Polymeric phthalates: Potential nonmigratory macromolecular plasticizers

Article abstract of DOI:10.1002/pola.26485

The synthesis of 4-vinyl-1,2-phthalate esters via Suzuki coupling is described, followed by nitroxide-mediated polymerization to prepare short homopolymers (degree of polymerization [DP] = 10-40, polydispersity index [PDI] = 1.1-1.3). Random copolymers with n-butyl acrylate (NBA) were prepared. Copolymers rich in phthalate ester residues of medium lengths (DP = 16-48, PDI = 1.2-1.8) and of shorter lengths (DP = 8-17, PDI = 1.2-1.3) were prepared. Copolymers rich in NBA residues were also prepared (DP = 13-19, PDI = 1.2-1.3). All polymers were oily liquids, with glass transitions temperatures undetected between 75 and -40 °C, indicating these polymeric phthalates hold promise as potential nonmigratory phthalate plasticizers. 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013. Copyright

Full text of DOI:10.1002/pola.26485

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Polymeric Phthalates: Potential Nonmigratory Macromolecular Plasticizers
€
Rebecca Braslau, Friederike Schaffner, Aruna Earla
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064
Correspondence to: R. Braslau (E-mail: rbraslau@ucsc.edu)
Received 14 September 2012; accepted 15 November 2012; published online 18 December 2012
DOI: 10.1002/pola.26485
ABSTRACT: The synthesis of 4-vinyl-1,2-phthalate esters via
Suzuki coupling is described, followed by nitroxide-mediated
polymerization to prepare short homopolymers (degree of
polymerization [DP] ¼ 10–40, polydispersity index [PDI] ¼ 1.1–
1.3). Random copolymers with n-butyl acrylate (NBA) were pre-
pared. Copolymers rich in phthalate ester residues of medium
lengths (DP ¼ 16–48, PDI ¼ 1.2–1.8) and of shorter lengths (DP
¼ 8–17, PDI ¼ 1.2–1.3) were prepared. Copolymers rich in NBA
residues were also prepared (DP ¼ 13–19, PDI ¼ 1.2–1.3). All
polymers were oily liquids, with glass transitions temperatures
undetected between 75 and ꢀ40 ꢁC, indicating these polymeric
phthalates hold promise as potential nonmigratory phthalate
C
V
plasticizers.
2012 Wiley Periodicals, Inc. J. Polym. Sci., Part
A: Polym. Chem. 2013, 51, 1175–1184
KEYWORDS: copolymerization; phthalate; plasticizer; radical
polymerization; synthesis
INTRODUCTION The use of poly(vinyl) chloride (PVC) in
consumer goods is widespread, ranging from applications in
construction materials, floor coverings, toys, food packaging,
medical devices, and blood storage bags. In 2005, phthalates
made up 87% of the 10.4 billion pounds/year (5.2 million
tons/year) of the worldwide plasticizer market.1 PVC is
inherently an inert, durable material, with good resistance to
heat and cold and physical abrasion. However, PVC is brittle,
requiring large amounts of plasticizers to impart flexibility2
and the ability to be processed using molds. The plasticizing
effect is postulated to result from an increase in the free vol-
ume, with a concomitant decrease in the glass transition
temperature. The macroscopic effect of the addition of plasti-
cizers is increased flexibility and workability, a reduced melt
viscosity, and lower elastic modulus.3 Small phthalate plasti-
cizers, most commonly di(2-ethylhexyl) phthalate 1 (DEHP,
Fig. 1, also known as dioctyl phthalate), are absorbed into
PVC to obtain the desired mechanical properties. However,
low molecular weight alkyl phthalate esters can leach out of
flexible PVC, changing the physical properties with age, and
contaminating the environment. Studies on the migration of
low molecular plasticizers and their decomposition products
into food and biological fluids like saliva or blood and the
resulting health risk have raised serious concerns.4–9 For
mammals, rodent studies indicate DEHP is toxic to the liver,
kidney, and testes,10 raising significant concerns about safety
for use in toys and medical applications. Oral and intrave-
nous introduction of phthalate plasticizers into humans is
the most common source of contamination, although the
highly hydrophobic sidechains of DEHP allow this plasticizer
to transverse the skin. Metabolism of DEHP forms endocrine
disrupting chemicals (EDC).11–13 Although the influence of
plasticizers and their metabolism products on human health
is not completely understood, toxicological data indicate that
phthalates may lead to a variety of medical problems, includ-
ing endocrine disruption resulting in decreased sperm count,
developmental abnormalities, and breast cancer. The use of
the phthalate esters DEHP, dibutyl phthalate, and butylbenzyl
phthalate in toys and other child care articles was forbidden
by the European Union in 2005 and was banned by the Con-
sumer Safety Commission in 2009 in the United States for
toys marketed to children younger than 12 years old, and
child care articles for children up to age 3. The use of three
additional phthalate esters: diisononyl phthalate, diisodecyl
phthalate (DIDP), and di-n-octyl phthalate (DnOP) in toys
and childcare products are now strongly restricted.14,15 For
the particular application of blood bags, red blood cells have
been found to survive for longer time intervals in the
presence of DEHP than without this phthalate ester plasti-
cizer.16,17 Thus, the use of DEHP is both advantageous and
deleterious in enhancing the storage stability of blood sam-
ples, while resulting in the leaching of the plasticizer into
the contents, which is then introduced intravenously to
patients. Plasticizers are widely used in medical devices,
food packaging, cosmetics and personal care products,
furnishings, garden hoses, construction materials, toys,
athletic shoes, and car interiors. Thus, there is an ongoing
need for effective ‘‘general purpose’’3 plasticizers that cannot
leach out of consumer products, yet still provide the desired
plasticizing properties.
Additional Supporting Information may be found in the online version of this article.
C
V
2012 Wiley Periodicals, Inc.
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been investigated. These polymeric plasticizers are miscible
with PVC and display reduced migration in comparison to
low molecular plasticizers, while their plasticizing effects are
useful for specific applications.29 The influence of molecular
weight and branching of PBAs on the plasticizer efficiency
and migration aptitude was recently studied by Hakkarainen
and coworker.30–33 A diblock copolymer made of polyethyl-
ene glycol and polycaprolactone has been developed for
manufacturing flexible biomedical supplies.34 The major dis-
advantage of these polyester plasticizers is their susceptibil-
ity toward hydrolysis, which changes their physical proper-
ties with aging and exposure to moisture.
FIGURE 1 DEHP is a widely used traditional small molecule
plasticizer.
Cross-linking PVC using a diamine has been probed to slow
plasticizer migration:18 a decrease in leaching of phthalate
esters was observed, but thermal degradation (most likely
due to enhanced elimination of HCl) was also accelerated.19
Covalent attachment of phthalate esters to PVC is a promis-
ing approach: Reinecke has demonstrated SN2 displacement
of chloride from PVC using the very nucleophilic thiol group
appended to the benzene ring of DEHP to provide nonleach-
able phthalate plasticization.20 Development of this strategy
to achieve solvent-free derivatization would be very attrac-
tive to industrial applications.
