2-Hexyl­idene-3-methyl­succinic acid

The title compound, C₁₁H₁₈O₄, also known as piliformic acid, was isolated from the endophytic fungus Xylariasp sp. No. 2508 from mangrove trees from the coast of the South China Sea. The two carboxyl groups form inter­molecular O—H...O hydrogen bonds, which link the mol­ecules into infinite chains extending along the c axis.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.004 Å
• Disorder in main residue
• R factor = 0.066
• wR factor = 0.224
• Data-to-parameter ratio = 14.3

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:      0.793     0.988
            Tmin(prime) and Tmax expected:      0.973     0.987
            RR(prime) =      0.814
            Please check that your absorption correction is appropriate.
PLAT061_ALERT_3_C Tmax/Tmin Range Test RR' too Large .............       0.81
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       3.29 Ratio
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.54 Ratio
PLAT301_ALERT_3_C Main Residue  Disorder .........................      25.00 Perc.
PLAT366_ALERT_2_C Short? C(sp?)-C(sp?) Bond  C3     -   C5     ...       1.32 Ang.
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          8

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   9 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
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Bruker, 1999); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

2-Hexylidene-3-methylsuccinic acid

Crystal data

C11H18O4	Z = 2
Mr = 214.25	F(000) = 232
Triclinic, P1	Dx = 1.109 Mg m^−3
a = 6.7208 (14) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.488 (2) Å	Cell parameters from 1921 reflections
c = 10.139 (2) Å	θ = 2.0–26.0°
α = 85.994 (4)°	µ = 0.08 mm^−1
β = 89.221 (4)°	T = 294 K
γ = 84.457 (4)°	Plate, colourless
V = 641.9 (2) Å^3	0.32 × 0.24 × 0.16 mm

Data collection

Bruker CCD area-detector diffractometer	2497 independent reflections
Radiation source: fine-focus sealed tube	1402 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
φ and ω scans	θmax = 26.0°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.793, Tmax = 0.988	k = −11→11
5098 measured reflections	l = −12→12

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)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.224	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.114P)^2 + 0.1365P] where P = (Fo^2 + 2Fc^2)/3
2497 reflections	(Δ/σ)max < 0.001
175 parameters	Δρmax = 0.24 e Å^−3
178 restraints	Δρmin = −0.22 e Å^−3

Special details

Experimental. The compound identity was conformed by the ¹H NMR,¹³C NMR spectra and FAB mass spectrum. ¹H NMR in DMSO-d₆ (500 MHz): 12.03 (brs, 2H), 6.66 (t, 7.5 Hz, 1H), 3.52 (q, 7.0 Hz, 1H), 2.24–2.10 (m, 2H), 1.39 (dt, 7.0 Hz, 7.0 Hz, 2H), 1.34–1.20 (m, 4H), 1.18 (d, 7.0 Hz, 3H), 0.86 (t, 7.0 Hz, 3H). ¹³C NMR in DMSO-d₆ (125 MHz): 174.3 (C), 167.3 (C), 142.2 (CH), 133.0 (C), 39.0 (CH₂), 36.8 (C), 30.7 (CH₂), 27.6 (CH₂), 27.5 (CH₂), 21.7 (CH₂), 15.7 (CH₃), 13.6 (CH₃).

The FAB mass spectrum showed M + 1 ions at 215.

