4-Oxocyclohexanecarboxylic acid: Hydrogen bonding in the monohydrate of a δ-keto acid

Article abstract of DOI:10.1107/S0108270103029329

The title monohydrate, C₇H₁₀O ₃·H₂O, aggregates as a complex hydrogen-bonding network, in which the water molecule accepts a hydrogen bond from the carboxyl group of one molecule and donates hydrogen bonds to ketone and carboxyl C=O functions in two additional molecules, yielding a sheet-like structure of parallel ribbons. The keto acid adopts a chiral conformation through rotation of the carboxyl group by 62.50 (15)° relative to the plane defined by its point of attachment and the ketone C and O atoms. Two C - H=O close contacts exist in the structure.

Full text of DOI:10.1107/S0108270103029329

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
4
-Oxocyclohexanecarboxylic
Figure 1
acid: hydrogen bonding in the
monohydrate of a d-keto acid
The asymmetric unit of (I); the water of hydration is shown, arbitrarily, in
its relation to the carboxyl OH group. Displacement ellipsoids are shown
at the 20% probability level.
Alan Barcon, Andrew P. J. Brunskill, Hugh W.
Thompson and Roger A. Lalancette*
molecules, is shown here in its relationship to atom O3, from
which it accepts a hydrogen bond.
The partial averaging of CÐO bond lengths and CÐCÐO
angles by disorder often seen in acids is unique to the
carboxyl-pairing hydrogen-bonding mode, whose geometry
permits transposition of the two carboxyl O atoms. As in other
hydrates that involve the acid, no signi®cant averaging is
observed for (I), whose bond lengths are 1.206 (3) and
Carl A. Olson Memorial Laboratories, Department of Chemistry, Rutgers
University, Newark, NJ 07102, USA
Correspondence e-mail: rogerlal@andromeda.rutgers.edu
Received 13 November 2003
Accepted 18 December 2003
Online 31 January 2004
Ê
ꢀ
1
Our own survey of 56 keto acid structures that are not acid
.326 (3) A, with angles of 124.5 (2) and 113.4 (2) (Table 1).
The title monohydrate, C H O ÁH O, aggregates as a
7
10
3
2
Ê
dimers gives average values of 1.200 (10) and 1.32 (2) A, and
complex hydrogen-bonding network, in which the water
molecule accepts a hydrogen bond from the carboxyl group
of one molecule and donates hydrogen bonds to ketone and
carboxyl C O functions in two additional molecules, yielding
a sheet-like structure of parallel ribbons. The keto acid adopts
a chiral conformation through rotation of the carboxyl group
ꢀ
1
accordance with typical values of 1.21 and 1.31 A, and 123 and
24.5 (14) and 112.7 (17) for these lengths and angles, in
Ê
ꢀ
1
12 cited for highly ordered dimeric carboxyls (Borthwick,
980).
Fig. 2 illustrates the packing in the cell and the hydrogen-
1
ꢀ
bonding network (Table 2). The latter does not incorporate
by 62.50 (15) relative to the plane de®ned by its point of
attachment and the ketone C and O atoms. Two CÐHÁ Á ÁO
close contacts exist in the structure.
Comment
Our studies of the crystallography of ketocarboxylic acids
explore the molecular characteristics that control their
hydrogen bonding. Beyond their ®ve known hydrogen-
bonding modes, keto acids sometimes occur as hydrates, with
complex hydrogen-bonding patterns that typically involve
both ketone and acid carbonyl groups. The title compound
crystallizes as a monohydrate, (I), with such a pattern of
hydrogen bonding. Although hydrate examples are known in
which the ketone function is as far as 12 atoms away from the
carboxyl group, most known hydrates are either ꢀ- or, like the
present case, ꢁ-keto acids.
Fig. 1 shows the asymmetric unit of (I). Although the
organic portion lacks inherent chirality, it adopts a chiral
conformation through rotation of its carboxyl unit about the
C1ÐC7 bond, the only conformational option available. This
group is turned so that the C1ÐC2 bond coincides with the
ꢀ
Figure 2
carboxyl plane [O2ÐC7ÐC1ÐC2 = 2.0 (4) ]. The dihedral
angle between the ketone (O1/C3±C5) and carboxyl (O2/O3/
A packing diagram, with the cell contents and extra molecules; several
water molecules have been included in order to clarify the hydrogen
bonding. For clarity, all C-bound H atoms have been omitted.
Displacement ellipsoids are shown at the 20% probability level.
ꢀ
C7/C1) planes is 48.91 (13) . The water molecule, which
donates hydrogen bonds to atoms O1 and O2 in separate
o140 # 2004 International Union of Crystallography
DOI: 10.1107/S0108270103029329
Acta Cryst. (2004). C60, o140±o142

