Environmentally benign synthesis of vinyl ester resin from biowaste glycerin

Article abstract of DOI:10.1039/c5ra03254g

We present here for the first time a novel environmentally benign protocol for the synthesis of vinyl ester resin (VER). Our synthetic strategy utilizes a commercial waste material, glycerin, from biodiesel manufacturing and converts it into a widely utilized resin. The VER was synthesized using bisphenol A (BPA) and glycidyl methacrylate (GMA) as precursors. GMA was synthesized via a multistep synthetic protocol using glycerin obtained from a biodiesel manufacturing waste stream. The structure of the intermediates was confirmed by ¹H NMR, HPLC and FT-IR spectroscopy.

Full text of DOI:10.1039/c5ra03254g

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Kim, Z. Huang, M. Jayamanna, A. Kokil, A. Pine, J. Kaltsas, E. Jahngen, D. Ryan, S. Yoon, R. F. Kovar and Y.
Lee, RSC Adv., 2015, DOI: 10.1039/C5RA03254G.
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Environmentally Benign Synthesis of Vinyl Ester Resin from Biowaste
Glycerin
Priyank N. Shah,*,† Namjoon Kim,‡ Zhuangrong Huang,‡ Mahesh Jayamanna,† Akshay Kokil,†
Alex Pine,⊥ Jarmin Kaltsas,⊥ Edwin Jahngen,† David K. Ryan,† Seongkyu Yoon,‡ Robert F.
Kovar∬ and Yongwoo Lee*,†
†Department of Chemistry, University of Massachusetts Lowell, One University Avenue, Lowell,
Massachusetts 01854, United States
⊥ Maine Standard Biofuels, 51 Ingersoll Dr. Portland, Maine 04103, United States
‡Department of Chemical Engineering, University of Massachusetts Lowell, One University
Avenue, Lowell, Massachusetts 01854, United States
∬R.F. Kovar & Associates, 203 Beach Street, Wrentham, MA 02093ꢀ1513
* Corresponding Authors:
Priyank N. Shah; emailꢀ Priyank_shah@uml.edu; Phone Noꢀ 978ꢀ934ꢀ3734
Yongwoo Lee; emailꢀ Yongwoo_Lee@uml.edu, Phone Noꢀ 978ꢀ934ꢀ3792
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ABSTRACT:
We present here for the first time a novel environmentally benign protocol for synthesis of vinyl
ester resin (VER). Our synthetic strategy utilizes a commercial waste material, glycerin, from
biodiesel manufacturing, and converts it into a widely utilized resin. The VER was synthesized
using bisphenol A (BPA) and glycidyl methacrylate (GMA) as precursors. GMA was
synthesized using glycerin obtained from a biodiesel manufacturing waste stream. Glycerin was
converted to GMA using a novel multistep synthetic protocol. The structure of intermediate was
confirmed by 1H NMR, HPLC and FTꢀIR spectroscopy.
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INTRODUCTION
Vinyl ester resin (VER), introduced in the late 1960s, is a lowꢀcost material that can be
processed to form a matrix of fiberꢀreinforced composites that are excellent materials for hulls,
transportation vehicles, and many other structural composites.1 Fiberꢀreinforced composites
produced from VER have especially become the material of choice for marine applications.
VER is therefore finding increasing applications in transportation, construction, marine, and
wind energy industries.2,3,4,5 According to recent investigations BPA has been shown as an
endocrine disrupter, has been found to bind to estrogen receptors and have estrogenic effects.6
Humans are exposed to BPA majorly through their diet as the food might be in contact with
containers or food packaging made with unꢀcrosslinked polymers containing BPA as the repeat
units. Vinyl ester resin typically contains BPA, because the chemical structure has displayed to
yield the best mechanical performance of the composites used mostly in the marine industry for
fabrication of hulls. We chose to utilize BPA as a building block for the environmentally benign
synthesis of VER resin to display the feasibility of this approach, which will be extended to
nonꢀBPA building blocks.
