Communications
Biomass Conversion
Butenolide Derivatives of Biobased Furans: Sustainable Synthetic
Dyes
Jan Saska, Zheng Li, Andrew L. Otsuki, Jiahui Wei, James C. Fettinger, and Mark Mascal*
Abstract: The dye and pigment manufacturing industry is one
of the most polluting in the world. Each year, over one million
tons of petrochemical colorants are produced globally, the
synthesis of which generates a large amount of waste. Naturally
occurring, plant-based dyes, on the other hand, are resource
intensive to produce (land, water, energy), and are generally
less effective as colorants. Between these two extremes would
be synthetic dyes that are fully sourced from biomass-derived
intermediates. The present work describes the synthesis of such
compounds, containing strong chromophores that lead to
bright colors in the yellow to red region of the visible spectrum.
The study was originally motivated by an early report of an
unidentified halomethylfurfural derivative which resulted from
hydrolysis in the presence of barium carbonate, now charac-
terized as a butenolide of 5-(hydroxymethyl)furfural (HMF).
The method has been generalized for the synthesis of dyes from
other biobased platform molecules, and a mechanism is
proposed.
Despite the large market for organic dyes, sustainable
chemistry research has primarily targeted fuels and polymers,
and virtually no reports of renewable synthetic colorants have
appeared to date. The present work thus represents an
approach to introducing a new major chemical commodity to
sustainable practice, that is, biobased synthetic dyes.
5-(Chloromethyl)furfural (CMF) 1 is a car-
bohydrate-derived renewable platform mole-
cule that is considered to be a disruptive
innovation in the field of green chemistry.[5,6]
Equivalent to 5-(hydroxymethyl)furfural
(HMF) 2 in its synthetic versatility, CMF
1 can be produced in high yield directly from
raw biomass, while HMF 2 is only practically
derived from fructose.[7]
CMF first appeared in the literature in 1901, when Henry
Fenton (of Fentonꢀs reagent fame)[8] described its production
in low yields by treatment of sugars or cellulose with HCl.[9]
We were intrigued by the description of an early investigation
into the chemistry of halomethylfurfurals that borrowed from
Fentonꢀs work, in which treatment of 5-(bromomethyl)furfu-
ral (BMF) with barium carbonate in hot water resulted in the
isolation of “a beautiful yellow … compound, which usually
crystallizes in canary-yellow needles.”[10] The proposed for-
mula was C11H10O4, and yields were described as variable
without being specified. No structural assignment was made,
although it was suggested that the product could be the result
of the reaction of BMF with levulinic acid, the latter of which
is a known decomposition product of HMF. With the benefit
of modern analytical techniques, we set out to determine the
structure of this compound and investigate the chemistry of its
formation.
We first reproduced the method as described in the
literature, but substituting the more practical CMF for BMF.
Thus CMF was suspended in water and the mixture was
heated from room temperature to 608C. Solid barium
carbonate was introduced portionwise. Once a clear solution
was obtained, an excess of BaCO3 was added and the mixture
was heated to near boiling and then filtered hot. The filtrate
deposited a yellow oil which on cooling gradually solidified to
a mass of deep yellow needles. We have now identified this
product as 3 (Scheme 1), the apparent result of the reaction of
I
ndustrial dyes and pigments are almost exclusively derived
from petrochemicals. The production for example of azo dyes,
the largest class of organic colorants, relies on polyaromatic
scaffolds from coal tar refining. Although many petroleum-
based materials can be recycled, 100% of dyes end up in
landfills, with all of their fossil carbon, ca. one million tons
globally per annum, ultimately emerging as CO2 in the
atmosphere.[1] An answer to this issue from the sustainability
movement has been to promote the use of plant-based dyes.[2]
However, these products are expensive, suffer from generally
inferior coloring performance, and many have poor substan-
tivity, requiring metal mordants as fixatives, most of which
ends up as effluent. Finally, natural dyes are low-yield crops
with consequent land, water, energy, and agrochemical
burdens. Alternative microbiologically-produced and waste-
based colorants embody creative alternatives to botanical
dyes,[3,4] although production limitations would suggest this is
not a comprehensive solution to the problem.
[*] Dr. J. Saska, Z. Li, A. L. Otsuki, J. Wei, Dr. J. C. Fettinger,
Prof. M. Mascal
Department of Chemistry, University of California Davis
1 Shields Avenue, Davis, California 95616 (USA)
E-mail: mjmascal@ucdavis.edu
Z. Li
College of Energy, Xiamen University
Xiangan South Road, Xiamen, Fujian, 361102 (China)
Supporting information and the ORCID identification number(s) for
Scheme 1. Original synthesis of 3 from CMF and aq. barium carbon-
ate.
Angew. Chem. Int. Ed. 2019, 58, 1 – 5
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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These are not the final page numbers!