Synthesis of oligoetherols with a carbazole ring and an azo group

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POLIMERY 2011, 56, nr 2
146
RENATA LUBCZAK
Rzeszow University of Technology
Department of Organic Chemistry
Al. Powstañców Warszawy 6, 35-959 Rzeszów
e-mail: [email protected]
Synthesis of oligoetherols with a carbazole ring and an azo group
RAPID COMMUNICATION
Summary — Diols with a carbazole ring were obtained in reactions of 9-(2,3-epoxypropyl)carbazole with water or ethylene glycol or in a reaction of 9-(2-chloroethyl)carbazole with diethanolamine. Then, the diols were further converted in a reaction with excess of ethylene or propylene
oxide (EO and PO, respectively) to obtain oligoetherols. The oligoetherols were derivatized into
azo compounds by reactions with 2-chloro-4-nitrophenylamine.The compounds were isolated and
characterized by elemental analysis, number-average molecular weight (Mn), hydroxyl number
(LOH), IR, UV-Vis and 1H NMR spectroscopy. It has been found that the products have enhanced
thermal stability in comparison with oligomers obtained from diols containing carbazole ring
without azo group.
Keywords: diols with a carbazole ring, hydroxyalkylation, diazotization, thermal properties.
SYNTEZA OLIGOETEROLI Z PIERŒCIENIEM KARBAZOLU I GRUP¥ AZOW¥
Streszczenie — W reakcjach 9-(2,3-epoksypropylo)karbazolu z wod¹ lub glikolem etylenowym
a tak¿e w reakcjach 9-(2-chloroetylo)karbazolu z dietanoloamin¹ otrzymuje siê diole zawieraj¹ce
w swej strukturze pierœcieñ karbazolu. Diole te poddane oksyalkilenowaniu nadmiarem tlenku
etylenu (EO) lub tlenku propylenu (PO) prowadz¹ do uzyskania dwufunkcyjnych oligoeteroli,
które dwuazowane za pomoc¹ chlorku 2-chloro-4-nitrobenzenodiazowego daj¹ barwne oligoeterole z pierœcieniem karbazolu i grup¹ azow¹. Oligomery scharakteryzowano za pomoc¹ analizy elementarnej, widm IR, 1H NMR i UV-Vis, a tak¿e liczby hydroksylowej (LOH) i liczbowo œredniego ciê¿aru cz¹steczkowego (Mn). Stwierdzono, ¿e oligoeterole zawieraj¹ce pierœcieñ karbazolu
i grupê azow¹ charakteryzuj¹ siê zwiêkszon¹ odpornoœci¹ termiczn¹ w stosunku do oligomerów
nie zawieraj¹cych ugrupowania azowego.
S³owa kluczowe: diole z pierœcieniem karbazolu, hydroksyalkilowanie, dwuazowanie, odpornoœæ
termiczna.
Presumption that considerable thermal stability of
carbazole [formula (I) in Scheme A] might lead to polymers containing carbazole ring of high thermal stability.
The synthesis of diols and oligoetherols containing a
carbazole ring has been described proviously [1—4].
They were obtained from carbazole and glycerol epichlorohydrine leading to 9-(2,3-epoxypropyl)carbazole
(EPC), which underwent opening of the epoxide ring
with water or ethylene glycol. The products were further
converted with oxiranes to bifunctional oligoetherols.
The latter opened a possible path towards polyurethanes
of enhanced thermal stability [3—4]. For further improvement of thermal stability, synthesis of oligoetherols
with azo-derivatives of carbazole suitable for obtaining
the polymers must be carried out. This kind of products
might have the unique physical properties, for example
they were shown to be photo- and electroluminescent,
they are often liquid crystals and posse electroconductivity and nonlinear optical properties, because of the
presence of azo groups [5—7].
EXPERIMENTAL
Materials
Carbazole, ethylene oxide (EO), propylene oxide
(PO), triethylamine, and 2-chloro-4-nitroaniline were
purchased from Fluka (Switzerland). Epichlorohydrine
was delivered by Aldrich (Germany). Diethanolamine
and 1,2-dichloroethane were purchased from POCh
(Poland). All substances were pure grade and were used
as received.
