Heterocyclic monomers via reissert chemistry

Article abstract of DOI:10.1002/pola.24821

An AA bisphenolic monomer (13), an AB activated fluoro-phenolic monomer (14), and an AB₂ alcohol-diester monomer precursor (17), all based on the isoquinoline nucleus, were prepared using Reissert compound chemistry. Additionally, model reactio

Full text of DOI:10.1002/pola.24821

Heterocyclic Monomers via Reissert Chemistry
HARRY W. GIBSON, MELVIN L. RASCO,* ZHENBIN NIU
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061-0212
Received 22 April 2011; accepted 30 May 2011
DOI: 10.1002/pola.24821
Published online 28 June 2011 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: An AA bisphenolic monomer (13), an AB activated
fluoro-phenolic monomer (14), and an AB2 alcohol-diester
monomer precursor (17), all based on the isoquinoline nucleus,
were prepared using Reissert compound chemistry. Addition-
ally, model reactions established the efficiency of condensation
of isoquinoline Reissert compounds with dihaloalkanes, pro-
viding evidence of the potential of this reaction to produce
high molecular weight polymers, which was subsequently real-
C
V
ized.
2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym
Chem 49: 3842–3851, 2011
KEYWORDS: heteroatom-containing polymers; isoquinoline; poly-
condensation; poly(ether ketones); poly(ether sulfones); Reissert
compounds
as pyridine, quinoline, benzimidazole, and phenanthridine,
formally add an acyl cyanide across a carbon–nitrogen dou-
ble bond to produce these derivatives.8 Reissert compounds
can be prepared by several protocols.7,9–11 The isoquinoline
Reissert compounds, 1 (Scheme 1), are the most studied
cases.
INTRODUCTION
Nitrogen-Containing Polymers
Nitrogen-containing polymers are a special class of materials
that exhibit useful features. Polyamides1(a) and polyimides1(b,c)
are useful in a variety of applications. Quaternary salt poly-
mers are used as anion exchange resins, coatings, adhesives,
ion conductors and in water treatment and coagulation.2 Aro-
matic nitrogen-containing polymers, such as polyimides,1(c)
polyquinoxalines, polyquinolines, polybenzimidazoles, poly-
benzothiazoles, and polybenzoxazoles, exhibit excellent
thermo-oxidative stability and retain useful mechanical prop-
erties at elevated temperatures for extended times.3
The acidic proton alpha to the cyano group in Reissert com-
pounds governs much of their chemistry.8 Reissert anions react
with aldehydes to form esters 2 via an intramolecular rear-
rangement driven by rearomatization (Scheme 1).8,12 Hydroly-
sis of the esters affords the corresponding secondary alcohols
3. This condensation process can be carried out with phenyl-
lithium in ether-dioxane,8,12(a–c) with sodium hydride in dime-
thylformamide12(d,e) or under phase transfer conditions with
50% sodium hydroxide/acetonitrile; in the latter case, mixtures
of the ester (2) and alcohol (3) or one of them exclusively
result, depending on the reaction time and temperature.13,14
Of the engineering thermoplastics poly(arylene ether)s, both
ketones4 and sulfones,5 are an outstanding family of materials
that display excellent mechanical performance coupled with
good thermal stability and heat resistance to loss of proper-
ties. Poly(arylene ether ketone)s are usually crystalline and
thus are resistant to solvent attack; this makes them ideal for
aerospace applications. They possess high moduli, are tough
and wear resistant, and display low flammability. Tgs for poly
The anions react with alkyl halides, forming 1-alkyl deriva-
tives 4, whose basic hydrolysis affords 1-alkylisoquinolines
(5) through rearomatization (Scheme 2).8,12(d),15,16 An intra-
molecular rearrangement in the absence of an electrophile
converts the Reissert anion into ketone 6.8,12(d),15 The tend-
ency to undergo rearrangement versus alkylation depends
on the nature of the acyl group (Scheme 3).16
ꢀ
(ether ketone)s range from 100 to 200 C and Tms from 300
to >400 ꢀC. They can be processed at temperatures as high
ꢀ
as 400 C because of their excellent thermo-oxidative stability,
ꢀ
and use temperatures can exceed 200 C. However, in spite of
the importance of heterocyclic polymers aforenoted, only a
few examples of poly(arylene ether)s incorporating aromatic
heterocyclic moieties have been reported.6
RESULTS AND DISCUSSION
In view of the impressive properties of poly(arylene ether)s
on the one hand and N-heterocyclic polymers on the other, the
combination of these two classes of materials via Reissert
compound chemistry was the objective of the work
reported herein. This effort constituted a continuation of our
Reissert Compounds
Reissert compounds, a-(acylamino)nitriles, were discovered
in 1905 by Reissert.7 Various nitrogen heterocycles, such
*Present address: Dow Chemical Company, Freeport, Texas 77541.
Correspondence to: H. W. Gibson (E-mail: hwgibson@vt.edu)
C
V
Journal of Polymer Science Part A: Polymer Chemistry, Vol. 49, 3842–3851 (2011) 2011 Wiley Periodicals, Inc.
