An X-ray diffraction study of the title compound, C
12H
11NO
4, has shown that this compound exists in the crystal as the 2-oxo-4-hydroxy tautomer. The formation of two O—H
O=C-type intramolecular hydrogen bonds leads to the elongation of both exocyclic and carboxylic C=O double bonds involved in the hydrogen bonding, causes shortening of the exocyclic C—O single bond, and also affects the C—C bond lengths in the dihydropyridine ring.
Supporting information
CCDC reference: 182609
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.002 Å
- R factor = 0.038
- wR factor = 0.116
- Data-to-parameter ratio = 11.6
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level C:
ABSMU_01 Alert C The ratio of given/expected absorption coefficient lies
outside the range 0.99 <> 1.01
Calculated value of mu = 0.108
Value of mu given = 0.110
SHFSU_01 Alert C The absolute value of parameter shift to su ratio > 0.05
Absolute value of the parameter shift to su ratio given 0.085
Additional refinement cycles may be required.
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check
The title compound was prepared according to the procedure of Ukrainets et
al. (1996).
All H atoms, except the H atoms of the hydroxy groups, were placed in calculated
positions and included in the refinement as riding, with Uiso
constrained to be 1.2Ueq of the carrier atom (1.5Ueq for
methyl H atoms). Hydroxy H atoms were located in a difference maps and refined
in the isotropic approximation.
Data collection: P3 (Siemens, 1989); cell refinement: P3; data reduction: XDISK (Siemens, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1991); software used to prepare material for publication: SHELXL97.
1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid
top
Crystal data top
C12H11NO4 | F(000) = 488 |
Mr = 233.22 | Dx = 1.426 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 9.278 (2) Å | Cell parameters from 24 reflections |
b = 14.050 (4) Å | θ = 10–11° |
c = 8.938 (2) Å | µ = 0.11 mm−1 |
β = 111.21 (3)° | T = 293 K |
V = 1086.2 (5) Å3 | Needles, colourless |
Z = 4 | 0.40 × 0.20 × 0.20 mm |
Data collection top
Siemens P3/PC diffractometer | Rint = 0.012 |
Radiation source: fine-focus sealed tube | θmax = 25.0°, θmin = 2.3° |
Graphite monochromator | h = −11→10 |
θ–2θ scans | k = 0→16 |
2133 measured reflections | l = 0→10 |
1885 independent reflections | 2 standard reflections every 98 reflections |
1153 reflections with I > 2σ(I) | intensity decay: 5% |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.116 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.97 | w = 1/[σ2(Fo2) + (0.0812P)2] where P = (Fo2 + 2Fc2)/3 |
1885 reflections | (Δ/σ)max = 0.085 |
162 parameters | Δρmax = 0.15 e Å−3 |
0 restraints | Δρmin = −0.14 e Å−3 |
Crystal data top
C12H11NO4 | V = 1086.2 (5) Å3 |
Mr = 233.22 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.278 (2) Å | µ = 0.11 mm−1 |
b = 14.050 (4) Å | T = 293 K |
c = 8.938 (2) Å | 0.40 × 0.20 × 0.20 mm |
β = 111.21 (3)° | |
Data collection top
Siemens P3/PC diffractometer | Rint = 0.012 |
2133 measured reflections | 2 standard reflections every 98 reflections |
1885 independent reflections | intensity decay: 5% |
1153 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.116 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.97 | Δρmax = 0.15 e Å−3 |
1885 reflections | Δρmin = −0.14 e Å−3 |
162 parameters | |
Special details top
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc.
and is not relevant to the choice of reflections for refinement.
