Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds

Connell, John W.

Hergenrother, Paul M.

English

NASA Technical Reports Server

I11111 ll11l 111 11111 11111 Il1 11111 11111 lllll 1111111 ll111l11 Il1 
United States Patent 
Connell et al. 
[54] POLYIMIDAZOLES VIA AROMATIC 
NUCLEOPHILIC DISPLACEMENT 
[75] Inventors: John W. Connell; Paul M. 
Hergenrother, both of Yorktown, 
Va. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 732,884 
[22] Filed: Jul. 19, 1991 
Related U.S. Application Data 
[62] 
[51] 
[52] 
Division of Ser. No. 508,316, Apr. 12, 1990, Pat. No. 
5,066,811. 
Int. 421.5 ................................................ C08G 8/02 
U.S. Cl. .................................... 528/125; 528/126; 
528/127; 528/128; 528/220; 528/224; 528/228; 
528/401 
Field of Search ............... 528/125, 126, 127, 128, 
528/220, 224, 228, 401  
[58] 
[561 References Cited 
U.S. PATENT DOCUMENTS 
5,066,811 11/1991 Connell et al. ...................... 548/119 
OTHER PUBLICATIONS 
Radlmann et al., Chem. Abs. vol. 75, No. 26, 15216511. 
US005116934A 
[113 Patent Number: 5,116,934 
[45] Date of Patent: May 26, 1992 
Kuenzel et al., Chem. Abs. vol. 72, No. 4, 6804711. 
Fargerfabriken, Chem. Abs. vol. 72, No. 12, 56103q. 
Primary Examiner-John Kight. I11 
Assistant Examiner-Sam A. Acquah 
Attorney, Agent, or Firm-George F. Helfrich 
1571 ABSTRACT 
Polyimidazoles (Pl) are prepared by the aromatic nu- 
cleophilic displacement reaction of di(hydroxypheny1) 
imidazole monomers with activated aromatic dihalides 
or activated aromatic dinitro compounds. The reactions 
are carried out in polar aprotic solvents such as N,N- 
dimethylacetamide, sulfolane, N-methylpyrrolidinone, 
dimethylsulfoxide, or diphenylsulfone using alkali metal 
bases such as potassium carbonate at elevated tempera- 
tures under nitrogen. The di(hydroxypheny1)imidazole 
monomers are prepared by reacting an aromatic alde- 
hyde with a dimethoxybenzil or by reacting an aromatic 
dialdehyde with a methoxybenzil in the presence of 
ammonium acetate. The di(methoxypheny1)imidazole is 
subsequently treated with aqueous hydrobromic acid to 
give the di(hydroxypheny1)imidazole monomer. This 
synthetic route has provided high molecular weight P1 
of new chemical structure, is economically and sytheti- 
cally more favorable than other routes, and allows for 
facile chemical structure variation due to the availabil- 
ity of a large variety of activated aromatic dihalides and 
dinitro compounds. 
7 Claims, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19920019508 2020-03-24T07:14:21+00:00Z
5,116.934 
1 2 
cerning the preparation and characterization of these 
materials. 
SUMMARY OF T H E  INVENTION 
The present invention constitutes new compositions 
of matter and a new process to prepare polyimidazoles 
(Pl). It concerns new P1, novel monomers, and the pro- 
cess for preparing the same. 
Another object of the present invention is to provide 
new P1 that are useful as adhesives, coatings, films, 
membranes, moldings, and composite matrices. 
Another object of the present invention is to provide 
several new di(hydroxypheny1)imidazole monomers. 
According to the present invention t,he foregoing and 
additional objects are obtained by synthesizing PI by the 
nucleophilic displacement reaction of di(hydroxy- 
pheny1)imidazole monomers with activated aromatic 
dihalides. The inherent viscosities (7 jnh)  of the P1 
ranged from 0.24 to 1.38 dL/g, and the glass transition 
temperatures (Tg) ranged from 230" C. to 3 18" C. Ther- 
mogravimetric analysis showed no weight loss occur- 
ring below 300" C. in air or nitrogen with a five percent 
weight loss occurring at about 400" C .  in air and at 
about 495" C. in nitrogen. 
The synthesis of PI involved the use of di(hydroxy- 
pheny1)imidazole monomers of two different types; 
those prepared from monoaldehydes as shown in Equa- 
tion (l), and those prepared from dialdehydes as de- 
picted in Equation (2) .  
POLYIMIDAZOLES VIA AROMATIC 
NUCLEOPHILIC DISPLACEMENT 
ORIGIN O F  THE INVENTION 5 
This is a divisional of copending application Ser. No. 
07/508,316 filed Apr. 12, 1990, now U.S. Pat. No. 
5,066,811. 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- lo 
factured and used by or for the Government for govern- 
mental purposes without the payment of any royalties 
thereon or therefor. 
