2,6-Dimethyl-4-oxocyclo­hexa­necarboxylic acid: ­a meso keto acid

The achiral meso title compound, C₉H₁₄O₃, is an inter­mediate for a series of structurally unique compounds. Inter­molecular O—H...O hydrogen bonds produce centrosymmetric R₂²(8) rings which dimerize the mol­ecules through the carboxyl group, while C—H...O inter­actions through the carboxyl α-H atom and the ketone O atom inter­connect the dimers via centrosymmetric R₄⁴(24) rings, producing infinite one-dimensional dimeric ribbons.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.047
• wR factor = 0.109
• Data-to-parameter ratio = 17.0

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
            Tmin and Tmax reported:      0.767     0.987
            Tmin(prime) and Tmax expected:      0.977     0.987
            RR(prime) =      0.785
            Please check that your absorption correction is appropriate.
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT061_ALERT_3_C Tmax/Tmin Range Test RR' too Large .............       0.78
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal (x 10000)         500 Deg.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT and SADABS (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: LS in TEXSAN (Molecular Structure Corporation, 1997) and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PLATON.

2,6-Dimethyl-4-oxocyclohexanecarboxylic acid

Crystal data

C9H14O3	Z = 2
Mr = 170.20	F(000) = 184
Triclinic, P1	Dx = 1.273 Mg m^−3
Hall symbol: -P 1	Melting point = 436–437 K
a = 5.2850 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.9516 (6) Å	Cell parameters from 1768 reflections
c = 12.1889 (9) Å	θ = 3.4–27.1°
α = 92.039 (5)°	µ = 0.09 mm^−1
β = 93.401 (5)°	T = 100 K
γ = 95.967 (5)°	Irregular, colorless
V = 444.21 (6) Å^3	0.24 × 0.24 × 0.14 mm

Data collection

Bruker Kappa-APEXII CCD area-detector diffractometer	1907 independent reflections
Radiation source: X-ray tube	1383 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
φ and ω scans	θmax = 27.1°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −6→6
Tmin = 0.767, Tmax = 0.987	k = −8→8
6305 measured reflections	l = −15→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.045P)^2 + 0.1427P] where P = (Fo^2 + 2Fc^2)/3
1907 reflections	(Δ/σ)max < 0.001
112 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.2554 (2)	0.58765 (18)	0.94013 (9)	0.0233 (3)
O2	−0.1491 (2)	0.62235 (18)	0.88727 (9)	0.0231 (3)
H2	−0.1774	0.5587	0.9414	0.035*
O3	0.7499 (2)	0.9280 (2)	0.58383 (10)	0.0311 (4)
C1	0.1741 (3)	0.7612 (2)	0.77803 (13)	0.0162 (4)
H1	0.0226	0.8133	0.7457	0.019*
C2	0.2685 (3)	0.6210 (2)	0.69197 (13)	0.0187 (4)
H2A	0.4163	0.5650	0.7250	0.022*
C3	0.3518 (3)	0.7333 (3)	0.59155 (14)	0.0216 (4)
H3A	0.4251	0.6473	0.5408	0.026*
H3B	0.2035	0.7783	0.5539	0.026*
C4	0.5428 (3)	0.9029 (3)	0.62358 (14)	0.0222 (4)
C5	0.4600 (3)	1.0380 (3)	0.70982 (14)	0.0243 (4)
H5A	0.3197	1.1028	0.6791	0.029*
H5B	0.6000	1.1361	0.7314	0.029*
C6	0.3753 (3)	0.9312 (2)	0.81209 (14)	0.0190 (4)
H6	0.5240	0.8794	0.8472	0.023*
C7	0.0986 (3)	0.6496 (2)	0.87674 (13)	0.0162 (4)
C8	0.0633 (3)	0.4572 (3)	0.65612 (15)	0.0247 (4)
H8A	−0.0866	0.5104	0.6277	0.037*
H8B	0.0225	0.3810	0.7181	0.037*
H8C	0.1245	0.3769	0.5999	0.037*
C9	0.2751 (3)	1.0712 (3)	0.89447 (15)	0.0256 (4)
H9A	0.1248	1.1192	0.8625	0.038*
H9B	0.4033	1.1776	0.9127	0.038*
H9C	0.2343	1.0048	0.9599	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0197 (6)	0.0284 (7)	0.0219 (7)	0.0007 (5)	−0.0001 (5)	0.0113 (5)
O2	0.0177 (6)	0.0298 (8)	0.0225 (7)	0.0011 (5)	0.0039 (5)	0.0121 (6)
O3	0.0211 (7)	0.0444 (9)	0.0300 (8)	0.0050 (6)	0.0071 (5)	0.0180 (6)
C1	0.0153 (8)	0.0170 (9)	0.0165 (9)	0.0013 (7)	0.0000 (6)	0.0049 (7)
C2	0.0205 (9)	0.0183 (9)	0.0175 (9)	0.0025 (7)	0.0005 (7)	0.0020 (7)
C3	0.0246 (9)	0.0240 (10)	0.0168 (9)	0.0036 (7)	0.0028 (7)	0.0034 (7)
C4	0.0214 (9)	0.0273 (10)	0.0193 (9)	0.0049 (7)	0.0003 (7)	0.0150 (8)
C5	0.0255 (10)	0.0200 (10)	0.0268 (10)	−0.0032 (7)	0.0024 (8)	0.0069 (8)
C6	0.0188 (8)	0.0181 (9)	0.0198 (9)	0.0007 (7)	−0.0004 (7)	0.0030 (7)
C7	0.0165 (8)	0.0151 (9)	0.0170 (9)	0.0019 (6)	0.0000 (6)	−0.0004 (7)
C8	0.0314 (10)	0.0194 (10)	0.0223 (10)	0.0005 (8)	−0.0023 (8)	0.0002 (8)
C9	0.0313 (10)	0.0197 (10)	0.0252 (10)	0.0012 (8)	0.0005 (8)	−0.0002 (8)