Terpolymers prepared by uncontrolled, azobisisobutyronitrile
(AIBN) initiated radical polymerization with various ratios of
maleic anhydride, styrene, and vinyl acetate (and derivatives
obtained by opening the anhydride with alcohols) have been
investigated as polymeric plasticizers.35,36 The plasticizing
results were not optimal: blending with additional additives
has been investigated.37 A terpolymer plasticizer made of
ethylene, vinyl acetate, and carbon monoxide, named
‘‘EVACO,’’ has been developed for food products.25
The inherent degradability of polyesters, leading to lower
molecular weight hydrolysis products makes polyester plasti-
cizers of limited utility. Thus, a nonhydrolyzable polymeric
plasticizer with widespread applicability is desirable. Phthal-
ate esters are benzene rings bearing ortho alkyl ester substi-
tution. As polystryene consists of a robust hydrocarbon chain
bearing pendant benzene rings on every other carbon, the
concept of polymeric phthalates, in which the benzene
groups of polystryene bear ortho alkyl ester substituents,
suggested the development of polymeric phthalates. Thus,
4-vinyl phthalate esters 4 (VPE, Fig. 3) were envisioned as
monomers to prepare polymeric phthalates, which would be
expected to show decreased migratory aptitude out of PVC,
while hopefully imparting plasticization to the bulk material.
Polymeric plasticizers have been investigated and do show
decreased migratory aptitude9 in comparison to small
molecule phthalate plasticizers. Polymeric plasticizers are
characterized as low, medium, or high molecular weight plas-
ticizers, with average molecular weights ranging from 1000
to 10,000. Although the migration resistance improves with
increasing molecular weight, the processability decreases.
Polyesters, such as poly(e-caprolactone) (PCL)
2 and
poly(butylene adipate) (PBA) 3 (Fig. 2), have been investi-
gated as polymeric plasticizers since 1947.21 In 1977, Hub-
bell and Cooper22 reported that PCL is compatible with PVC
in a concentration range of 10–90%, and demonstrated effi-
cient plasticizing properties. In considering the miscibility of
polyester plasticizers with PVC, molecular dynamics simula-
tions by Lee et al.23 indicate that a ratio of three to four
methylene units per ester is a lower limit for miscibility,
while the upper limit is 10–12 methylene units per ester. An
optimal ratio of six methylene units per ester was deter-
mined, which was corroborated by experimental data: the
melting point depression method gave an optimal length of
7, whereas thermodynamic measurements gave an optimal
length of 5, corresponding to PVC/poly(caprolactone) blends.
The plasticizing behavior of polycaprolactone–polycarbon-
ate,24 and commercial elastomers such as poly(ethylene-co-
vinyl acetate-co-carbon monoxide) terpolymers (Elvaloy 741
and Elvaloy 742 developed by DuPont),25,26 poly(1,3-butyl-
The alkyl group of the phthalate esters can be easily manipu-
lated to mimic various phthalate esters used in PVC plastici-
zation. As moderate molecular weight polyester plasticizers
have been found to be optimal, the use of nitroxide-mediated
radical polymerization38,39 (NMRP) was chosen to control
the approximate size of the polymeric phthalates. Use of the
alkoxyamine initiator 5 based on 2,2,5-trimethyl-4-phenyl-3-
azahexane-3-nitroxide (TIPNO)38 enables the facile prepara-
tion of either homopolymers 6, or random copolymers 7
between VPE and acrylates, to ‘‘dilute’’ the phthalate ester
R
ene adipate) (ReoplexV developed by Ciba-Geigy),27 and
28
poly(1,2-propylene glycol adipate) with nano-CaCO3 have
FIGURE 2 Hydrolyzable polyester plasticizers PCL 2 and PBA 3.
FIGURE 3 A VPE, a monomer to prepare poly(vinyl phthalates).
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SCHEME 1 Homo and random copolymers of vinyl phthalate esters.
density in these polymeric phthalates (Scheme 1). As
opposed to the current polyester plasticizers, these
poly(vinylphthalates) are linked together by an all-carbon
polymer backbone: hydrolysis will release only alcohols,
rather than phthalates. Thus, degradation products should
pose no danger of being metabolized to form endocrine dis-
ruptor chemicals.
temperatures were measured using
a
Mettler Toledo
1
DSC822e differential scanning calorimeter. H, 13C and DEPT
NMR spectra of vinyl phthalate ester monomers 10a-e are
available in the Supporting Information.
Preparation of 4-Bromo-phthalic Acid Monosodium Salt 8
Following the general procedure of Sabourin,40 sodium
hydroxide (27.03 g, 675.9 mmol) was dissolved in 224 mL of
deionized H2O; phthalic anhydride (50.00 g, 337.6 mmol)
was added and stirred until all solids had dissolved. Ice-
cooled bromine (18.2 mL, 356 mmol) was added droꢁpwise
while stirring. The reaction mixture was heated at 90 C for
7 h. After cooling, the mixture was allowed to sit at room
temperature overnight: the resulting precipitate was isolated
by filtration and recrystallized41 twice from hot water. The
resulting solid was dissolved in hot water, and the solution
was adjusted to approximately pH ¼ 1.5 by the addition of
concentrated hydrochloric acid, cooled to room temperature,
and extracted with ethyl acetate, dried over MgSO4, and the
solvent removed in vacuo to give 20.2 g (22% yield) of the
monosodium salt of 4-vinyl phthalic acid as a solid.
EXPERIMENTAL
Materials
Phthalic anhydride, bromine, ethanol, isopropanol, isobutanol,
3,3,5-trimethyl-1-hexanol, 2-ethyl-1-hexanol, palladium(II)
acetate, thionylchloride, triphenyl phosphine, trimethyl
borate, vinylmagnesium bromide, and calcium carbonate
were used as received. n-Butyl acrylate (NBA) (99þ%, Acros
Organics) was distilled under vacuum before use. Water was
deionized.
Characterization
NMR spectra were recorded at ambient temperature on a
Varian 500 MHz spectrometer, in CDCl3 as solvent, unless
otherwise noted. Gel permeation chromatography (GPC) was
performed using a Waters apparatus equipped with two
PLgel 5 lm MIXED-D columns (Agilent) and a guard column
(Agilent). Tetrahydrofuran (THF) was used as the eluent at a
flow rate of 0.35 mL/min at ambient temperature. A refrac-
tive index detector was used and the molecular weights
were calibrated against eight linear polystyrene standards
ranging from 370 to 371,100 (Mn [g/mol]). IR spectra were
recorded neat on a Perkin-Elmer spectrometer. Each sample
was prepared by casting a film on a KBr cell. Glass transition
ꢁ
mp > 260 C.
1H NMR (500 MHz, DMSO-d6, d): 8.06 (br s, 1H), 7.88 (br s,
1H), 7.74 (m, 1H).
Preparation of 4-Bromo-phthalic Diacid42
To characterize the above material, a sample of the monoso-
dium salt 8 was dissolved in hot water, and a large excess of
concentrated HCl was added. The volatiles were reduced in
vacuo, and the residue was extracted with acetone. Removal
of the acetone in vacuo provided the diacid.