3A
2A
1A
Number
of oligoetherol
CH3
(a)
(d)
(b)
(g)
(d)
(c)
(a)
(a)
(a)
O H 2 C H 2C
H
(c)
H O HC H2C
(b)
CH3
(b)
(e)
N
N
(h)
2 (b)
(i)
(e)
(b)
N N
(f)
CH3
(a)
(g)
(j)
(b)
NO2
(g)
(d)
(b)
N N
(f)
(b)
(g)
(i)
N
(b)CH2
(a)
(h)
(c) CH2
( a)
(g)
(d)
(g)
(a)
(d)
N N
O H2C H2C N CH2 CH2 O
y
(a)
(d)
(d)
Cl
CH3
(f)
NO2
(c)
(a)
(a)
CH2 CH2 O
(e)
(b)
(a)
CH2 CH O
NO2
O CH CH2 O CH2 CH2 O
y (c)
2 (b)
(h)
Cl
H
x
(b)
H
x (a)
O CH CH2 O CH2 CH O H
y (c)
x
(c)
(d)CH
(e)
(c) CH
(d)
H O HC H2C
(b)
(a)
(e)
(c)
Cl
Formula of oligoetherol
T a b l e 1. Results of analysis of the obtained oligoetherols
27
25
38
Yield,
%
N 9.05
H 6.09,
C 56.86,
% found:
N 9.22
H 6.32,
C 56.88,
% calculated:
N 7.09
H 6.62,
C 60.56,
% found:
N 6.86
H 6.86,
C 60.26,
% calculated:
N 7.53
H 6.52,
C 60.11,
% found:
N 7.25
H 6.86,
C 60.58,
% calculated:
Elemental
analysis
LOH,
mg KOH/g
IR bands, cm-1
3350 (OH), 3084—3049
(Ar-H), 2869 (CH2),
1626—1484 (C=C); 1594
(N=N), 1520, 1337 (NO2),
calculated:
calculated:
1453 (CH2, OH), 1377
759.5
147.7
(CH2), 1324 (C-N), 1154
found: 745.3 found: 133.2
(C-O in ethers), 1112
(C-Cl); 1046—1020 (C-O in
alcohols); 744—724 (Ar-H)
3444 (OH), 3052—3023
(Ar-H), 2969—2869 (CH3,
CH2), 1626—1483 (C=C),
1594 (N=N), 1521, 1338
calculated:
calculated:
(NO2), 1460—1452 (CH2,
816,.5
137.4
OH), 1374 (CH3), 1325
(C-N), 1153 (C-O in ethers),
1111 (C-Cl), 1087—1046
(C-O in alcohols), 749—723
(Ar-H)
3434 (OH), 3052 (Ar-H),
2969—2869 (CH2),
1626—1483 (C=C), 1594
calculated:
calculated:
(N=N), 1521, 1339 (NO2),
772.5
145.2
1460—1452 (CH2, OH),
1374 (CH3), 1325 (C-N),
1153 (C-O in ethers), 1112
(C-Cl), 1082—1046 (C-O in
alcohols), 749—723 (Ar-H)
Mn
(a) 3.10—3.80 m;
(b) 3.80—4.00 m;
(c) 4.30—4.60 m;
(d) 7.10—7.90 m;
(e) 7.75 d, J1 = 9 Hz;
(f) 8.05 dd, J1 = 9 Hz,
J2 = 2 Hz;
(g) 8.15—8.35 m;
(h) 8.45 d; J = 2 Hz;
(i) 8.80 d, J2 = 2 Hz.
440
441
442
(a) 0.60—1.20 m;
(b) 2.80—3.75 m;
(c) 3.75—4.10 m;
(d) 4.20—4.60 m;
(e) 7.00—7.90 m;
(f) 7.75 d, J1 = 9 Hz;
(g) 8.05 dd, J1 = 9 Hz,
J2 = 2 Hz;
(h) 8.15—8.35 m;
(i) 8.40 d, J = 2 Hz;
(j) 8.80 d, J2 = 2 Hz.
(a) 0.60—1.20 m;
(b) 2.70—4.10 m;
(c) 4.10—4.70 m;
(d) 6.90—7.70 m;
(e) 7.55 d, J1 = 9 Hz;
(f) 7.75 dd, J1 = 9 Hz,
J2 = 2 Hz;
(g) 7.90—8.15 m;
(h) 8.40 d; J = 2 Hz;
(i) 8.80 d; J2 = 2 Hz.
