AFB also exhibits
1
A study of the reactions of p-XDA with alicyclic
dianhydrides showed that the fluorinated dianhydride
(AFB) is more reactive in acylation, which is due to
the high electronegativity of the fluorine atom at the
C F vibration band at 1260 1300 cm , and the PAI
1
derived from ACB, a C Cl band at 860 cm . No
bands characteristic of uncyclized amido acid frag-
ments were detected.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 8 2003

1308
ZHUBANOV et al.
The structural features of polyimides derived from
(2) A series of new (including fluoro and chloro
derivatives) polyimides were prepared by condensa-
tion of p-xylylenediamine with tricyclodecenetetra-
carboxylic dianhydrides in polar aprotic solvents
(amides). These polymers exhibit high, for this class
of materials, physicomechanical and dielectric charac-
teristics and high heat resistance.
tricyclodecenetetracarboxylic dianhydrides (presence
of the alicyclic structure and, in the case of AFB and
ACB, also of halogen atoms) are responsible for some
specific properties; for example, the glass transition
points Tg decrease somewhat. Comparison of the glass
transition points of PAIs, determined by dielectric
measurements [22], showed that they are within 265
280 C; Tg of the halogenated polymers is 10 15 C
lower, compared to the PAI derived from AB; intro-
duction of Cl decreases Tg to a greater extent, com-
pared to F (Table 4, polymer nos. 1, 2).
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