BACKGROUND OF T H E  INVENTION 15 
1. Field of the Invention 
This invention relates to structural resins and in par- 
ticular to new polyimidazoles formed from the aromatic 
nucleophilic displacement reaction of novel di(hydrox- 
ypheny1)imidazole monomers with activated aromatic 20 
dihalides or activated aromatic dinitro compounds, 
whereby economically produced, high molecular 
weight polyimidazoles useful as adhesives, coatings, 
films, membranes, moldings, and composite matrices 
are obtained. 25 
2. Description of the Related Art 
Polyimidazoles (PI) are heterocyclic polymers which 
were synthesized by the reaction of bis(pheny1-a-dike- 
tone) with an aromatic dialdehyde in the presence of 
ammonia as represented below: 30 
0 0  0 0  
II II II  II 
Ph-C-C-Ar-C-C-Ph +OHC-R-CHO 
NH400CCH3 35 
solvent 
Ph Ph 
where Ar  is a divalent aromatic radical such as 
45 
etc. R is a divalent aromatic radical which may be 
50 
55 
etc: 
described in 1967 [V. B. Krieg and G. Manecke, Die 
Makromolekulare Chemie, 108,210 (1967)l. The poly- 
mers were of relatively low molecular weight, and only 
a few physical properties were determined. P1 prepared 
by the reaction of bis(pheny1-a-diketone) with aromatic 65 
dialdehydes in the presence of ammonia generally are of 
low molecular weight, presumably due to side reac- 
tions. Therefore, there are relatively few reports con- 
The synthesis and characterization of P1 was first 60 
EQUATION (1) 
OCH3 + OHC-R 
1) NH400CHj 
2) HBr/CH3COOH 1. 
'f NH 
R 
where R can be H, CH2CH3, OCH3, CH3, CF3, 
5,116,934 
3 
-continued 
z@, Z 
z&z 
Z hz 
4 
10 
15 
HO 
I )  NHiOOCCHz 
2) HBr/CH?COOH 
N 
AI'< 
N 
H %3 
20 Where Ar' is 0, 0.OH 
25 
where Z can be CH3, CF3, OCH3, Ph, NO2, I, C1, Br, F, 
and CH2CH3. The catenation of the hydroxy group 
may be meta meta, para para, or meta para. 3o Where G is nil. CH2, 0, S. C=O. S02. 
The general reaction sequence for the Preparation of The catenation of the hydroxy group may be meta meta, 
the di(hydroxypheny1)imidazoles prepared from dialde- para para Or meta para. 
The general reaction sequence for the synthesis of PI - 
hydes is represented in Equation (2). 35 is represented below: 
40 
45 
50 
55 
65 
5,116,934 
I x 
6 
Q 
I 
? X 0 
7 
where R can be H, CH3. CHrCH3, OCH3, CF3 
5,116,934 
8 
-continued 
& Z I z&z, 
z@, Z Z J& Z 
5 
10 
15 
20 
25 
30 
35 
0 0 
I I  
C- -8 
where Z can be CH3, CF3,OCH3, Ph, NO2, I, C1, Br, F, 
CH2CH3, etc. Where Ar can be 
0 -m&- 40 
DESCRIPTION OF T H E  PREFERRED 
EMBODIMENTS 
45 Having generally described the invention, a more 
complete understanding thereof can be obtained by 
reference to the following specific examples which are 
provided herein for purposes of illustration only and do 
not limit the invention. 
EXAMPLES 
EXAMPLE 1 
50 
Where G can be nil, CHz, 0, S, C=O,  S02. 
meta, para para, or meta para, and X can be 
The substitution of the hydroxy group may be meta 
The following example illustrates the reaction se- 
5 5  quence for the synthesis of ,a polyimidazole where R is 
a phenyl group and X is terephthaloyl and Y is F (see 
Equation (3)). 
MONOMER SYNTHESIS 
4,5-Bis(4-hydroxyphenyl)-2-phenylimidazole 
0 '  0 
It -c-, --s02--, -c 
0 -!op C- 0 II -P- , Into a one liter three neck round bottom flask equipped with a mechanical stirrer, thermometer, nitro- gen inlet and reflux condenser was placed 4,4'-dime- thoxybenzil (13.53 g, 0.05 mol) and acetic acid (300 ml). 
65 The mixture was stirred with heating to give a yellow 
solution. Ammonium acetate (68.0 g, 0.88 mol) and 
benzaldehyde (26.0 g, 0.25 mol) were added along with 
additional acetic acid (100 ml). The solution was heated 
5,116,934 
9 10 
to reflux (about 120" C.) overnight under nitrogen. The 
orange solution was cooled and poured into water to 
give an off-white precipitate which was collected, 
washed repeatedly with water and dried at 125" C. 
Yield was 17.5 g (98%) of white solid. Recrystallization 
was 5.0 g (99%) of off-white polymer with a glass tran- 
sition temperature of 259" C. The inherent viscosity of 
a 0.5% solution in DMAc at 25" C. was 0.61 dL/g. Thin 
films cast from DMAC solution gave tensile strength, 
tensile modulus and elongation at 25" c. of 13,300 psi, 5 
from ethanol/water (3:l) gave 15.8 g (89%) of white 
crystals, m.p. 198"-200" C. 
4,5-Bis(4-methoxyphenyl)-2-phenylimidazole (15.8 g, 
0.044 mol) was placed in a 250 ml three neck round 
bottom flask equipped with a mechanical stirrer, nitro- 
gen inlet, thermometer, reflux condenser and hydrogen 
bromide gas trap along with acetic acid (75 ml) and 
47-49% aqueous hydrogen bromide solution (130 ml). 
The mixture was heated to reflux for 16 hours, cooled, 
poured into water to give a white solid, which was 
neutralized with sodium hydroxide, collected, washed 
with water and dried at loo" C. Yield was 13.7 E of 
405,200 psi and 5.0% andat 177" C. of 9,500 psi. 400,500 
psi and 3.3% respectively. 