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43
ꢁ
ꢁ
mp 175 C (lit. mp 176–178 C).
Preparation of 4-Bromo-di(2-ethyl-1-hexyl)-phthalate
Ester47 9d
1H NMR (500 MHz, acetone-d6, d): 11.6 (br s, 2H), 7.91 (d,
J ¼ 2.0 Hz, 1H), 7.84 (dd, J ¼ 2.0, 8.0 Hz, 1H), 7.76 (d, J ¼
8.0 Hz, 1H).
12.3 g (79% yield) of the product was obtained as a slightly
yellow oil.
TLC: 40:1 hexanes/ethyl acetate, UV, Rf: 0.74.
Esterification to form 4-Bromo-dialkyl-phthalate Esters
(Et, iPr, iBu, and 2-ethyl-1-hexyl): The following procedure is
representative.
IR (neat): 2960, 2861, 1732, 1589, 1566, 1463, 1381, 1288,
1125, 1089, 1068, 957, 766 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.81 (d, J ¼ 2 Hz, 1H), 7.68–
7.60 (m, 2H), 4.27–4.18 (m, 4H), 1.74–1.65 (m, 2H), 1.44–
1.31 (m, 16H), 0.95–0.89 (m, 12H).
Preparation of 4-Bromo-diethyl-phthalate Ester44 9a
Following the general procedure of Hosangadi and Dave45
and modified from that of Norman et al.,41 thionyl chloride
(7.3 mL, 101 mmol) was added dropwise to a suspension of
4-bromo-phthalic acid monosodium salt (6.00 g, 22.5 mmol)
in 47 mL of ethanol while cooling the flask in an ice bath.
The reaction mixture was heated to reflux (85 ꢁC) for 2 h.
Upon cooling, volatiles were evaporated, 90 mL of H2O was
added, and the reaction mixture was extracted three times
with ethyl acetate. The combined organic phase was washed
with aqueous NaHCO3, dried over MgSO4, filtered, and con-
centrated in vacuo. The resulting oil was purified by silica
gel column chromatography with 20:1 hexanes/ethyl acetate,
to give 4.82 g (86% yield) of a title compound as a slightly
yellow oil.
13C NMR (125 MHz, CDCl3, d): 166.9, 166.7, 134.7, 134.0,
131.9, 130.9, 130.6, 125.7, 68.7, 68.4, 38.8, 30.4, 29.0, 23.7,
23.0, 14.1, 11.0.
DEPT (125 MHz, CDCl3, d): 134 (CH), 132 (CH), 130 (CH),
68 (CH2) 39 (CH), 30.5 (CH2), 29 (CH2), 23.9 (CH2), 23
(CH2), 14 (CH3), 11 (CH3).
Preparation of 4-Bromo-di(3,5,5-trimethyl-1-hexyl)-phthalate
Ester 9e
4-Bromo-phthalic acid monosodium salt (2:1 mixture with
phthalic acid monosodium salt, 12.0 g, 33 mmol) was dis-
solved in 3,5,5-trimethyl-1-hexanol (77 mL, 147 mmol). The
ꢁ
reaction mixture was heated to 175 C for 5 h. The residual
TLC: 10:1 hexanes/ethyl acetate, UV, Rf: 0.72.
3,5,5-trimethyl-1-hexanol was removed by distillation with
heating up to 160 ꢁC under mild vacuum, and the resulting
oil was purified by silica gel column chromatography with
98:2 hexanes/ethyl acetate as the eluent, followed by a
second flash column using 40:1 hexanes/ethyl acetate as the
eluent, to give 14.8 g (90% yield) of the product as a slightly
yellow oil, free from contamination from the nonbrominated
material.
1H NMR (500 MHz, CDCl3, d): 7.84 (d, J ¼ 1.5 Hz, 1H), 7.69–
7.62 (m, 2H), 4.40–4.35 (m, 4H), 1.40–1.36 (m, 6H).
Preparation of 4-Bromo-di(isopropyl)-phthalate Ester 9b
7.10 g (96% yield) of the product was obtained as a slightly
yellow oil.
TLC: 5:1 hexanes/ethyl acetate, UV, Rf: 0.42.
IR (neat): 2982, 2937, 2878, 1736, 1589, 1566, 1467, 1375,
TLC: 10:1 hexanes/ethyl acetate, UV, Rf: 0.51.
1291, 1135, 1108, 918, 845, 829, 768 cmꢀ1
.
IR (neat): 2956, 1732, 1589, 1567, 1469, 1393, 1365, 1288,
1H NMR (500 MHz, CDCl3, d): 7.92 (d, J ¼ 1.5 Hz, 1H), 7.65–
1129, 1089, 1070, 960, 840, 767 cmꢀ1
.
7.58 (m, 2H), 5.28–5.21 (m, 2H), 1.38–1.36 (m, 12H).
1H NMR (500 MHz, CDCl3, d): 7.82 (d, J ¼ 1.5 Hz, 1H),
7.68–7.60 (m, 2H), 4.36–4.43 (m, 4H), 1.79–1.70 (m, 2H),
1.70–1.63 (m, 2H), 1.62–1.54 (m, 2H), 1.30–1.25 (m, 2H),
1.15–1.10 (m, 2H), 1.00–0.09 (dd; J ¼ 3 Hz, J ¼ 3.5 Hz, 6H),
0.91–0.90 (m, 18 H).
13C NMR (125 MHz, CDCl3, d): 166.2, 166.0, 134.9, 133.8,
131.8, 131.2, 130.6, 125.4, 69.8, 69.6, 21.8.
DEPT (125 MHz, CDCl3, d): 134 (CH), 132 (CH), 130 (CH),
70 (CH), 22 (CH3).
13C NMR (125 MHz, CDCl3, d): 166.8, 166.6, 134.6, 134.0,
131.9, 130.8, 130.6, 125.7, 64.8, 64.6, 51.1, 37.7, 31.2, 30.0,
27.3, 26.4, 22.6.
Preparation of 4-Bromo-di(isobutyl)-phthalate46 9c
3.30 g (84% yield) of the product was obtained as a slightly
yellow oil.
DEPT (125 MHz, CDCl3, d): 134 (CH), 132 (CH), 130 (CH),
65 (CH2), 51 (CH2), 38 (CH2), 30 (CH3), 26 (CH), 23 (CH3).
TLC: 20:1 hexanes/ethyl acetate, UV, Rf: 0.67.
IR (neat): 2962, 1729, 1589, 1566, 1470, 1367, 1287, 1126,
1089, 1069, 981, 946, 840, 767 cmꢀ1
.
Suzuki vinylation of 4-bromo-dialkyl phthalate esters: The
following procedure is representative.
1H NMR (500 MHz, CDCl3, d): 7.829 (d, 1H, J ¼ 2), 7.682–
7.624 (m, 2H), 4.105–4.078 (m, 4H), 2.09–1.998 (m, 4H),
1.003–0.982 (m, 12H).