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ARTICLE
SCHEME 1 Formation of the anion of an isoquinoline Reissert compound 1 and its reaction with an aldehyde to form the ester 2,
which can undergo hydrolysis to the alcohol 3.
applications of Reissert compounds in polymer chemis-
try12(e,f),12(e),17–19 in addition to our interest in the stereo-
chemistry of these compounds.20
chromate) worked well for oxidation of the alcohol moiety,
but the presence of the methylene signals at 5.2 ppm in the
NMR spectrum of the product indicated that the benzylic
methylene moiety was not oxidized. However, the use of man-
ganese dioxide (MnO2) in refluxing benzene with a Dean–
Stark trap22 provided good yields of the diketones 11 (92%)
and 12 (78%) from 9 and 10, respectively (Scheme 4).
Difunctional Isoquinoline Monomers
Activated Fluoroketone Phenol (AB) and Bisphenol (AA)
Monomers
The initial target functionalities were activated fluoroketone
phenol and diphenolic monomers for poly(ether ketone)s4 and
poly(ether sulfone)s.5 The first step involved the synthesis of 4-
substituted isoquinolines. This reaction followed the method
reported21 by Minter and Re as adapted by us earlier.22 p-Ben-
zyloxybenzaldehyde23 on reaction with isoquinoline yielded
the corresponding 4-substituted isoquinoline product 7 in
quantitative yield (Scheme 4). Formation of the Reissert com-
pound 8 from this 4-substituted isoquinoline via the methylene
chloride/water two-phase method proceeded in a yield of 89%.
The last step in the heteroarylene ether monomer synthesis
was deprotection of the benzyl ethers. Refluxing the dibenzyl
ether 11 in HBr/acetic acid afforded the bisphenol 13 in
quantitative yield. Similar treatment of the fluoro-benzyl
ether 12 in HCl solution yielded AB monomer 14 in 96%
yield (Scheme 4).
AB2 Monomer Containing Two Carboxylic Acid Moieties
and an Alcohol Moiety
Methyl p-formylbenzoate on reaction with isoquinoline yielded
the corresponding 4-substituted isoquinoline product 15 in an
unoptimized yield of 40% (Scheme 5). Formation of the Reis-
sert compound 16 from this 4-substituted isoquinoline via the
methylene chloride/water two-phase method proceeded in an
85% yield. The 4-(p-carbomethoxy) Reissert compound 16
using the NaH/N,N-dimethylformamide (DMF) protocol in the
condensation reaction with methyl p-formylbenzoate yielded
ester 17 in 77% yield. Compound 17 can be hydrolyzed to
give the dicarboxy alcohol compound 18, an AB2 type mono-
mer for formation of hyperbranched heterocyclic polyesters.
This next step in the arylene monomer synthesis was con-
densation of the Reissert compound with aldehydes to yield
the secondary alcohols. Reactions of 8 with p-benzyloxyben-
zaldehyde and p-fluorobenzaldehyde yielded the expected
alcohols 9 (100%) and 10 (91%), respectively, by condensa-
tion in 50% NaOH (Scheme 4).
Concomitant oxidation of the benzylic alcohols and the meth-
ylene units to carbonyls was carried out to make the resulting
polymers more rigid along the backbone and remove the la-
bile benzylic hydrogens, and in the fluoro compound activate
it toward nucleophilic aromatic substitution. Sodium dichro-
mate in refluxing glacial acetic acid (i.e., pyridinium chloro-
Other AA and AB Monomers
Here, it is appropriate to point out that the carboxy phenol
(AB) monomer 21 could be readily prepared in high yield
SCHEME 2 Reaction of the anion of an isoquinoline Reissert
compound with an alkyl halide to form 4, which can be hydro-
lyzed under basic conditions to a 1-substituted isoquinoline 5.
SCHEME 3 Rearrangement of an isoquinoline Reissert anion to
a 1-acylisoquinoline 6.
HETEROCYCLIC MONOMERS VIA REISSERT CHEMISTRY, GIBSON, RASCO, AND NIU
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
kylation of the isoquinoline Reissert compound 1, R ¼ C6H5
with butyl halides was examined using the NaH/DMF
method to form the 1-butylated Reissert compound (4, R ¼
C6H5, R0 ¼ n-C4H9; Scheme 2). This compound had been
made previously, but by using a large excess of the butyl hal-
ide.12(d) Because step-growth polymerizations are carried out
at exactly 1:1 stoichiometry, this study was essential to
determine whether a quantitative yield could be obtained at
this stoichiometry, thus insuring a high degree of polymer-
ization (DP) according to the Carrothers equation: DP ¼ 1/
(1 ꢁ p), in which p is the fraction of conversion to the
desired product. The first exercise was to determine the best
halide to use. The bromide gave the highest yield (99.5%) in
2 h. Butyl chloride reacted slowly in this time frame (2 h)
and the product was very crude, probably contaminated
with the rearrangement product, 1-benzoylisoquinoline (6, R
¼ C6H5), as a result of the competitive rearrangement pro-
cess; the yield was 59%. Butyl iodide reacted much faster
(30 min) than the other two compounds, but there was a
low yield (68%), probably due to elimination promoted by
the basic conditions.
Model Studies: Monofunctional Reissert Compound with
Difunctional Alkyl Halide
SCHEME 4 Synthesis of AA monomer 13 and AB monomer 14.
Isoquinoline is converted to the 4-benzyl derivative 8, which is
converted to the Reissert compound 9. Via its anion, compound
9 is converted to the alcohols 9 and 10 by condensations with p-
benzyloxybenzaldehyde and p-fluorobenzaldehyde, respec-
tively. Oxidations of 9 and 10 lead to the diketones 11 and 12,
whose deprotection affords 13 and 14, respectively.