EXAMPLE3 . 
The following example illustrates the reaction se- 
quence for the synthesis of the polyimidazole where Ar' 
is l,Cphenylene, X is isophthaloyl and Y is F (See Eua- 
tion 3). 
0 
MONOMER SYNTHESIS 
l,4-Bis[2-imidazolyl-4-(4-hydroxyphenyl)-5-(phenyl)]- 
benzene w 
white solid. Recrystallization from ethanol/water (3: 1) 2o 
~ ~ ~ 1 .  Calcd. for c ~ ~ H ~ ~ N ~ ~ ~ :  c, 76.80%; H, 4.91%; N, 
8.5370. Found: C, 76.50%; H, 5.00%; N, 8.44%. 
gave 11.5 g (79%) of white crystals, m.p. 327O-330" C. Into a 500 ml three neck round bottom flask equipped 
with a mechanical stirrer, thermometer, nitrogen inlet 
and reflux condenser was placed 4-hydroxybenzil (9.05 
g, 0.04 mol) and acetic acid (100 ml). The mixture was 
POLYIMIDAZOLE SYNTHESIS 25 stirred with heating to give a yellow solution. Tereph- 
Into a 100 ml three neck round bottom flask equipped thalaldehyde (2.68 g, 0.02 mol) was subsequently added 
with a mechanical stirrer, thermometer, nitrogen inlet, along with ammonium acetate (43.1 g, 0.56 mol) and 
moisture trap and reflux condenser was placed 4,5-bis(4- acetic acid (50 ml). The mixture was stirred with heat- 
hydroxyphenyl)-2-phen~limidazole (2.4267 g, 7.5 ing and within one hour a yellow precipitate formed. 
mmol), 1,4-bis(4-fluorobenzoyl)benzene (2.4173 g, 7.5 30 The mixture was then heated to reflux (about 120" C.) 
mmol), pulverized anhydrous potassium carbonate (2.4 for six hours. The mixture was cooled and poured into 
g, 17.0 mmol, 15% excess), dry N,N-dimethYlacetamide ice water, and the yellow solid collected, washed with 
@MAC) (20 ml, 20% solids) and toluene (30 ml). The water, and dried at 100" C. Yield was 10.7 g (98%). The 
mixture was heated to about 135" c. for four hours and 35 solid was recrystallized from N,N-dimethylformamide 
then heated to 155" c* Overnight under nitrogen. The (100 ml) and water (25 ml) using activated charcoal to 
viscous dark red solution was diluted with DMAc (20 give 8.6 (79%) of yellow solid, m.p. about 3900 c. 
ml) and precipitated into waterlacetic acid mixture, ~ ~ ~ 1 ,  Calcd for c ~ ~ H ~ ~ N ~ ~ ~ :  c, 79.10%; H, 4.79%; N, 
collected, washed successively in water and methanol 10.25%. Found: c ,  78.81%; H, 4.87%; N, 10.12%. 
and dried at 125" C. Yield was 4.4 g (97%) of yellow 40 
polymer with a glass transition temperature of 248" C. POLYIMIDAZOLE SYNTHESIS 
The inherent viscosity of a 0.5% solution in DMAc at 
250 '. was 0.89 dL/g. Thin 'Ims from DMAc 
a 100 ml three neck round bottom flask equipped 
with a mechanical stirrer, thermometer, nitrogen inlet, 
gave and 45 moisture trap and reflux condenser was placed 1,4-bis[2- 
imidazolyl-4-(4-hydroxyphenyl)-5-(phenyl)]benzene 
(2.7330 g, 0.005 mol), 1.3-bis(4-fluorobenzoyl)benzene 
gation at 250 c' Of 149200 psi, 4079000 Psi and 6.0%; at 
1770 c' Of 89200 psi, 3069000 psi and 6'o%; and at 2oo" c' 
of 6,600 psi, 273,500 psi and 7.5%. (1.61 15 g, 0.005 mol), pulverized anhydrous potassium 
EXAMPLE 2 carbonate (1.6 g, 0.0115 mol, 15% excess), dry DMAc 
50 (18 ml, 18% solids) and toluene (25 ml). The mixture The following example illustrates the reaction se- 
quence for the synthesis of the polyimidazole where R was heated t' about 13'" c. for four and then 
is a phenyl group, is a carbonyl group, and is (see heated to 155" c. overnight under nitrogen. The viscous 
dark red solution was diluted with DMAc (20 ml) and Equation (3)). 
a 100 ml three neck round bottom flask equipped 5 5  precipitated into water/acetic acid mixture, collected, 
with a mechanical stirrer, thermometer, nitrogen inlet, washed successively in water and methanol and dried at 
moisture trap and reflux condenser was placed 4,5-bis(4- 125" c. Yield was 4.04 g (97%) Of yellow Polymer with 
hydroxypheny1)-2-phenylimidaz0le (3.2836 g, 10.0 a glass transition temperature of 273" C. The inherent 
mmol), 4,4'-difluorobenzophenone (2.1819 g, 10.0 viscosity of a 0.5% solution in DMAc at 25" C. was 1.38 
mmol), pulverized anhydrous po@sium carbonate (3.2 dL/g. Thin films Cast from m-CreSOl Solution gave ten- 
g, 23.0 mmol, 15% excess), dry DMAc (22 ml, 20% sile strength, tensile modulus and elongation at 25" C. of 
solids) and toluene (35 ml). The mixture was heated to 17,600 psi, 464,000 psi and 8.1%, at 93" C. of 15,300 psi, 
about 135" C. for four hours and then heated to 155" C. 402,000 psi and 5.6% and at 232" C. of 7400 psi, 285,300 
overnight under nitrogen. The viscous dark red solution 65 psi and 4.8% sespectively. 
was diluted with DMAc (20 ml) and precipitated into Polymer characterization is presented in Table 1, and 
watedacetic acid mixture, collected, washed succes- thin film and adhesive properties are presented in Table 
sively in water and methanol and dried at 125" C. Yield 2 and Table 3, respectively. 