R-factors based on F2 are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.59133 (12) | 0.83381 (8) | 0.03227 (14) | 0.0409 (3) | |
C2 | 0.43989 (17) | 0.80711 (11) | −0.00738 (18) | 0.0456 (4) | |
C3 | 0.34375 (17) | 0.85989 (11) | 0.0589 (2) | 0.0496 (4) | |
C4 | 0.40513 (19) | 0.93366 (12) | 0.1649 (2) | 0.0536 (4) | |
C5 | 0.56517 (18) | 0.95893 (10) | 0.21021 (17) | 0.0468 (4) | |
C6 | 0.6329 (2) | 1.03379 (12) | 0.3190 (2) | 0.0655 (5) | |
H6 | 0.5735 | 1.0678 | 0.3649 | 0.079* | |
C7 | 0.7857 (3) | 1.05629 (13) | 0.3568 (2) | 0.0750 (6) | |
H7 | 0.8296 | 1.1058 | 0.4278 | 0.090* | |
C8 | 0.8748 (2) | 1.00548 (13) | 0.2898 (2) | 0.0675 (5) | |
H8 | 0.9784 | 1.0213 | 0.3164 | 0.081* | |
C9 | 0.81315 (18) | 0.93217 (12) | 0.1848 (2) | 0.0528 (4) | |
H9 | 0.8755 | 0.8985 | 0.1420 | 0.063* | |
C10 | 0.65706 (16) | 0.90758 (10) | 0.14141 (16) | 0.0408 (4) | |
C11 | 0.68548 (19) | 0.78072 (12) | −0.04404 (19) | 0.0532 (4) | |
H11A | 0.7574 | 0.8243 | −0.0645 | 0.064* | |
H11B | 0.6178 | 0.7556 | −0.1464 | 0.064* | |
C12 | 0.7752 (2) | 0.69946 (13) | 0.0598 (2) | 0.0661 (5) | |
H12A | 0.8447 | 0.7242 | 0.1601 | 0.099* | |
H12B | 0.8331 | 0.6669 | 0.0056 | 0.099* | |
H12C | 0.7044 | 0.6558 | 0.0795 | 0.099* | |
O13 | 0.38718 (13) | 0.73776 (8) | −0.10185 (14) | 0.0662 (4) | |
C14 | 0.1795 (2) | 0.83414 (15) | 0.0133 (3) | 0.0746 (6) | |
O15 | 0.12440 (15) | 0.76423 (12) | −0.0903 (2) | 0.0885 (5) | |
H15O | 0.201 (4) | 0.738 (2) | −0.123 (3) | 0.091 (8)* | |
O16 | 0.09477 (17) | 0.87788 (12) | 0.0696 (2) | 0.1101 (6) | |
O17 | 0.32029 (18) | 0.98451 (10) | 0.22852 (19) | 0.0829 (5) | |
H17O | 0.222 (3) | 0.9531 (19) | 0.192 (3) | 0.121 (10)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0403 (7) | 0.0421 (7) | 0.0412 (7) | 0.0043 (5) | 0.0158 (5) | −0.0010 (5) |
C2 | 0.0449 (8) | 0.0430 (8) | 0.0459 (9) | 0.0024 (7) | 0.0128 (7) | 0.0067 (7) |
C3 | 0.0427 (8) | 0.0507 (9) | 0.0585 (10) | 0.0065 (7) | 0.0221 (7) | 0.0155 (8) |
C4 | 0.0604 (10) | 0.0506 (9) | 0.0634 (10) | 0.0209 (8) | 0.0387 (9) | 0.0170 (8) |
C5 | 0.0596 (10) | 0.0405 (8) | 0.0422 (9) | 0.0099 (7) | 0.0209 (7) | 0.0047 (7) |
C6 | 0.0934 (14) | 0.0476 (10) | 0.0530 (10) | 0.0155 (9) | 0.0235 (10) | −0.0006 (8) |
C7 | 0.0901 (15) | 0.0486 (10) | 0.0629 (12) | −0.0044 (10) | −0.0006 (10) | −0.0086 (9) |
C8 | 0.0580 (11) | 0.0567 (11) | 0.0689 (12) | −0.0080 (9) | 0.0001 (9) | 0.0053 (9) |
C9 | 0.0459 (9) | 0.0520 (9) | 0.0564 (10) | 0.0015 (7) | 0.0135 (7) | 0.0044 (8) |
C10 | 0.0438 (8) | 0.0377 (8) | 0.0392 (8) | 0.0045 (6) | 0.0131 (6) | 0.0051 (6) |
C11 | 0.0533 (9) | 0.0603 (10) | 0.0503 (9) | 0.0076 (7) | 0.0240 (7) | −0.0085 (8) |
C12 | 0.0644 (11) | 0.0625 (11) | 0.0718 (12) | 0.0199 (8) | 0.0249 (9) | −0.0054 (9) |
O13 | 0.0608 (7) | 0.0593 (7) | 0.0683 (8) | −0.0096 (6) | 0.0112 (6) | −0.0122 (6) |
C14 | 0.0520 (11) | 0.0740 (13) | 0.1048 (17) | 0.0096 (10) | 0.0367 (11) | 0.0335 (12) |
O15 | 0.0539 (8) | 0.0856 (10) | 0.1138 (12) | −0.0165 (7) | 0.0156 (8) | 0.0185 (9) |
O16 | 0.0656 (10) | 0.1137 (13) | 0.1771 (17) | 0.0137 (9) | 0.0755 (11) | 0.0292 (12) |
O17 | 0.0919 (10) | 0.0780 (10) | 0.1055 (11) | 0.0259 (8) | 0.0678 (10) | 0.0038 (8) |
Geometric parameters (Å, º) top