UV-Vis
from
lmax, nm
1H NMR
signals, ppm
147
148
Syntheses of semi-products
The s y n the s i s o f E P C, 3 - ( 9 - c a r ba z o l y l ) pr opane-1,2-diol (CPD) and 6-(9-carbazolyl)-3-oxahexane-1,5-diol (COHD) by epoxide ring opening of EPC
with water or ethylene glycol and synthesis of 5-[2-(carbazol-9-yl)ethyl]-3-azapentane-1,5-diol (CEAPD) from
9-(2-chloroethyl)carbazole and diethanolamine was performed according to the published procedure [1]. Reactions of the semi-products with oxiranes like EO and PO
were described in [2—4].
Synthesis of diazo dyes
In a 100 cm 3 beaker 2.588 g (0.015 mole) of
2-chloro-4-nitroaniline were dispersed in 32.4 cm3 of
water. To this suspension 10.2 cm3 of concentrated hydrochloric acid were added. The mixture was cooled down to
below 5 °C. The solution of 1.034 g (0.015 mole) of sodium
nitrite in 744 cm3 water was added in small portions. The
solution of the diazo salt was further stirred in 0—5 °C for
next 30 minutes.
Coupling of diols with the diazo salt of
2-chloro-4-nitroaniline
In a three-necked flask equipped with mechanical
stirrer, thermometer and reflux condenser 8.58 g of the
products of reaction between CPD and PO or 9.1 g of
product of reaction of COHD with PO or 8.43 g of products of reaction between CEAPD and EO (molar ratio
CPD, COHD or CEAPD:oxirane was 1:6) in 20 cm3 of
isobutyl alcohol was placed. This suspension was heated
up to 40 °C, and then to this mixture the solution of the
diazo salt of 2-chloro-4-nitroaniline was added dropwise
within one hour. The mixture was stirred for next
24 hours, then the product was precipitated, filtered off,
washed with a small amount of isobutyl alcohol, then
with water until the filtrate was neutral. The product was
crystallized from 1,2-dichloroethane.
Methods of testing
The progress of reactions with oxiranes was monitored by determination of epoxide number using hydrochloric acid in dioxane method [8]. In oligoetherols the
hydroxyl number (LOH) was determined according to
Glinka and Majewska method [9].
The number-average molecular weight (Mn) of obtained polymers was determined cryoscopically in
DMSO solvent.
The IR spectra of products were recorded with
Specord 71 IR, Carl Zeiss spectrophotometer in capillary
film or in KBr pellet.
The 1H NMR spectra were recorded at 500 MHz using
Beckman DU-640 spectrometer in d6-DMSO, with HMDS
internal reference.
UV spectra were obtained with Specord (Carl Zeis,
Jena) in 1 cm cell with in 50 000—14 000 cm-1 wave number range using water as reference.
The thermal analysis of oligoetherols and urethane
oligomers was conducted with Paulik-Paulik-Erdey
thermogravimetric apparatus (MOM, Hungary).
RESULTS AND DISCUSSION
The diols with a carbazole ring were obtained according to Scheme A. CPD and COMD rings [formula (III)
and (IV), respectively] were obtained by ring opening of
EPC [formula (II)] with water or ethylene glycol [1]. A
similar diol i.e. CEAPD [formula (VI)] was synthesized by
reaction of 9-(2-chloroethyl)-carbazole [formula (V)],
H2O, H+
N
CH2 Cl
CH2 CH CH2 OH
OH
O
N
H
N
CH2 CH CH2
O
(II)
(I)
(III)
HO (CH2)2 OH
N
CH2 CH CH2 O CH2 CH2 OH
OH
(IV)
HN (CH2 CH2 OH)2
Cl CH2 CH2 Cl
N
CH2 CH2 Cl
(V)
Scheme A. Syntheses of azo derivatives with a carbazole ring
N
CH2 CH2 OH
CH2 CH2 N
CH2 CH2 OH
(VI)
149
N
CH3
H
CH3
CH2
O HC H2C
O CH CH2 O
y
CH2 CH O
H
x
Cl
N N
NO2
N
CH3
H
CH2
O HC H2C
CH3
O CH CH2 O CH2 CH O H
y
x
N
CH3
H
O HC H2C
CH2
CH3
y
CH2 CH O
H
x
Cl
N N
NO2
N
CH3
H O HC H2C
CH2
CH3
y
CH2 CH O
H
x
CH2 CH2 O
H
x
N
CH2
CH2
H
O H 2C H 2 C
y
Cl
N N
NO2
N
CH2
CH2
H
O H 2 C H 2C
y
CH2 CH2 O
H
x
150
Cl
R2
O2N
n O
N
(CH2)x
HO R1 OH
N
R2
R2
(CH2)x
H O HC H2C O R1 O CH2 CH O H
z
(VII)
y
Cl
N2Cl
x = 2, when R1 =
R2 =
CH(OH)CH2 or R1 =
NO
N
(CH2)x
R2
R2
H O HC H2C O R1 O CH2 CH O H
z
(VIII)
where: x = 1, when R1 =
N N
y
(IX)
CH2 CH(OH) CH2 O CH2 CH2
CH2 CH2 N CH2 CH2
H,
CH3
y+z=n
Scheme B. Synthesis of oligoetherols
obtained from carbazole and 1,2-dichloroethane, with
diethanolamine.