5,116,934 
11 
TABLE 1 
12 
POLYMER 
POLYMER CHARACTERIZATION 
Ph 
X 
INHERENT' GLASS  TRANSITION^ 
VISCOSITY, dL/c TEMPERATURE, 'C. 
PI 
P2 
P3 
P4 
P5 
0 
- P- 
Ph 
I I  
I 
so2 
co 
-C 
0 
-!mi- 
P6 
0.24 
0.41 
0.61 
0.53 
0.40 
0.89 
0.49 
0.50 
0.64 
PI0 0 0.55 -mi- 
318 
277 
259 
258 
240 
248 
239 
23 1 
230 
230 
TABLE 2-continued 
THIN FILM PROPERTIES' TABLE 2 60 
TEST TENSILE TENSILE 
POLY- TEMP., STRENGTH, MODULUS. 
MER 'C. KSI KSI 
THIN FILM PROPERTIES' 
ELONG.. % TEST TENSILE TENSILE 
POLY- TEMP., STRENGTH, MODULUS, 
MER 'C. KSI KSI ELONG.. % p7 25 13.8 390.0 6.3 
177 8.4 285.0 6.2 
P3 25 13.3 405.2 
177 8.3 336.4 3.0 177 9.5 400.0 3.4 
P6 25 14.2 407.0 6.0 
177 8.2 306.0 6.0 'Ta~cd according IO ASTM D882. average of four rpccimcns per lcsi condition 
200 6.6 273.0 7.5 
5.0 65 p;o I5 12.0 362.4 4.0 
13 
5,116,934 
14 
TABLE 3 
.4DHESIVE PROPERTIES* 
Y NH 
Ph 
BONDING TEST TI/TI TENSILE 
C 0 N D I T IO N S TEMP, "C. SHEAR STRENGTH. PSI FAILURE MODE 
300' C., 100 PSI, 1 HR 25 4660 50% COHESIVE 
300' C., 5 0 0  PSI, 1 HR 25 4120 20% COHESIVE 
300' C., 200 PSI, 1 HR 25 4810 75% COHESIVE 
93 3800 30% COHESIVE 
177 3700 40% COHESIVE 
200 3050 45% COHESIVE 
Tested according to ASTM D1002. avcrage of four specimens per test. 
Inherent viscosity of polymer 0.57 dL/g, glass transition rempcrature 245' C 
What is new and desired to be secured by Letters 
Patent of the United States is: 
1. A process for synthesizing polyimidazoles by aro- 
matic nucleophilic displacement? which comprising 25 
reacting a di(hydroxypheny1)imidazole with an acti- 
vated aromatic dihalide or dinitro compound having the 
general structure: 
30 
35 
wherein X is a radical selected from the group consist- 
ing of: 
0 0 
-c-, -s02--, -c llo!-s II 
0 
0 
' II  6, 
0 0 
II 
C- -8 
40 
45 
50 
55 
60 
65 
-continued 
0 -!Q OL 0 
wherein Y is selected from the group consisting of: 
CI. F. and NO2; 
wherein said reaction is carried out in a polar aprotic 
solvent selected from the group consisting of: 
N,N-dimethylacetamide, 
N,-meth ylp yrrolidinone, 
sulfolane, 
diphenylsulfone, 
N-cyclohexylpyrrolidinone, and 
dimethylsulfoxide; 
wherein said reaction is carried out in the presence of an 
alkali metal base; and wherein said reaction is carried 
out with the application of heat. 
2. The method of claim 1, wherein R is a phenyl 
group. 
3. The method of claim 1, wherein Ar' is 1,4-pheny- 
lene. 
4. The method of claim 1, wherein Ar' is 1,4-pheny- 
lene and X is isophthaloyl. 
5. The method of claim 1, wherein Y is selected from 
the group consisting of F and C1. 
6. The method of claim 5, wherein Y is F. 
7. The method of claim 1, wherein the solvent is 
N,N-dimeth ylacetamide. * * * * *  


Polyimidazoles via aromatic nucleophilic displacement

Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds

United States Patent 1191 [ I I ]  Patent Number: 5,066,811 
Connell et al. [45] Date of Patent: Nov. 19, 1991 
[54] POLYIMIDAZOLES VIA AROMATIC 
NUCLEOPHILIC DISPLACEMENT 
[75] Inventors: John W. Conneb Paul M. 
Hergemother, both of Yorktown, 
Va. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 508,316 
[22] Filed: Apr. 12, 1990 
1511 hit. ( 3 . 5  ...................... C07F 9/28; C07D 211/70; 
C07D 21 1/82 
[52] U.S. Cl. .................................... 548/119; 548/336; 
548/337; 548/342 
[58] Field of Search ................ 548/337, 342, 119, 336 
1561 References Cited 
PUBLICATIONS 
Radlmann et al., Chem. Abstracts, vol. 75, No. 26, 
152165~. 