organic compounds
any water-to-water hydrogen bonds (cf. Brunskill et al., 2001);
however, in an arrangement identical in its essentials to at
least two previously reported cases (Lalancette et al., 1990,
Crystal data
C H O ÁH O
7
10
3
2
Z = 2
�
3
M
r
= 160.17
Triclinic, P1
D
x
= 1.324 Mg m
Mo Kꢂ radiation
1
997), the water molecule accepts a hydrogen bond from the
Ê
a = 6.7298 (8) A
b = 7.2091 (11) AÊ
Ê
c = 8.4367 (12) A
ꢂ = 85.928 (13)
ꢃ = 83.075 (17)
Cell parameters from 19
re¯ections
carboxyl group of one molecule and donates hydrogen bonds
to ketone and acid C O functions in two separate molecules.
This produces three-bond intermolecular connections of both
the acid-to-water-to-acid and the acid-to-water-to-ketone
type, plus a four-bond acid-to-water-to-ketone connection, all
of which lie in a two-dimensional sheet of separate, parallel,
ribbon-like structures. This structure may be contrasted with
instances bearing exactly the same types of connections, which
produce structures that are three-dimensional rather than
lamellar (Thompson & Lalancette, 2001; Lalancette et al.,
ꢀ
ꢄ = 3.8±9.9
ꢀ
ꢀ
ꢀ
� 1
ꢅ = 0.11 mm
T = 243 (2) K
ꢀ = 82.132 (16)
V = 401.88 (10) A
Flat plate, colorless
0.45 Â 0.45 Â 0.02 mm
Ê
3
Data collection
Siemens P4 diffractometer
h = � 7 ! 1
2
1
1
ꢄ/ꢄ scans
798 measured re¯ections
405 independent re¯ections
k = � 8 ! 8
l = � 10 ! 10
3 standard re¯ections
every 97 re¯ections
intensity variation: <1.2%
2
002).
We characterize the geometry of hydrogen bonding to
920 re¯ections with I > 2ꢆ(I)
int = 0.023
R
ꢀ
ꢄ
max = 25.0
carbonyls using a combination of the HÁ Á ÁO C angle and the
HÁ Á ÁO CÐC torsion angle. These describe the approach of
the H atom to the O atom in terms of its deviation from,
Re®nement
2
2
2
o
2
ꢀ
Re®nement on F
2
w = 1/[ꢆ (F ) + (0.0363P)
respectively, C O axiality (ideal = 120 ) and planarity with
ꢀ
2
R[F > 2ꢆ(F )] = 0.045
wR(F ) = 0.105
S = 1.03
+ 0.0971P]
where P = (F + 2F )/3
o c
the carbonyl group (ideal = 0 ). In (I), the HÁ Á ÁO C and
2
2
2
ꢀ
HÁ Á ÁO CÐC angles are 145.2 (10) and 85.0 (16) for the
(Á/ꢆ)max < 0.001
3
Ê
�
ꢀ
1405 re¯ections
121 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
Áꢇmax = 0.15 e A
Áꢇmin = � 0.14 e AÊ
water-to-acid hydrogen bond, and 122.7 (9) and 8.5 (11) for
ꢀ
� 3
the water-to-ketone hydrogen bond. In particular, the 85.0
value departs dramatically from the supposed `ideal' value of
ꢀ
0
lie within normal parameters, between 2.606 (3) and
. The OÁ Á ÁO distances in this hydrogen-bonding network all
Ê
.797 (3) A.
2
Table 1
Selected geometric parameters (A, ).
Ê
ꢀ
Intermolecular CÐHÁ Á ÁO close contacts were found for the
Ê
acid carbonyl (2.56 A to atom H6B in a centrosymmetrically
O2ÐC7
1.206 (3)
124.5 (2)
O3ÐC7
1.326 (3)
113.4 (2)
Ê
related molecule) and for the water molecule (2.69 A to atom
H2B in a molecule translationally related along b). These
Ê
distances lie within the 2.7 A range that we employ as stan-
O2ÐC7ÐC1
O3ÐC7ÐC1
dard for non-bonded HÁ Á ÁO packing interactions (Steiner,
1
contacts, Steiner & Desiraju (1998) ®nd signi®cant statistical
Ê
directionality, even as far away as 3.0 A, and conclude that
997). Using compiled data for a large number of CÐHÁ Á ÁO
Table 2
Hydrogen-bonding geometry (A, ).
Ê
ꢀ
these are legitimately viewed as `weak hydrogen bonds', with a
greater contribution to packing forces than simple van der
Waals attractions.
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
O3ÐH3Á Á ÁO4
O4ÐH41Á Á ÁO1
O4ÐH42Á Á ÁO2
0.97 (4)
0.91 (3)
0.87 (4)
1.64 (4)
1.90 (3)
1.93 (4)
2.606 (3)
2.797 (3)
2.795 (3)
172 (3)
171 (3)
178 (3)
i
The solid-state (KBr) IR spectrum of the hydrate (I)
ii
�
1
displays a single broadened C O absorption at 1702 cm for
Symmetry codes: (i) x � 1; y � 1; z; (ii) � x; 1 � y; 2 � z.
both the acid and the ketone. In CHCl solution, where dimers
3
�
1
predominate, a single absorption is centered at 1711 cm .
All H atoms were found in electron-density difference maps. C-
Ê
bound H atoms were placed in calculated positions (CÐH = 0.98 A
Experimental
Ê
for methylene H atoms and 0.99 A for methine H atoms) and allowed
Compound (I) was synthesized by catalytic hydrogenation of an
ethanol solution of p-hydroxybenzoic acid over a rhodium catalyst;
Jones oxidation of the resulting oil yielded crystalline material.
Crystals of the monohydrate (I) suitable for X-ray diffraction (m.p.
to re®ne as riding on their respective C atoms; their displacement
parameters were allowed to re®ne. The hydroxy and water H atoms
were not constrained positionally and their displacement parameters
were allowed to re®ne.
3
36 K) were obtained from diethyl ether/hexane mixtures. The an-
hydrous form has also been reported (Perkin, 1904; Hardegger et al.,
944; Applequist & Klieman, 1961), although its melting point
341 K) is so close to that of (I) that in some reports one cannot tell
Data collection: XSCANS (Siemens, 1996); cell re®nement:
XSCANS; data reduction: XSCANS; program(s) used to solve
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
SHELXP97 (Sheldrick, 1997); software used to prepare material for
publication: SHELXL97.
1
(
which form was present. Combustion analyses of the anhydrate seem
always to err on the low-carbon side, suggesting, as we have found,
that this material hydrates easily.
ꢁ
Acta Cryst. (2004). C60, o140±o142
Alan Barcon et al.
7 10
C H O
3
2
ÁH O
o141