N1—C2 | 1.3712 (19) | C5—C10 | 1.416 (2) |
N1—C10 | 1.4026 (18) | C6—C7 | 1.370 (3) |
N1—C11 | 1.4885 (19) | C7—C8 | 1.382 (3) |
C2—O13 | 1.2660 (18) | C8—C9 | 1.371 (2) |
C2—C3 | 1.442 (2) | C9—C10 | 1.400 (2) |
C3—C4 | 1.381 (2) | C11—C12 | 1.516 (2) |
C3—C14 | 1.473 (3) | C14—O16 | 1.239 (3) |
C4—O17 | 1.333 (2) | C14—O15 | 1.320 (3) |
C4—C5 | 1.435 (2) | O15—H15O | 0.93 (3) |
C5—C6 | 1.416 (2) | O17—H17O | 0.96 (3) |
| | | |
C2—N1—C10 | 121.94 (12) | C10—C5—C4 | 118.39 (14) |
C2—N1—C11 | 117.44 (12) | C7—C6—C5 | 120.25 (17) |
C10—N1—C11 | 120.62 (11) | C6—C7—C8 | 120.08 (17) |
O13—C2—N1 | 119.70 (14) | C9—C8—C7 | 121.23 (17) |
O13—C2—C3 | 121.51 (14) | C8—C9—C10 | 120.52 (17) |
N1—C2—C3 | 118.79 (13) | C9—C10—N1 | 121.38 (14) |
C4—C3—C2 | 120.34 (14) | C9—C10—C5 | 118.63 (14) |
C4—C3—C14 | 120.17 (17) | N1—C10—C5 | 120.00 (12) |
C2—C3—C14 | 119.48 (17) | N1—C11—C12 | 112.32 (13) |
O17—C4—C3 | 122.31 (16) | O16—C14—O15 | 120.84 (19) |
O17—C4—C5 | 117.21 (17) | O16—C14—C3 | 120.7 (2) |
C3—C4—C5 | 120.47 (14) | O15—C14—C3 | 118.42 (19) |
C6—C5—C10 | 119.29 (15) | C14—O15—H15O | 111.5 (18) |
C6—C5—C4 | 122.31 (15) | C4—O17—H17O | 104.4 (17) |
| | | |
C10—N1—C2—O13 | −177.35 (13) | C6—C7—C8—C9 | 0.1 (3) |
C11—N1—C2—O13 | 2.1 (2) | C7—C8—C9—C10 | 0.7 (2) |
C10—N1—C2—C3 | 3.32 (19) | C8—C9—C10—N1 | 179.00 (13) |
C11—N1—C2—C3 | −177.25 (12) | C8—C9—C10—C5 | −1.0 (2) |
O13—C2—C3—C4 | 178.31 (14) | C2—N1—C10—C9 | 177.95 (13) |
N1—C2—C3—C4 | −2.4 (2) | C11—N1—C10—C9 | −1.5 (2) |
O13—C2—C3—C14 | −1.3 (2) | C2—N1—C10—C5 | −2.05 (19) |
N1—C2—C3—C14 | 178.00 (13) | C11—N1—C10—C5 | 178.53 (13) |
C2—C3—C4—O17 | 179.75 (15) | C6—C5—C10—C9 | 0.6 (2) |
C14—C3—C4—O17 | −0.6 (2) | C4—C5—C10—C9 | 179.77 (13) |
C2—C3—C4—C5 | 0.2 (2) | C6—C5—C10—N1 | −179.38 (12) |
C14—C3—C4—C5 | 179.79 (14) | C4—C5—C10—N1 | −0.2 (2) |
O17—C4—C5—C6 | 0.6 (2) | C2—N1—C11—C12 | −94.27 (16) |
C3—C4—C5—C6 | −179.75 (14) | C10—N1—C11—C12 | 85.17 (17) |
O17—C4—C5—C10 | −178.49 (13) | C4—C3—C14—O16 | −0.2 (3) |
C3—C4—C5—C10 | 1.1 (2) | C2—C3—C14—O16 | 179.42 (16) |
C10—C5—C6—C7 | 0.1 (2) | C4—C3—C14—O15 | 178.91 (15) |
C4—C5—C6—C7 | −179.02 (15) | C2—C3—C14—O15 | −1.5 (2) |
C5—C6—C7—C8 | −0.5 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O17—H17O···O16 | 0.96 (3) | 1.66 (3) | 2.548 (2) | 151 (3) |
O15—H15O···O13 | 0.93 (3) | 1.67 (3) | 2.505 (2) | 147 (3) |
C9—H9···O16i | 0.93 | 2.36 | 3.227 (2) | 154 |
Symmetry code: (i) x+1, y, z. |
Experimental details
Crystal data |
Chemical formula | C12H11NO4 |
Mr | 233.22 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 9.278 (2), 14.050 (4), 8.938 (2) |
β (°) | 111.21 (3) |
V (Å3) | 1086.2 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.40 × 0.20 × 0.20 |
|
Data collection |
Diffractometer | Siemens P3/PC diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2133, 1885, 1153 |
Rint | 0.012 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.116, 0.97 |
No. of reflections | 1885 |
No. of parameters | 162 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.15, −0.14 |
Selected bond lengths (Å) topN1—C2 | 1.3712 (19) | C3—C14 | 1.473 (3) |
N1—C10 | 1.4026 (18) | C4—O17 | 1.333 (2) |
N1—C11 | 1.4885 (19) | C4—C5 | 1.435 (2) |