Kuenzel et al., Chem. Abstracts., vol. 72, No 4, 68047n. 
Farberfabriken, Chem. Abstracts, vol. 72, No. 12, 
56103q. 
Primary Examiner-Johann Richter 
Attorney, Agent, or Firm-George F. Helfrich 
WI ABSTRACT 
Polyimidazoles (PI) are prepared by the aromatic nu- 
cleophilic displacement reaction of di(hydroxypheny1- 
)imidazole monomers with activated aromatic dihalides 
or activated aromatic dinitro compounds. The reactions 
are carried out in polar aprotic solvents such as N,N- 
dimethylacetamide, sulfolane, N-methylpyrroldinone, 
dimethylsulfoxide, or diphenylsulfone using alkali metal 
bases such as potassium carbonate at elevated tempera- 
ture under nitrogen. The di(hydroxypheny1)imidazole 
monomers are prepared by reacting an aromatic alde- 
hyde with a dimethoxybenzil or by reacting an aromatic 
dialdehyde with a methoxybenzil in the presence of 
ammonium acetate. The di(methoxypheny1)imidazole is 
subsequently treated with aqueous hydrobromic acid to 
give the di(hydroxypheny1)imidazoIe monomer. This 
synthetic route has provided high molecular weight P1 
of new chemical structure, is economically and synthet- 
ically more favorable than other routes, and allows for 
facile chemical structure variation due to the availabil- 
ity of a large variety of activated aromatic dihalides and 
dinitro compounds. 
8 Claims, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=20080008270 2019-08-30T03:34:30+00:00Z
1 
5,066,8 11 
2 
SUMMARY OF THE INVENTION 
The present invention constitutes new compositions 
of matter and a new process to prepare polyimidazoles 
5 (PI). It concerns new PI, novel monomers, and the 
Process for Preparing the same. 
Another object of the present invention is to provide 
new PI that are useful as adhesives, coatings, films, 
Another object of the present invention is to provide 
several new di(hydroxypheny1)imidazole monomers. 
According to the present invention the foregoing and 
1. Field of the Invention additional objects are obtained by synthesizing PI by 
This invention relates to structural resins and in par- ,5 the nucleophilic displacement reaction of di(hydroxy- 
ticular to new polyimidazoles formed from the aromatic pheny1)imidazole monomers with activated aromatic 
nucleophilic displacement reaction of novel di(hydrox- dihalides. The inherent viscosities (Tinh) of the PI 
ypheny1)iidazole monomers with activated aromatic ranged from 0.24 to 1.38 dL/g, and the glass transition 
dihalides or activated aromatic dinitro compounds, temperatures (Tg) ranged from 230" C. to 318" C. Ther- 
whereby economically produced, high molecular 20 mogravimetric analysis showed no weight loss occur- 
weight polyimidazoles useful as adhesives, coatings, ring below 300' C. in air or nitrogen with a five percent 
films, membranes, moldings, and composite matrices weight loss occurring at about 400" C. in air and at 
are obtained. about 495" C. in nitrogen. 
The PI is a polyimidazole having the general struc- 
POLYIMIDAZOLES VIA AROMATIC 
NUCLEOPHILIC DISPLACEMENT 
ORIGIN O F  THE INVENTION 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government for govern- 
mental purposes without the payment of any royalties 1o membranes, moldings, and composite matrices. 
thereon or therefor. 
BACKGROUND OF THE INVENTION 
2. Description of the Related Art 
Polyimidazoles (PI) are heterocyclic polymers which 25 tural formula: 
were synthesized by the reaction of a bis(pheny1-a-dike- 
tone) with an aromatic dialdehyde in the presence of 
ammonia as represented below: 
0 0  0 0  30 
Ph-C-C-Ar-C-C-Ph II II II It + OHC-R-CHO wherein the substitution of oxygen is selected from the 
group consisting of meta meta, para para, and paya 
meta; wherein Ar is a radical selected from the group 
consisting of: 
35 
where Ar is a divalent aromatic radical such as 
a, 0, etc. 
R is a divalent aromatic radical which may be 
Q, 0, etc. 
40 
wherein R is selected from the group consisting of: H, 
CH3, CF3, CH2CH3, OCH3, 
45 
55 
The synthesis and characterization of PI was first 
described in 1967 [v. B. Krieg and G. Manecke, Die 
Makromolekulare Chemie, 108,210 (1967)l. The poly- 60 
mers were of relatively low molecular weight, and only 
a few physical properties were determined. PI prepared 
by the reactin of bis(pheny1-a-diketone) with aromatic 
dialdehydes in the presence of ammonia generally are of 
low molecular weight, presumably due to side reac- 65 
tions. Therefore, there are relatively few reports con- 
cerning the preparation and characterization of these 
materials. 
@,& Z Z' 
3 
5,066,8 11 
4 
-continued -continued 
2 
0 0 
wherein Z is a radical selected from the group consist- 10 
ing of: CF3, F, C1, Br, I, CH3, OCH3, CH2CH3, NOz, 
and Ph; and 
(b) 15 
0 d;=;&, ' 20 
wherein Ar' is selected from the group consisting of: 
25 and wherein n is an integer between 4 and 100. 
