2,5-Dimeth­oxy-3,4,6-tri­methyl­benzaldehyde

Wickramasinhage, R.; McAdam, C.J.; Simpson, J.

doi:10.1107/S2414314616003072

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 1| Part 2| February 2016| x160307

https://doi.org/10.1107/S2414314616003072

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2,5-Dimethoxy-3,4,6-trimethylbenzaldehyde

Ravindra Wickramasinhage,^a C. John McAdam ^a ^* and Jim Simpson ^a

^aDepartment of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand
^*Correspondence e-mail: John.McAdam@otago.ac.nz

Edited by P. C. Healy, Griffith University, Australia (Received 21 February 2016; accepted 22 February 2016; online 27 February 2016)

In the molecule of the title compound, C₁₂H₁₆O₃, the methyl and aldehyde substituents are disordered over four inversion-related C atoms on the benzene ring with an occupancy ratio of 0.75:0.25. The crystal structure features weak C—H⋯O hydrogen bonds and C—H⋯π contacts between a methoxy/methyl group and the benzene ring.

Keywords: crystal structure; 2,5-dimethoxy-3,4,6-trimethylbenzaldehyde; disorder; hydrogen bonds.

CCDC reference: 1454961

Structure description

The title compound, (I), was synthesized as a precursor to quinone-based electrochemical actuators as part of our ongoing research in this area (Goswami et al., 2013 ). In the structure of (I), Fig. 1, which lies about an inversion centre situated at the centroid of the benzene ring, the methyl and aldehyde substituents are disordered on the C2 and C3 carbon atoms and their inversion equivalents in a 0.75:0.25 ratio, commensurate with the molecular formula C₁₂H₁₆O₃. The methoxy substituent on C1 is fully ordered. The non-hydrogen atoms of the methyl and aldehyde substituents lie close to the benzene ring plane while the methoxy groups are almost orthogonal to the ring with the dihedral angle between the C1–C3 and C1,O1,C11 planes being 87.15 (19)°. In the crystal weak C—H⋯O hydrogen bonds and C—H⋯π contacts, Table 1, stack the molecules along the a-axis direction, Fig. 2.

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C1–C3/C1^v–C3^v benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C21A—H21C⋯O1ⁱ	0.98	2.66	3.506 (15)	144
C11—H11B⋯O2ⁱⁱ	0.98	2.71	3.195 (9)	111
C11—H11A⋯O3ⁱⁱⁱ	0.98	2.42	2.788 (9)	102
C31A—H31C⋯Cg1ⁱ	0.98	2.71	3.48 (2)	138
C31A—H31C⋯Cg1^iv	0.98	2.71	3.48 (2)	138
Symmetry codes: (i) x+1, y, z; (ii) -x+2, -y+1, -z+2; (iii) $[-x+2, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) -x+2, -y+1, -z+1; (v) −x + 1, −y + 1, −z + 1.

Figure 1
The structure of (I), showing the atom-numbering, with displacement ellipsoids drawn at the 50% probability level. Only one set of the disorder components is shown for clarity.

Figure 2
Crystal packing of (I) viewed along the a-axis direction. Only one set of the disorder components is shown for clarity. Hydrogen bonds are drawn as blue dashed lines and a representative C—H⋯π contact is drawn as a dotted green line with the ring centroid shown as a red sphere.

para-Dimethoxybenzenes with aldehyde substituents are not common, with only six unique examples in the Cambridge Structural Database (Version 5.37 Nov 2015 plus 1 update; Groom & Allen, 2014 ). These include the archetypal 2,5-dimethoxyterephthaldehyde (Moorthy et al., 2005 ; Nielsen et al. 2005 ; Kretz et al., 2007 ) and an even closer relative of the title compound, 2,5-dimethoxy-3,6-dimethylterephthaldehyde (Moorthy et al., 2005).

Synthesis and crystallization

2,5-Dimethoxy-3,4,6-trimethylbenzaldehyde was synthesized using a literature method (Häupler et al. et al., 2014 ). Colourles needle-like crystals were obtained from EtOH/H₂O at ambient temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The C2 and C3 carbon atoms and their inversion opposites each carry disordered aldehyde and methyl substituents. Refining the disorder converged with occupancies of approximately 0.25 for the aldehyde and 0.75 for the methyl group, as would be expected with one aldehyde and three methyl substituents overall. The occupancies were therefore fixed at these values in the final refinement cycles.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₂H₁₆O₃
M_r	208.25
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	4.5856 (3), 14.2281 (9), 8.3312 (4)
β (°)	98.515 (5)
V (Å³)	537.57 (6)
Z	2
Radiation type	Cu Kα
μ (mm⁻¹)	0.75
Crystal size (mm)	0.42 × 0.13 × 0.06

Data collection
Diffractometer	Agilent SuperNova Dual Source diffractometer with an Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2014 )
T_min, T_max	0.719, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	4051, 1068, 907
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.623

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.065, 0.186, 1.12
No. of reflections	1068
No. of parameters	103
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.24
Computer programs: CrysAlis PRO (Agilent, 2014), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), TITAN2000 (Hunter & Simpson, 1999 ), Mercury (Macrae et al., 2008 ), enCIFer (Allen et al., 2004 ), PLATON (Spek, 2009 ), publCIF (Westrip, 2010 ), WinGX (Farrugia, 2012 ).

