Retracted: 2,6-Dimethoxy­benzohydrazide

The title compound, C₉H₁₂N₂O₃, is an important inter­mediate for the synthesis of biologically active heterocyclic compounds. The planar hydrazide group is oriented with respect to the benzene ring at a dihedral angle of 82.93 (3)°.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.066
• wR factor = 0.109
• Data-to-parameter ratio = 20.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    N1     -   N2      ..      20.22 su
PLAT230_ALERT_2_B Hirshfeld Test Diff for    N2     -   C9      ..      21.22 su
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for         N2

Alert level C
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         40 Perc.
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.98
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.12 Ratio
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C1     -   C2      ..       5.28 su
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1B    ...          ?
PLAT420_ALERT_2_C D-H Without Acceptor       N2     -   H2A    ...          ?

   0 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
   7 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
   6 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Aromatic hydrazides are important intermediates in heterocyclic chemistry and have been used for the synthesis of various biologically active five-membered heterocycles such as 2,5-disubstituted-1,3,4-oxadiazoles (Zheng et al., 2003; Al-Talib et al., 1990) and 5-substituted-2-mercapto-1,3,4-oxadiazoles (Yousif et al., 1986; Ahmad et al., 2001; Al-Soud et al., 2004; El-Emam et al., 2004). In view of the versatility of these compounds, we have synthesized the title compound, (I), and reported its crystal structure.

In the molecule of the title compound, (I), (Fig. 1), the bond lengths and angles are within normal ranges (Allen et al., 1987). The dihedral angle between the planar hydrazidic group (C9/O3/N1/N2) and benzene ring (C1—C6) is 97.07 (3)°.

Related literature

For general background, see: Zheng et al. (2003); Al-Talib et al. (1990); Yousif et al. (1986); Ahmad et al. (2001); Al-Soud et al. (2004); El-Emam et al. (2004); Allen et al. (1987); Furniss et al. (1978).

S2. Experimental

The title compound, (I), is synthesized by reaction of the methyl ester of 3,5-difluorobenzoic acid with hydrazine hydrate using a reported procedure (Furniss et al., 1978). For the preparation of (I), a mixture of methyl-2,6-dimethoxybenzoate (1.96 g, 10 mmol) and hydrazine hydrate (80%, 15 ml) in absolute ethanol (50 ml) was refluxed for 5 h at 413–423 K. The excess solvent was removed by distillation. The solid residue was filtered off, washed with water and recrystallized from ethanol (30%) to give the title compound (yield 1.78 g, 91%; m.p. 517–519 K). Colorless single crystals of (I) were obtained by slow evaporation of an ethanol solution at room temperature.

S3. Refinement

H atoms were positioned geometrically, with N—H = 0.86 Å (for NH and NH₂) and C—H = 0.93 and 0.96 Å for aromatic and methyl H atoms, respectively, and constrained to ride on their parent atoms, with U_iso(H) = xU_eq(C,N), where x = 1.5 for methyl H, and x = 1.2 for all other H atoms.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick,1997); program(s) used to refine structure: SHELXL97 (Sheldrick,1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. The formation of the title compound.

2,6-Dimethoxybenzohydrazide

Crystal data

C9H12N2O3	Dx = 1.257 Mg m^−3
Mr = 196.21	Melting point: 244(2) K
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 1520 reflections
a = 7.2598 (5) Å	θ = 2.7–24.9°
b = 14.2558 (11) Å	µ = 0.10 mm^−1
c = 20.0412 (11) Å	T = 294 K
V = 2074.1 (2) Å^3	Block, colourless
Z = 8	0.16 × 0.14 × 0.06 mm
F(000) = 832

Data collection

Bruker APEXII diffractometer	2615 independent reflections
Radiation source: rotating-anode generator	1044 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.043
φ and ω scans	θmax = 28.7°, θmin = 2.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.981, Tmax = 0.993	k = −19→19
14489 measured reflections	l = −26→26

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.066	H-atom parameters constrained
wR(F^2) = 0.109	w = 1/[σ^2(Fo^2) + 0.1639P] where P = (Fo^2 + 2Fc^2)/3
S = 1.99	(Δ/σ)max < 0.001
2615 reflections	Δρmax = 0.37 e Å^−3
128 parameters	Δρmin = −0.40 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick,1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0102 (7)