The synthesis of PI involved the use of di(hydroxy- 
pheny1)imidazole monomers of two different types; 
those prepared from monoaldehydes as shown in Equa- 
tion (l), and those prepared from dialdehydes as de- 
picted in Equation (2). 
' 
30 . 
EQUATION ( 1 )  
wherein G is not OGQ a substituent or is a substituent selected 35 H $ X o ' - ' - @ - O C H 3  + OHC--R 
1) N H 4 W H 3  
2) HBr/CHjCOOH I from the group consisting of: CH2, 0, S, c---O, and SOz; wherein X is a radical selected from the group - 
consisting of: 
0 0 0 
-c-,-so2-.-cfJ'-96 II II 0 II 
40 \L 
45 
. Y N H  R 
50 where R can be H, CHzCH3, OCH3, CH3, CF3, 
60 
65 
5,066,811 
5 6 
-continued -continued 
10 
z@* Z J& Z 
I5 i 
where Z can be CH3, CF3,OCH3, Ph, NO2, I, C1, Br, F, 
and CH2CH3. The catenation of the hydroxy group 
may be meta meta, para para, or meta para. 
the di(hydroxypheny1)imidazoles prepared from dialde- 
hydes is represented in Equation (2). 
The general reaction sequence for the preparation of 2o 
Where Ar' is 
Where G is nil, CH2, 0, S, C=O, S02. 
para para or meta para. 
is represented below: 
25 The catenation of the hydroxy group may be meta meta, 
The general reaction sequence for the synthesis of PI OHC-Ar-CHO + 2 
aprotic solvent 
alkali metal base 
heat 
HO 8 L'4 N N N f &  H .OH .YNH I R  
5,066,811 
7 8 
-continued Where Y can be C1, F, or NO2 
where R can be H, CH3, CH2CH3, OCH3, CF3 0 
5 
C- 
15 
20 
0 
0 -%m+- =@, z Z & Z 35 
Where Z can be CH3, CF3,OCH3, Ph, N02, I, C1, Br, 
Where Ar' can be 
F, CH2CH3, etc. 
DESCRIPTION OF THE PREFERRED 
EMBODIMENTS 
30 
40 Having generally described the invention, a more 
complete understanding thereof can be obtained by 
reference to the following specific examples which are 
provided herein for purposes of illustration only and do 
not limit the invention. 
EXAMPLES 
Example 1 
The following example illustrates the reaction se- 
quence for the synthesis of a polyimidazole where R is 
50 a phenyl group and X is terephthaloyl and Y is F (see 
Equation (3)). 
45 
Where G can be nil, CH2, 0, S, C k O ,  S02. 
meta, para para, or meta para, and X can be 
The substitution of the hydroxy group may be meta 
Monomer Synthesis 
4,5-Bis(4-hydroxyphenyl)-2-phenylimidazole 
0 0 Into a one liter three neck round bottom flask 
equipped with a mechanical stirrer, thermometer, nitro- 
gen inlet and reflux condenser was placed 4,4'-dime- 
thoxybenzil(l3.53 g, 0.05 mol) and acetic acid (300 ml). 
60 The mixture was stirred with heating to give a yellow 
solution. Ammonium acetate (68.0 g, 0.88 mol) and 
benzaldehyde (26.0 g, 0.25 mol) were added along with 
II 
additional acetic acid (100 ml). The solution was heated 
to reflux (about 120" C.) overnight under nitrogen. The 
65 orange solution was cooled and poured into water to 
give an off-white precipitate which was collected, 
washed repeatedly with water and dried at 125" C. 
Yield was 17.5 g (98%) of white solid. Recrystallization 
55 
0 
lloi-*-c-, -s02-, -c 
0 
II 
9 
5,066,8 1 1 
from ethanol/water (3:l) gave 15.8 g (89%) of white 
crystals, m.p. 198"-200' C. 
4,5-Bis(4-methoxyphenyl)-2-phenylimidazole (15.8 g, 
0.044 mol) was placed in a 250 ml three neck round 
bottom flask equipped with a mechanical stirrer, nitro- 
gen inlet, thermometer, reflux condenser and hydrogen 
bromide gas trap along with acetic acid (75 ml) and 
4749% aqueous hydrogen bromide solution (130 ml). The following example illustrates the reaction se- 
The mixture was heated to reflux for 16 hours, cooled, lo quence for the synthesis of the polyimidazole where Ar' 
poured into water to give a white solid, which was is l,Cphenylene, X is isophthaloyl and Y is F (See 
neutralized with sodium hydroxide, collected, washed Equation 3). 
with water and dried at 100" C. Yield was 13.7 g of 
white solid. Recrystallization from ethanol/water (3:l) 15 
gave 11.5 g (79%) of white crystals, m.p. 327'-330" C. 
Anal. Calcd. for C~lH16N202: C, 76.80%; H, 4.91%; N, 
8.53%. Found: C, 76.50%; H, 5.00%; N, 8.44%. 
a 0.5% solution in DMAc at 25" C. was 0.61 dL/g. Thin 
films cast from DMAc solution gave tensile strength, 
tensile modulus and elongation at 25" C. of 13,300 psi, 
405,200 psi and 5.0% and at 177" C. of 9,500 psi, 400,500 
psi and 3.4% respectively. 