Next in the model study was the reaction of 2 equiv of the
isoquinoline Reissert compound 1, R ¼ C6H5 with an alkyl-
ene dibromide, in this case 1,10-dibromodecane. If the
resulting dimer 24 could be formed in 100% yield, it could
be safely assumed that the condensation of dihaloalkanes
with bis(Reissert compound)s is, in general, a feasible poly-
merization protocol. The reaction, in fact, did proceed to
afford a quantitative yield of the dimer 24 (Scheme 7).
from Reissert compound 16 and p-benzyloxybenzyl chloride
via intermediates 19 and 20 (Scheme 6), in the manner of
conversion of 1 to 5. Similarly, by the reaction of the anion
of Reissert compound 16 with methyl p-bromomethylben-
zoate, diacid (AA) monomer 23 can be readily accessed via
intermediate 22.
Preliminary Polymerization Results
The polymerization of bis(Reissert compound) 2517(a) with
1,10-dibromodecane was performed by the NaH/DMF
method (Scheme 8). The rather rigid bis(Reissert compound)
was not very soluble, requiring 15 mL of DMF per gram. It
was postulated that maybe as the anion formed, it would
become soluble, thereby enabling the bis(Reissert com-
pound) to totally dissolve over a period of time. However,
this was not the case: throughout the polymerization reac-
tion, the bis(Reissert compound) could be seen floating in
solution. After workup, low molecular weight polymer 26
was obtained (Table 1). The low molecular weight was
Preliminary Studies of Efficiency of Reissert Reactions
for Polymerization
Model Studies: Monofunctional Reissert Compound with
Monofunctional Alkyl Halides
To determine if the polymerization of bis(Reissert com-
pound)s with dihaloalkanes via the anions was feasible, al-
SCHEME 5 Synthesis of AB2 monomer 18. Isoquinoline is converted to the 4-benzyl derivative 15, which is converted to the Reis-
sert compound 16. Via its anion, compound 16 is converted to the ester 17 by condensation with p-carbomethoxybenzaldehyde.
Hydrolysis of 17 will produce 18.
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SCHEME 6 Proposed syntheses of AB monomer 21 and AA monomer 23. Reissert compound 16 via its anion is reacted with p-
benzyloxybenzyl chloride to form 19, whose basic hydrolysis will produce 20. The latter on deprotection will yield 21. Reaction of
16 with p-carbomethoxybenzyl bromide will produce diester 22, which on basic hydrolysis and acidification will afford 23.
attributed to the insolubility of starting monomer in DMF
and the resultant stoichiometric imbalance in solution.
hydes produced polyester 33c with high molecular weight
(Table 1), substantiating the fact that the o-toluyl derivative
is significantly less prone to rearrange than the benzoyl ana-
log.19 Indeed, the benzoyl analog 27 produced polymers 33a
and 33b of lower molecular weight because of the competi-
tive rearrangement process; in fact, the initially isolated sam-
ple of 33a exhibited a very broad molecular weight distribu-
tion (MWD, Table 1), presumably because the rearrangement
destroyed the reactive anionic end group and replaced it
with the unreactive phenyl ketone moiety, as illustrated in
structure 34 (Scheme 12), and upset the stoichiometric bal-
ance of the monomers. Fractionation did produce a sample
with a reasonable MWD (Table 1).
Polymerization of the more flexible and hence more soluble
(CH2)10 bis(Reissert compound) 2717(a) with 1,10-dibromo-
decane and 1,5-dibromopentane also led to polymers 28
with low intrinsic viscosities (Scheme 9, Table 1). The n ¼
10 polymer 28a did show promise with its intrinsic viscosity
of 0.109 g/dL, but the low molecular weights of 28a and
28b were further evidenced by the brittle nature of their
films cast onto Teflon from chloroform solution.
The most probable reason for the low molecular weights of
28a and 28b is rearrangement of the Reissert anion. Mono-
meric benzoyl Reissert compounds are known to rearrange
(Scheme 3) and sometimes this rearrangement reaction is
preferred over alkylation.16 Thus, the rearrangement could
be expected in the polymerization reactions of the bis(Reis-
sert compound)s with dihaloalkanes, especially as the sub-
strates are consumed and the rate of alkylation slows, and
this would alter the stoichiometry and lead to low molecular
weight.
CONCLUSIONS
Through the chemistry of Reissert compounds several new
heterocyclic monomers and monomer precursors were pre-
pared. These new monomers will be useful for the synthesis
of heterocyclic poly(arylene ether ketone)s, poly(arylene
ether sulfone)s, aromatic polyesters, and other polymers.
These studies demonstrate that the versatile chemistry of
Reissert compounds provides efficient syntheses of heterocy-
clic monomers for production of novel new polymers.
We previously found that isoquinoline Reissert compound
1, R ¼ C6H5 had a strong tendency to rearrange rather
than alkylate, whereas the Reissert compound 29 from
ortho toluyl chloride was alkylated in good yield.16 In fact,
even in the absence of an electrophile, the anion from the
o-toluyl Reissert compound 29 did not rearrange. In this
study, the reaction of the o-toluyl Reissert compound 29
with n-butyl bromide at exactly 1:1 stoichiometry afforded
a quantitative yield of the expected product 30 (Scheme
10). Condensation of 29 with 1,5-dibromopentane at exactly
EXPERIMENTAL
General
Dichloromethane was obtained from Fisher Scientific and
dried over molecular sieves before use. DMF was distilled
from calcium hydride and tetrahydrofuran (THF) from so-
dium/benzophenone before use. Sodium hydride was used
as 60 or 80% dispersion in mineral oil as obtained from
Aldrich Chemicals. All other solvents were used as received
from the vendor. Melting points were determined in a Mel-
temp II melting point apparatus and are corrected. NMR
spectra were recorded on a Bruker 270 MHz instrument, a
1:1 stoichiometry afforded
a quantitative yield of the
expected product 31.