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	1.2879 (3)	0.5941 (2)	0.03452 (19)	0.0730 (6)
O2	1.3895 (3)	0.3756 (2)	0.1144 (2)	0.0793 (7)
H2	1.4859	0.3881	0.0661	0.119*
O3	1.3725 (4)	0.5459 (3)	0.3607 (2)	0.0864 (8)
O4	1.3343 (4)	0.3667 (3)	0.5093 (2)	0.0902 (8)
H4	1.4393	0.3901	0.5373	0.135*
C1	1.2646 (4)	0.4893 (3)	0.1072 (2)	0.0596 (7)
C2	1.0787 (4)	0.4776 (3)	0.1911 (3)	0.0691 (8)
H2A	0.9928	0.4209	0.1434	0.083*
C3	1.1218 (4)	0.3968 (4)	0.3236 (3)	0.0697 (8)
C4	1.2864 (5)	0.4419 (4)	0.4007 (3)	0.0705 (8)
C5	1.0155 (5)	0.2960 (4)	0.3743 (3)	0.0941 (11)
H5	1.0559	0.2540	0.4565	0.113*
C11	0.9598 (5)	0.6218 (4)	0.2037 (4)	0.0962 (12)
H11A	0.9368	0.6681	0.1173	0.144*
H11B	1.0341	0.6793	0.2554	0.144*
H11C	0.8340	0.6084	0.2463	0.144*
C6	0.8405 (7)	0.2425 (5)	0.3160 (5)	0.1216 (14)	0.520 (8)
H6A	0.7275	0.3131	0.3245	0.146*	0.520 (8)
H6B	0.8667	0.2357	0.2222	0.146*	0.520 (8)
C7	0.7809 (15)	0.1057 (9)	0.3700 (12)	0.136 (3)	0.520 (8)
H7A	0.7694	0.1077	0.4653	0.163*	0.520 (8)
H7B	0.8860	0.0323	0.3512	0.163*	0.520 (8)
C8	0.5906 (15)	0.0667 (13)	0.3183 (12)	0.152 (3)	0.520 (8)
H8A	0.5163	0.0217	0.3894	0.182*	0.520 (8)
H8B	0.5106	0.1519	0.2846	0.182*	0.520 (8)
C9	0.627 (2)	−0.0305 (15)	0.2121 (15)	0.174 (4)	0.520 (8)
H9A	0.7309	−0.1041	0.2403	0.209*	0.520 (8)
H9B	0.6768	0.0218	0.1350	0.209*	0.520 (8)
C10	0.449 (2)	−0.0995 (17)	0.1726 (17)	0.176 (5)	0.520 (8)
H10A	0.4890	−0.1682	0.1098	0.265*	0.520 (8)
H10B	0.3518	−0.0288	0.1332	0.265*	0.520 (8)
H10C	0.3921	−0.1458	0.2492	0.265*	0.520 (8)
C6'	0.8405 (7)	0.2425 (5)	0.3160 (5)	0.1216 (14)	0.480 (8)
H6'A	0.7918	0.3082	0.2433	0.146*	0.480 (8)
H6'B	0.7350	0.2391	0.3820	0.146*	0.480 (8)
C7'	0.8854 (18)	0.0999 (10)	0.2668 (14)	0.150 (3)	0.480 (8)
H7'A	0.9413	0.0357	0.3384	0.180*	0.480 (8)
H7'B	0.9862	0.1048	0.1976	0.180*	0.480 (8)
C8'	0.7057 (19)	0.0400 (16)	0.2131 (14)	0.167 (4)	0.480 (8)
