3-tert-Butyl-2-hydr­oxy-5-methyl­benzaldehyde: a redetermination

In the mol­ecule of the title compound, C₁₂H₁₆O₂, all atoms except one methyl group and two H atoms are located on a crystallographic mirror plane; thus the mol­ecule is essentially planar. An intra­molecular O—H...O hydrogen bond and weak C—H...O inter­molecular hydrogen bonds stabilize the packing. The structure has been previously reported in the non-centrosymmetric space group P2₁; our study shows that the correct space group is P2₁/m.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.039
• wR factor = 0.109
• Data-to-parameter ratio = 12.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.77 mm
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety        C11
PLAT391_ALERT_3_C Deviating Methyl C11     H-C-H Bond Angle ......     101.90 Deg.

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

   0 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
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Hydroxy-substituted benzaldehyde reagents used for condensation with primary amines, hydrazines, hydroxylamine and other primary amine derivatives afford imine derivatives which can function as ligands towards a number of metal cations (Loudon, 2002; Khandar & Nejati, 2000; Khandar & Rezvani, 1999).

The structure of (I) has been previously reported [Matilainen or Matlainen et al., 1996; Cambridge Structural Database (Allen, 2002) refcode ZOJRAR]; however, the choice of the space group P2₁ appears to be wrong and the correct space group is P2₁/m. All atoms except for one methyl and two H atoms are located in a crystallographic mirror plane thus the molecule except for one methyl is perfectly planar (Fig. 1). A significant intramolecular interaction is noted, involving phenol atom H1 and carbonyl atom O2, such that a six-membered ring is formed (Table 1 and Fig. 1). The aromatic ring C—C bond distances in (I) agree with those observed in bis(3-formyl-4-hydroxy-5-methoxyphenyl)methane (Odabaşoğlu et al., 2006). The C7—O1 bond distance in (I) is also consistent with the value of the C═O double bond in carbonyl compounds (Loudon, 2002).

S2. Experimental

A mixture of 2-tert-butyl-4-methylphenol (0.1 mol) and CHCl₃ (0.4 mol) and NaOH (0.8 mol) in ethyl alcohol was stirred at reflux temperature for 2 h. The 50 ml 20% H₂SO₄ solution was added to this reaction mixture and crude product was purified with neutral alumina column. Well shaped crystals of (I) were obtained by slow evaporation from ethyl alcohol solution (yield 0.96 g, 5%, m.p. 345 K).

S3. Refinement

All H atoms were located at first in a Fourier difference map without any problem. However, because of the need to reduce the number of free parameters, the H atoms of the aromatic ring and the C9 methyl group were place in calculated positions and refined as riding, with C—H distances in the range 0.96 (2)–0.93 (2) Å and U_iso(H) = 1.5U_eq of the parent atom for methyl and U_iso(H) = 1.2U_eq of the parent atom for aromatic H atoms. The H atoms on O2 (which takes part in a hydrogen bond) and on C10 and C11 belonging to the mirror plane were located in a Fourier difference map and their coordinates were refined using C—H and O—H restraints of 0.96 and 0.85 Å, respectively, and with U_iso(H) = 1.5U_eq(methyl C) and U_iso(H) = 1.2U_eq(O).

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. A view of (I), showing the atomic numbering scheme and the intramolecular hydrogen bond as a dashed line. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A packing diagram of (I), showing the hydrogen-bonding scheme (dashed lines).

3-tert-butyl-2-hydroxy-5-methylbenzaldehyde

Crystal data

C12H16O2	F(000) = 208
Mr = 192.25	Dx = 1.194 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 5006 reflections
a = 8.3633 (8) Å	θ = 3.0–28.8°
b = 6.6200 (6) Å	µ = 0.08 mm^−1
c = 9.7328 (11) Å	T = 100 K
β = 97.170 (9)°	Prism, yellow
V = 534.64 (9) Å^3	0.77 × 0.50 × 0.20 mm
Z = 2

Data collection

Stoe diffractometer	1037 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 26.0°, θmin = 3.4°
Detector resolution: 6.67 pixels mm^-1	h = −10→10
ϕ scan rotation method	k = −8→8
5006 measured reflections	l = −12→12
1136 independent reflections

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0624P)^2 + 0.1473P] where P = (Fo^2 + 2Fc^2)/3
1136 reflections	(Δ/σ)max < 0.001
95 parameters	Δρmax = 0.30 e Å^−3
5 restraints	Δρmin = −0.21 e Å^−3