Preparation of 4-Vinyl-diethyl-phthalate Ester 10a
Following the procedure of Grosjean et al.,48 vinylboronic
acid was prepared in situ: vinylmagnesium bromide (36 mL,
0.7 M solution in THF, 25.2 mmol) was added to trimethyl-
borate (2.84 mL, 25.2 mmol) in anhydrous toluene (88 mL)
at ꢀ78 ꢁC under a nitrogen atmosphere. The mixture was
allowed to warm to room temperature, and 4-bromo-diethyl-
13C NMR (125 MHz, CDCl3, d): 166.83, 166.63, 134.6, 133.9,
131.9, 130.9, 130.68, 125.7, 72.26, 72.07, 27.74, 19.17.
DEPT (125 MHz, CDCl3, d): 134 (CH), 132 (CH), 130 (CH),
72 (CH2) 28 (CH), 19 (CH3).
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SCHEME 2 Bromination of phthalic anhydride.
phthalate (2.53 g, 8.40 mmol), K2CO3 (2.32 g, 16.8 mmol),
and H2O (22 mL) were added. The resulting suspension was
degassed by bubbling the solution with N2 for 30 min. Cata-
lytic palladium(II) acetate (38 mg, 0.17 mmol, 2 mol %) and
triphenylphosphine (110 mg, 0.42 mmol, 5 mol %) were
added. The reaction mixture was heated at 85 ꢁC for 12 h,
and then the temperature was increased to 90 ꢁC for 18 h.
Upon cooling, the organic and aqueous phases were sepa-
rated, and the organic phase was washed with brine, dried
over MgSO4, filtered, and concentrated in vacuo. The result-
ing oil is purified by silica gel column chromatography with
3:1 hexanes/ethyl acetate and by silica gel column chroma-
tography with 4:1 hexanes/ethyl acetate, to give 1.01 g
(49% yield) of the title vinyl phthalate ester as a slightly yel-
low oil.
DEPT (125 MHz, CDCl3, d): 136 (CH), 130 (CH), 128 (CH),
126.5 (CH) 117.5 (CH2), 62 (CH2), 14 (CH3).
Preparation of 4-Vinyl-di(isopropyl)-phthalate Ester 10b
0.901 g (78% yield) was obtained as a slightly yellow oil.
TLC: 5:1 hexanes/ethyl acetate, UV, Rf: 0.72.
IR (neat): 2982, 1723, 1605, 1468, 1374, 1351, 1288, 1199,
1135, 1108, 1068, 989, 918, 849 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.71–7.65 (m, 2H), 7.52–7.50
(m, 1H), 6.77–6.71 (dd, J ¼ 11 Hz, J ¼ 6.5 Hz, 1H), 5.88–5.85
(d, J ¼ 17.5 Hz, 1H), 5.42–5.40 (d, J ¼ 11 Hz, 1H), 5.30–5.21
(m, 2H), 1.39–1.36 (m, 12H).
13C NMR (125 MHz, CDCl3, d): 167.5, 166.7, 140.5, 135.4, 133.9,
131.1, 130.9, 129.6, 128.9, 128.1, 126.4, 117.1, 69.4, 69.2, 21.8.
TLC: 5:1 hexanes/ethyl acetate, UV, Rf: 0.53.
DEPT (125 MHz, CDCl3, d): 135.5 (CH), 129.8 (CH), 128
(CH), 126 (CH) 117 (CH2), 69 (CH), 22 (CH3).
IR (neat): 2984, 1732, 1605, 1446, 1390, 1367, 1287, 1197,
1130, 1070, 1020, 921, 849, 789 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.74–7.69 (m, 2H), 7.54–7.28
(m, 1H), 6.76–6.71 (dd, 1H, J ¼ 11 Hz, J ¼ 6.5 Hz), 5.89–5.85
(d, 1H, J ¼ 17.5 Hz), 5.42–5.39 (d, 1H, J ¼ 11 Hz), 4.40–4.33
(m, 4H), 1.39–1.35 (m, 6H).
Preparation of 4-Vinyl-di(iso-butyl)-phthalate Ester 10c
2.00 g (78% yield) was obtained as a slightly yellow oil.
TLC: 20:1 hexanes/ethyl acetate, UV, Rf: 0.82.
13C NMR (125 MHz, CDCl3, d): 168.0, 167.0, 140.7, 135.3,
134.0, 133.5, 131.9, 131.1, 130.6, 129.7, 129, 128.35, 126.5,
117.5, 61.6, 61.8, 14.15.
IR (neat): 2963, 1726, 1605, 1471, 1377, 1285, 1196, 1127,
1070, 986, 919, 851, 783 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.75–7.69 (m, 2H), 7.55–7.53
(m, 1H), 6.78–6.72 (dd, J ¼ 11 Hz, J ¼ 6.5 Hz, 1H), 5.90–5.86
SCHEME 4 Suzuki vinylation of 4-bromo-phthalic esters.
SCHEME 3 Esterification of 4-bromo-phthalic acid monoso-
dium salt.
SCHEME 5 Polymerization of VPE.
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TABLE 1 Homopolymerization of VPE at 125 8C
b
Equiv.
Yieldgr
.
YieldNMR
MnNMR
Mn GPC
Mn ave
R
monomera
Timepolym
19 h
(%)
(%)
Mn gr (g/mol)
(g/mol)
(g/mol)
PDI
(g/mol)
DP
Et
30
20
30
20
60
60
30
20
20
43
50
46
41
46
75
72
72
100
100
100
100
98
3,323
2,644
3,891
2,463
8,492
13,822
6,758
4,637
8,751
7,248
4,940
8,129
5,426
5,070
5,580
8,763
6,197
8,751
4,825
3,389
4,623
3,463
11,275
11,303
3,424
3,835
1,633
1.20
1.20
1.25
1.27
1.20
1.20
1.20
1.30
1.10
4,074
2,692
4,257
2,963
9,884
12,562
5,091
4,236
5,192
16
12
15
10
31
40
16
13
12
i-Pr
19 h
i-Bu
4 h
84
19 h
92
95
99
2-Et-1-Hex
19 h
100
a
Compared to 1 equiv. of alkoxyamine initiator 5.
b
Average of Mn gr and Mn GPC
.
(d, J ¼ 18 Hz, 1H), 5.43–5.41 (d, J ¼ 11 Hz, 1H), 4.11–4.08
(m, 2H), 1.31–1.26 (m, 2H), 1.15–1.11 (m, 2H), 1.01–0.99
(m, 4H), 2.07–2.03 (m, 2H), 1.00–0.99 (m, 12H).
(dd, J ¼ 2.5 Hz, J ¼ 4.0 Hz, 6H), 0.92–0.91 (m, 18H).
13C NMR (125 MHz, CDCl3, d): 168.2, 167.3, 140.7, 135.3, 133.6,
130.8, 129.6, 129, 128.3, 126.5, 117.2, 72, 71.8, 27.80, 27.75, 19.2.
13C NMR (125 MHz, CDCl3, d): 168.2, 167.3, 140.6, 135.3,
133.5, 131, 130.7, 129.6, 128.3, 126.5, 117.2, 64.5, 64.3,
51.1, 37.8, 31.2, 30.4, 30, 29, 27.3, 26.4, 22.7.