H8'A	0.6403	0.1144	0.1538	0.200*	0.480 (8)
H8'B	0.7574	−0.0352	0.1582	0.200*	0.480 (8)
C9'	0.544 (2)	−0.0186 (19)	0.2967 (16)	0.181 (4)	0.480 (8)
H9'A	0.4907	0.0561	0.3517	0.217*	0.480 (8)
H9'B	0.6076	−0.0940	0.3556	0.217*	0.480 (8)
C10'	0.368 (3)	−0.076 (2)	0.237 (2)	0.196 (6)	0.480 (8)
H10D	0.2791	−0.1055	0.3064	0.294*	0.480 (8)
H10E	0.4141	−0.1563	0.1882	0.294*	0.480 (8)
H10F	0.2994	−0.0040	0.1791	0.294*	0.480 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0661 (13)	0.0882 (14)	0.0598 (12)	0.0081 (10)	−0.0029 (9)	0.0097 (11)
O2	0.0714 (14)	0.0915 (15)	0.0689 (13)	0.0110 (12)	0.0034 (10)	0.0116 (11)
O3	0.0902 (16)	0.1136 (18)	0.0570 (12)	−0.0282 (14)	−0.0231 (11)	0.0125 (12)
O4	0.0849 (16)	0.132 (2)	0.0529 (12)	−0.0208 (14)	−0.0236 (10)	0.0179 (12)
C1	0.0534 (15)	0.0829 (19)	0.0405 (13)	0.0033 (14)	−0.0146 (11)	−0.0009 (13)
C2	0.0511 (15)	0.103 (2)	0.0511 (15)	−0.0016 (15)	−0.0135 (12)	0.0011 (14)
C3	0.0555 (16)	0.102 (2)	0.0505 (15)	−0.0066 (15)	−0.0073 (12)	0.0024 (14)
C4	0.0634 (17)	0.106 (2)	0.0401 (13)	−0.0008 (16)	−0.0078 (12)	0.0022 (14)
C5	0.075 (2)	0.133 (3)	0.072 (2)	−0.019 (2)	−0.0212 (17)	0.023 (2)
C11	0.075 (2)	0.133 (3)	0.072 (2)	0.024 (2)	0.0024 (16)	0.0102 (19)
C6	0.106 (3)	0.142 (3)	0.117 (3)	−0.035 (2)	−0.029 (2)	0.022 (2)
C7	0.124 (5)	0.141 (5)	0.148 (5)	−0.047 (4)	−0.013 (4)	0.003 (4)
C8	0.141 (5)	0.153 (5)	0.169 (6)	−0.048 (4)	−0.006 (5)	−0.018 (4)
C9	0.164 (6)	0.176 (6)	0.189 (6)	−0.041 (5)	−0.002 (5)	−0.034 (5)
C10	0.179 (8)	0.172 (8)	0.190 (9)	−0.056 (7)	−0.012 (7)	−0.045 (7)
C6'	0.106 (3)	0.142 (3)	0.117 (3)	−0.035 (2)	−0.029 (2)	0.022 (2)
C7'	0.148 (5)	0.156 (5)	0.146 (5)	−0.008 (4)	−0.034 (5)	−0.009 (4)
C8'	0.171 (6)	0.161 (6)	0.174 (6)	−0.027 (5)	−0.029 (5)	−0.021 (5)
C9'	0.189 (6)	0.181 (7)	0.176 (7)	−0.028 (5)	−0.010 (5)	−0.030 (5)
C10'	0.183 (9)	0.201 (9)	0.211 (10)	−0.046 (7)	0.001 (8)	−0.023 (8)

