Synthesis of Renewable Bisphenols from Creosol
105. elemental analysis calcd. (%): C 70.81, H 6.99; found: C 70.84,
H 7.13.
phenylethane framework typically results in depressed melting
points compared to methylene or 2,2-diphenylpropane linkag-
es.[19] Despite this discrepancy, the melting point exhibited a
drastic decrease upon extension of the reaction from acetalde-
hyde to propionaldehyde, and 5 was isolated as a viscous oil.
For applications as precursors to thermosetting composites,
lower melting resins should allow simplified and lower-cost
fabrication methods.
5,5’-Methylenebis(2-methoxy-4-methylphenol) (3)
Compound 1 (5.03 g, 36.4 mmol) and 37% formaldehyde (1.47 g,
18.1 mmol) were diluted with deionized H2O (40 mL). Concentrated
HCl (10 mL) was slowly added, and the reaction was heated to
reflux under N2 for 3 h. A precipitate formed, the solution was dec-
anted, and the solid was washed with 10% ethanol solution.
The solid was dissolved in ether and precipitated with heptane.
Compound 3 was isolated as a crystalline white solid (3.29 g, 63%).
Crystals suitable for an X-ray diffraction study were obtained from
the slow evaporation of an ether solution at room temperature.
Conclusions
A series of bisphenols has been synthesized from creosol, a re-
newable phenol that can be produced from abundant waste
lignin. The functional groups on the ring and choice of catalyst
allow for control of the condensation productsand these reac-
tions can be conducted with stoichiometric amounts of the
phenol. The ability to recycle the acid catalysts, perform the re-
action in the absence of organic solvents, and isolate the prod-
ucts without resorting to solvent-intense purification methods
make these phenols intriguing renewable and sustainable
precursors to a variety of polymeric materials. Further work on
the conversion of these bisphenols to resins and polymers is
ongoing.
1
m.p. 131–1348C; H NMR ([D6]DMSO): d=2.08 (s, 6H), 3.56 (s, 2H),
3.71 (s, 6H), 6.30 (s, 2H), 6.72 (s, 2H), 8.54 ppm (s, 2H); 13C NMR
([D6]DMSO): d=19.0, 35.0, 56.2, 115.0, 117.0, 126.3, 131.3, 144.8,
146.6 ppm; MS: m/z=288, 273, 257, 241, 227, 213, 195, 181, 165,
150; elemental analysis calcd. (%): C 70.81, H 6.99; found: C 70.66,
H 7.16.
5,5’-(Ethane-1,1-diyl)bis(2-methoxy-4-methylphenol) (4)
Compound
1 (5.1 g, 37.0 mmol) and acetaldehyde (1.06 g,
24.1 mmol) were diluted with deionized H2O (40 mL). Concentrated
HCl (10 mL) was slowly added, and the mixture was heated to
reflux under N2 for 4 h. The supernatant was carefully decanted
from the resulting dense oil. Compound 4 was obtained as a white
solid after extraction into ether and precipitation with heptane
(3.74 g, 68%). Crystals suitable for an X-ray diffraction study were
obtained from the slow evaporation of an ether solution at room
Experimental Section
General
2-Methoxy-4-methylphenol (1), acetaldehyde, propionaldehyde,
formaldehyde (37%), Zn(Ac)2·2H2O, and concentrated HBr (48%)
were purchased from Aldrich and used as received. Concentrated
HCl and H2SO4 were purchased from Fisher Scientific and used as
received. NMR spectra were collected by using a Bruker Avance II
300 MHz NMR spectrometer. Samples of bisphenols were prepared
in [D6]DMSO, and spectra were referenced to the solvent peaks
(d=2.50 and 39.5 ppm for 1H and 13C NMR spectra, respectively).