DEPT (125 MHz, CDCl3, d): 135.5 (CH), 130 (CH), 128.1
(CH), 126.5 (CH), 137.3 (CH2), 72 (CH2), 28 (CH), 19.3 (CH3).
DEPT (125 MHz, CDCl3, d): 135.3 (CH), 129.6 (CH), 128.3
(CH), 126.5 (CH), 117.2 (CH2), 64.5 (CH2), 51.1 (CH2), 38
(CH2), 30 (CH3), 26.4 (CH), 22.7 (CH3).
Preparation of 4-Vinyl-di(2-ethyl-1-hexyl)-phthalate
Ester 10d
1.78 g (26% yield) was obtained as a yellow oil.
Homopolymerization of 4-Vinyl-di-alkyl-phthalate
Esters 10a–10d
TLC: 20:1 hexanes/ethyl acetate, UV, Rf: 0.4.
The following procedure using the di-isobutyl vinyl
phthalate is representative of the general procedure: a mix-
ture of 2,2,5-trimethyl-3-phenyl-ethoxy-4-phenyl-3-azahexane
5 (12.7 mg, 0.039 mmol) and 4-vinyl-di-isobutyl-phthalate
10c (347 mg, 1.14 mmol) was degassed in an ampoule by
three consecutive freeze–pump–thaw cycles and sealed
under nitrogen. The ampoule was immersed in an oil bath at
IR (neat): 2960, 2931, 2874, 2861, 1732, 1605, 1464, 1381,
1283, 1195, 1127, 1070, 987, 961, 915, 851, 791, 772 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.73–7.68 (m, 2H), 7.55–7.53
(m, 1H), 6.78–6.72 (dd, J ¼ 11 Hz, J ¼ 6.5 Hz, 1H), 5.89–5.86
(d, J ¼ 17.5 Hz, 1H), 5.43–5.41 (d, J ¼ 10.5 Hz, 1H), 4.27–
4.18 (m, 4H), 1.70–1.70 (m, 2H), 1.45–1.32 (m, 16H), 0.95–
0.90 (m, 12H).
ꢁ
125 C for 19 h and then cooled to room temperature.
A crude 1H NMR spectrum was taken to provide data to
allow calculation of % yieldNMR and molecular weight
(MnNMR, g/mol). For samples containing residual unpolymer-
ized 4-vinyl-di-alkyl-phthalate ester, the copolymer was
transferred using a minimum amount of dichloromethane to
a Thermo Scientific SnakeSkin Dialysis Tubing (3.5 K MWCO)
and dialysed for 24 h using ethanol as solvent. The homopol-
ymer was concentrated in vacuo and the sample weighed to
determine the gravimetric yield (yieldgr); a molecular weight
(Mn gr, g/mol) was calculated. Analysis by GPC using THF as
the eluent (calibrated against eight polystyrene samples)
gave a third value of molecular weight (Mn GPC).
13C NMR (125 MHz, CDCl3, d): 168.3, 167.3, 140.6, 135.4,
133.7, 131.0, 130.8, 129.6, 128.9, 128.2, 126.5, 117.2, 68.4,
68.2, 38.8, 30.4, 29.0, 23.8, 23.0, 14.1, 11.0.
DEPT (125 MHz, CDCl3, d): 135.4 (CH), 129.6 (CH), 128.2
(CH), 126.5 (CH), 117.2 (CH2), 68.4 (CH2), 68.2 (CH2), 38.8
(CH), 30.4 (CH2), 29.0 (CH2), 23.8 (CH2), 23.0 (CH2), 14.1
(CH3) 11.0 (CH3).
Preparation of 4-Vinyl-di(3,5,5-trimethyl-1-hexyl)-phthalate
Ester 10e
1.37 g (49% yield) was obtained as a yellow oil.
Copolymerization of 4-Vinyl-di-alkyl-phthalate Esters
10a–10e with NBA
TLC: 20:1 hexanes/ethyl acetate, UV, Rf: 0.71.
IR (neat): 2956, 2869, 1728, 1605, 1469, 1365, 1286, 1195,
The following procedure is representative of the general
procedure: a mixture of 2,2,5-trimethyl-4-phenyl-3-azahex-
ane-3-nitroxide (TIPNO) (0.2 mg, 0.0009 mmol, 2.3% with
respect to the alkoxyamine initiator), 2,2,5-trimethyl-3-phe-
nyl-ethoxy-4-phenyl-3-azahexane 5 (12.7 mg, 0.039 mmol),
4-vinyl-di-ethyl-phthalate 10a (270 mg, 1.09 mmol), and
1129, 1071, 987, 963, 915, 851, 790 cmꢀ1
.
1H NMR (500 MHz, CDCl3, d): 7.73–7.69 (m, 2H), 7.54–7.52
(m, 1H), 6.77–6.71 (dd, J ¼ 11 Hz, J ¼ 6.5 Hz, 1H), 5.89–5.86
(d, J ¼ 17.5 Hz, 1H), 5.43–5.41 (d, J ¼ 11 Hz, 1H), 4.37–4.28
(m, 4H), 1.80–1.72 (m, 2H), 1.72–1.64 (m, 2H), 1.63–1.55
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TABLE 2 Copolymerizations of VPE with NBA at 125 8C
Series 3: with respect to 1.0 equivalent of alkoxyamine ini-
tiator: 1 mol % free nitroxide, 20 equivalents of acrylate,
1.7 equivalents of vinyl phthalate monomer (similar to
Series 2, but a large excess of acrylate monomer: ratio of
acrylate: vinyl phthalate monomer approximately 12:1).
Equiv. alkoxyamine
Equiv.
Equiv.
NBA
Equiv.
VPE
Series
initiator 5
nitroxide
1
2
3
1.0
1.0
1.0
0.025
0.01
0.01
25
10
20
29
12
2
RESULTS AND DISCUSSION
Synthesis of VPE
The only literature method for the preparation of 4-vinyl-
phthalic acid derivatives is the 1994 work of Rectanus and
Stadler49 (preparing 4-vinyl phthalic anhydride), using a
Heck reaction in an autoclave with 40 bars of ethylene gas.
The German patent literature describes the formation of
copolymers of 4-vinylphthalic acid, 4-vinylphthalic anhydride,
and 4-vinylphthalic esters with styrene using uncontrolled
AIBN-initiated radical polymerization, with the aim of mak-
ing heat resistant polystyrenes50 and polymer blends with
enhanced impact strength.51
NBA (125 mg, 0.974 mmol) was degassed in an ampoule by
three consecutive freeze–pump–thaw cycles and sealed
under nitrogen. The ampoule was immersed in an oil bath at
ꢁ
125 C for 19 h and then cooled to room temperature.
A crude 1H NMR spectrum was taken to provide data to allow
calculation of % yieldNMR, and the ratio of vinyl phthalate
ester versus NBA incorporated into the polymer, from which a
molecular weight (MnNMR, g/mol) was calculated (see Tables
3–5). For samples containing only unpolymerized NBA as the
remaining monomer, the copolymer sample was transferred to
a flask using dichloromethane and all volatiles (including
NBA) were removed in vacuo. For samples containing residual
unpolymerized 4-vinyl-di-alkyl-phthalate esters, the copoly-
mer was transferred using a minimum amount of dichlorome-
thane to a Thermo Scientific SnakeSkin Dialysis Tubing (3.5 K
MWCO) and dialysed for 24 h using ethanol as solvent. The co-
polymer was concentrated in vacuo and the sample weighed
to determine the gravimetric yield (yieldgr); a molecular
weight (Mn gr, g/mol) was calculated. Analysis by GPC using
THF as the eluent (calibrated against eight polystyrene sam-
ples) gave a third value of molecular weight (Mn GPC).