Subsequently, the use of 4,40-coupled o-toluyl bis(Reissert
compound) 32 (Scheme 11) in polymerization with dialde-
SCHEME 7 Reaction of 1,10-
dibromodecane with the anion
of Reissert compound
1
to
form 24.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
SCHEME 8 Polymerization of bis(Reissert compound) 25 with 1,10-dibromodecane, leading to polymer 26.
400-MHz Varian Unity or a JEOL Eclipse 500 MHz machine
using tetramethylsilane as an internal standard; the follow-
ing abbreviations are used: b, broad; s, singlet; d, doublet; m,
multiplet; t, triplet; ArH, aromatic hydrogen. FTIR spectra
were recorded on a Nicolet MX-I with KBr pellets or films on
salt plates. Thermogravimetric analysis (TGA) was done on a
Perkin–Elmer 7700 Thermal Analysis System. Differential
scanning calorimetry (DSC) was performed on a DuPont
2100 Dual-Sample machine at l0 ꢀC/min. Gel permeation
chromatography (GPC) was carried out in THF using either a
Waters 150-C equipped with a Viscotek 100 viscometric de-
tector to provide absolute molecular weights via the univer-
sal calibration or a Waters Model 590 using a refractive
index detector and calibration with polystyrene standards.
Mass spectra of compounds 13 and 14 were acquired on an
in-house Agilent 6220 Accurate Mass TOF LC/MS Spectrome-
ter. Elemental analyses were performed by Atlantic Microlab,
Norcross, GA.
ether, which was dried over Na2SO4 and evaporated to yield
47 g (100%) of crude producꢀt which was recrystallized from
ethanol–water, mp 93.5–96.0 C.
1H NMR (270 MHz, CDCl3): d 4.33, s, 2H, ArCH2; 5.00, s, 2H,
OCH2; 6.85, d (J ¼ 8), 2H, ArH; 7.14, d (J ¼ 8), 2H, ArH; 7.2–
7.7, m, 7H, ArH; 7.92, d (J ¼ 8), 1H, H5; 7.98, d (J ¼ 8), 1H,
H8; 8.40, s, 1H, H3; 9.18, s, 1H, H1. ELEM. ANAL, Calcd for
C23H19NO: C, 84.89; H, 5.89; N, 4.30. Found: C, 84.91; H,
5.92.
2-Benzoyl-4-(p-benzyloxybenzyl)-1,2-dihydroisoquinaldo-
nitrile (8)
To a three-necked round-bottomed flask fitted with a me-
chanical stirrer, dropping funnel, and N2 inlet containing a
mixture of 4-(p-benzyloxybenzyl)isoquinoline (7, 15.67 g, 50
mmol), 9.77 g (150 mmol) of KCN in 30 mL of water and
100 mL CH2Cl2 was added benzoyl chloride (11.6 mL, 100
mmol) over 2 h; vigorous stirring was continued for 9 h, af-
ter which water (100 mL) was added and stirring continued
for 2 h. The organic phase was washed 3ꢂ with water, 2ꢂ
with 5% NaOH, 1ꢂ with satd. NaHCO3, 3ꢂ with water, 3ꢂ
with 10% HCl, and 3ꢂ with water, dried over Na2SO4 and
evaporated. The crude product (20.3 g, 89%) was recrystal-
4-(p-Benzyloxybenzyl)isoquinoline (7)
A solution of 19.37 g (150 mmol) of isoquinoline, 152 mL
(152 mmol) of 1.0 M NaBEt3H in THF was stirred for 30
min under N2. After p-benzyloxybenzaldehyde23 (32.26 g,
152 mmol) was added, the mixture was stirred for 4 h,
cooled to 0 ꢀC and quenched with 320 mL of 0.5 N NaOH
and 160 mL of 30% H2O2, both added dropwise in sequence.
The resulting mixture was stirred for 3 h, poured into 2 L of
water and stirred overnight. The product was extracted with
ꢀ
lized from ethanol: mp 172.5–174.0 C.
FTIR: amide C¼¼O at 1668.9 cm-1. 1H NMR (270 MHz,
CDCl3): d 3.75, AB q (J ¼ 14), 2H, ArCH2; 5.0, s, 2H, OCH2;
6.4, bs, 1H, H3; 6.55, bs, 1H, H1; 6.85, d (J ¼ 8), 2H, ArH;
TABLE 1 Characterization of Polymers from Reissert Compounds
a
a
Polymer
[g] (dL/g, CHCl3)
Mn (kDa)
Mw (kDa)
Tg (ꢀC)
TGA5% loss (ꢀC, Air)
26
–
3.2
12
123
72
225
198
225
200
28a
28b
33a19
0.109
0.053
0.30
0.36b
0.31
0.60
–
–
–
–
103
93
(1.2)
(31.0)c
(4.1)
22.4
(40.0)
(69.0)c
(35.4)
54.7
33b19
33c19
a
79
87
260
225
Values without parentheses are based on GPC using polystyrene
standards. Values in parentheses (xx) are absolute molecular weights
determined by GPC with an in-line viscometer and the universal
calibration.