VER can be processed at ambient temperature using vacuumꢀassisted resin transfer
molding (VARTM) into massive carbonꢀfiberꢀreinforced composites.5 The synthetic protocols
used for manufacture of VER has two main disadvantages. First, VER is currently synthesized
from petroleum feedstock, which reduces the sustainability. Second, VER is synthesized from
epichlorohydrin which is a known environmental hazard that produces acute toxicity in case of
inhalation, oral, and dermal exposure.
Hence, for reducing the environmental impact, it is essential to develop VER synthesis
routes that are not dependent on petroleum based feedstock. Moreover, investigations of the
VER synthesis routes that lead to elimination of the use of hazardous chemicals, such as
epichlorohydrin, are necessary. To assure sustainability of the new processing route, starting
materials should be derived from readily available renewable resources.
Recently, significant advances have been made for obtaining biodiesel, a renewable
biofuel for use in diesel engines and heating applications. Biodiesel can be produced by base
catalyzed hydrolysis of rapeseed oil,7 soybean and wastes of cooked oil,8 rice straw,9 vegetable
oil mixtures of cottonseed, soybean and castor oils,10 jatropha oil,11 and crude palm oil.12
Biodiesel is environmentally beneficial because it is biodegradable, nontoxic and has low
emission.13 During manufacturing of biodiesel, approximately a 10 % volume of glycerin is
produced as a byꢀproduct or waste.14 Therefore, the effective utilization of glycerin enlarges the
economy of biodiesel production; moreover, the conversion of glycerin to value added
chemicals can expand the scope of green chemistry.15 Although biodiesel uses nonꢀpetroleum
feedstocks, it is still subject to the price fluctuations of the petroleum liquid fuels market.
Subsidization also plays an important role in the overall market price of biodiesel. These two
market factors often make it very important for biodiesel manufacturers to sell as many of their
byproducts as possible.
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Only limited systematic investigations are reported on the use of functional vinyl
monomer such as glycidyl methacrylate (GMA),16 which is a versatile bidentate monomer
capable of imparting oxirane functionality to VER. It is also worth mentioning that bisphenol A
(BPA) is an important chemical used to manufacture polycarbonate plastic, epoxy resin, flame
retardants, and other specialty products,17 and is manufactured by acid catalyzed condensation
of acetone and phenol.18
In the present work, we focused on the synthesis of the green vinyl ester resins (GVER)
from renewable sources using three steps (Figure 1): 1) synthesis of GMA from waste glycerin;
2) conversion of phenol into BPA using environmentally benign conditions, and 3) synthesis of
GVER from BPA and GMA.
Step 1. Synthesis of glycidyl methacrylate from glycerin
O
O
OH
O
O
O
O
Na2SO4,
O
O
O
O
HO
OH
OH
O
HO
K2CO3,
73-75C
140-180C
K+-C
N
O
OH
Step 2. Synthesis of vinyl ester monomer (VER)
OH
OH
O
O
OH
N
O
O
O
O
OH
H
Cl
HS
OH
O
O
OH
Figure 1. Synthesis of vinyl ester oligomer from phenol and glycerin.
EXPERIMENTAL SECTION
Materials.
Crude glycerin (Maine Standard Biofuels), potassium carbonate (99 % SigmaꢀAldrich),
dimethyl carbonate (99 % AlfaꢀAesar), sodium sulfate (99.9 % AlfaꢀAesar), methyl
methacrylate (99.9 % AlfaꢀAesar), potassium cyanide (SigmaꢀAldrich), 2,4,ꢀdimethyl,6ꢀtertꢀ
butyl phenol (AlfaꢀAesar), phenol (99 % SigmaꢀAldrich), acetone (99.9 % SigmaꢀAldrich),
Amberlyst® 15 hydrogen form (SigmaꢀAldrich), 2ꢀdiethylaminoethanethiol hydrochloride
(95 % SigmaꢀAldrich) and N,Nꢀdimethylbenzylamine were used as received.
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Characterization.
l
NMR Spectroscopy. H NMR spectra of the synthesized materials were recorded at 25 ˚C on a
Bruker 500 MHz spectrometer using DMSO (Cambridge Isotope Lab., Inc.) as the solvent and
tetramethylsilane (TMS) as the internal reference (δ H 0.00).