Example 3 
Monomer Synthesis 
1,4-Bis[2-imidazolyl-C(Chydroxyphenyl)-5-(phenyl)]- 
benzene 
Into a 500 ml three neck round bottom flask equipped 
20 with a mechanical stirrer, thermometer, nitrogen inlet 
and reflux condenser was placed Chydroxybenzil(9.05 
g, 0.04 mol) and acetic acid (100 ml). The mixture was 
stirred with heating to give a yellow solution. Tereph- 
thalaldehyde (2.68 g, 0.02 mol) was subsequently added 
7'5 25 along with ammonium acetate (43.1 g, 0.56 mol) and 
acetic acid (50 ml). The mixture was stirred with heat- 
The mixture was then heated to reflux (about 120" 
Polyimidazole Synthesis 
Into a 100 ml three neck round bottom flask equipped 
with a mechanical stirrer, thermometer, nitrogen inlet, 
moisture trap and reflux condenser was placed 4,5-bis(4- 
hydroxyphenyl)-2-phenylimidazole (2.4267 g, 
mmol), l,Cbis(Cfluorobenzoyl)benzene (2.4 173 g, 7.5 
mmol), pulverized anhydrous potassium carbonate (2.4 
(DMAc) (20 ml, 20% solids) and toluene (30 ml). The 
g, 17.0-01, 15% excess), dry N,N-dimethy]acemide 
mixture was heated to about 135" C. for four hours and 30 for six hours' The mixture was 
then heated to 1550 c. overnight under The 
viscous dark red solution was diluted with DMAc (20 
ing and within One hour a yellow precipitate 
and poured into 
ice Water, and the yellow solid collected, washed with 
water, and dried at loo" c. was g (98%). The 
ml) and precipitated into water/acetic acid mixture, 
collected, washed successively in water and methanol 
and dried at 125" C. Yield was 4.4 g (97%) of yellow 
polymer with a glass transition temperature of 248" C. 
The inherent viscosity of a 0.5% solution in DMAc at 
25" C. was 0.89 dL/g. Thin films cast from DMAc 
solution gave tensile strength, tensile modulus and elon- 
gation at 25" C. of 14,200 psi, 407,000 psi and 6.0%; at 
177" C. of 8,200 psi, 306,000 psi and 6.0%; and at 200' C. 
of 6,600 psi, 273,500 psi and 7.5%. 
Example 2 
The following example illustrates the reaction se- 
quence for the synthesis of the polyimidazole where R 
is a phenyl group, X is a carbonyl group, and Y is F (see 
Equation (3)). 
Into a 100 ml three neck round bottom flask equipped 
with a mechanical stirrer, thermometer, nitrogen inlet, 
moisture trap and reflux condenser was placed 4,5-bis(C 
hydroxyphenyl)-2-phenylimidazole (3.2836 g, 10.0 
mmol), 4,Cdifluorobenzophenone (2.18 19 g, 10.0 
mmol), pulverized anhydrous potassium carbonate (3.2 
g, 23.0 mmol, 15% excess), dry DMAc (22 ml, 20% 
solids) and toluene (35 ml). The mixture was heated to 
about 135' C. for four hours and then heated to 155' C. 
overnight under nitrogen. The viscous dark red solution 
was diluted with DMAc (20 ml) and precipitated into 
water/acetic acid mixture, collected, washed succes- 
sively in water and methanol and dried at 125" C. Yield 
was 5.0 g (99%) of off-white polymer with a glass tran- 
sition temperature of 259' C. The inherent viscosity of 
solid was recrystallized from N,N-dimethylformamide 
35 (100 ml) and water (25ml) using activated charcoal to 
give 8.6 g (79%) of yellow solid, m.p. about 390" C. 
Anal. Calcd. for C3&26N402: C, 79.10%; H, 4.79%; N, 
10.25%. Found: C, 78.81%; H, 4.87%; N, 10.12%. 
40 Polyimidazole Synthesis 
Into a 100 ml three neck round bottom flask equipped 
with a mechanical stirrer, thermometer, nitrogen inlet, 
moisture trap and reflux condenser was placed l,Cbis[2- 
(2.7330 g, 0.005 mol), 1,3-bis(4-fluorobenzoyl)benzene 
(1.6 1 15 g, 0.005 mol), pulverized anhydrous potassium 
carbonate (1.6 g, O.Oi15 mol, 15% excess), dry DMAc 
(18 ml, 18% solids) and toluene (25 ml). The mixture 
was heated to about 135" C. for four hours, and then 
heated to 155" C. overnight under nitrogen. The viscous 
dark red solution was diluted with DMAc (20 ml) and 
precipitated into watedacetic acid mixture, collected, 
55 washed successively in water and methanol and dried at 
125" C. Yield was 4.04 g (97%) of yellow polymer with 
a glass transition temperature of 273' C. The inherent 
viscosity of a 0.5% solution in DMAc at 25" C. was 1.38 
60 dL/g. Thin films cast from m-cresol solution gave ten- 
sile strength, tensile modulus and elongation at 25" C. of 
17,600 psi, 464,000 psi and 8.1%, at 93' C. of 15,300 psi, 
402,000 psi and 5.6% and at 232" C. of 7400 psi, 285,300 
Polymer characterization is presented in Table 1, and 
thin film and adhesive properties are presented in Table 
2 and Table 3, respectively. 
