The benzofuran moiety of the title molecule, C
10H
8O
2, is planar and forms a dihedral angle of 6.69 (9)° with the attached acetyl group. In the crystal structure, symmetry-related molecules are linked to form chains by C—H
O intermolecular hydrogen bonds involving the furan H atom and the O atom of the acetyl group. Adjacent chains are interlinked through weak C—H
π interactions involving the furan ring.
Supporting information
CCDC reference: 209909
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.003 Å
- R factor = 0.036
- wR factor = 0.092
- Data-to-parameter ratio = 13.0
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
The title compound was synthesized employing a phase-transfer catalytic technique. Salicylaldehyde (6.12 ml, 0.05 mol) and chloroacetone (4.0 ml, 0.05 mol) were taken in benzene (30 ml) and the reaction mixture was magnetically stirred for 3 h with 20% aqueous potassium carbonate (20 ml) solution in the presence of a catalytic amount of tetrabutylammonium hydrogen sulfate (200 mg) as a phase-transfer catalyst. The solid obtained was filtered off and dried in air. Recrystallization from 1,4-dioxane afforded the crystals. The yield of the isolated product was 86%.
The H atoms were fixed geometrically and were treated as riding on their parent C atoms, with isotropic displacement parameters. The methyl group was found to be disordered over two positions rotated from each other by 60°. It was refined as an idealized disordered methyl group.
Data collection: CAD-4 Software (Enraf-Nonius, 1994); cell refinement: MolEN (Fair, 1990); data reduction: MolEN; program(s) used to solve structure: SIR97 (Altomare et al. 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Crystal data top
C10H8O2 | Dx = 1.303 Mg m−3 |
Mr = 160.16 | Melting point: 344–345 K K |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 25 reflections |
a = 8.3865 (13) Å | θ = 10–15° |
b = 18.273 (4) Å | µ = 0.09 mm−1 |
c = 10.652 (2) Å | T = 293 K |
V = 1632.4 (5) Å3 | Block, light brown |
Z = 8 | 0.3 × 0.3 × 0.3 mm |
F(000) = 672 | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | θmax = 25.0°, θmin = 2.2° |
ω–2θ scans | h = 0→9 |
1419 measured reflections | k = 0→21 |
1419 independent reflections | l = 0→12 |
907 reflections with I > 2σ(I) | 2 standard reflections every 100 reflections |
Rint = 0 | intensity decay: none |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.036 | w = 1/[σ2(Fo2) + (0.0348P)2 + 0.2715P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.092 | (Δ/σ)max < 0.001 |
S = 1.03 | Δρmax = 0.10 e Å−3 |
1419 reflections | Δρmin = −0.12 e Å−3 |
109 parameters | |
Crystal data top
C10H8O2 | V = 1632.4 (5) Å3 |
Mr = 160.16 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 8.3865 (13) Å | µ = 0.09 mm−1 |
b = 18.273 (4) Å | T = 293 K |
c = 10.652 (2) Å | 0.3 × 0.3 × 0.3 mm |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0 |
1419 measured reflections | 2 standard reflections every 100 reflections |
1419 independent reflections | intensity decay: none |
907 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.092 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.10 e Å−3 |
1419 reflections | Δρmin = −0.12 e Å−3 |
109 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
O1 | 0.58354 (15) | 0.03542 (6) | 0.72975 (11) | 0.0612 (4) | |
