3,5-Dimeth­oxy-2-[(4-propyl­phen­yl)imino­meth­yl]phenol

Zarife Sibel Şahin; Ayşen Alaman Ağar; Ferda Erşahin; Şamil Işık

doi:10.1107/S1600536809007958

. 2009 Mar 11;65(Pt 4):o718. doi: 10.1107/S1600536809007958

3,5-Dimethoxy-2-[(4-propylphenyl)iminomethyl]phenol

Zarife Sibel Şahin ^a,^*, Ayşen Alaman Ağar ^b, Ferda Erşahin ^b, Şamil Işık ^a

PMCID: PMC2968940 PMID: 21582454

Abstract

The title compound, C₁₈H₂₁NO₃, crystallizes in the phenol–imine tautomeric form, with the H atom attached to oxygen rather than on nitrogen. This H atom is involved in a strong intramolecular O—H⋯N hydrogen bond. A C—H⋯π interaction is also present. The dihedral angle between the aromatic rings is 12.23 (7)°.

Related literature

Schiff base compounds can be classified by their photochromic and thermochromic characteristics, see: Cohen et al. (1964 ▶); Hadjoudis et al. (1987 ▶); Calligaris et al. (1972 ▶); Hökelek et al. (2000 ▶); Dey et al. (2001 ▶); Ünver et al. (2002 ▶); Karadayı et al. (2003 ▶). Bernstein et al. (1995 ▶) describe the use of graph-set models for the description of hydrogen bonds.

Experimental

Crystal data

C₁₈H₂₁NO₃
M _r = 299.36
Monoclinic,
a = 15.1143 (15) Å
b = 7.2587 (5) Å
c = 17.737 (2) Å
β = 123.669 (7)°
V = 1619.5 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.48 × 0.26 × 0.12 mm

Data collection

Stoe IPDS-II diffractometer
Absorption correction: none
18964 measured reflections
3353 independent reflections
1337 reflections with I > 2σ(I)
R _int = 0.075

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.145
S = 0.86
3353 reflections
200 parameters
H-atom parameters constrained
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.21 e Å⁻³

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, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809007958/zl2174sup1.cif

e-65-0o718-sup1.cif^{(19KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809007958/zl2174Isup2.hkl

e-65-0o718-Isup2.hkl^{(161.1KB, 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
O2—H2⋯N1	0.82	1.87	2.602 (2)	148
C18—H18B⋯Cg2ⁱ	0.96	2.80	3.764 (3)	178

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Symmetry code: (i) Inline graphic . Cg2 is the centroid of the C7–C12 ring.

Acknowledgments

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

supplementary crystallographic information

Comment

Schiff bases have been extensively used as ligands in the field of coordination chemistry (Calligaris et al., 1972). There are two characteristic properties of Schiff bases, viz. photochromism and thermochromism (Cohen et al., 1964). These properties result from proton transfer from the hydroxyl O atom to the imine N atom (Hadjoudis et al., 1987). Schiff bases display two possible tautomeric forms, namely the phenol-imine (Dey et al., 2001; Karadayı et al., 2003) and keto-amine (Hökelek et al., 2000; Ünver et al., 2002) forms.

In the structure of the title compound the N1—C16 bond length of 1.280 (3)Å is typical of a double bond. The dihedral angle between the C1—C6 and C8—C13 benzene rings is 12.23 (7)°. The C1—C16—N1—C7 torsion angle is 178.7 (2)°. Fig. 1 also shows a strong intramolecular hydrogen bond (O2—H2···N1) which can be described with an S(6) graph set motif (Bernstein et al.,1995). The compound also contains one intermolecular C—H···π interaction. Atom C18 in the molecule at (x, y, z) acts as hydrogen-bond donor to the centroid Cg2 of the ring C7—C12 in the molecule at (1 - x, 1/2 + y, 3/2 - z), thus forming a chain running parallel to the [010] direction. The details of C—H···π interaction are given in Table 1.

Experimental

The compound 3,5-dimethoxy-2-[(4-propylphenylimino)methyl]phenol was prepared by refluxing of a mixture of a solution containing 2-hydroxy-4,6-dimethoxy-benzaldehyde (0.0236 g 0.129 mmol) in 20 ml ethanol and a solution containing 4-propylaniline (0.0175 g 0.129 mmol) in 20 ml ethanol. The reaction mixture was stirred for 1 h under reflux. Recrystallization from ethanol gave the pure product. The crystals of 4,6-dimethoxy-2-[(4-propylphenylimino)methyl]phenol suitable for X-ray analysis were obtained from ethylalcohol by slow evaporation (yield % 67; m.p.346–348 K) (Fig. 2).