organic compounds
Lalancette, R. A., Brunskill, A. P. J. & Thompson, H. W. (1997). Acta Cryst.
C53, 1838±1842.
Lalancette, R. A., Brunskill, A. P. J. & Thompson, H. W. (2002). Acta Cryst.
C58, o491±o493.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: FR1456). Services for accessing these data are
described at the back of the journal.
Lalancette, R. A., Vanderhoff, P. A. & Thompson, H. W. (1990). Acta Cryst.
C46, 1682±1686.
Perkin, W. H. Jr (1904). J. Chem. Soc. 85, 416±438.
Sheldrick, G. M. (1997). SHELXL97, SHELXP97 and SHELXS97. Bruker
AXS Inc., Madison, Wisconsin, USA.
Siemens (1996). XSCANS. Version 2.2. Siemens Analytical X-ray Instruments
Inc., Madison, Wisconsin, USA.
Steiner, T. (1997). Chem. Commun. pp. 727±734.
Steiner, T. & Desiraju, G. R. (1998). Chem. Commun. pp. 891±892.
Thompson, H. W. & Lalancette, R. A. (2001). Acta Cryst. C57, 841±843.
References
Applequist, D. E. & Klieman, J. P. (1961). J. Org. Chem. 26, 2178±2182.
Borthwick, P. W. (1980). Acta Cryst. B36, 628±632.
Brunskill, A. P. J., Lalancette, R. A. & Thompson, H. W. (2001). Acta Cryst.
C57, 1075±1078.
Hardegger, E., Plattner, P. A. & Blank, F. (1944). Helv. Chim. Acta, 27, 793±
8
00.
ꢁ
o142 Alan Barcon et al.
C
7
H
10
O
3
2
ÁH O
Acta Cryst. (2004). C60, o140±o142