Structural data

CCDC reference: 1454961

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314616003072/hg4003sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616003072/hg4003Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314616003072/hg4003Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b) and TITAN2000 (Hunter & Simpson, 1999); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b), enCIFer (Allen et al., 2004), PLATON (Spek, 2009), publCIF (Westrip, 2010) and WinGX (Farrugia, 2012).

2,5-Dimethoxy-3,4,6-trimethylbenzaldehyde top

Crystal data top

C₁₂H₁₆O₃	F(000) = 224
M_r = 208.25	D_x = 1.287 Mg m⁻³
Monoclinic, P2₁/c	Cu Kα radiation, λ = 1.54184 Å
a = 4.5856 (3) Å	Cell parameters from 1932 reflections
b = 14.2281 (9) Å	θ = 6.1–72.2°
c = 8.3312 (4) Å	µ = 0.75 mm⁻¹
β = 98.515 (5)°	T = 100 K
V = 537.57 (6) Å³	Needle, pale yellow
Z = 2	0.42 × 0.13 × 0.06 mm

Data collection top

Agilent SuperNova Dual Source diffractometer with an Atlas detector	1068 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	907 reflections with I > 2σ(I)
Detector resolution: 5.1725 pixels mm^-1	R_int = 0.046
ω scans	θ_max = 73.8°, θ_min = 6.2°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −5→5
T_min = 0.719, T_max = 1.000	k = −17→17
4051 measured reflections	l = −10→10

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.065	H-atom parameters constrained
wR(F²) = 0.186	w = 1/[σ²(F_o²) + (0.0763P)² + 0.4967P] where P = (F_o² + 2F_c²)/3
S = 1.12	(Δ/σ)_max = 0.008
1068 reflections	Δρ_max = 0.22 e Å⁻³
103 parameters	Δρ_min = −0.24 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
C11	0.6051 (6)	0.3451 (2)	0.8420 (3)	0.0435 (7)
H11A	0.5783	0.2929	0.7644	0.065*
H11B	0.5706	0.3229	0.9489	0.065*
H11C	0.8067	0.3693	0.8495	0.065*
O1	0.3988 (4)	0.41887 (13)	0.7878 (2)	0.0396 (5)
C1	0.4525 (5)	0.45903 (17)	0.6431 (3)	0.0309 (6)
C2	0.6504 (5)	0.53395 (17)	0.6492 (3)	0.0305 (6)
C21A	0.804 (3)	0.5700 (11)	0.8144 (17)	0.047 (4)	0.75
H21A	0.7146	0.5403	0.9015	0.070*	0.75
H21B	0.7807	0.6383	0.8198	0.070*	0.75
H21C	1.0141	0.5542	0.8271	0.070*	0.75
C21B	0.794 (5)	0.568 (2)	0.796 (5)	0.026 (6)	0.25
H21D	0.7573	0.5343	0.8898	0.031*	0.25
O2	0.965 (3)	0.6353 (7)	0.8209 (11)	0.068 (3)	0.25
C3	0.6994 (5)	0.57594 (16)	0.5033 (3)	0.0307 (6)
C31A	0.919 (4)	0.6577 (13)	0.4994 (19)	0.044 (4)	0.75
H31A	0.8575	0.7110	0.5609	0.065*	0.75
H31B	0.9226	0.6768	0.3867	0.065*	0.75
H31C	1.1164	0.6372	0.5480	0.065*	0.75
C31B	0.891 (11)	0.649 (3)	0.502 (3)	0.027 (6)	0.25
H31D	0.8952	0.6778	0.3992	0.033*	0.25
O3	1.053 (2)	0.6826 (7)	0.6122 (13)	0.063 (2)	0.25