33d derived therefrom possessed a tensile strength of 38 MPa and a
maximum strain of 6%.
c
After fractionation of the original sample by two reprecipitations from
CHCl3 solution by the addition of CH3OH.
b
A film of this sample of 33a cast from chloroform displayed a tensile
strength of 13 MPa and a maximum strain of 3%, whereas the polyol
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ARTICLE
SCHEME 9 Polymerization of bis(Reissert compound) 27 with 1,10-dibromodecane and 1,5-dibromopentane, leading to polymers
28a and 28b, respectively.
7.15, d (J ¼ 8), 2H, ArH; 7.2–7.7, m, 14H, ArH. ELEM. ANAL,
Calcd for C31H24N2O2: C, 81.56; H, 5.30; N, 6.14. Found: C,
81.62; H, 5.34.
1-[4-(p-Benzyloxybenzyl)isoquinolyl] p-Fluorophenyl
Carbinol (10)
This compound was analogously prepared from Reissert
compound 8 and p-fluorobenzaldehyde: 91%, mp 157.0–
-1
1
ꢀ
159.0 C (ethanol). FTIR: OH at 3400 cm , no C¼¼O. H NMR
(270 MHz, CDCl3): d 4.35, s, ArCH2; 5.02, s, 2H, OCH2; 6.2, s,
1H, OH; 6.35, s, 1H, CHO; 6.9–7.5, m, 13H, ArH; 7.61, t (J ¼
8), 1H, H6; 7.92 d, (J ¼ 8), 1H, H5; 7.97, d (J ¼ 8), 2H, H8;
8.40, s, 1H, H3. ELEM. ANAL, Calcd for C30H24FNO3: C, 80.16; H,
5.38; F, 4.23; N, 3.12. Found: C, 79.89; H, 5.38; N, 3.19.
1-[4-(p-Benzyloxybenzyl)isoquinolyl] p-Benzyloxyphenyl
Carbinol (9)
A mixture of 8.70 g (19 mmol) of Reissert compound 8, p-
benzyloxybenzaldehyde23 (4.4 g, 21 mmol) and a catalytic
amount (0.12 g) of triethylbenzylammonium chloride in ace-
tonitrile (100 mL) was stirred for 30 min at room tempera-
ture. A heat gun was used to keep the Reissert compound in
solution. Then, 800 mL of 50% NaOH was added and stirring
was continued for 45 min. The mixture was allowed to reflux
for 30 min, during which time it became viscous and yellow.
Water (500 mL) was added and the precipitate was filtered,
dried and purified by recrystallization from ethanol: 10.2 g,
Oxidation of Alcohols to Diketones: 11 and 12
A mixture of the alcohol (9 or 10, 5 g), 150 mL of benzene,
and 50 g of MnO2 was allowed to reflux for 2 days using a
Dean–Stark trap. The mixture was filtered through Celite and
the Celite was washed with chloroform. The MnO2/Celite
was Soxhlet extracted for 4 days with CHCl3. The combined
extract was dried over Na2SO4 and evaporated to yield the
product, which was recrystallized from ethanol.
ꢀ
100%, mp 190.5–192.5 C.
1
FTIR: OH at 3400 cm-1, no C¼¼O. H NMR (270 MHz, CDCl3):
d 4.35, s, 2H, ArCH2; 5.00, 2s, 4H, OCH2; 6.31, s, 1H, OH; 6.9,
m, 4H, ArH; 7.0–7.7, m, 16H; 7.96, bd (J ¼ 8), 2H, H8; 8.4, s,
1H, H3. ELEM. ANAL, Calcd for C37H31NO3: C, 82.66; H, 5.81; N,
2.61. Found: C, 82.57; H, 5.88; N, 2.56.
1,4-Bis(p-benzyloxybenzoyl)isoquinoline (11)
Yield 92%, mp 152.5–155.0 ꢀC. FTIR: C¼¼O at 1655.6 cm-1.
1H NMR (270 MHz, CDCl3): d 5.15, s, 4H, OCH2; 7.0–7.1, m,
SCHEME 10 Reaction of o-toluyl Reissert compound 29 with n-butyl bromide and 1,5-dibromopentane, leading to 30 and 31,
respectively.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
SCHEME 11 Polymers produced from bis(Reissert compound)s by condensation with dialdehydes. Bis(o-toluyl Reissert compound)
32 produced high molecular weight polymer 33c (Table 1).
4H, ArH; 7.4–7.6, m, 4H, ArH; 7.65, t (J ¼ 8), 1H, H7; 7.73,
t (J ¼ 8), 1H, H6; 7.85–8.00, m, 4H, ArH; 8.05, d (J ¼ 8), 1H,
H5; 8.18, d (J ¼ 8), 1H, H8: 8.65, s, 1H, H3. ELEM. ANAL, Calcd
for C37H27NO4: C, 80.86; H, 4.95; N, 2.55. Found: C, 80.81; H,
4.97; N, 2.51.
refluxed for another 4 h. After the bright yellow solution had
cooled, NH4OH was added until pH ¼ 8, causing fine powder
to precipitate. The resulting suspension was extracted with
CH2Cl2 twice. The organic phase was washed with DI water
(3ꢂ). A silica gel column was used to purify the crude prod-
uct (CH2Cl2/MeOH ¼ 98/2, v/v) and pale yellow solid was
ꢀ
1-(p-Fluorobenzoyl)-4-(p-benzyloxybenzoyl)isoquinoline
(12)
obtained (161 mg, 96%), mp: 98.1–100.0 C.
