CHEMSUSCHEM
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vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether,
azelaic acid, phosphoric acid, 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU), and chloroform-d were obtained from Sigma–Aldrich. Suc-
cinic acid was obtained from Sigma–Aldrich (petrochemical based)
and BioAmber (bio-based), with no difference in properties. Potas-
sium permanganate was obtained from TCI. Epoxidized sucrose
soyate (ESS) was prepared as previously reported.[4]
~1 with concentrated HCl, during which a pale yellow precipitate
was formed. The precipitate was isolated by filtration, washed with
excess water and dried in a high vacuum at 608C to give a pale
yellow solid in 5.04 g (64% yield). 1H NMR (500 MHz, [D6]DMSO):
d=7.28 ppm (s, 2H); HRMS [ESI-MS] m/z: Calculated for C6H3O4Na
[MÀOH] 139.0026 found 139.0018.
Synthesis of brassylic acid (BrA)
Synthesis of 2,5-furandicarboxylic acid from fructose
To a 1000 mL three-necked flask equipped with a refluxing con-
denser and a mechanical stirrer, was added erucic acid (from TCI,
recrystallized with 95% ethanol) (110 g, 0.325 mol), freshly distilled
tert-butanol (650 mL), 30% H2O2 (221 mL, 1.95 mol), and tungstic
acid (8.09 g, 0.0325 mol). The mixture was stirred at reflux for 60 h.
After completion, the yellow catalyst was filtered off and washed
with hot methanol (about 20 mL) at once. The catalyst was recov-
ered (about 100%). The excess H2O2 was decomposed with sodium
sulfite solution (10%) (until potassium iodide starch paper shows
a negative test) before it was concentrated under reduced pres-
sure. The residue was then extracted with ethyl acetate (5ꢁ
200 mL) and dried using anhydrous MgSO4. The drying reagent
was filtered off. The solvent was then removed under reduced
pressure. The residue was then put in a freezer for about 5 h. Final-
ly, some white solid appeared and hexane (100 mL) was added.
The product brassylic acid was obtained by filtration (42 g, 53%).
The pure compound was finally obtained by recrystallization in
acetone:H2O, with a melting point of 110–1148C.
Step 1. Synthesis of 5-hydroxymethylfurfural (HMF) from fructose
(Scheme 3): A modified literature procedure was adopted.[10] To an
oven dried 250 mL 2-neck RB fitted with a condenser, d-fructose
(10 g, 55.5 mmol) and N,N-dimethylacetamide (DMAc, 100 mL)
were added under a nitrogen atmosphere. To this, LiBr (10 g) was
Scheme 3. Reaction scheme for the synthesis of HMF.
added, followed by catalytic amount of H2SO4 (0.326 g, 3.33 mmol,
0.06 equiv 0.17 mL) and stirred at 1008C for 6 h. After completion,
the reaction mixture was cooled to room temperature and filtered
through a bed of Celite to remove the insolubles. The Celite bed
was washed with ethyl acetate (3ꢁ25 mL). The Ethyl acetate in the
filtrate was removed under reduced pressure followed by DMAc
using vacuum distillation. The residue left after vacuum distillation
was diluted with ethyl acetate, washed with saturated brine solu-
tion, dried over Na2SO4 and the solvent removed under vacuum.
Pure compound was obtained by column chromatography using
hexane-ethyl acetate (60:40) as an eluent and silica gel (300–400
Mesh) as a stationary phase. 5-hydroxymethylfurfural was obtained
as a pale yellow viscous liquid (which solidifies upon cooling) in
Synthesis of blocked acids
Synthesis of ethyl vinyl ether blocked succinic acid (EVE-SuA): Ethyl
vinyl ether (24.43 g, 338.7 mmol) and succinic acid (10.00 g,
84.68 mmol) were combined in a single neck round bottom flask,
followed by the addition of phosphoric acid (0.0553 g, 0.565 mmol)
while stirring. The mixture was heated at 308C and stirred for 5 h
at this temperature. The reaction mixture was allowed to cool to
room temperature and was then transferred to a separatory
funnel. To this, 40 mL of 0.05m KOH in water was added to remove
the phosphoric acid. The isolated organic layer was then placed in
a fresh round bottom flask, and the excess ethyl vinyl ether was re-
moved via rotary evaporation. This afforded EVE-SuA as a clear
liquid. The amount of EVE-SuA recovered and the calculated acid
number show that 99% of the initial succinic acid is recovered.
1H NMR (500 MHz, CDCl3): d=1.17 (t, 6H), 1.35 (d, 6H), 2.64 (m,
4H), 3.42 and 3.61 (m, 4H), 5.93 ppm (q, 2H). Similar NMR data
was obtained for the other blocked acids.
1
3.17 g (45% yield). H NMR (400 MHz, CDCl3): d=9.53 (s, 1H), 7.19
(d, 1H, J=3.5 Hz), 6.49 (d, 1H, J=3.5 Hz), 4.68 (s, 2H), 3.27 ppm (s
(broad), 1H).
Step 2. Synthesis of 2,5-furandicarboxylic acid (FDCA) (Scheme 4): A
modified literature procedure was adopted.[11] To a solution of HMF
(6.99 g, 55.5 mmol) in H2O (370 mL), aq. NaOH (51 g, 12.8 mol in
Synthesis of propyl vinyl ether blocked succinic acid (PVE-SuA): The
procedure for the synthesis of EVE-SuA was followed, with the re-
action being stirred at 708C for 5 h rather than at 308C.
Synthesis of butyl vinyl ether blocked succinic acid (BVE-SuA): The
procedure for the synthesis of EVE-SuA was followed, with the re-
action being stirred at 808C for 5 h rather than at 308C.
Scheme 4. Reaction scheme for the synthesis of FDCA.
Synthesis of isobutyl vinyl ether blocked succinic acid (IBVE-SuA):
The procedure for the synthesis of EVE-SuA was followed, with the
reaction being stirred at 808C for 5 h rather than at 308C.
93 mL of H2O) was added and then KMnO4 (0.127 mmol) was
added and the reaction mixture was stirred at room temperature
for 3–12 h. After completion, the reaction mixture was filtered to
remove the insoluble and the filtrate was subsequently cooled to
0–58C with ice. After cooling, pH of the solution was adjusted to
Synthesis of ethyl/propyl/butyl/isobutyl vinyl ether blocked azelaic
acid (EVE-AzA, PVE-AzA, BVE-AzA, and IBVE-AzA): The synthesis pro-
cedure used for the equivalently blocked succinic acid was used
for the azelaic acid reactions.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemSusChem 0000, 00, 1 – 7
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Kovash Jr., Curtiss S.