Chromatographic system. The liquid chromatograph (Water’s Alliance system model 2695
HPLC system) is equipped with a photodiode array (PDA) detector (Water’s model 2996)
monitored at 277 nm and a 4.6 mm × 15 cm column that contains 3ꢀµm packing (Polar ꢀ Diol).
The column temperature is maintained at 25 ˚C with a flow rate of 1.0 mL/min and an injection
volume of 1 uL. The system was run isocratic with a 70:30 mixture of hexane and ethyl acetate.
Samples were prepared in ethyl acetate.
Synthesis of glycidyl methacrylate (GMA) from glycerin.
The GMA was synthesized by a multistep synthesis. The first intermediate, glycerol
carbonate, was synthesized from glycerin and dimethyl carbonate under basic condition. The
second intermediate, glycidol, was synthesized by decarboxylation of glycerol carbonate in the
presence of sodium sulfate at high temperature. Finally, the GMA was synthesized by reaction
of glycidol and methyl methacrylate as described in Figure 1. Following is the procedure for
synthesis of each intermediate.
Glycerol carbonate.
In a typical setup, a 250 mL flask equipped with a magnetic stirrer, condenser and thermometer
was charged with glycerin (40.05 g, 0.435 mol), dimethyl carbonate (117.45 g, 1.305 mol) and
K2CO3 (1.8 g, 13.05 mmol). The reaction mixture was refluxed (73–75 ˚C) for 3 h. After
completion of the reaction, methanol and the excess of dimethyl carbonate were distilled off at
40 ˚C under reduced pressure. The remaining glycerol carbonate was analyzed by 1H NMR and
FTꢀIR spectroscopy. Glycerol carbonate was isolated with 98.5 % conversion. Glycerol
1
carbonate: H NMR (DMSO, 500 MHz),
δ
(ppm), 5.20 (1H, ꢀOH), 4.80 (1H, ꢀCH2ꢀCHꢀ), 4.49,
(ppm): 155.97
4.31 (2H, ꢀOꢀCH2), 3.67, 3.53 (2H, ꢀCH2ꢀCHꢀ). 13C NMR (DMSO, 125 MHz)
δ
(COꢀOꢀ), 77.17 (ꢀOHꢀCH2ꢀCHꢀ), 65.87 (ꢀOHꢀCH2ꢀCHꢀ), 60.80 (ꢀOHꢀCH2ꢀCHꢀCH2). IR (cmꢀ1):
3428 (ꢀOH stretching), 2920 (ꢀCH stretching aliphatic), 1761 (ꢀC=O stretching), 1480, 1399,
1277 (ꢀCH bending).
Glycidol.
A distillation apparatus with a 100 mL flask was placed in an oil bath with magnetic stirring.
The flask was charged with 40.0 g of the glycerol carbonate and 4.0 g of anhydrous sodium
sulphate. The reaction mixture was continuously stirred using magnetic stirrer under reduced
pressure and the flask was heated to 160 ˚C. Glycidol was allowed to be distilled off for 3 h.
The success of the reactions (i.e., purity of both glycerol carbonate and glycidol) were
determined by H1 NMR and FTIR. Glycidol was isolated in pure form with 33.0% yield.
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1
Glycidol: H NMR (CDCl3, 500 MHz),
δ (ppm), 4.83 (1H, ꢀOH), 2.99 (1H, ꢀCH2ꢀCHꢀ), 3.60,
3.33 (2H, ꢀOꢀCH2), 2.68, 2.53 (2H, ꢀCH2ꢀCHꢀ). 13C NMR (CDCl3, 125 MHz)
OHꢀCH2ꢀCHꢀ), 52.44 (ꢀOHꢀCH2ꢀCHꢀ), 44.30 (ꢀOHꢀCH2ꢀCHꢀCH2). IR (cmꢀ1): 3420 (ꢀOH
δ (ppm): 62.13 (ꢀ
stretching), 2926 (ꢀCH stretching aliphatic), 1397, 1269 (ꢀCH bending).