Our synthesis of VPE started with the large-scale electro-
philic bromination of phthalic anhydride40,41 (Scheme 2),
which resulted in mixtures of the dicarboxylic acid, the
monosodium salt, or the disodium salt, depending on the
work-up. Acidification with concentrated HCl to approxi-
mately pH ¼ 1.5 (as judged by pH paper) and extraction
with ethyl acetate gave the monosodium salt 8. If acidifica-
tion was performed with a large excess of concentrated HCl,
followed by removal of volatiles in vacuo, extraction with ac-
etone delivered the diacid.52 Attempts to accomplish 4-bro-
mination using sodium bromate and sulfuric acid as an alter-
native route were unsuccessful.
Three different series of copolymerizations were performed:
Esterification (Scheme 3) was performed with five different
alcohols: ethanol, isopropanol, isobutanol, 3,5,5-trimethyl-1-
hexanol, and 2-ethyl-1-hexanol, with the later forming a
direct analogue of the branched alkyl phthalate plasticizer
DEHP. In all cases except for 3,5,5-trimethyl-1-hexanol, an
excess of thionyl chloride was added to an alcoholic solution
of 4-bromo-phthalic acid monosodium salt following the
method of Hosangadi and Dave.45 Use of thionyl chloride
Series 1: with respect to 1.0 equivalent of alkoxyamine ini-
tiator: 2.5 mol % free nitroxide, 25 equivalents of acrylate,
29.4 equivalents of vinyl phthalate monomer.
Series 2: with respect to 1.0 equivalent of alkoxyamine ini-
tiator: 1 mol % free nitroxide, 10 equivalents of acrylate,
11.7 equivalents of vinyl phthalate monomer (2.5 times
more initiator than in Series 1).
TABLE 3 Copolymerizations of VPE with NBA
a
Yieldgr
(%)
YieldNMR
(%)
Mn gr
MnNMR
Mn GPC
Ratio VPE:NBA
by NMR
Mn ave
R
Timepolym
(g/mol)
(g/mol)
(g/mol)
PDI
(g/mol)
DPb
Et
4 h
29
60
26
62
54
58
/
44
83
40
58
84
82
92
80
68
3,279
6,353
3,223
7,200
6,910
9,752
/
4,781
6,759
13,506
5,206
11,920
14,027
18,341
8,289
8,303
6,565
1.2
1.5
1.3
1.4
1.5
1.5
1.8
1.2
1.5
4.3:1
5,019
9,929
4,214
9,560
10,468
4,046
8,289
6,566
7,848
23
48
16
36
46
39
17
16
19
19 h
4 h
8,650
2.6:1
i-Pr
4,720
VPE only
VPE only
1.3:1
19 h
19 h
19 h
43 h
19 h
43 h
6,739
i-Bu
10,538
13,642
15,220
13,316
11,399
3,3,5-triMe-1-Hex
2.9:1
0.8:1
2-Et-1-Hex
28
54
4,828
9,132
VPE only
VPE only
a
Average of Mn gr and Mn GPC
.
b
DP calculated from the Mn ave and the ratio of VPE:NBA incorporation as determined by 1H NMR.Series 1: 29.4 equiv. VPE þ 25.0 equiv. NBA þ 1.0
equiv. alkoxyamine 5 þ 2.5 mol % NitOꢂ at 125 ꢁC
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TABLE 4 Copolymerizations of VPE with NBA
a
Yieldgr
YieldNMR
(%)
Mn gr
MnNMR
Mn GPC
Ratio VPE:
Mn ave
R
Timepolym
(%)
(g/mol)
(g/mol)
(g/mol)
PDI
NBA by NMR
(g/mol)
DPb
Et
19 h
19 h
19 h
19 h
19 h
50
74
63
59
42
67
94
96
89
78
2,377
3,655
3,413
2,235
2,915
3,059
4,562
5,021
3,211
5,189
3,316
3,264
3,640
3,478
2,640
1.2
1.2
1.2
1.3
1.3
1.5:1
2,846
3,460
3,526
2,856
2,778
15
17
16
8
i-Pr
1.3:1
i-Bu
1.3:1
3,3,5-triMe-1-Hex
2.3:1
2-Et-1-Hex
VPE only
7
a
Average of Mn gr and Mn GPC
.
b
DP calculated from the Mn ave and the ratio of VPE:NBA incorporation as determined by 1H NMR.Series 2: 11.8 equiv. VPE þ 10.0 equiv. NBA þ 1.0
equiv. alkoxyamine 5 þ 1 mol % NitOꢂ at 125 ꢁC
with 3,5,5-trimethyl-1-hexanol led to the formation of a side-
product, thus esterification with this alcohol was performed
at 175 C without thionyl chloride.
copolymers can be produced, in which the density of the
phthalate residues can be easily varied. NBA was chosen as
the comonomer, as earlier studies involving in situ polymer-
ization of NBA in PVC53 and of vinyl chloride in poly(NBA)54
indicate that these should form homogenous mixtures. Thus,
three different series (Table 2) of copolymerizations of 4-
vinyl-phthalate esters with NBA (Scheme 6) were performed:
the first used a close to 1:1 ratio of the two monomers, the
second used 2.5 times more alkoxyamine initiator than the
first (to provide shorter polymers), and the third used 10
times more NBA, with the aim of preparing copolymers rich
in NBA residues, with a small amount of VPE incorporated.
ꢁ
With five different 4-bromo-phthalate esters in hand, the
vinyl group was introduced in a straightforward manner
using a Suzuki coupling reaction. Vinylboronic acid is prone
to polymerization, thus an in situ generation of vinylboronic
acid from vinyl Grignard and trimethylborate developed by
Grosjean et al.48 was adopted, resulting in low to good yields
of the desired VPE 10a–10e (VPE) (Scheme 4).
Polymerizations
In the first series of VPE-r-NBA copolymerizations, a 1.2:1.0
ratio of VPE:NBA was used (Table 3). The resulting copoly-
mers incorporated much larger amounts of VPE than the
ratio of starting monomers, indicating that polymers termi-
nated with a VPE residue preferentially add to another VPE
monomer, compared to NBA. This phenomenon has been
observed in a somewhat related NMRP copolymerization
using substituted styrenes and methacrylates.55 In some
cases, only VPE residues were incorporated into the polymer,
as assessed by 1H NMR. These medium-sized copolymers
had estimated DP values varying between 16 and 48, largely
governed as a function of polymerization time.
