3-Meth­oxy-2-[(E)-(4-meth­oxy­phen­yl)imino­meth­yl]phenol

Gonca Özdemir Tari; Şamil Işık; Ramazan Özkan; Ayşen Alaman Ağar

doi:10.1107/S1600536811000596

. 2011 Jan 12;67(Pt 2):o343–o344. doi: 10.1107/S1600536811000596

3-Methoxy-2-[(E)-(4-methoxyphenyl)iminomethyl]phenol

Gonca Özdemir Tari ^a, Şamil Işık ^a, Ramazan Özkan ^b, Ayşen Alaman Ağar ^b,^*

PMCID: PMC3051687 PMID: 21523025

Abstract

The title compound, C₁₅H₁₅NO₃, adopts the enol–imine tautomeric form. The two rings are twisted with respect to each other, making a dihedral angle of 44.08 (5)°. The 3-methoxy-2-[(E)-(4-methoxyphenyl)-iminomethyl]phenol unit is almost planar, the largest deviation from the mean plane being 0.047 (2) Å. Such a planar conformation might be related to the occurrence of an intramolecular O—H⋯N hydrogen bond. In the crystal, intermolecular C—H⋯O hydrogen bonds link the molecules into sheets parallel to (010). These sheets are interconnected by weak C—H⋯π interactions.

Related literature

For background to the properties and uses of Schiff bases, see: Barton & Ollis (1979 ▶); Layer (1963 ▶); Ingold (1969 ▶); Cohen et al. (1964 ▶); Taggi et al. (2002 ▶). For hydrogen-bond motifs, see: Etter et al. (1990 ▶); Bernstein et al. (1995 ▶). For related structures, see: Özdemir Tarı et al. (2010 ▶); Şahin et al. (2005 ▶).

Experimental

Crystal data

C₁₅H₁₅NO₃
M _r = 257.28
Monoclinic,
a = 14.2658 (8) Å
b = 14.1553 (11) Å
c = 6.5893 (17) Å
β = 96.398 (9)°
V = 1322.3 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.65 × 0.32 × 0.14 mm

Data collection

Stoe IPDS 2 diffractometer
Absorption correction: integration (X-RED32; Stoe, 2002) ▶ T _min = 0.991, T _max = 0.997
7244 measured reflections
2585 independent reflections
1622 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.122
S = 1.04
2585 reflections
172 parameters
H-atom parameters constrained
Δρ_max = 0.11 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: X-AREA (Stoe, 2002) ▶; cell refinement: X-AREA ▶; data reduction: X-RED32 (Stoe, 2002 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶), ORTEP-3 for Windows (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811000596/dn2646sup1.cif

e-67-0o343-sup1.cif^{(17.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811000596/dn2646Isup2.hkl

e-67-0o343-Isup2.hkl^{(124.4KB, hkl)}

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

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

Cg1 is the centroid of the C1—C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13—H13⋯O2ⁱ	0.93	2.60	3.428 (3)	149
C14—H14A⋯O1ⁱⁱ	0.96	2.49	3.412 (3)	162
O2—H2A⋯N1	0.82	1.87	2.590 (2)	146
C5—H5⋯Cg1ⁱⁱⁱ	0.93	2.80	3.486 (2)	132

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant No. F279 of the University Research Fund).

supplementary crystallographic information

Comment

Schiff bases are used as starting materials in the synthesis of important drugs, such as antibiotics and antiallergic, antiphlogistic, and antitumor substances (Barton et al., 1979; Layer, 1963; Ingold 1969). On the industrial scale, they have a wide range of applications, such as dyes and pigments (Taggi et al., 2002). There are two characteristic properties of Schiff bases, viz. Photochromism and thermochromism (Cohen et al., 1964). In general, Schiff bases display two possible tautomeric forms, the phenol-imine (OH) and the keto-amine (NH) forms. Depending on the tautomers, two types of intramolecular hydrogen bonds are observed in Schiff bases: O—H···N in phenol-imine (Özdemir Tarı et al., 2010) and N—H···O in keto-amine tautomers (Şahin et al., 2005). Another form of the Schiff base compounds is also known as zwitterion having an ionic intramolecular hydrogen bond (N⁺—H···O^-) and this form is rarely seen in the solid state (Özdemir Tarı et al., 2010).

The title compound, C₁₅H₁₅O₃N₁, adopts the enol-imine tautomeric form. The C7=N1 [1.278 (3) Å] and C8=N1 [1.419 (2) Å] bond distances are of double-bond character, whereas, C6—O2 [1.356 (2) Å] distance is single bond. These distances are similar to that reported in the literature [1.269 (8) Å] and [1.397 (7) Å] for C=N and [1.332 (8) Å] for C—O respectively (Özdemir Tarı et al., 2010).

The two phenyl rings are twisted with respect to each other making dihedral angle of 44.08 (5)° (Fig. 1). The 4-methoxyphenylimino)phenol moiety is planar with the largest deviation from the mean plane being 0.047 (2)Å at C7. Such planar conformation might be related to the occurrence of the O—H···N intramolecular hydrogen bond (Fig. 1, Table 1). This intramolecular N—H···O hydrogen bond results in the formation of an S(6) ring (Etter et al., 1990; Bernstein et al., 1995).

Intermolecular C—H···O hydrogen bonds link the molecules forming sheets parallel to the (0 1 0) plane (Fig. 2, Table 1). These sheets are interconnected by weak C—H···π interactions (Table 1, Cg1 is the centroid of the C1—C6 phenyl ring).

Experimental

(E)-3-methoxy-2-((4-methoxyphenylimino)methyl)phenol was prepared by refluxing a mixture of a solution containing 2-hydroxy-6- methoxybenzaldehyde (15.2 mg, o.1 mmol) in ethanol (30 ml) and a solution containing 4-methoxyaniline (12.3 mg, 0.1 mmol) in ethanol (20 ml). The reaction mixture was stirred for 2 h under reflux. Single crystals of the title compound for x-ray analysis were obtained by slow evaporation of an ethanol solution (yield 72%; m.p 346–348 K).