Glycidyl methacrylate.
A flask was charged with 50.0 g (0.5 moles) of methyl methacrylate; 7.4 g (0.1 mol) of
glycidol; 0.05 grams of 2,4ꢀdimethylꢀ6ꢀtert butyl phenol as polymerization inhibitor; and 0.055
g (0.85 millimoles) of potassium cyanide and the mixture heated to 70ꢀ80 °C for 2 h. They were
immediately vacuum distilled and two fractions were collected. Glycidyl methacrylate was
1
isolated with 25.3 % yield. Glycidyl methacrylate: H NMR (CDCl3, 500 MHz),
δ (ppm), 6.09,
5.72 (2H, ꢀC=CH2), 4.48, 3.92 (2H, ꢀCH2ꢀCHꢀ), 3.25 (1H, ꢀCH2ꢀCHꢀ), 2.82, 2.67 (2H, ꢀOꢀCH2),
1.90 (3H, ꢀCꢀCH3). 13C NMR (CDCl3, 125 MHz)
(ppm): 166.35 (=CꢀCOꢀOꢀ), 135.70 (ꢀ
δ
CH2=CꢀCOꢀO), 125.51 (ꢀCH2=CꢀCOꢀO), 64.92 (ꢀOꢀCH2ꢀepoxy ring), 48.93 (ꢀOꢀCH2ꢀCH
(epoxy ring)), 43.96 (ꢀOꢀCH2 (epoxy ring)), 17.78 (ꢀCH2=Cꢀ CH3). IR (cmꢀ1): 2995, 2951 (ꢀCH
stretching aliphatic), 1726 (ꢀC=O stretching), 1452, 1397,1326, 1269 (ꢀCH bending).
Synthesis of bisphenol A from phenol.
A 50 mL flask was charged with phenol (10.0 g, 106.3 mmol), 100 mg Amberlystꢀ15, 187.75
mg of 2ꢀdiethylaminoꢀethanethiol hydrochloride and acetone (2.80 g, 48.31 mmol). The
reaction mixture was heated to 65ꢀ90 ˚C for 24 h with constant stirring. After 24 hours, the
reaction mixture was cooled to ambient temperature, and the product was analysed by TLC and
1H NMR. The BPA was purified by column chromatography using 3:7 ethyl acetate: hexane
1
ratio. The H NMR showed that the conversion of BPA from phenol was ~27.0 %, but after
1
column purification, we could successfully isolated BPA with 9.0 % yield. Bisphenol A. H
NMR (DMSO, 500 MHz),
δ
(ppm), 9.12 (2H, ꢀOH), 6.98, 6.62 (8H, ꢀArH), 1.54 (6H, ꢀCꢀCH3).
(ppm): 155.39 (OHꢀC(ArC)), 141.57 (ꢀCH3ꢀCꢀC(ArC)), 127.7
13C NMR (DMSO, 125 MHz)
δ
(ꢀCH3ꢀCꢀC(ArC)ꢀC(ArC)), 155.08 (OHꢀC(ArC))ꢀC(ArC)), 41.38 (ꢀCH3ꢀCꢀC(ArC)), 31.40 (ꢀ
CH3ꢀCꢀC(ArC)). IR (cmꢀ1): 3320 (ꢀOH stretching), 2963 (ꢀCH stretching Ar), 1508, 1434, 1383
(ꢀCH bending).
Synthesis of vinyl ester resins (VER).
A 25 mL RB flask was charged with BPA (1.14 g, 5 mmol), GMA (1.42 g, 10 mmol) and N,Nꢀ
dimethylbenzylamine (0.0065 g, 0.05 mmol). The flask had continuous flow of argon, and the
temperature was raised to 70 ˚C, which was maintained for 6 h. After the reaction, the highly
1
viscous liquid was transferred to a glass vial, and the product was analysed by TLC, H NMR,
and FTꢀIR. By HPLC, the conversion of difunctional VER was observed to be 69.3 %.