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C11	0.0497 (16)	0.0457 (15)	0.0356 (14)	0.0075 (12)	0.0077 (12)	0.0112 (11)
O1	0.0443 (10)	0.0467 (11)	0.0292 (9)	0.0074 (8)	0.0105 (7)	0.0074 (7)
C1	0.0317 (12)	0.0360 (13)	0.0252 (11)	0.0084 (9)	0.0053 (9)	0.0046 (9)
C2	0.0299 (12)	0.0351 (13)	0.0253 (11)	0.0078 (9)	0.0005 (9)	−0.0033 (9)
C21A	0.058 (6)	0.056 (6)	0.022 (3)	0.007 (4)	−0.007 (3)	−0.010 (3)
C21B	0.016 (9)	0.026 (12)	0.037 (13)	0.007 (7)	0.009 (8)	0.000 (8)
O2	0.083 (7)	0.057 (6)	0.054 (5)	−0.016 (5)	−0.018 (5)	−0.021 (4)
C3	0.0274 (11)	0.0323 (12)	0.0322 (12)	0.0057 (9)	0.0034 (9)	−0.0021 (9)
C31A	0.033 (5)	0.039 (5)	0.060 (7)	−0.003 (3)	0.012 (4)	0.002 (4)
C31B	0.026 (12)	0.034 (14)	0.020 (11)	0.014 (11)	−0.002 (8)	0.002 (8)
O3	0.053 (5)	0.062 (6)	0.073 (6)	−0.029 (4)	0.004 (5)	−0.017 (5)

Geometric parameters (Å, º) top

C11—O1	1.440 (3)	C21A—H21C	0.9800
C11—H11A	0.9800	C21B—O2	1.24 (4)
C11—H11B	0.9800	C21B—H21D	0.9500
C11—H11C	0.9800	C3—C31B	1.37 (6)
O1—C1	1.389 (3)	C3—C1ⁱ	1.403 (3)
C1—C2	1.396 (4)	C3—C31A	1.54 (2)
C1—C3ⁱ	1.403 (3)	C31A—H31A	0.9800
C2—C21B	1.39 (4)	C31A—H31B	0.9800
C2—C3	1.402 (3)	C31A—H31C	0.9800
C2—C21A	1.538 (15)	C31B—O3	1.19 (5)
C21A—H21A	0.9800	C31B—H31D	0.9500
C21A—H21B	0.9800

O1—C11—H11A	109.5	H21A—C21A—H21C	109.5
O1—C11—H11B	109.5	H21B—C21A—H21C	109.5
H11A—C11—H11B	109.5	O2—C21B—C2	128 (3)
O1—C11—H11C	109.5	O2—C21B—H21D	115.8
H11A—C11—H11C	109.5	C2—C21B—H21D	115.8
H11B—C11—H11C	109.5	C31B—C3—C2	121.3 (12)
C1—O1—C11	112.30 (18)	C31B—C3—C1ⁱ	120.1 (12)
O1—C1—C2	118.7 (2)	C2—C3—C1ⁱ	118.7 (2)
O1—C1—C3ⁱ	118.7 (2)	C2—C3—C31A	121.9 (6)
C2—C1—C3ⁱ	122.6 (2)	C1ⁱ—C3—C31A	119.4 (6)
C21B—C2—C1	121.2 (12)	C3—C31A—H31A	109.5
C21B—C2—C3	120.1 (12)	C3—C31A—H31B	109.5
C1—C2—C3	118.7 (2)	H31A—C31A—H31B	109.5
C1—C2—C21A	119.8 (6)	C3—C31A—H31C	109.5
C3—C2—C21A	121.5 (6)	H31A—C31A—H31C	109.5
C2—C21A—H21A	109.5	H31B—C31A—H31C	109.5
C2—C21A—H21B	109.5	O3—C31B—C3	129 (3)
H21A—C21A—H21B	109.5	O3—C31B—H31D	115.6
C2—C21A—H21C	109.5	C3—C31B—H31D	115.6

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C1–C3/C1^v–C3^v benzene ring [symmetry code: (v) = -x + 1, -y + 1, -z + 1].

D—H···A	D—H	H···A	D···A	D—H···A
C21A—H21C···O1ⁱⁱ	0.98	2.66	3.506 (15)	144
C11—H11B···O2ⁱⁱⁱ	0.98	2.71	3.195 (9)	111
C11—H11A···O3^iv	0.98	2.42	2.788 (9)	102
C31A—H31C···Cg1ⁱⁱ	0.98	2.71	3.48 (2)	138
C31A—H31C···Cg1^v	0.98	2.71	3.48 (2)	138

Symmetry codes: (ii) x+1, y, z; (iii) −x+2, −y+1, −z+2; (iv) −x+2, y−1/2, −z+3/2; (v) −x+2, −y+1, −z+1.

Acknowledgements

The authors thank the New Zealand Ministry of Business, Innovation and Employment Science Investment Fund (grant No. UOO-X1206), for support of this work, and the University of Otago for the purchase of the diffractometer. JS also thanks the Chemistry Department University of Otago for support of his work.

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