1,1′-(2,5-Dimethyl­thio­phene-3,4-di­yl)diethanone

Chengpeng Li; Qiaozheng Qi; Sheng Wang; Guohua Ding

doi:10.1107/S1600536811029710

. 2011 Aug 2;67(Pt 9):o2219. doi: 10.1107/S1600536811029710

1,1′-(2,5-Dimethylthiophene-3,4-diyl)diethanone

Chengpeng Li ^a, Qiaozheng Qi ^a, Sheng Wang ^b,^*, Guohua Ding ^a,^*

PMCID: PMC3200822 PMID: 22064921

Abstract

The title compound, C₁₀H₁₂O₂S, crystallizes with four molecules in the asymmetric unit. The main conformational difference between these molecules is the orientation of the acetyl groups with respect to the ring. Whereas one acetyl group is only slightly twisted with respect to the thiophene ring [C—C—C—O torsion angles = 165.7 (4), −164.6 (4), 164.3 (4) and −163.6 (4)°], the other acetyl group is markly twisted out of the ring plane [C—C—C—O torsion angles = −61.2 (6), 61.3 (7), −59.7 (7) and 59.9 (6)°]. In the crystal, molecules are linked by weak C—H⋯O interactions into infinite chains along the c axis.

Related literature

For the synthesis of the title compound, see: Li et al. (2011 ▶); Wang et al. (2004 ▶). For a related structure, see: Yu et al. (2010 ▶).

Experimental

Crystal data

C₁₀H₁₂O₂S
M _r = 196.26
Monoclinic,
a = 12.142 (2) Å
b = 12.129 (2) Å
c = 27.446 (6) Å
β = 99.387 (2)°
V = 3987.8 (14) Å³
Z = 16
Mo Kα radiation
μ = 0.29 mm⁻¹
T = 296 K
0.38 × 0.30 × 0.21 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.898, T _max = 0.942
14665 measured reflections
7205 independent reflections
4969 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.092
S = 1.02
7205 reflections
485 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.23 e Å⁻³
Absolute structure: Flack (1983 ▶), 3486 Friedel pairs
Flack parameter: 0.05 (7)

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT-Plus (Bruker, 2001 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811029710/bt5559sup1.cif

e-67-o2219-sup1.cif^{(31KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811029710/bt5559Isup2.hkl

e-67-o2219-Isup2.hkl^{(352.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811029710/bt5559Isup3.cml

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
C35—H35C⋯O6ⁱ	0.96	2.44	3.276 (6)	145
C39—H39A⋯O6ⁱ	0.96	2.56	3.435 (6)	152

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 20802065), the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry (No. 2009–1001) and the Doctoral Special Funds of Zhanjiang Normal University (No. ZL0803).

supplementary crystallographic information

Comment

Azomethines are an important class of compounds which have been intensively investigated owning to their strong coordination capability, antibacterial activity, antitumor property and so on. Considering this, on our way to getting novel photochromic molecules on which we focused in the past few years, we first designed and synthesized a key intermediate 1-(2,5-Dimethylthiophen-3,4-yl) diethanone, which has two carbonyl groups. Usually, azomethines are obtained by the condensation of carbonyl compounds with primary amines. Herein, the design and synthesis of this compound provides a wide space for the new azomethines of thiophene. Recently the introduction of Schiff base ligands into photochromic diarylethene system and their photochromic properties in solution has been reported (Li et al., 2011). We are trying to push forward that work through introducing the title compound to the system. Moreover, in our recent study we also found that the title compound played a good role in the synthesis of Schiff-base macrocycles. When we took different type or the length of chain diamines, we got varying size of the macrocycles and some of them had good ability of cooperation with metals.

Experimental

We used 2-methylthiophene as the starting material via, in turn, Vilsmeier, Wolff-Kishner-Huang, and Friedel-Crafts reactions and got the title compound. The synthetic processes are as follows:

5-Methylthiophene-2-carbaldehyde

To a 10 g anhydrous dimethylformamide solution of 2-methylthiophene (10 g, 0.1 mol), a (17 g, 0.11 mol) phosphorus oxychloride (POCl₃) was added drop by drop slowly at 0°C. After addition, the ice bath was removed and the mixture was stirred for 0.5 h at room temperature. Then, the reddish solution was heated slowly to reflux. After refluxed for 1 h and cooled to room temperature, the mixture was poured into ice water and K₂CO₃ was added until pH=10. The mixture was extracted with diethyl ether (3×25 ml). The combined organic layers were washed with a saturated NaCl solution (2×25 ml) and H₂O (1×25 ml), dried (MgSO₄), filtered and the solvents evaporated in vacuum to yield: 10.8 g, 84.2%.

2,5-Dimethylthiophene

To a 360 ml e thyl glycol solution of 5-methyl-thiophene-2-carbaldehyde (112 g, 0.9 mol), a 120 ml hydrazine hydrate (85%) was added in 1000 ml flask. The mixture was refluxed for 0.5 h, and then evaporated the excessive water and hydrazine hydrate until the oil drops showed up. After the evaporation, KOH (20 g, 0.3 mol) was added in portions to the cooled mixture. Then refluxed for 0.5 h, distilled and the mixture of oil and water was washed with a saturated NaCl solution (3× 25 ml), After being extracted, the organic phase was distilled and the fraction boiling between 134 °C and 135 °C was collected to yield 110 g, 91%.

1-(2,5-Dimethylthiophen-3,4-yl) diethanone

To a 200 ml dichloromethane solution of anhydrous aluminium chloride (41 g,0.3 mol), a 11 ml dichloromethane solution of acetyl chloride(16.4 g, 0.21 mol) and 15 ml dichloromethane solution of 2,5-Dimethylthiophene (23.5 g, 0.21 mol) was added dropwise in turn at 0°C. After addition, the reaction mixture was stirred for 8 h at room temperature. Then the mixture was poured into 45 ml ice-hydrochloric acid. The product was extracted with dichloromethane and the solution was dried (MgSO₄). After evaporation of the solvent, the pure product was obtained as a yellow solid (33.5 g, 81%) by column chromatography with petroleum/ethyl acetate(8:1) as eluent.