Difunctional bisphenol A: 1H NMR (CDCl3, 500 MHz),
3.92 (2H, ꢀCH2ꢀCHꢀ), 3.25 (1H, ꢀCH2ꢀCHꢀ), 2.82, 2.67 (2H, ꢀOꢀCH2), 1.90 (3H, ꢀCꢀCH3). C
δ (ppm), 6.09, 5.72 (2H, ꢀC=CH2), 4.48,
13
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NMR (DMSO, 125 MHz)
δ (ppm): 167.09 (=CꢀCOꢀOꢀ), 156.58 (ꢀCH2ꢀOꢀC(ArC)), 143.25 (ꢀ
CH3ꢀCꢀC(ArC)), 136.13 (ꢀCH2=CꢀCOꢀO), 127.78 (ꢀCH2=CꢀCOꢀO), 126.45 (ꢀCH2ꢀOꢀC(ArC)ꢀ
C(ArC)), 114.10 (ꢀCH3ꢀCꢀC(ArC)ꢀC(ArC)), 69.27 (COꢀOꢀCH2ꢀCHꢀ CH2), 67.35(COꢀOꢀCH2ꢀ
CHꢀ CH2), 66.01(COꢀOꢀCH2ꢀCHꢀCH2), 39.48 (ꢀCH3ꢀCꢀC(ArC)), 30.78 (ꢀCH3ꢀCꢀC(ArC)),
18.35(ꢀCH2=CꢀCH3). IR (cmꢀ1): 3424 (ꢀOH stretching), 2963, 2926 (ꢀCH stretching aliphatic),
1724 (ꢀC=O stretching), 1634, 1607, 1597, 1403, 1362 (ꢀCH bending).
RESULTS AND DISCUSSION
Here we demonstrate the sustainable, environmentally benign synthesis of 'green' vinyl
ester resin (GVER). The GVER was synthesized predominantly from bioꢀwaste, namely
glycerin, recovered from biodiesel wastes. Such source materials are renewable, lowꢀcost, and
are becoming increasingly abundant and thus are expected to significantly reduce the
dependence on petroleum feedstock.
Synthesis of glycidyl methacrylate from glycerin
GMA was synthesized using glycerin as the main precursor. Glycerin is a sideꢀproduct
of the transesterification of triglyceraldehyde in manufacturing of biodiesel or the hydrolysis of
triglyceraldehyde during saponification. Figure 2 demonstrates the mixture of products
generated during the synthesis of biodiesel at Maine Standard Biofuels (MSB), which has
biodiesel in the top layer, soaps in the middle, and waste glycerin in the bottom. We obtained
the glycerin from waste stream of a biodiesel production facility of MSB. The crude glycerin
was purified using vacuum distillation at 190 °C, and isolated in pure form as shown in Figure 3.
Figure 2. Small scale biodiesel reaction at Maine Standard Biofuels (MSB). Biodiesel/methyl
esters (top), soaps (middle), crude glycerin (bottom).
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Figure 3. 1H NMR of the distilled glycerin.
Figure 4. 1H NMR of glycerol carbonate and glycidol.
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Glycerol carbonate (GC), a first intermediate in the synthetic route to GMA from the distilled
glycerin, is an attractive intermediate having a large number of applications in various fields.
Various approaches had been adopted by different groups for the synthesis of the GC; such as,
using (a) Novozyme 435 catalyst and dimethyl carbonate as a precursor,17 and (b) metal oxide
as a catalyst and urea as a precursor.18 In a new approach, GC was synthesized by reaction
between glycerin and dimethyl carbonate at 73 ˚C for 3 h in the presence of potassium
carbonate.19 The method is promising, with several challenges for example the separation of
potassium carbonate from the reaction mixture. Firstly, the reaction was performed at 73 ˚C and
1
the GC was synthesized successfully. The product formation was confirmed by H NMR as
shown in Figure 4. The peak integration value suggested ~ 98.5 % conversion of glycerin to GC
at 73 ˚C. In order to complete the reaction to 100.0 %, the reaction temperature was increased to
100 ˚C; however, as the temperature increased to 100 ˚C, formation of some side product was
observed and unreacted glycerin was also found in the final mixture. The FTꢀIR spectra of
glycerol carbonate synthesized at 73 ˚C clearly showed peaks of –C=O at 1772.51 cmꢀ1 and –
OH at 3456.9 cmꢀ1 as shown in Figure S2 in Supporting Information.
