6-[(5-tert-Butyl-2-hydroxy­anilino)methyl­ene]cyclo­hexa-2,4-dienone

Uwe Böhme; Sabine Fels

doi:10.1107/S1600536807061211

. 2007 Dec 6;64(Pt 1):o14. doi: 10.1107/S1600536807061211

6-[(5-tert-Butyl-2-hydroxyanilino)methylene]cyclohexa-2,4-dienone

Uwe Böhme ^a,^*, Sabine Fels ^a

PMCID: PMC2914976 PMID: 21200704

Abstract

In the title compound, C₁₇H₁₉NO₂, the dihedral angle between the two aromatic rings is 26.02 (5)°. One phenol O atom is deprotonated and the N atom of the azomethine unit carries the H atom, forming an intramolecular hydrogen bond. The packing is stabilized by an O—H⋯O hydrogen bond.

Related literature

Aromatic Schiff bases with ortho-hydroxy groups are useful as acyclic polydentate ligands for the preparation of chelate complexes with a wide variety of metal ions (Freeman & White, 1956 ▶; Calligaris & Randaccio, 1987 ▶; Pettinari et al., 2001 ▶; Hernández-Molina & Mederos, 2004 ▶). For related literature, see: Böhme & Günther (2006 ▶, 2007 ▶); Böhme, Wiesner & Günther (2006 ▶); Dubs et al. (2000 ▶); Hopfl et al. (1998 ▶); Nazir et al. (2000 ▶); Pradeep (2005 ▶).

Experimental

Crystal data

C₁₇H₁₉NO₂
M _r = 269.33
Monoclinic,
a = 10.3600 (4) Å
b = 9.5756 (3) Å
c = 14.7335 (6) Å
β = 99.664 (2)°
V = 1440.87 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 153 (2) K
0.5 × 0.37 × 0.25 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: none
14317 measured reflections
3478 independent reflections
2819 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.108
S = 1.08
3478 reflections
193 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: SMART (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807061211/bt2630sup1.cif

e-64-00o14-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807061211/bt2630Isup2.hkl

e-64-00o14-Isup2.hkl^{(170.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H3⋯O1	0.939 (16)	1.83 (2)	2.601 (1)	137.8 (13)
O2—H2⋯O1ⁱ	0.84	1.75	2.583 (1)	174 (1)

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

Recently, we are working on silicon and titanium complexes with tridentate O,N,O-ligands (Böhme & Günther, 2006; Böhme, Wiesner & Günther, 2006; Böhme & Günther, 2007). The title compound, C₁₇H₁₉NO₂, was prepared in order to extend the series of available ligands. The preparation of the title compound was performed according to methods described in the literature for the parent compound salicyclidene-o-aminophenol ("salopH₂") (Freeman and White, 1956; Pettinari et al., 2001) by reaction of salicyclaldehyde and 2-amino-4-tert-butylphenol in ethanol. The molecule is non-planar with a dihedral angle between the two aromatic rings of 26.02 (5)°. The atom H3 forms an intramolecular hydrogen bond between the phenolic oxygen atom O1 and N1 of the azomethine unit. The hydrogen atom H3 is localized at a distance of 0.94 (2) Å from N1. This hints to the presence of the keto-amine form. The presence of a quinoidal structure is further supported by the shortening of the bond O1—C3 to 1.296 (1) Å and the lengthening of the adjacent C—C bonds in the phenyl ring [C2—C3 1.437 (2), C3—C4 1.426 (2) Å] (Nazir et al., 2000). There are few structure reports of Schiff-bases with oxygen in ortho-position where the intramolecular bridging hydrogen atom is localized at the nitrogen atom (e.g. Pradeep, 2005; Dubs et al., 2000; Hopfl et al., 1998). The crystal packing is stabilized by a hydrogen bond O2—H2···O1 forming a helix along the crystallographic 2₁ axis.

Experimental

2-Amino-4-tert-butylphenol (3.07 g, 18.6 mmol) was dissolved in ethanol (100 ml). This solution was heated slowly to 313 K and after a few minutes salicylaldehyde (2.27 g, 1.96 ml, 18.6 mmol) was added with a syringe. The reaction mixture was boiled at reflux temperature for 1.5 h. After that time a red solution was formed. The solution was concentrated in a vacuum to a small volume (30 ml) until a red crystalline precipitate deposited. The precipitate was filtered off and washed with ethanol. After drying, the product was purified by recrystallization with ethanol. Red prisms (4.38 g, 87.6%, m.p. 415 K). NMR (CDCl₃, 300 K, TMS): ¹H: δ=12,37 (s, OH), 8.64 (s, CH—N), 7.41–6.92 (m, CH_aromatic), 1.33 (s, C(CH₃)₃); ¹³C: 163.5 (C1), 160.5 (C3), 147.4 (C9), 144.0 (C12), 135.0, 133.4, 132.5, 125.6, 119.4, 119.3, 117.2, 115.4, 115.4 (9 signals for aromatic C), 34.3 (C14), 31.5 (C15—C17).