1H NMR (CDCl3, 400 MHz): d 6.88, d (J ¼ 7.6 Hz), 2H, ArH
ortho to OH; 6.98, bs, 1H, OH; 7.17, t (J ¼ 8.6 Hz), 2H, ArH
ortho to F; 7.69, dd (J ¼ 8.4, 1.2 Hz), 1H, H5; 7.85–7.76, m,
3H, ArH; 8.04, m, 2H, ArH; 8.12, d (J ¼ 8.5 Hz), 1H, ArH;
8.20, d (J ¼ 8.5 Hz), 1H, H8; 8.60, s, 1H, H3. 13C NMR
(DMSO-d6, 100 MHz): d 115.8, 116.0, 116.2, 125.44, 126.2,
126.6, 129.1, 130.2, 132.3, 132.5, 132.5, 133.3, 133.6, 133.7,
134.8, 140.8, 158.2, 161.7, 165.6, 167.6, 192.8, 193.9 (theor.
19 C, found 23 C; four extra aromatic signals attributed to
the presence of the phenolate anion in the polar solvent).
HR-ESIMS: Calcd for [M þ H]þ: 372.1036, found m/z,
372.1062 [M þ Hþ], error: 6.9 ppm.
Yield 78%, mp 139.0–140.0 ꢀC. IR: C¼¼O at 1648.4 and 1668.9
cm-1. 1H NMR (270 MHz, CDCl3): d 5.2, s, 2H, OCH2; 7.05–7.95,
m, 13H, ArH; 8.0–8.1, m, 3H, ArH; 8.25, d (J ¼ 8), 1H, H8; 8.65,
s, 1H, H3. ELEM. ANAL Calcd for C30H20FNO3: C, 78.08; H, 4.37; F,
4.12; N, 3.04. Found: C, 77.67; H, 4.35; N, 2.99.
1,4-Bis(p-hydroxybenzoyl)isoquinoline (13)
HBr gas was bubbled through glacial acetic acid for 1 h.
Then, 1.00 g (1.82 mmol) of the benzyl ether 11 was stirred
into 15 mL of this reddish solution and a homogeneous solu-
tion resulted. After 15 min, solid (the salt) precipitated out
of the solution. On refluxing, this solid went back into solu-
tion and after refluxing for 1 h another solid precipitated
from solution. The reaction was stopped and the mixture
was poured into water. The solution was made just basic
(pH ¼ 8) with NH4OH and CaCO3 and filtered, yielding 0.67
g (100%) of crude product. The solid was boiled in deinon-
ized ꢀ(DI) water and collected by filtration (83%), mp: 155–
157 C.
4-(p-Carbomethoxybenzyl)isoquinoline (15)
This compound was synthesized from methyl p-formylben-
zoate and isoquinolineꢀby the procedure aforeoutlined for 7:
40%, mp 108.5–111.0 C (hexane–ethyl acetate).
FTIR: C¼¼O at 1716.8 cm-1. 1H NMR (270 MHz, CDCl3): d
3.90, s, 3H, CH3; 4.45, s, 2H, CH2; 7.25, d (J ¼ 8), 2H, ArH;
FTIR: broad OH at 3300 cm-1, C¼¼O at 1674 cm-1. 1H NMR
(CDCl3, 500 MHz): d 6.85–6.90, m, 4H, ArH; 7.64–7.67, m,
6H, ArH; 8.09, d (J ¼ 8 Hz), 1H, H5; 8.12, d (J ¼ 8 Hz), 1H,
H8; 8.62, s, 1H, H3. 13C NMR (DMSO-d6, 125 MHz): d 116.0,
116.1, 125.2, 125.3, 126.5, 127.6, 128.9, 129.2, 131.7, 132.4,
133.4, 133.6, 133.9, 140.7, 159.4, 163.7, 163.8, 192.8, 193.7
(19 peaks as required). HR-ESIMS: Calcd for [M þ H]þ:
370.1079, found m/z, 370.1103 [M þ Hþ], error: 6.4 ppm.
1-(p-Fluorobenzoyl)-4-(p-hydroxybenzoyl)
isoquinoline (14)
A suspension of dibenzyl ether 12 (209 mg, 0.453 mmol) in
8 mL of HCl (30% aq.) was refluxed for 2 h. The solid did
not dissolve. Acetic acid (5 ml) was added. The mixture was
SCHEME 12 The unreactive end-group moiety (in box) result-
ing from rearrangement of the anion derived from bis(Reissert
compound) 27 in its reaction with dibromoalkanes.
3848
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ARTICLE
7.55–7.70, m, 2H, ArH; 7.8, d (J ¼ 8), 1H, ArH; 7.9–8.05, m,
ArH. ELEM. ANAL, Calcd for C44H42N4O2ꢃ1/3(C4H8O2): C,
79.11%; H, 6.54%; N, 8.14%. Found: C, 78.90%; H, 6.57%;
N, 8.26%.
3H, ArH; 8.45, s, 1H, H1; 9.20, s, 1H, H3. ELEM. ANAL, Calcd for
C18H15NO2: C, 77.96; H, 5.45; N, 5.05. Found: C, 77.79; H,
5.48.