Conversion of the VPE into short polymers was then pursued.
Short homopolymers were prepared by NMRP (Scheme 5,
Table 1), forming polymers with an estimated degree of poly-
merization (DP) ranging from 10 to 40 monomers, with excel-
lent control of polydispersities (Table 2). As expected, use of
larger ratios of vinyl phthalate monomer compared to alkoxy-
amine initiator resulted in longer polymers given the same
polymerization time (19 h). Unreacted vinyl phthalate ester
monomer was removed by dialysis: the isolated polymers
were all viscous liquids. To calculate a rough DP, the average
of the gravimetric and GPC Mn values was taken, as the NMR
derived yields and MnNMR values were less reliable. It should
be noted that the Mn GPC values cannot be considered highly
accurate, as polystyrene samples are used to calibrate the
GPC.
In the second series of VPE-r-NBA copolymerizations, the
same ratio of VPE:NBA was used, but the amount of alkoxy-
amine initiator was increased by a factor of 2.5, producing
shorter random copolymers (Table 4). Incorporation of NBA
was higher than in Series 1, with the exception of the 2-
Potential plasticizers must be miscible with PVC. One of the
advantages of using NMRP is that a variety of random
TABLE 5 Copolymerizations of VPE with NBA
a
Yieldgr
Timepolym (%)
.
YieldNMR
(%)
MnNMR
Mn GPC
Ratio VPE:
Mn ave
R
Mn gr (g/mol) (g/mol)
(g/mol)
PDI NBA by NMR (g/mol)
DPb
Et
19 h
19 h
19 h
89
81
85
80
73
66
70
69
54
59
2,963
2,757
2,944
2,975
2,711
2,291
2,440
2,447
2,127
2,254
2,275
2,115
2,265
1,979
2,001
1.2
1.2
1.2
1.3
1.2
0.1:1
0.1:1
0.1:1
0.2:1
0.2:1
2,619
2,436
2,604
2,477
2,356
19
17
18
14
13
i-Pr
i-Bu
3,3,5-triMe-1-Hex 19 h
2-Et-1-Hex
19 h
a
Average of Mn gr and Mn GPC
.
b
DP calculated from the Mn
and the ratio of VPE:NBA incorporation as determined by 1H NMR.Series 3: 1.7 equiv. VPE þ 19.7 equiv. NBA þ 1.0
ave
equiv. alkoxyamine 5 þ 1 mol % NitOꢂ at 125 ꢁC.
1182
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lengths and density of plasticizer mimics were varied. All
the polymers were viscous yellow liquids, with Tg values
apparently below ꢀ40 ꢁC, indicating promise as possible
plasticizers. The possibility that these polymers can be
used to replace DEHP and other phthalate plasticizers in
PVC is intriguing. Polymeric phthalates used in PVC blends
are expected to resist migration and are unlikely to be
metabolized into small EDC.
SCHEME 6 Random copolymerization of VPE with NBA.
ethyl-1-hexyl VPE, which did not show any NBA incorpora-
tion. In this series, these shorter random copolymers gave
estimated DP values of 7–16 monomer units, with good con-
trol of polydispersity. All polymerization times were standar-
dized in Series 2 to 19 h. It is interesting to note that the
long-branched alkyl chain phthalate esters resulted in sub-
stantially shorter polymers than the short-chained phthalate
esters.
ACKNOWLEDGMENTS
The authors thank the University of California, Cancer Research
Coordinating Committee for financial support of this work. F.
€
Schaffner thanks the Deutsche Forschungsgemeinschaft for
postdoctoral support. The authors thank Greg O’Bryan (Sandia
National Laboratories) for DSC measurements.
REFERENCES AND NOTES
In the third series of VPE-r-NBA copolymerizations, an
almost 12-fold excess of NBA compared to VPE monomer
was used, with the aim of producing poly(NBA) with small
amounts of incorporated phthalate esters (Table 5). This was
successful, producing moderate length random copolymers
with DP values estimated at 13–19 residues. These copoly-
mers consist largely of NBA residues containing approxi-
mately two to three phthalate ester moieties. Again, the
long-branched alkyl chain phthalate esters resulted in
shorter polymers than the short-chained phthalate esters, all
with good control over polydispersity.
1 Tullo, A. H. Chem. Eng. News 2005, 83, 29–31.
2 M. Rahman, C. S. Brazel, Prog. Polym. Sci 2004, 29,
1223–1248.
3 L. G. Krauskopf, J. Vinyl Add. Technol. 2003, 9, 159–171.
4 S. H. Swan, K. M. Main, F. Liu, S. L. Stewart, R. L. Kruse, A.
M. Calafat, C. S. Mao, J. B. Redmon, C. L. Ternand, S. Sullivan,
J. L. Teague, Environ. Health Perspect. 2005, 113, 1056–1061.
5 H. Frederiksen, N. E. Skakkebaek, A. M. Andersson, Mol.
Nutr. Food Res. 2007, 51, 899–911.
6 J. L. Lyche, A. C. Gutleb, A. Bergman, G. S. Eriksen, A. J.
Murk, E. Ropstad, M. Saunders, J. U. Skaare, J. Toxicol. Envi-
ron. Health B 2009, 12, 225–249.
All of the homo and random copolymers were obtained as
viscous, slightly yellow liquids. Differential scanning calorim-
7 E. Lague, J. J. Tremblay, Endocrinology 2008, 149,
4688–4694.
ꢁ
ꢁ
etry (DSC) analysis starting at 25 C with cooling to ꢀ40 C
followed by heating to 75 ꢁC did not show evidence of a
glass transition temperature for any of the samples. Thus, it
is assumed that all of the samples have Tg values below ꢀ40
ꢁC. As low glass transition temperatures are indicative of
good plasticizing properties, these polymerized phthalates
hold promise as possible plasticizers in PVC blends. These
polymeric materials would not be expected to migrate easily
out of the PVC products, and even if they did, ingestion or
absorption into mammalian systems would not give the
same metabolic products as small molecule phthalate esters.
Thus, this approach toward polymeric phthalate plasticizers
could mitigate the health concerns stemming from the cur-
rent widespread use of phthalate esters in PVC consumer
products. Work toward determining the miscibility of these
polyphthalate esters with PVC and the plasticization efficacy
of these materials is now being pursued.
8 J. J. K. Jaakkola, T. L. Knight, Environ. Health Perspect. 2008,
116, 845–853.
9 M. Hakkarainen, Adv. Polym. Sci. 2008, 211, 159–185.
10 J. A. Tickner, T. Schettler, T. Guidotti, M. McCally, M. Rossi,
Am. J. Ind. Med. 2001, 39, 110–111.
11 T. Colborn, F. S. V. Saal, A. M. Soto, Environ. Health Per-
spect. 1993, 101, 378–384.
12 E. Diamanti-Kandarakis, J. P. Bourguignon, L. C. Giudice, R.
Hauser, G. S. Prins, A. M. Soto, R. T. Zoeller, A. C. Gore,
Endocr. Rev. 2009, 30, 293–342.