Glycidol is the second intermediate during the synthesis of GMA from glycerin.
Glycidol was obtained by decarboxylation of GC as shown in Figure 1. In a typical setup for the
synthesis of glycidol, a vacuum distillation apparatus was utilized. Glycidol was synthesized by
heating the glycerol carbonate in the presence of sodium sulfate at 180 ˚C for 3 h.20 The
1
formation of glycidol was confirmed by H NMR by matching the integration value of each
proton as shown in Figure 4. Strong evidence is provided by the FTꢀIR exhibiting a clear
disappearance of the –C=O peak at 1761 cmꢀ1 as shown in Figure S2 in Supporting Information.
Glycidol was isolated with 33.0 % yield.
Figure 5. 1H NMR of glycidyl methacrylate.
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Glycidyl methacrylate (GMA) is one of the precursors for the synthesis of vinyl ester
resin monomer along with bisphenol A. GMA was synthesized by transesterfication between
methyl methacrylate and the oxirane moiety in the presence of potassium cyanide as a catalyst
and 2,4ꢀdimethylꢀ6ꢀtertbutylphenol.21 First, the pressure was reduced in the reaction flask, and
the temperature was raised to 70 ˚C. The temperature of 70 ˚C was maintained for 2 h, and after
that unreacted methyl methacrylate and methanol were distilled off. In a second fraction
unreacted glycidol was collected and in last fraction GMA was obtained. The structure of GMA
was confirmed by 1H NMR as shown in Figure 5. The GMA was isolated with 25.3 % yield.
Synthesis of bisphenol A (BPA).
BPA was synthesized using a solventꢀfree environmentally benign synthetic protocol, in
which phenol was first melted in an oil bath at 60 ˚C then combined with acetone in the
presence of thioglycolic acid as a promoter.16 The reaction was performed in a reactor sealed
with a plastic stopper. The mixture yielded a crude product subsequently identified as a mixture
1
of BPA and unreacted phenol using thin layer chromatography and H NMR. The synthesized
BPA was purified by column chromatography using hexane: ethyl acetate in a 7:3 ratio as a
1
solvent mixture. The BPA was isolated with 9.0 % yield and product was confirmed by H
NMR as shown in Figure 6.
Figure 6. 1H NMR of bisphenol A.
Synthesis of vinyl ester resin (VER) monomer.
VER are formulated from VER monomer using a solvent/reactive diluent, typically
styrene, as well as additives to meet specific needs. In general, VER has several advantages
over other polymers. For example, toughened and brominated VER produces resins with higher
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strengths than polyesters and lower viscosity than epoxies. This low viscosity is critical for
fabricating large and intricate structures by vacuum infusion. Fiberglassꢀreinforced VER
composites are preferred for many structural composite applications. Recent advances in
compatible sizing have enabled stiffer reinforcement of VERs using carbon fiber.
The VER monomer was synthesized by a reaction between BPA and GMA in the
1
presence of amine catalyst. The reaction was performed at 70 ˚C under argon.22 The H NMR
did not exhibit the –OH peak of the BPA, so it was presumed that the reaction was 100 %
complete but, the integration value did not matching precisely. Thin layer chromatography
1
(TLC) displayed three spots. The integration values in the H NMR and the higher number of
spots in TLC confirmed the presence of product in the reaction mixture as shown in Figure 7.
V inyl Ester Resin
OH
O
O
OH
O
OH
O
O
O
OH
OH
O
O
O
O
O
O
OH
Figure 7. TLC of vinyl ester resin mixture in ethyl acetate and hexane in 3:7 ratios.
After confirming the presence of three different products in the reaction mixture; all
fraction were separated by column chromatography using a 3:7 ethyl acetate: hexane ratio and
1
1
analysed using H NMR as shown in Figure 8. The H NMR clearly indicated the presence of
nonꢀfunctional BPA (NF) in the first fraction; monoꢀfunctional BPA (MF), GMAꢀBPA, in the
second fraction; and diꢀfunctional BPA (DF), GMAꢀBPAꢀGMA, in the third fraction. The data
clearly suggested that a 2 h reaction time was insufficient to obtain the maximum amount of DF.
