The Synthesis of Rhodizonic and Croconic Acid

The Synthesis of Rhodizonic and Croconic Acid
Lucille Ames, Steven Merrill, and Dr. Douglas Smith
Department of Chemistry and Biochemistry
California State University, San Bernardino
Abstract
Croconic acid and rhodizonic acid were prepared from
glyoxal according to the method of Fatiadi.1 Croconic
acid was prepared in three steps with an overall yield of
9%. Rhodizonic acid was prepared in two steps with an
overall yield of 9%. Materials were recrystallized and
purity was determined by 13C NMR spectroscopy.
Introduction
Croconic acid (2, below) belongs to a family of compounds known as
oxocarbon acids, that are a series of cyclic organic molecules that contain
one or more carbonyl groups (C=O), two hydroxyl groups (-OH) and one
carbon-carbon double bond (C=C). Recently, croconic acid was reported
by Horiuchi2 to be ferroelectric. Ferroelectric materials possess
polarization that can be reversed by applying an external electric field.
Closely related to ferroelectricity is the property of piezoelectricity. In
piezoelectricty, the application of pressure to a material will lead to the
production of an electrical charge. Ferroelectric materials may
potentionally be used in creating ferroelectric RAM in computers and
piezoelectric materials may be used as pressure sensors. Thus,
discovering new ferroelectric and piezoelectric materials is highly
desirable.
The current research focuses upon the production and testing of rhodizonic
acid (1), croconic acid (2), squaric acid (3, a known anti-ferroelectric
substance), and deltic acid (4), and their derivatives. It is postulated that
due to their structural similarities, these molecules and/or their derivatives
may possess previously unreported properties such as those mentioned
above.
O
HO C O
C C
C C
HO C O
O
Rhodizonic Acid (1)
HO
HO
C
C
O
C
CO
C
O
Croconic Acid (2)
HO
HO
CC
CC
O
O
Squaric Acid (3)
Discussion
Methods and Materials
1
Croconic acid and rhodizonic accid were prepared according to the method of Fatiadi and
are pictured in Scheme 1 and Scheme 2 below.
Preparation of Croconic Acid (2):
The preparation of croconic acid is shown below in Scheme 1.
Rhodizonic Acid (1) was prepared in an overall yield of
13
9% from glyoxal. When the
C NMR spectrum was taken
of rhodizonic acid (shown below) the following peaks
were observed: 190.2, 141.2, and 93.9 ppm. This is
consistent with data reported in the literature.
The disodium salt of tetrahydroxybenzoquinone (6) was prepared as follows. Sodium sulfite
(400 g), sodium bicarbonate (150 g), and glyoxal (5, 180 g) were placed in 3 L of water and
heated to 90oC with stirring and a continuous stream of air was bubbled through the
solution. The air was discontinued and the mixture was then heated to reflux. After boiling,
the solution was allowed to cool to room temperature and the mixture was filtered to
provide, after drying, 28 g of a black solid (15% yield).
Next, 21 g of the above disodium salt, 40 g sodium hydroxide and 55 g manganese (IV)
oxide were placed in 1 L of water and heated to reflux. The solution was filtered hot and
then concentrated hydrochloric acid was added to filtrate. Barium chloride (50 g) was then
added and the resulting solution was heated to 85 oC. The solution was then cooled to room
temperature and filtered to provide, after drying, 26 g of barium croconate (7, 85% yield).
Finally, 20 g of barium croconate was added to an aqueous solution of sulfuric acid and
then the resulting solution was stirred with heating to 60 oC. The resulting mixture was
filtered, the solvent was concentrated and the crystals were isolated to provide, after
drying, 19 g of croconic acid (2, 71% yield).
Preparation of Rhodizonic Acid (1):
The prepartaion of rhodizonic acid is shown below in Scheme 2.
The disodium salt of tetrahydroxybenzoquinone (6) was preformed as described above.
Interestingly, croconic Acid (2) also had an overall
yield of 9% from glyoxal. When the 13C NMR of
Croconic Acid was obtained (see below), the
following peaks were observed: 182.4, 149.3, and
86.9 ppm. An additional peak was observed in the
13C spectrum for croconic acid. This peak, which had
a chemical shift of 192 ppm was determined to be
the dianion of dissociation of H+ from both hydroxyl
groups. Again, this data is consistent with the
literature.
Disodium salt (6, 35 g) was heated in an oven to 175 oC for 24 hrs. The resulting solid was
then treated with 2.5 M HCl and then cooled in an ice bath. The crystals were recovered
and recrystallized to provide 19 g of rhodizonic acid (1, 60% yield).
HO
C
CO
C
HO
Deltic Acid (4)
References
1. Fatiadi, A.; Isbell, H.; Sager, W., "Cyclic Poluhydroxy Ketones, I.
Oxidation Products of Hexahydroxybenzene (Benzenehexol),"
Journal of Research of the national Bureau of Standards- A.
Physics and Chemistry. 1962, 67A. 153-162.
2. Horiuchi, S.; Tokunaga, Y.; Giovannetti, G.; Picozzi, S.; Itol, H.;
Shimano, R.; Kumai, R.; Tokura, T., "Above-Room-Temperature
Ferroelectricity in a Single-Component Molecular Crystal," Nature
2010, 463. 789-792.
3. Stadeli, W.; Hollenstein, R.; von Philipsborn, W., "13C-NMR.
Spectra, Structure and Reactivity of Cyclic Oxocarbons," Helv.
Chim. Acta. 1977, 60, 948-958.
Acknowledgements
Upward Bound Program, California State University, San
Bernardino
Department of Education, Upward Bound #P047A080976
The Department of Chemistry and Biochemistry ,
California State University, San Bernardino
Department of Defense #W911NF1210080
National Science Foundation, CREST NSF-HRD #1435163
Amylee M. Martin
Steven R. Merrill
Katie L Morrow
Dr. Douglas C. Smith, Professor of Chemistry