J Chem Crystallogr (2009) 39:638–641
639
The Synthesis of N-(2,3,4-Trimethoxy-6-
methylbenzylidene)-2-methyl-benzenamine
Table 1 Crystal and experimental data for the title compound
Compound
C18H21NO3
Brown/block
299.36
Colour/shape
To a solution of o-toluidine (0.535 g, 5 mmol) and potas-
sium acetate (10 mmol) in distilled water (10 mL), 2,3,4-
trimethoxy-6-methylbenzaldehyde (1.04 g, 5 mmol) in
ethylalcohol (20 mL) was added drop by drop, the solution
was stirred magnetically for 1 h at reflux temperature.
After cooling to room temperature, the product was filtered
and dried. Yield 89%. Anal. Calcd. (%) for C18H21NO3: C
72.14, H 7.01, N 4.68. Found (%): C 72.30, H 7.09, N 4.76.
Selected IR data (cm-1): 1,636 (s, –C=N), 1,200 (s, Ar–O).
1H NMR data (CD3COCD3, ppm): d = 8.61 (s, 1H), 7.14
(m, 2H), 7.05 (d, H),6.22 (s, 1H), 3.83 (s, 9H), 2.40 (s, 6H).
The single crystal suitable for X-ray determination was
obtained by evaporation from ethanol solution after a week.
Formula weight
CCDC deposit no.
Crystal system
Space group
686722
Monoclinic
P21/n
˚
a = 7.2804(5) A
Unit cell dimensions
˚
b = 8.5909(9) A
˚
c = 26.117(3) A
b = 92.056(2)ꢁ
3
˚
Volume
1,632.5(3) A
Z
4
Density (calculated)
Absorption coefficient
F(000)
1.218 g cm-3
0.083 mm-1
640
Crystal size
0.42 9 0.31 9 0.05 mm3
X-ray Structure Determination
h range for data collection
Index ranges
1.56–25.00ꢁ
-8 B h B 8; -10 B k B 10;
-31 B l B 21
A brown single crystal of the title compound with dimen-
sions of 0.42 mm 9 0.31 mm 9 0.05 mm was selected for
X-ray diffraction. The reflection data was collected on a
Bruker SMART diffractometer with a graphite mono-
Reflections collected
Independent reflections
Reflections observed (I [ 2r(I))
Refinement method
7,936
2,879
1,698
Full-matrix least-squares on F2
˚
chromatized Mo–Ka radiation (k = 0.71073 A). The
structure was solved by SHELXS-97 and refined with
Data/parameters
2,879/205
SHELXL-97 [7, 8]. The positions of the H atoms bonded to
˚
C atoms were calculated (C–H distance 0.96 A), and
Goodness-of-fit on F2
R indices [I [ 2r (I)]
R indices (all data)
1.024
R1 = 0.0497; wR2 = 0.1157
R1 = 0.0938; wR2 = 0.1453
refined using a riding model. The H atom displacement
parameters were restricted to be 1.2Ueq or 1.5Ueq (methyl
C) of the parent atom. Crystallographic data (excluding
structure factors) for the structures reported in this paper
have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no. 686722.
-3
˚
0.194 and -0.195 e. A
Largest diff. peak and hole
Results and Discussion
The Schiff reaction of 2,3,4-trimethoxy-6-methylbenzal-
dehyde with o-toluidine in a 1:1 ratio which was confirmed
by the elemental analysis, IR spectra and 1H NMR spectra.
The details of the X-ray data collection, experimental
conditions, and structure solution and structure refinements
aregiveninTable 1. AsseenfromTable 1, thecrystalbelongs
to monoclinic, space group P21/n, with a = 7.2804(5), b =
Fig. 1 Molecular structure of the title compound at 30% probability
thermal ellipsoids
˚
8.5909(9),c = 26.117(3)A, b = 92.056(2)ꢁ, V = 1,632.4(3)
3
-3
˚
˚
A , Z = 4, Dc = 1.218 g cm , k = 0.71073 A, l(Mo
Ka) = 0.083 mm-1, F(000) = 640. The final refinement
gave R = 0.0497, wR(F2) = 0.1157 for 2,879 observed
reflections with I [ 2r(I).
As seen from Fig. 1, the molecule adopts a trans config-
uration with respect to the central C=N functional bond. The
˚
benzene ring (C2–C7) is nearly planar to within 0.008(3) A,
˚
the displacements of C8, C9 and C10 are -1.172(2) A,
The molecular structure of the title compound is shown
in Fig. 1 and the crystal packing of the compound are
depicted in Fig. 2. The selected bond lengths and angles
are given in Table 2.
˚
-1.118(3) A and 0.355(2) A, respectively, from this plane.
˚
Another benzene ring (C12–C17) is nearly planar to within
˚
0.008(3) A, and the displacement of C18 is 0.841(2) A. The
˚
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