Polymer 26 from Bis(Reissert Compound) 25 with
1,10-Dibromodecane
2-Benzoyl-4-(p-carbomethoxybenzyl)-1,2-
dihydroisoquinaldonitrile (16)
To a 50 mL two-necked round bottom flask fitted with an N2
inlet and outlet, 1.0000 g (1.606 mmol) of the bis(Reissert
compound) 2517(a) and 15 mL of dry DMF (distilled from
CaH2 and stored over molecular sieves) were added. The
Reissert compound was insoluble but the mixture was
This Reissert compound was prepared from 15 in a manner
analogous to that used to prepare 8: 85%, mp 145.0–146.0
ꢀC (hexane–ethyl acetate). FTIR: amide C¼¼O at 1668.9 cm-1;
ester C¼¼O at 1716.8 cm-1. 1H NMR (270 MHz, CDCl3): d
3.85, s, 3H, CH3; 3.75–3.95, AB q (J ¼ 14), 2H, ArCH2; 6.5,
bs, 1H, H1; 6.6, bs, 1H, H3; 7.25–7.7, m, 11H, ArH; 7.9–8.0, m,
2H, ArH. ELEM. ANAL, Calcd for C26H20N2O3: C, 76.45; H, 4.94;
N, 6.86. Found: C, 76.34; H, 4.99.
ꢀ
stirred at 0 C for 15 min, at which time NaH (0.135 g, 60%
dispersion, 35 mmol) was added. The solution immediately
turned dark red. After stirring for 10 min, dibromodecane
(0.495 g, 16 mmol) was added with the aid of 2 mL of DMF.
After stirring under N2 for 3 days, the mixture was precipi-
tated into water; the solid was dissolved in DMF and precipi-
tated into methanol: 1.233 g (100%) of white powder. 1H
NMR (270 MHz, CDCl3) demonstrated the disappearance of
the acidic proton at 6.2 ppm and FTIR showed the amide
carbonyl at 1662.1 cm-1. GPC: Mn ¼ 3.2 kDa, Mw ¼ 12 kDa.
1-[4-(p-Carbomethoxybenzyl)isoquinolyl]
p-(Carbomethoxy)phenyl Carbinyl Benzoate (17)
To a solution of 2.25 g (5.5 mmol) of Reissert compound 16
in 25 mL DMF at 0 ꢀC, 0.175 g (5.8 mmol) of 80% disper-
sion of NaH was added. The solution immediately became
red and after 10 min, 0.90 g (5.5 mmol) of p-carbomethoxy-
benzaldehyde was added. The solution was stirred at 0 ꢀC
for 4 h and poured into water. The product was extracted
with chloroform; the extract was dried over MgSO4 and
evaporated to yield yellow oil, 2.55 g (77%), which crystal-
lized on standing and was recrystallized from ethanol as off-
ꢀ
ꢀ
DSC: Tg ¼ 123 C. TGA: stable to 225 C in air.
Polymers 28a and 28b from Bis(Reissert Compound)
27 and Dihaloalkanes
The C10 bis(Reissert compound) 2717(a) (0.8711 g, 1.000
mmol) was dissolved in 8 mL DMF at 0 ꢀC under N2. Then,
the dibromoalkane (1.000 mmol) was added and the mixture
was stirred for 30 min, at which time NaH (0.096 g of 60%
dispersion, 2.4 mmol) was added. The solution immediately
became viscous and dark red. Stirring was continued for 24–
72 h, at which time the brownish mixture was precipitated
into water. The solid was collected and precipitated twice
into methanol from DMF using a blender. The polymer was
dried in a drying pistol. Compound 28a: 73% yield (some
ꢀ
white solid, mp 177–180 C.
FTIR: ester C¼¼O at 1723.6 cm-1. H NMR (270 MHz, CDCl3):
1
d 3.88, s, 3H, CH3; 3.89, s, 3H, CH3; 4.43, s, 2H, CH2; 7.4–
8.95, m, 19H, ArH and Ar2CHO. ELEM. ANAL, Calcd for
C34H27NO6: C, 74.85; H, 4.99; N, 2.57. Found: C, 74.42; H,
5.17; N, 2.52.
1-Butyl-2-benzoyl-1,2-dihydroisoquinaldonitrile
(4: R 5 C6H5, R0 5 n-Bu)
ꢀ
spillage), [g] ¼ 0.109 dL/g (CHCl3, 25 C). DSC: Tg ¼ 72 ꢀC.
1
ꢀ
To a stirred solution of isoquinoline Reissert compound 1, R
¼ C6H5 (2.6030 g, 0.01 mol) in 40 mL of dry DMF at 0 ꢀC,
the butyl halide (0.01 mol) was added. After 10 min, NaH
(0.4 g of 60% dispersion, 0.01 mol) was added and stirring
was continued. When the mixture became clear yellow, it
was poured onto cracked ice. The product was isolated as
white solid and recrystallized from ethanol, mp 105–107 ꢀC
TGA: 5% wt. loss @ 198 C (in air). H NMR confirmed total
loss of the acidic proton of the Reissert compound at 6.5
ppm. IR: amide carbonyl at 1662.1 cm-1. 28b: 80% yield, [g]
¼ 0.053 dL/g (CHCl3, 25 C). DSC: Tg ¼ 103 C. TGA: 5% wt.
ꢀ
ꢀ
ꢀ
loss @ 225 C (in air).