13 L. N. Vandenberg, T. Colborn, T. B. Hayes, J. J. Heindel, D.
R. Jacobs, D. H. Lee, T. Shioda, A. M. Soto, F. S. vom Saal, W.
V. Welshons, R. T. Zoeller, J. P. Myers, Endocr. Rev. 2012, 33,
378–455.
14 Consumer Product Safety Improvement Act (CPSIA), H.R.
4040, Public Law 110–314, signed into law on Aug. 14, 2008:
http://www.cpsc.gov/cpsia.pdf (accessed online 7–23-12).
15 Directive 2005/84/EC of the European Parliament and of the
Council of December 14, 2005: http://eur-lex.europa.eu/LexUri-
Serv/LexUriServ.do?uri¼OJ:L:2005:344:0040:0043:en:PDF,
(accessed online 7–23-12).
CONCLUSIONS
Five different 4-vinyl dialkyl phthalate esters were prepared
from phthalic anhydride by electrophilic bromination,
esterification, and Suzuki coupling. NMRP using TIPNO
alkoxyamine gave homopolymers, in which each residue
mimics a small molecule plasticizer, but these phthalate
esters are stitched together by a robust all-carbon chain.
Similarly, random copolymerization by NMRP using NBA
produced three series of copolymers, in which the polymer
16 J. P. AuBuchon, T. N. Estep, R. J. Davez, Blood 1988, 71, 448–452.
17 J. Simmchen, R. Ventura, J. Segura, Transf. Med. Rev. 2012,
26, 27–37.
18 P. M. R. Tendero, A. Jimenez, A. Greco, A. Maffezzoli, Eur.
Polym. J. 2006, 42, 961–969.
19 V. Ambrogi, W. Brostow, C. Carfagna, M. Pannico, P. Per-
sico, Polym. Eng. Sci. 2012, 52, 211–217.
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20 R. Navarro, M. P. Perrino, M. G. Tardajos, H. Reinecke, Mac-
romolecules 2010, 43, 2377–2381.
40 E. T. Sabourin, A. Onopchenko, J. Org. Chem. 1983, 48,
5135–5137.
21 Resinous Products and Chemical Co., British Patent 586,826l,
April 1, 1947, and British Patent 588,574, May 28, 1947.
41 M. H. Norman, J. L. Kelly, E. B. Hollingsworth, J. Med.
Chem. 1993, 36, 3417–3428.
22 D. S. Hubbell, S. L. Cooper, J. Appl. Polym. Sci. 1977, 21,
3035–3061.
42 G. Markl, K. Gschwendner, I. Rotzer, P. Kreitmeier, Helv.
Chim. Acta 2004, 87, 825–844.
23 S. Lee, J. G. Lee, H. Lee, S. J. Mumby, Polymer 1999, 40,
5137–5145.
43 G. S. Skinner, J. A. Gladner, R. F. Heitmiller, J. Am. Chem.
Soc. 1951, 73, 2230–2233.
24 M. Hakkarainen, Polym. Degrad. Stab. 2003, 80, 451–458.
44 Y. Hiraiwa, A. Morinaka, T. Fukushima, T. Kudo, Bioorg.
Med. Chem. Lett. 2009, 19, 5162–5165.
25 J. L. Audic, D. Reyx, J. C. Brosse, J. Appl. Polym. Sci. 2003,
89, 1291–1299.
45 B. D. Hosangadi, R. H. Dave, Tetrahedron Lett. 1996, 37,
26 N. L. Thomas, J. Appl. Polym. Sci. 2004, 94, 2022–2031.
6375–6378.
27 C. Oriol-Hemmerlin, Q. T. Pham, Polymer 2000, 41,
46 S.-J. Sun, X.-J. Li, W.-Q. Xu, Huaxue Shiji 2010, 32, 87–90.
4401–4407.
47 Z. Wang, S.-J. Sun, X.-J. Li, J.-L. Luo, Anhui Nongye Kexue
2009, 37, 7814–7815.
28 X. H. Li, Y. Xiao, B. A. Wang, Y. Tang, Y. Q. Lu, C. J. Wang,
J. Appl. Polym. Sci. 2012, 124, 1737–1743.
48 C. Grosjean, A. P. Henderson, D. Herault, G. Ilyashenko, J.
P. Knowles, A. Whiting, A. R. Wright, Org. Process Res. Dev.
2009, 13, 434–441.
29 R. F. Grossman, Handbook of Vinyl Formulating, 2nd ed.;
Wiley: United States, 2008; p 174.
30 A. Lindstrom, M. Hakkarainen, J. Appl. Polym. Sci. 2006,
100, 2180–2188.
49 S. Rectanus, R. Stadler, Polym. Bull. 1994, 32, 373–380.
50 A. Gottschalk, F. Seitz, K. Muehlbach, S. Rectanus, R. Sta-
dler, M. Weber, Copolymers of 4-vinylphthalic acid deriva-
tives in polymer blends. German Patent 4316024 A1
19931125, November 25, 1993; SciFinder Scholar 2012:17418–
74-5.
31 A. Lindstrom, M. Hakkarainen, Biomacromolecules 2007, 8,
1187–1194.
32 A. Lindstrom, M. Hakkarainen, J. Appl. Polym. Sci. 2007,
104, 2458–2467.
33 A. Lindstrom, M. Hakkarainen, J. Polym. Sci. Part B: Polym.
Phys. 2007, 45, 1552–1563.
51 A. Gottschalk, M. Weber, F. Seitz, K. Muehlbach, S. Recta-
nus, R. Stadler, Polymer blends containing 4-vinylphthalic acid
derivative copolymers. German Patent 4338124 A1 19950511,
May 11, 1995; SciFinder Scholar 2012: 17418–74-5.
34 T. Zhang, M. Y. Pan, J. Dai, Z. X. Song, L. He, Z. S. Jiang,
J. Appl. Polym. Sci. 2009, 114, 107–115.
35 A. Boztug, J. Appl. Polym. Sci. 2004, 94, 1586–1589.
36 A. Boztug, S. Basan, J. Appl. Polym. Sci. 2003, 89, 296–299.
37 A. Boztug, Mater. Res. Innovations 2007, 11, 169–172.
52 The pKa for 4-bromo-phthalic acid is estimated to be 2.86:
SciFinder Scholar 2012: calculated using Advanced Chemistry
C
V
Development (ACD/Labs) Software V11.02 ( 1994–2012 ACD/
Labs).
38 D. Benoit, V. Chaplinski, R. Braslau, C. J. Hawker, J. Am.
Chem. Soc. 1999, 121, 3904–3920.
53 D. J. Walsh, C. K. Sham, Polymer 1984, 25, 1023–1027.
54 D. J. Walsh, G. L. Cheng, Polymer 1982, 23, 1965–1970.
39 D. Gigmes, J. Vinas, N. Chagneux, C. Lefay, T. N. T. Phan,
T. Trimaille, P.-E. Dufils, Y. Guillaneuf, G. Carrot, F. Boue, D.
Bertin, ACS Symp. Ser. 2009, 1024, 245–262.
55 B. H. Lessard, E. J. Y. Ling, M. Maric, Macromolecules 2012,
45, 1879–1891.
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