45 imidazolyl4(Chydroxyphenyl)-5-(phenyl)]benzene 
65 psi and 4.8% respectively. 
11 
5,066,811 
TABLE 1 
12 
POLYMER CHARACTERIZATION 
Ph 
INHERENT' GLASS  TRANSITION^ 
POLYMER X VISCOSITY, dL/g TEMPERATURE, 'C. 
P1 0 0.24 318 
II 
P2 
P3 
P4 
P5 
P6 
P7 
P8 
-P- 
I 
Ph 
so2 
co 
0 
-C QQp C- 
0.41 
0.61 
0.53 
0.40 
0.89 
0.49 
0.38 
277 
259 
258 
248 
248 
239 
23 1 
230 
PI0 0 -w 0.55 230 
TABLE 2 
THIN FILM PROPERTIES' 
TEST TENSILE TENSILE 
POLY- TEMP., STRENGTH, MODULUS, ELONG., 
MER 'C. KSI KSI z 
P3 25 13.3 405.2 5.0 
177 9.5 400.0 3.4 
P6 25 14.2 407.0 6.0 
I77 8.2 306.0 6.0 
200 6.6 273.0 7.5 
60 
65 
TABLE 2-continued 
THIN FILM PROPERTIES' 
TEST TENSILE TENSILE 
POLY- TEMP., STRENGTH, MODULUS, ELONG., 
MER 'C. KSI KSI z 
P7 25 13.8 390.0 6.3 
177 8.4 285.0 6.2 
PI0 23 12.0 362.4 4.0 
177 8.3 336.4 3.8 
'Tested according to ASTM D882, average of four specimens pcr test condition. 
13 
5,066,811 
TABLE 3 
ADHESIVE PROPERTIES' 
N 
Ph 
BONDING TEST TImI TENSILE FAILURE 
CONDITIONS TEMP., 'C. SHEAR STRENGTH, PSI MODE 
300' C., 100 PSI, I HR 25 4660 50% COHESIVE 
ux)" C., 500 PSI, 1 HR 25 4120 20% COHESIVE 
3W C., 200 PSI, 1 HR 25 4810 75% COHESIVE 
93 3800 30% COHESIVE 
177 3700 40% COHESIVE 
200 3050 45% COHESIVE 
*Tested wording to ASTM Dl002, average of four spccimena per 1st. Inherent wscmity of polymer 0.57 dL/& gllss 
tiansition temperature 245' C. 
What is new and desired to be secured by letters 
1. A polyimidazole having the general structural 
patent of the United States is: 
formula: 25 
wherein the substitution of oxygen is selected from the 
group consisting of meta meta, para para, and para 
meta; wherein Ar is a radical selected from the group 
consisting of: 35 
wherein R is selected from the group consisting of  H, 
CH3, CF3, CH2CH3, OCH3, 
45 
50 
55 
60 
65 
14 
-con tin ued 
'@;and 2 z ,& z 
wherein Z is a radical selected from the group consist- 
ing of CF3, F, C1, Br, I, CH3, OCH3, CH2CH3, NO2, 
and Ph; and 
wherein Ar' is selected from the group consisting of 
wherein G is a bond or is a substituent selected from the 
group consisting of: CH2, 0, S, C==O, and S02; 
wherein X is a radical selected from the group consist- 
ing of: 
0 0 
II 
0 
- c - , - s o 2 - , - ! g j y - , 6  II 
5,066,s 11 
15 
continued 
16 
-continued 
0 0 
I1 
C- -8 5 
10 
IS 
20 
25 
30 
3s 
40 
and wherein n is an integer between 4 and 100. 
radical of the structure: 
2. The polyimidazole of claim 1, wherein Ar is a 
45 
Y N  
N 
R 
so 
and wherein R is a phenyl group. 
3. The polyimidazole of claim 2, wherein X is se- 
lected from the group consisting of: 5s  
0 0 
-c-, --soz-, -c llo!-r 60 I1 
-!Q&jJ 0 0 !-, 
4. The polyimidazole of claim 1, wherein Ar is a 
radical of the structure: 
and wherein Ar' is 1,4phenylene. 
thalo yl. 
structure: 
5. The polyimidazole of claim 4, wherein X is isoph- 
6. A di(hydroxypheny1)imidazoIe having the general 
HO-@ OH 
wherein the catenation of the hydroxy radicals is se- 
lected from the group consisting of meta meta, para 
para, or para meta; wherein Ar is selected from the 
group consisting: 
17 18 
>=( 
Y NH; 
N 
R 
5,066,811 
(a) 
wherein R is selected from the group consisting of: H, 1o wherein is selected from the group consisting of: 
CF3, CHh CH2CH3, OCH3, 
=@; Z and Z & Z
and wherein G is a bond or is a substituent selected from 
the group consisting of CH2, 0, S, c--O, and S02. 
7. The di(hydroxypheny1)imidazole of claim 6, 
25 wherein Ar has the general structure: 
and wherein R is a phenyl group. 
wherein Ar has the general structure: 
35 8. The di(hydroxypheny1)imidazole of claim 6, 
wherein Z is a radical selected from the group consist- 
ing of: CF3, F, C1, Br, I, CH3, OCH3, CH2CH3, NO2, 
and Ph; and 
45 and wherein Ar' is l&phenylene. * * * * *  
50 
55 
60 
65 


Polyimidazoles via aromatic nucleophilic displacement

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