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
O1	−0.0885 (3)	0.45612 (13)	0.41648 (11)	0.0982 (7)
O2	0.4159 (3)	0.29139 (14)	0.33521 (9)	0.0827 (6)
O3	−0.0195 (3)	0.24193 (13)	0.37742 (10)	0.0873 (6)
N1	0.1159 (4)	0.1846 (2)	0.49375 (14)	0.1344 (12)
H1A	0.0378	0.1475	0.4751	0.161*
H1B	0.1633	0.1701	0.5317	0.161*
N2	0.1671 (3)	0.27065 (13)	0.46145 (9)	0.0542 (5)
H2A	0.2450	0.3082	0.4796	0.065*
C1	0.1691 (4)	0.37920 (17)	0.37441 (12)	0.0623 (7)
C2	0.0721 (5)	0.4629 (2)	0.38130 (15)	0.0787 (9)
C3	0.1419 (6)	0.5447 (2)	0.35300 (17)	0.1006 (11)
H3A	0.0796	0.6014	0.3575	0.121*
C4	0.3060 (6)	0.5399 (3)	0.31813 (17)	0.1075 (13)
H4A	0.3530	0.5945	0.2994	0.129*
C5	0.4017 (5)	0.4583 (3)	0.31005 (15)	0.0969 (11)
H5A	0.5103	0.4572	0.2855	0.116*
C6	0.3336 (4)	0.3771 (2)	0.33932 (13)	0.0713 (8)
C7	−0.1954 (5)	0.5395 (2)	0.42662 (18)	0.1352 (15)
H7A	−0.3034	0.5246	0.4522	0.203*
H7B	−0.2314	0.5648	0.3842	0.203*
H7C	−0.1230	0.5850	0.4503	0.203*
C8	0.5861 (4)	0.2843 (2)	0.29912 (15)	0.1081 (11)
H8A	0.6286	0.2205	0.3001	0.162*
H8B	0.6766	0.3243	0.3194	0.162*
H8C	0.5670	0.3034	0.2537	0.162*
C9	0.0935 (4)	0.29037 (18)	0.40452 (14)	0.0637 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.1089 (17)	0.0674 (13)	0.1182 (17)	0.0212 (13)	0.0054 (15)	−0.0019 (12)
O2	0.0755 (14)	0.0910 (15)	0.0816 (13)	−0.0016 (12)	0.0144 (11)	0.0078 (11)
O3	0.0909 (15)	0.0748 (13)	0.0963 (15)	−0.0186 (12)	−0.0211 (12)	0.0075 (11)
N1	0.128 (3)	0.142 (3)	0.133 (3)	−0.016 (2)	−0.016 (2)	0.043 (2)
N2	0.0614 (13)	0.0551 (12)	0.0461 (11)	−0.0188 (11)	−0.0156 (11)	0.0142 (10)
C1	0.0708 (19)	0.0545 (16)	0.0617 (17)	−0.0057 (16)	−0.0072 (16)	−0.0024 (14)
C2	0.096 (2)	0.0639 (19)	0.077 (2)	−0.0052 (19)	−0.0124 (19)	−0.0016 (17)
C3	0.137 (3)	0.060 (2)	0.104 (3)	−0.011 (2)	−0.031 (2)	0.0052 (19)
C4	0.139 (4)	0.082 (3)	0.102 (3)	−0.043 (3)	−0.019 (3)	0.024 (2)
C5	0.109 (3)	0.092 (2)	0.090 (2)	−0.032 (2)	−0.007 (2)	0.016 (2)
C6	0.082 (2)	0.0689 (19)	0.0632 (18)	−0.0172 (18)	−0.0092 (17)	0.0040 (16)
C7	0.149 (4)	0.092 (3)	0.164 (4)	0.052 (3)	−0.001 (3)	−0.017 (2)
C8	0.082 (2)	0.138 (3)	0.104 (2)	−0.002 (2)	0.027 (2)	0.016 (2)
C9	0.0566 (17)	0.0564 (17)	0.078 (2)	0.0001 (14)	0.0090 (16)	−0.0064 (15)

Geometric parameters (Å, º)

O1—C2	1.366 (3)	C2—C3	1.393 (4)
O1—C7	1.434 (3)	C3—C4	1.383 (4)
O2—C6	1.362 (3)	C3—H3A	0.9300
O2—C8	1.436 (3)	C4—C5	1.364 (4)
O3—C9	1.202 (3)	C4—H4A	0.9300
N1—N2	1.436 (3)	C5—C6	1.390 (4)
N1—H1A	0.8600	C5—H5A	0.9300
N1—H1B	0.8600	C7—H7A	0.9600
N2—C9	1.291 (3)	C7—H7B	0.9600
N2—H2A	0.8600	C7—H7C	0.9600
C1—C6	1.386 (3)	C8—H8A	0.9600
C1—C2	1.393 (3)	C8—H8B	0.9600
C1—C9	1.506 (3)	C8—H8C	0.9600
C2—O1—C7	118.4 (3)	C4—C5—H5A	120.7
C6—O2—C8	118.1 (2)	C6—C5—H5A	120.7
N2—N1—H1A	120.0	O2—C6—C5	124.5 (3)
N2—N1—H1B	120.0	O2—C6—C1	115.3 (3)
H1A—N1—H1B	120.0	C5—C6—C1	120.2 (3)
C9—N2—N1	118.5 (2)	O1—C7—H7A	109.5
C9—N2—H2A	120.7	O1—C7—H7B	109.5
N1—N2—H2A	120.7	H7A—C7—H7B	109.5
C6—C1—C2	120.3 (3)	O1—C7—H7C	109.5
C6—C1—C9	119.9 (2)	H7A—C7—H7C	109.5
C2—C1—C9	119.7 (3)	H7B—C7—H7C	109.5
O1—C2—C3	125.5 (3)	O2—C8—H8A	109.5
O1—C2—C1	115.0 (3)	O2—C8—H8B	109.5
C3—C2—C1	119.5 (3)	H8A—C8—H8B	109.5
C2—C3—C4	118.5 (3)	O2—C8—H8C	109.5
C2—C3—H3A	120.7	H8A—C8—H8C	109.5
C4—C3—H3A	120.7	H8B—C8—H8C	109.5
C5—C4—C3	122.8 (3)	O3—C9—N2	123.8 (3)
C5—C4—H4A	118.6	O3—C9—C1	123.4 (3)
C3—C4—H4A	118.6	N2—C9—C1	112.7 (2)
C4—C5—C6	118.6 (3)