Geometric parameters (Å, º)

O1—C1	1.217 (3)	C7—H7B	0.9700
O2—C1	1.300 (3)	C8—C9	1.469 (7)
O2—H2	0.8200	C8—H8A	0.9700
O3—C4	1.233 (4)	C8—H8B	0.9700
O4—C4	1.297 (3)	C9—C10	1.488 (7)
O4—H4	0.8200	C9—H9A	0.9700
C1—C2	1.511 (4)	C9—H9B	0.9700
C2—C3	1.516 (4)	C10—H10A	0.9600
C2—C11	1.528 (5)	C10—H10B	0.9600
C2—H2A	0.9800	C10—H10C	0.9600
C3—C5	1.320 (5)	C7'—C8'	1.507 (7)
C3—C4	1.476 (4)	C7'—H7'A	0.9700
C5—C6	1.472 (6)	C7'—H7'B	0.9700
C5—H5	0.9300	C8'—C9'	1.496 (7)
C11—H11A	0.9600	C8'—H8'A	0.9700
C11—H11B	0.9600	C8'—H8'B	0.9700
C11—H11C	0.9600	C9'—C10'	1.498 (7)
C6—C7	1.464 (6)	C9'—H9'A	0.9700
C6—H6A	0.9700	C9'—H9'B	0.9700
C6—H6B	0.9700	C10'—H10D	0.9600
C7—C8	1.478 (7)	C10'—H10E	0.9600
C7—H7A	0.9700	C10'—H10F	0.9600
C1—O2—H2	109.5	C9—C8—H8A	109.4
C4—O4—H4	109.5	C7—C8—H8A	109.4
O1—C1—O2	123.7 (3)	C9—C8—H8B	109.4
O1—C1—C2	122.1 (3)	C7—C8—H8B	109.4
O2—C1—C2	114.1 (3)	H8A—C8—H8B	108.0
C1—C2—C3	112.6 (2)	C8—C9—C10	115.0 (12)
C1—C2—C11	112.1 (3)	C8—C9—H9A	108.5
C3—C2—C11	113.0 (3)	C10—C9—H9A	108.5
C1—C2—H2A	106.2	C8—C9—H9B	108.5
C3—C2—H2A	106.2	C10—C9—H9B	108.5
C11—C2—H2A	106.2	H9A—C9—H9B	107.5
C5—C3—C4	119.7 (3)	C9—C10—H10A	109.5
C5—C3—C2	123.9 (3)	C9—C10—H10B	109.5
C4—C3—C2	116.3 (3)	H10A—C10—H10B	109.5
O3—C4—O4	123.0 (3)	C9—C10—H10C	109.5
O3—C4—C3	120.3 (2)	H10A—C10—H10C	109.5
O4—C4—C3	116.8 (3)	H10B—C10—H10C	109.5
C3—C5—C6	127.5 (3)	C8'—C7'—H7'A	108.8
C3—C5—H5	116.3	C8'—C7'—H7'B	108.8
C6—C5—H5	116.3	H7'A—C7'—H7'B	107.7
C2—C11—H11A	109.5	C9'—C8'—C7'	124.4 (14)
C2—C11—H11B	109.5	C9'—C8'—H8'A	106.2
H11A—C11—H11B	109.5	C7'—C8'—H8'A	106.2
C2—C11—H11C	109.5	C9'—C8'—H8'B	106.2
H11A—C11—H11C	109.5	C7'—C8'—H8'B	106.2
H11B—C11—H11C	109.5	H8'A—C8'—H8'B	106.4
C7—C6—C5	117.7 (5)	C8'—C9'—C10'	121.9 (14)
C7—C6—H6A	107.9	C8'—C9'—H9'A	106.8
C5—C6—H6A	107.9	C10'—C9'—H9'A	106.8
C7—C6—H6B	107.9	C8'—C9'—H9'B	106.8
C5—C6—H6B	107.9	C10'—C9'—H9'B	106.8
H6A—C6—H6B	107.2	H9'A—C9'—H9'B	106.7
C6—C7—C8	114.8 (8)	C9'—C10'—H10D	109.5
C6—C7—H7A	108.6	C9'—C10'—H10E	109.5
C8—C7—H7A	108.6	H10D—C10'—H10E	109.5
C6—C7—H7B	108.6	C9'—C10'—H10F	109.5
C8—C7—H7B	108.6	H10D—C10'—H10F	109.5
H7A—C7—H7B	107.5	H10E—C10'—H10F	109.5
C9—C8—C7	111.0 (10)
O1—C1—C2—C3	−144.9 (3)	C5—C3—C4—O4	8.4 (5)
O2—C1—C2—C3	38.7 (4)	C2—C3—C4—O4	−175.0 (3)
O1—C1—C2—C11	−16.3 (4)	C4—C3—C5—C6	176.5 (4)
O2—C1—C2—C11	167.4 (3)	C2—C3—C5—C6	0.2 (7)
C1—C2—C3—C5	−133.6 (4)	C3—C5—C6—C7	163.1 (7)
C11—C2—C3—C5	98.2 (4)	C5—C6—C7—C8	172.9 (8)
C1—C2—C3—C4	49.9 (4)	C6—C7—C8—C9	98.3 (14)
C11—C2—C3—C4	−78.3 (3)	C7—C8—C9—C10	167.9 (12)
C5—C3—C4—O3	−172.1 (3)	C7'—C8'—C9'—C10'	179.8 (15)
C2—C3—C4—O3	4.5 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.83	2.652 (3)	176
O4—H4···O3^ii	0.82	1.82	2.617 (3)	164

Symmetry codes: (i) −x+3, −y+1, −z; (ii) −x+3, −y+1, −z+1.