C2 | 0.6746 (2) | 0.00551 (10) | 0.63421 (15) | 0.0547 (4) | |
C3 | 0.6747 (2) | 0.04877 (10) | 0.53242 (16) | 0.0575 (5) | |
H3 | 0.7277 | 0.0399 | 0.4572 | 0.069* | |
C4 | 0.5316 (2) | 0.17426 (11) | 0.4978 (2) | 0.0713 (6) | |
H4 | 0.5641 | 0.1831 | 0.4157 | 0.086* | |
C5 | 0.4360 (3) | 0.22329 (11) | 0.5604 (2) | 0.0797 (6) | |
H5 | 0.4031 | 0.2656 | 0.5193 | 0.096* | |
C6 | 0.3873 (2) | 0.21127 (11) | 0.6835 (2) | 0.0774 (6) | |
H6 | 0.3236 | 0.2459 | 0.7232 | 0.093* | |
C7 | 0.4314 (2) | 0.14917 (10) | 0.7477 (2) | 0.0695 (5) | |
H7 | 0.3991 | 0.1407 | 0.8299 | 0.083* | |
C8 | 0.5263 (2) | 0.10015 (10) | 0.68320 (16) | 0.0555 (5) | |
C9 | 0.5787 (2) | 0.11078 (10) | 0.56100 (16) | 0.0555 (5) | |
C21 | 0.7495 (2) | −0.06530 (10) | 0.66040 (17) | 0.0616 (5) | |
C22 | 0.8610 (2) | −0.09450 (11) | 0.56308 (19) | 0.0772 (6) | |
H22A | 0.9441 | −0.1221 | 0.6031 | 0.116* | 0.5 |
H22B | 0.9071 | −0.0545 | 0.5172 | 0.116* | 0.5 |
H22C | 0.8035 | −0.1256 | 0.5064 | 0.116* | 0.5 |
H22D | 0.8257 | −0.0794 | 0.4813 | 0.116* | 0.5 |
H22E | 0.8627 | −0.147 | 0.5673 | 0.116* | 0.5 |
H22F | 0.9663 | −0.0759 | 0.5781 | 0.116* | 0.5 |
O21 | 0.72146 (19) | −0.09825 (7) | 0.75714 (13) | 0.0808 (4) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0704 (8) | 0.0599 (7) | 0.0533 (7) | 0.0007 (6) | 0.0086 (7) | 0.0016 (6) |
C2 | 0.0540 (10) | 0.0610 (11) | 0.0491 (9) | −0.0048 (9) | 0.0013 (9) | −0.0087 (9) |
C3 | 0.0522 (10) | 0.0720 (11) | 0.0482 (10) | −0.0095 (10) | −0.0001 (9) | −0.0030 (10) |
C4 | 0.0660 (13) | 0.0729 (12) | 0.0751 (12) | −0.0148 (11) | −0.0053 (11) | 0.0131 (12) |
C5 | 0.0771 (15) | 0.0593 (12) | 0.1028 (17) | −0.0088 (11) | −0.0156 (14) | 0.0150 (12) |
C6 | 0.0656 (13) | 0.0623 (13) | 0.1043 (17) | 0.0025 (10) | −0.0035 (13) | −0.0101 (12) |
C7 | 0.0693 (12) | 0.0653 (11) | 0.0738 (12) | −0.0032 (11) | 0.0079 (11) | −0.0048 (11) |
C8 | 0.0530 (10) | 0.0531 (10) | 0.0604 (11) | −0.0057 (9) | −0.0014 (9) | 0.0008 (9) |
C9 | 0.0507 (10) | 0.0603 (11) | 0.0553 (10) | −0.0124 (9) | −0.0058 (9) | 0.0043 (9) |
C21 | 0.0647 (11) | 0.0626 (11) | 0.0575 (10) | −0.0035 (10) | −0.0091 (10) | −0.0083 (10) |
C22 | 0.0728 (13) | 0.0756 (13) | 0.0833 (13) | 0.0080 (11) | 0.0005 (12) | −0.0165 (11) |
O21 | 0.1054 (12) | 0.0714 (8) | 0.0657 (8) | 0.0089 (8) | −0.0034 (8) | 0.0052 (8) |
Geometric parameters (Å, º) top
O1—C8 | 1.369 (2) | C6—H6 | 0.93 |
O1—C2 | 1.3848 (19) | C7—C8 | 1.381 (2) |
C2—C3 | 1.342 (2) | C7—H7 | 0.93 |
C2—C21 | 1.465 (3) | C8—C9 | 1.388 (2) |
C3—C9 | 1.423 (2) | C21—O21 | 1.216 (2) |
C3—H3 | 0.93 | C21—C22 | 1.495 (3) |
C4—C5 | 1.374 (3) | C22—H22A | 0.96 |
C4—C9 | 1.398 (2) | C22—H22B | 0.96 |
C4—H4 | 0.93 | C22—H22C | 0.96 |
C5—C6 | 1.391 (3) | C22—H22D | 0.96 |
C5—H5 | 0.93 | C22—H22E | 0.96 |
C6—C7 | 1.376 (3) | C22—H22F | 0.96 |
| | | |
C8—O1—C2 | 105.55 (13) | O21—C21—C2 | 121.04 (18) |
C3—C2—O1 | 111.21 (16) | O21—C21—C22 | 122.12 (19) |
C3—C2—C21 | 132.36 (17) | C2—C21—C22 | 116.84 (17) |
O1—C2—C21 | 116.43 (15) | C21—C22—H22A | 109.5 |
C2—C3—C9 | 107.21 (16) | C21—C22—H22B | 109.5 |
C2—C3—H3 | 126.4 | H22A—C22—H22B | 109.5 |
C9—C3—H3 | 126.4 | C21—C22—H22C | 109.5 |
C5—C4—C9 | 118.18 (19) | H22A—C22—H22C | 109.5 |
C5—C4—H4 | 120.9 | H22B—C22—H22C | 109.5 |
C9—C4—H4 | 120.9 | C21—C22—H22D | 109.5 |
C4—C5—C6 | 121.7 (2) | H22A—C22—H22D | 141.1 |