C2—O13 | 1.2660 (18) | C5—C10 | 1.416 (2) |
C2—C3 | 1.442 (2) | C14—O16 | 1.239 (3) |
C3—C4 | 1.381 (2) | C14—O15 | 1.320 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O17—H17O···O16 | 0.96 (3) | 1.66 (3) | 2.548 (2) | 151 (3) |
O15—H15O···O13 | 0.93 (3) | 1.67 (3) | 2.505 (2) | 147 (3) |
C9—H9···O16i | 0.93 | 2.36 | 3.227 (2) | 154.1 |
Symmetry code: (i) x+1, y, z. |
The derivatives of 4-hydroxyquinol-2-one can exist in different tautomeric forms depending on the substituent in the 3 position. They provide a relatively rare example of the systems where more than two tautomeric forms are conceivable. These forms differ from each other in the H-atom positions and the location of hydroxy and carbonyl groups. Therefore, these compounds have been the focus of several structural investigations (Ukrainets et al., 1992, 1996; Garsia Ruano et al., 1991). In the present paper, we report the crystal and molecular structure of 1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid, (I) (Fig. 1).
The C2—O13, C4—O17, C14—O16 and C3—C4 bond lengths [1.266 (2), 1.333 (2), 1.239 (3) and 1.381 (2) Å, respectively] indicate that the title compound exists in the crystal as the 2-oxo-4-hydroxy tautomer. This conclusion is also confirmed by the positions of the H atoms of the hydroxy and carboxy groups, which were located in a difference map.
All non-H atoms of this molecule with the exception of the C12 atom lie in one plane. The formation of the O15—H15O···O13 and O17—H17O···O16 hydrogen bonds [H15O···O13 1.67 (3) Å, O15···O13 2.505 (2) Å, O15—H15O···O13 147 (3)°; H17O···O16 1.66 (3) Å, O17···O16 2.548 (2) Å, O17—H17O···O16 151 (3)°] leads to the significant change of bond lengths in the hydroxy, carboxy and carbonyl groups: the O13—C2 and O16—C14 bonds are longer as compared with standard value for the C═O bond of 1.210 Å (Bürgi & Dunitz, 1994) and the O17—C4 bond is shorter than standard value for the Csp2—O (1.362 Å). The presence of intramolecular hydrogen bonds causes noticeable redistribution of the electron density within the dihydropyridine ring. As a result, the C3—C4 and C5—C10 bonds are longer and the C2—C3 and C4—C5 bonds are shorter than the standard values for the C═C (1.334 Å) and Csp2—Csp2 (1.455 Å) bonds (Bürgi & Dunitz, 1994), respectively.
The repulsion between the substituent at the N1 atom, carbonyl group and the H atom in the peri-position of the aromatic ring {the shortened intramolecular contacts O13···H11b 2.33 Å [van der Waals radii sum is 2.45 Å according to Zefirov & Zorky (1995)], H9···C11 2.55 Å (2.87 Å), H9···H11a 2.06 Å (2.32 Å)} causes an elongation of the N1—C2, N1—C10 and N1—C11 bonds up to 1.371 (2), 1.403 (2) and 1.488 (2) Å, respectively [standard values for the N—Csp2 and N—Csp3 bonds are 1.355 and 1.464%A (Bürgi & Dunitz, 1994)]. The C12 atom of the substituent at the N1 atom is oriented orthogonal with respect to the plane of the dihydrocycle [the C2—N1—C11—C12 torsion angle is -94.2 (2)°].
Molecules of the title compound are linked into infinite chains stretched along the x axis of the crystal due to the C9—H9···O16i intermolecular hydrogen bond (H···Oi 2.36 Å and C—H···Oi 154°; symmetry code: (i) 1 + x, y, z).