The products were further analyzed by using an Agilent 6890-GC
system with a Restek RTX-5MS 30-meter column. The GC inlet tem-
perature was 2508C, and the column oven temperature program
began at 408C for three minutes and increased to 3508C at
108CminÀ1. An Agilent mass selective detector (MSD) 5973 system
was used to identify various products. Elemental analysis was per-
formed by Atlantic Microlabs Inc. Norcross, GA.
1
temperature. m.p. 143–1468C; H NMR ([D6]DMSO): d=1.30 (d, J=
7 Hz, 3H), 2.06 (s, 6H), 3.69 (s, 6H), 4.05 (t, J=7 Hz, 1H), 6.48 (s,
2H), 6.66 (s, 2H), 8.57 ppm (s, 2H); 13C NMR ([D6]DMSO): d=18.5,
21.3, 36.1, 56.0, 114.6, 115.0, 125.7, 137.0, 144.6, 145.5 ppm; MS: m/
z=303, 287, 269, 240, 211, 195, 164, 145, 128, 105; elemental anal-
ysis calcd.(%): C 71.50, H 7.33; found: C 71.58, H 7.46.
5,5’-(Propane-1,1-diyl)bis(2-methoxy-4-methylphenol) (5)
Compound 1 (5.02 g, 36.4 mmol) and propionaldehyde (1.04 g,
17.9 mmol) were diluted with deionized H2O (10 mL). 48% aqueous
HBr (20 mL) was slowly added, and the reaction was stirred
at room temperature overnight. The supernatant was carefully de-
canted from the resultant oil, and the product was washed with
water. Work up by using the method described above yielded 5 as
a viscous tan oil (3.82 g, 67%). The product formed a solvent
adduct with DMSO that crystallized from ether solutions upon
6,6’-Methylenebis(2-methoxy-4-methylphenol) (2)
1
standing at room temperature. H NMR ([D6]DMSO): d=0.85 (t, J=
Compound
1 (5 g, 36.2 mmol), 37% formaldehyde (1.56 g,
7 Hz, 3H), 1.73 (t, J=7 Hz, 2H), 2.10 (s, 6H), 3.69 (s, 6H), 3.81 (t, J=
7 Hz, 1H), 6.52 (s, 2H), 6.65 (s, 2H), 8.55 ppm (s, 2H); 13C NMR
([D6]DMSO): d=13.1, 18.9, 28.9, 43.3, 56.1, 114.9, 115.0, 126.3,
135.5, 144.5, 145.6 ppm; MS: m/z=316, 287, 257, 240, 211, 195,
167, 151, 131, 115; elemental analysis calcd. for 5·1.5H2O: C 66.45,
H 7.92; found: C 66.33, H 7.78.
19.2 mmol), and Zn(ac)2·2H2O (70 mg, 3.2ꢂ10À4 mol) were heated
to reflux overnight under N2. The resulting oil was washed with
10% ethanol, and extracted into ether. The ether was removed on
a rotary evaporator and the resulting oil was heated to 1008C
overnight under reduced pressure (133.3 Pa). The resulting solid
was dissolved in ether and precipitated with heptane. The light-tan
solid was collected by filtration, washed with excess heptane, and
dried to yield 2.13 g (41%) of 2. m.p. 123–1258C; 1H NMR
([D6]DMSO): d=2.11 (s, 6H), 3.71 (s, 2H), 3.74 (s, 6H), 6.35 (d, J=
2 Hz, 2H), 6.58 (d, J=2 Hz, 2H), 8.20 ppm (s, 2H); 13C NMR
([D6]DMSO): d=21.1, 29.0, 56.2, 110.7, 122.7, 127.4, 127.7, 141.9,
147.5 ppm; MS: m/z=288, 271, 255, 239, 212, 195, 165, 138, 121,
Acknowledgements
The authors would like to thank Dr. Michael Wright and Dr. Matt
Davis for helpful discussions, Ms. Roxanne Quintana for GC–MS
ChemSusChem 2012, 5, 206 – 210
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
209