C4—C5—H5 | 119.1 | H22B—C22—H22D | 56.3 |
C6—C5—H5 | 119.1 | H22C—C22—H22D | 56.3 |
C7—C6—C5 | 121.3 (2) | C21—C22—H22E | 109.5 |
C7—C6—H6 | 119.3 | H22A—C22—H22E | 56.3 |
C5—C6—H6 | 119.3 | H22B—C22—H22E | 141.1 |
C6—C7—C8 | 116.3 (2) | H22C—C22—H22E | 56.3 |
C6—C7—H7 | 121.9 | H22D—C22—H22E | 109.5 |
C8—C7—H7 | 121.9 | C21—C22—H22F | 109.5 |
O1—C8—C7 | 125.59 (17) | H22A—C22—H22F | 56.3 |
O1—C8—C9 | 110.47 (16) | H22B—C22—H22F | 56.3 |
C7—C8—C9 | 123.94 (18) | H22C—C22—H22F | 141.1 |
C8—C9—C4 | 118.57 (18) | H22D—C22—H22F | 109.5 |
C8—C9—C3 | 105.57 (16) | H22E—C22—H22F | 109.5 |
C4—C9—C3 | 135.86 (18) | | |
| | | |
C8—O1—C2—C3 | −0.20 (19) | C7—C8—C9—C4 | −0.9 (3) |
C8—O1—C2—C21 | −179.59 (15) | O1—C8—C9—C3 | −0.49 (18) |
O1—C2—C3—C9 | −0.1 (2) | C7—C8—C9—C3 | 178.76 (17) |
C21—C2—C3—C9 | 179.16 (18) | C5—C4—C9—C8 | 0.3 (3) |
C9—C4—C5—C6 | 0.5 (3) | C5—C4—C9—C3 | −179.22 (18) |
C4—C5—C6—C7 | −0.7 (3) | C2—C3—C9—C8 | 0.35 (18) |
C5—C6—C7—C8 | 0.2 (3) | C2—C3—C9—C4 | 179.92 (19) |
C2—O1—C8—C7 | −178.81 (17) | C3—C2—C21—O21 | −173.37 (19) |
C2—O1—C8—C9 | 0.43 (18) | O1—C2—C21—O21 | 5.9 (3) |
C6—C7—C8—O1 | 179.79 (17) | C3—C2—C21—C22 | 6.7 (3) |
C6—C7—C8—C9 | 0.6 (3) | O1—C2—C21—C22 | −174.04 (14) |
O1—C8—C9—C4 | 179.85 (15) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3···O21i | 0.93 | 2.42 | 3.190 (2) | 140 |
C7—H7···Cg1ii | 0.93 | 2.89 | 3.431 (2) | 119 |
Symmetry codes: (i) −x+3/2, −y, z−1/2; (ii) x−1/2, y, −z+3/2. |
Experimental details
Crystal data |
Chemical formula | C10H8O2 |
Mr | 160.16 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 293 |
a, b, c (Å) | 8.3865 (13), 18.273 (4), 10.652 (2) |
V (Å3) | 1632.4 (5) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.3 × 0.3 × 0.3 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1419, 1419, 907 |
Rint | 0 |
(sin θ/λ)max (Å−1) | 0.594 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.092, 1.03 |
No. of reflections | 1419 |
No. of parameters | 109 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.10, −0.12 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3···O21i | 0.93 | 2.42 | 3.190 (2) | 140 |
C7—H7···Cg1ii | 0.93 | 2.89 | 3.431 (2) | 119 |
Symmetry codes: (i) −x+3/2, −y, z−1/2; (ii) x−1/2, y, −z+3/2. |
A convenient method of preparing 2-acetylbenzofuran, (I), from 2-hydroxybenzaldehyde and chloroacetone in the presence of KOH has been reported (Elliot, 1951). We have obtained (I) using a phase-transfer catalytic method. The present X-ray diffraction study was undertaken to understand the geometry of the benzofuran ring system and the effect of acetyl group substitution at the second position of the furan ring.
In (I), the benzofuran moiety is planar and the acetyl group is slightly twisted about the C2—C21 bond, as seen from the torsion angles O1—C2—C21—O21 = 5.9 (3)° and C3—C2—C21—C22 = 6.7 (3)°. The geometry of the benzofuran ring is comparable to that found in ethyl 3-hydroxybenzo[b]furan-2-carboxylate (Gould et al., 1998). In the solid state, the symmetry-related molecules are linked by C3—H3···O21(3/2 − x, −y, −1/2 + z) hydrogen bonds to form chains along the c axis. The adjacent chains related by the symmetry operation (−1/2 + x, y, 3/2 − z) are linked by C—H···π hydrogen bonds involving the furan ring (Table 1), to form double chain structures.