1-Butyl-2-(o-toluyl)-1,2-dihydroisoquinaldonitrile (30)
To a stirred solution of o-toluyl Reissert compound 2916
(1.000 g, 3.64 mmol) and n-bromobutane (0.4988 g, 3.64
mmol) in 20 mL DMF at 0 ꢀC, NaH (0.1602 g, 60% disper-
sion, 4.00 mmol) was added. The solution immediately
turned dark red; stirring was continued for 4 h. The solution
was poured into 200 mL of water and the resulting white
solid was filtered and dried, 1.22 g (100%). The product
was purified by passage through a silica gel column with
(lit. 106–107 C12(d)).
ꢀ
Dimer 24 from Isoquinoline Reissert Compound
1, R 5 C6H5 and 1,10-Dibromodecane
To a stirring solution of 1.301 g (5.00 mmol) of Reissert
compound 1, R ¼ C6H5 and 1,10-dibromodecane (0.7502 g,
ꢀ
2.5 mmol) in 15 mL of DMF at 0 C, NaH (0.24 g of 60% dis-
persion, 6.0 mmol) was added. The solution immediately
turned dark red. After stirring overnight at 25 ꢀC, the solu-
tion was poured into 250 mL of water. Filtration yielded
1.657 g (100%) of white solid, a mixture of diastereomers,
ꢀ
hexane–ethyl acetate, mp 85.0–87.0 C.
IR: amide C¼¼O at 1655 cm-1. 1H NMR (270 MHz, CDCl3): d
0.8, m, 3H, CH3; 1.1–1.4, m, 4H, inner CH2; 2.15 and 2.6, m,
2H, diastereotopic CH2; 2.35, s, 3H, CH3; 5.6, d (J ¼ 8), 1H,
H4; 6.3, d (J ¼ 8), 1H, H3; 7.0, t (J ¼ 8), 1H, H6; 7.65, t (J ¼
8), 1H, H7; 7.2–7.4, m, 6H, ArH. ELEM. ANAL, Calcd for
ꢀ
mp 75.0–85.0 C. Purification was done using a silica gel col-
umn and 50/50 hexane/ethyl acetate.
IR: amide carbonyl at 1655 cm-1. NMR (270 MHz, CDCl3): d
0.8–1.4, m, 16H, CH2; 2.25–2.50, m, 4H, diastereotopic CH2;
5.7, d (J ¼ 8), 2H, H4; 6.5, d (J ¼ 8), 2H, H3; 7.1–7.8, m, 18H,
C
22H22N2Oꢃ1/4(C4H8O2): C, 78.38; H, 6.86; N, 7.95. Found: C,
78.56; H, 7.14; N, 7.67.
HETEROCYCLIC MONOMERS VIA REISSERT CHEMISTRY, GIBSON, RASCO, AND NIU
3849

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
193–198; (c) Chan, K. P.; Wang, Y.-F.; Hay, A. S.; Hronowski, X. L.;
Cotter, R. J. Macromolecules 1995, 28, 6705–6717; (d) Bottino, F. A.;
Di Pasquale, G.; Leonardi, N.; Pollicino, A. J Macromol Sci Pure Appl
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Dimer 31 from o-Toluyl Reissert Compound 29 and 1,5-
Dibromopentane
To a solution of o-toluyl Reissert compound 2916 (1.000 g,
3.64 mmol) and dibromopentane (0.4185 g, 1.82 mmol) in
20 mL DMF at 0 ꢀC, NaH (0.1602 g, 60% dispersion, 4.0
mmol) was added. The initially dark red solution was stirred
for 4 h and poured into 200 mL of water; the resulting white
solid was filtered and dried: 1.289 g (100%). Purification
was achieved using a silica gel column (60/40, hexane/ethyl
ꢀ
acetate), mp 95.5–101.5 C (mixture of diastereomers).
1H NMR (270 MHz, CDCl3): d 1.1–1.4, m, 6H; 2.15 and 2.6,
m, 4H, diastereotopic CH2; 2.35, s, 6H, CH3; 5.6, d (J ¼ 8),
2H, H4; 6.2, d (J ¼ 8), 2H, H3; 7.05, t (J ¼ 8), 2H, H6; 7.6, m,
2H, H7; 7.2–7.4, m, 8H, ArH. ELEM. ANAL, Calcd for
7 Reissert, A. Chem Ber 1905, 38, 1603–1614.
8 (a) McEwen, W. E.; Cobb, R. L. Chem Rev 1955, 55,
511–549; (b) Popp, F. D. Adv Heterocyclic Chem 1968, 9,
1–25; (c) Popp, F. D. Adv Heterocyclic Chem 1979, 24,
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John Wiley & Sons: New York, 1982, pp 353–375; (e) Cooney,
J. V. Heterocyclic Chem 1983, 20, 823–837; (f) Duarte, F. F.;
Popp, F. D. Heterocycles 1991, 32, 723–726.
C41H36N4O2: C, 79.84; H, 5.88; N, 9.08. Found: C, 79.65; H,
6.27; N, 8.69.
The authors thank the Donors of the Petroleum Research Fund
administered by the American Chemical Society for support of
this research through grant 19625 AC7. They are grateful to the
National Science Foundation for funds to purchase the Agilent
6220 Accurate Mass TOF LC/MS Spectrometer (CHE-
0722638). They extend their gratitude to T. C. Ward and his stu-
dents for gel permeation chromatography (GPC), DSC, and TGA
determinations.
9 Grosheintz, J. M.; Fischer, H. O. L. J Am Chem Soc 1941, 63,
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