Geometric parameters (Å, º)

O1—C7	1.2212 (19)	C3—H3B	0.9700
O2—C7	1.3174 (19)	C4—C5	1.500 (3)
O2—H2	0.8200	C5—C6	1.539 (2)
O3—C4	1.222 (2)	C5—H5A	0.9700
C1—C7	1.506 (2)	C5—H5B	0.9700
C1—C6	1.533 (2)	C6—C9	1.529 (2)
C1—C2	1.546 (2)	C6—H6	0.9800
C1—H1	0.9800	C8—H8A	0.9600
C2—C8	1.521 (2)	C8—H8B	0.9600
C2—C3	1.537 (2)	C8—H8C	0.9600
C2—H2A	0.9800	C9—H9A	0.9600
C3—C4	1.494 (2)	C9—H9B	0.9600
C3—H3A	0.9700	C9—H9C	0.9600
C7—O2—H2	109.5	C4—C5—H5B	109.2
C7—C1—C6	110.59 (13)	C6—C5—H5B	109.2
C7—C1—C2	108.86 (13)	H5A—C5—H5B	107.9
C6—C1—C2	112.27 (13)	C9—C6—C1	111.39 (14)
C7—C1—H1	108.3	C9—C6—C5	110.38 (14)
C6—C1—H1	108.3	C1—C6—C5	110.02 (14)
C2—C1—H1	108.3	C9—C6—H6	108.3
C8—C2—C3	109.92 (14)	C1—C6—H6	108.3
C8—C2—C1	111.55 (14)	C5—C6—H6	108.3
C3—C2—C1	109.58 (14)	O1—C7—O2	123.39 (15)
C8—C2—H2A	108.6	O1—C7—C1	122.24 (15)
C3—C2—H2A	108.6	O2—C7—C1	114.36 (14)
C1—C2—H2A	108.6	C2—C8—H8A	109.5
C4—C3—C2	111.85 (14)	C2—C8—H8B	109.5
C4—C3—H3A	109.2	H8A—C8—H8B	109.5
C2—C3—H3A	109.2	C2—C8—H8C	109.5
C4—C3—H3B	109.2	H8A—C8—H8C	109.5
C2—C3—H3B	109.2	H8B—C8—H8C	109.5
H3A—C3—H3B	107.9	C6—C9—H9A	109.5
O3—C4—C3	122.86 (18)	C6—C9—H9B	109.5
O3—C4—C5	122.88 (17)	H9A—C9—H9B	109.5
C3—C4—C5	114.25 (14)	C6—C9—H9C	109.5
C4—C5—C6	112.00 (14)	H9A—C9—H9C	109.5
C4—C5—H5A	109.2	H9B—C9—H9C	109.5
C6—C5—H5A	109.2
C7—C1—C2—C8	59.25 (17)	C7—C1—C6—C9	−59.96 (18)
C6—C1—C2—C8	−177.98 (14)	C2—C1—C6—C9	178.25 (14)
C7—C1—C2—C3	−178.81 (13)	C7—C1—C6—C5	177.31 (14)
C6—C1—C2—C3	−56.03 (17)	C2—C1—C6—C5	55.51 (18)
C8—C2—C3—C4	176.73 (15)	C4—C5—C6—C9	−176.08 (14)
C1—C2—C3—C4	53.81 (19)	C4—C5—C6—C1	−52.76 (19)
C2—C3—C4—O3	125.42 (17)	C6—C1—C7—O1	−52.9 (2)
C2—C3—C4—C5	−53.8 (2)	C2—C1—C7—O1	70.9 (2)
O3—C4—C5—C6	−126.11 (17)	C6—C1—C7—O2	128.23 (16)
C3—C4—C5—C6	53.09 (19)	C2—C1—C7—O2	−107.98 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.84	2.6573 (16)	177
C1—H1···O3^ii	0.98	2.57	3.476 (2)	153

Symmetry codes: (i) −x, −y+1, −z+2; (ii) x−1, y, z.