In order to increase the yield the reaction time was increased up to 6 h and sample was taken out
at periodic interval of time, and the molar ratio of the GMA: BPA was increased to 4:1. A very
strong evidence of the formation of the vinyl ester resin can be observed in the shifting of the
1
aromatic peaks in H NMR of the vinyl ester resin as shown in Figure S9 in the Supporting
Information. The peaks for the BPA aromatic protons can be observed at 7.10 (OHꢀCꢀ
CH(ArH)) and 6.83 (CHꢀCꢀCꢀCH3), which shift to 6.98 (ꢀOꢀCꢀCH) and 6.63(CHꢀCꢀCꢀCH3).,
respectively. The peak for all four aromatic protons can be observed at 7.10 (OHꢀCꢀCH(ArH)),
6.98 (ꢀOꢀCꢀCH), 6.83 (CHꢀCꢀCꢀCH3), and 6.63(CHꢀCꢀCꢀCH3) as shown in Figure S9 in the
Supporting Information.
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Figure 8. 1H NMR of each fraction from column separation.
In order to determine the kinetics of the reaction, the quantification of NF, MF and DF
in the reaction mixture is very essential. Such quantification can be obtained by high
performance liquid chromatographic (HPLC) separation of the mixture. Therefore, preliminary
work was conducted to develop a HPLC method for the separation and determination of BPA
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and reaction products in the synthesis of a VER. The ultimate goal was to separate each fraction
without overlapping retention time.
Chromatograms shown in Figure S4, S5 and S6 in Supporting Information clearly
demonstrate that the 3 compounds have very different retention times on the diol column with
7:3 hexane: ethyl acetate and should be easily separated and determined in a reaction mixture.
The first fraction (NF), second fraction (MF) and third fraction (DF) exhibited retention time of
5.218, 7.946, and 13.686 min respectively.
Table 1. Percentage of various components in VERꢀreaction mixture at different time intervals.
Different functional BPA
Reaction time (h)
Non
Mono
49.24
46.28
40.63
28.27
18.05
Di
2h
3h
4h
5h
6h
32.00
20.79
14.13
13.38
12.70
18.76
32.93
45.23
58.34
69.26
We quantified the NF, MF, and DF BPA by calculating and comparing the area under
the peak of the chromatogram obtained at different time intervals as shown in Table 1. The
results suggested that reaction proceeds well as time progresses. However, it did not attain
completion at 6 h, 69.26 % of the DF VER monomer was obtained. Experiments are in progress
and the results will be published in near future with additional work to further improve the yield
of this synthesis.
CONCLUSIONS
Glycidyl methacrylate, a valuable monomer in its own right, was successfully
synthesized using glycerin from biodiesel waste stream and environmentally benign reaction
conditions. During the novel synthetic protocol other valuable intermediates, such as glycerol
carbonate and glycidol, were also obtained. The second precursor, bisphenol A was synthesised
by the reaction of phenol and acetone using an environmentally benign synthetic protocol. The
GVER was synthesized by reaction of BPA and GMA. This synthetic strategy opens avenues
for obtaining this valuable resin using sustainable environmentally benign routes.
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DOI: 10.1039/C5RA03254G
ACKNOWLEDGEMENT. The author would like to thank the Strategic Environmental
Research and Development Program (SERDP WPꢀ1755; WPꢀ2317) for financial support of this
work.
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Table of contents
Environmentally Benign
Synthesis of Vinyl Ester
Resin from Biowaste
Glycerin
Priyank N. Shah,* Namjoon Kim,
Zhuangrong Huang, Mahesh
Jayamanna, Akshay Kokil, Alex
Pine, Jarmin Kaltsas, Edwin
Jahngen, David K. Ryan, Seongkyu
Yoon, Robert F. Kovar, and
Yongwoo Lee*
16