Special details

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
C1	0.55851 (17)	0.2500	0.48411 (16)	0.0178 (3)
C2	0.49028 (17)	0.2500	0.34480 (15)	0.0167 (3)
C3	0.32167 (17)	0.2500	0.31042 (15)	0.0162 (3)
C4	0.23035 (17)	0.2500	0.41980 (15)	0.0168 (3)
H4	0.1188	0.2500	0.3990	0.020*
C5	0.29523 (18)	0.2500	0.55985 (15)	0.0176 (3)
C6	0.46025 (18)	0.2500	0.58976 (15)	0.0176 (3)
H6	0.5070	0.2500	0.6816	0.021*
C7	0.73224 (18)	0.2500	0.51989 (17)	0.0218 (4)
H7	0.7722	0.2500	0.6134	0.026*
C8	0.24411 (18)	0.2500	0.15894 (15)	0.0191 (4)
C9	0.29509 (14)	0.44005 (19)	0.08592 (11)	0.0279 (3)
H9A	0.2469	0.4391	−0.0089	0.042*
H9B	0.4103	0.4425	0.0895	0.042*
H9C	0.2600	0.5577	0.1315	0.042*
C10	0.0601 (2)	0.2500	0.14759 (17)	0.0276 (4)
H10A	0.017 (3)	0.2500	0.0513 (11)	0.041*
H10B	0.0202 (18)	0.1301 (18)	0.1902 (15)	0.041*
C11	0.1852 (2)	0.2500	0.67075 (17)	0.0250 (4)
H11A	0.243 (2)	0.2500	0.7616 (13)	0.037*
H11B	0.1125 (15)	0.1377 (18)	0.6625 (15)	0.037*
O1	0.83007 (13)	0.2500	0.43643 (13)	0.0277 (3)
O2	0.58647 (13)	0.2500	0.24303 (12)	0.0245 (3)
H2	0.6816 (14)	0.2500	0.2856 (19)	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0160 (7)	0.0120 (6)	0.0249 (8)	0.000	0.0010 (6)	0.000
C2	0.0170 (7)	0.0141 (7)	0.0199 (7)	0.000	0.0064 (6)	0.000
C3	0.0174 (7)	0.0132 (7)	0.0178 (7)	0.000	0.0019 (5)	0.000
C4	0.0134 (7)	0.0160 (7)	0.0210 (7)	0.000	0.0025 (5)	0.000
C5	0.0200 (7)	0.0145 (7)	0.0190 (7)	0.000	0.0054 (6)	0.000
C6	0.0216 (8)	0.0141 (7)	0.0163 (7)	0.000	−0.0007 (6)	0.000
C7	0.0182 (8)	0.0169 (7)	0.0293 (8)	0.000	−0.0011 (6)	0.000
C8	0.0206 (7)	0.0199 (7)	0.0164 (7)	0.000	0.0012 (5)	0.000
C9	0.0354 (6)	0.0271 (7)	0.0204 (5)	−0.0036 (5)	−0.0005 (4)	0.0055 (4)
C10	0.0217 (8)	0.0379 (10)	0.0215 (8)	0.000	−0.0041 (6)	0.000
C11	0.0260 (8)	0.0300 (9)	0.0203 (8)	0.000	0.0085 (6)	0.000
O1	0.0145 (5)	0.0274 (6)	0.0414 (7)	0.000	0.0045 (5)	0.000
O2	0.0163 (5)	0.0344 (7)	0.0241 (6)	0.000	0.0079 (4)	0.000

Geometric parameters (Å, º)

C1—C6	1.394 (2)	C7—H7	0.9300
C1—C2	1.404 (2)	C8—C10	1.529 (2)
C1—C7	1.451 (2)	C8—C9	1.5315 (14)
C2—O2	1.3517 (17)	C8—C9^i	1.5315 (14)
C2—C3	1.408 (2)	C9—H9A	0.9600
C3—C4	1.385 (2)	C9—H9B	0.9600
C3—C8	1.5348 (19)	C9—H9C	0.9600
C4—C5	1.403 (2)	C10—H10A	0.961 (10)
C4—H4	0.9300	C10—H10B	0.974 (9)
C5—C6	1.375 (2)	C11—H11A	0.953 (10)
C5—C11	1.503 (2)	C11—H11B	0.957 (9)
C6—H6	0.9300	O2—H2	0.850 (10)
C7—O1	1.223 (2)
C6—C1—C2	120.43 (13)	C1—C7—H7	117.5
C6—C1—C7	119.19 (14)	C10—C8—C9	107.60 (9)
C2—C1—C7	120.39 (14)	C10—C8—C9^i	107.60 (9)
O2—C2—C1	120.02 (13)	C9—C8—C9^i	110.48 (13)
O2—C2—C3	119.72 (13)	C10—C8—C3	111.73 (12)
C1—C2—C3	120.25 (13)	C9—C8—C3	109.70 (8)
C4—C3—C2	116.69 (13)	C9^i—C8—C3	109.70 (8)
C4—C3—C8	122.06 (13)	C8—C9—H9A	109.5
C2—C3—C8	121.26 (13)	C8—C9—H9B	109.5
C3—C4—C5	124.28 (13)	H9A—C9—H9B	109.5
C3—C4—H4	117.9	C8—C9—H9C	109.5
C5—C4—H4	117.9	H9A—C9—H9C	109.5
C6—C5—C4	117.52 (13)	H9B—C9—H9C	109.5
C6—C5—C11	122.45 (14)	C8—C10—H10A	109.0 (13)
C4—C5—C11	120.03 (13)	C8—C10—H10B	111.4 (9)
C5—C6—C1	120.83 (13)	H10A—C10—H10B	107.9 (12)
C5—C6—H6	119.6	C5—C11—H11A	112.4 (13)
C1—C6—H6	119.6	C5—C11—H11B	112.2 (9)
O1—C7—C1	124.99 (15)	H11A—C11—H11B	108.7 (11)
O1—C7—H7	117.5	C2—O2—H2	104.4 (14)

Symmetry code: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1	0.85 (1)	1.80 (1)	2.5954 (16)	155 (2)
C4—H4···O1^ii	0.93	2.49	3.3717 (18)	159

Symmetry code: (ii) x−1, −y+1/2, z.