In Scheme B it was presented how the obtained diols
[formula (VII)] were further converted by reaction with
oxiranes to get oligoetherols [formula (VIII)]. Due to
good solubility of CPD, COHD, and CEAPD in oxiranes
no extra solvent was needed. Diazotization of 2-chloro-4-nitroaniline was performed with NaNO2/HCl mixture. In the next step the obtained oligoetherols were coupled with carbazole oligoetherols [formula (IX)]. The
products were dark red resins. Results of analysis of the
obtained oligoetherols are listed in Table 1. Elemental
analysis determined values of Mn and LOH allowed to
identify the products (compare Table 1).
In the IR spectra of products there were observed aromatic bands, including these for a carbazole ring (at 1626,
1451, 1327, 1010—928 cm-1). The N=N valence band at
1594—1606 cm-1 region as well as the bands of benzene-attached substituents were present (NO 2 at
1320—1340 cm-1, C-Cl at 1120 cm-1). The valence and deformation bands of OH group are present at: 3360—3400
cm-1 and 1120—1060 cm-1 regions, respectively.
The UV-Vis spectra of products indicated maximum
at the visible region, centered at 440—442 nm due to N=N
chromophore.
In the 1H NMR spectra the aromatic protons signal at
7.0—9.0 ppm and hydroxyl proton signal at 2.7—4.9
ppm, as well as methyl proton (0.6—1.2 ppm), methylene
(2.9—3.8 ppm) and methine (at ca. 4.2 ppm) signals are
observed. It is consistent with the structure of the expected products.
The obtained oligoetherol dyes were studied also by
thermal stability analysis and results are presented in
Table 2. The mass loss in function of temperature proved
their high thermal stability except oligoetherol 3A. The
10 % mass loss occurs at 240—320 °C temperature region,
while maximum decomposition temperature reaches in
some cases 420 °C. Slight mass losses (ca. 5 %) are observed mostly above 260 °C. Comparing the thermal stability of oligoetherols — carbazole derivatives without
azo groups (Table 2, oligoetherols 1, 3 and 5) with that of
analogous products with azo groups incorporated into
molecule (Table 2, oligoetherols 1A and 2A) it can be seen
that the latter posses considerably higher thermal stability except oligoetherol 3A (Table 2). Further studies will
be continued on the application of obtained oligomers to
produce linear polyurethanes of enhanced thermal stability.
CONCLUSIONS
Coupling of oligoetherols containing a carbazole ring
with 2-chloro-4-nitrobenzenediazo chloride leads to
resin dye products. It has been found that introducing a
phenylazo group into oligoetherols considerably increased their thermal stability.
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Lubczak R.: Heterocycl. Comm. 2006, 12, 201.
Lubczak R.: Polimery 2008, 53, 587.
Lubczak R.: J. Appl. Polym. Sci. 2008, 110, 3501.
Lubczak R.: J. Appl. Polym. Sci. 2010, 117, 16.
Ke X. J., Yan X. Z., Srisanit N., Wang M., Yang J. W., Huang X.
F., Shong S. Z.: Appl. Phys. 2003, 217, 69.
Lee J. H., Woo H. S., Kim T. W, Park J. W.: Optical Mat. 2003,
21, 225.
Tirapattur S., Belletete M., Drolet N., Leclerc N., Durocher
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Received 21 VI 2010.

Synthesis of oligoetherols with a carbazole ring and an azo group

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