organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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Di­methyl 4,5-di­chloro­phthalate

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aDepartment of Chemistry, Pomona College, 645 N. College Ave., Claremont, CA 91711, USA, bDepartment of Chemistry and Biochemistry, W.M. Keck Foundation Center for Molecular Structure, California State University San Marcos, 333. S. Twin Oaks Valley Road, San Marcos, CA 92096, USA, and cDepartment of Chemistry, Harvey Mudd College, 301 Platt Blvd., Claremont, CA 91711, USA
*Correspondence e-mail: Daniel_OLeary@pomona.edu

Edited by R. J. Butcher, Howard University, USA (Received 3 August 2021; accepted 7 October 2021; online 13 October 2021)

While endeavoring to synthesize new chlorinated ligands for ruthenium-based metathesis catalysts, the title compound dimethyl 4,5-di­chloro­phthalate, C10H8Cl2O4, was prepared from commercially available 4,5-di­chloro­phthalic acid in ∼77% yield. The title mol­ecule, which also finds utility as a precursor mol­ecule for the synthesis of drugs used in the treatment of Alzheimer's disease, shows one carbonyl-containing methyl ester moiety lying nearly co-planar with the chlorine-derivatized aromatic ring while the second methyl ester shows a significant deviation of 101.05 (12)° from the least-squares plane of the aromatic ring. Within the crystal, structural integrity is maintained by the concerted effects of electrostatic inter­actions involving the electron-deficient carbonyl carbon atom and the electron-rich aromatic ring along the a-axis direction and C—HO hydrogen bonds between neighboring mol­ecules parallel to b.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

While endeavoring to synthesize new chlorinated ligands for ruthenium-based metathesis catalysts (Anderson et al., 2006[Anderson, D. R., Hickstein, D. D., O'Leary, D. J. & Grubbs, R. H. (2006). J. Am. Chem. Soc. 128, 8386-8387.]), the title compound, 1, was prepared from commercially available 4,5-di­chloro­phthalic acid in ∼77% yield. The title mol­ecule also finds utility as a precursor mol­ecule for the synthesis of drugs used in the treatment of Alzheimer's disease (Hennessy & Buchwald, 2005[Hennessy, E. J. & Buchwald, S. L. (2005). J. Org. Chem. 70, 7371-7375.]).

Compound 1 crystallizes in the centrosymmetric triclinic space group P[\overline{1}] with a full mol­ecule of the title compound as the contents of asymmetric unit (Fig. 1[link], Table 1[link]). Within the structure of 1, one of the carbonyl-containing ester groups is nearly co-planar with the aromatic ring demonstrating a deviation of 3.41 (12)° from the least-squares plane of the chlorine-derivatized aromatic ring. The second ester group reveals a much larger deviation from planarity as the dihedral angle involving the second carbonyl group is 101.05 (12)°.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C5—H5⋯O1i 0.95 2.33 3.2327 (15) 159
C10—H10B⋯O3ii 0.98 2.68 3.5380 (16) 147
Symmetry codes: (i) [x, y-1, z]; (ii) [-x+1, -y, -z].
[Figure 1]
Figure 1
Anisotropic displacement ellipsoid plot of 1 with ellipsoids set to the 50% probability level.

Looking down the a-axis, and involving a second mol­ecule of 1 related by inversion, the centroid of the electron-rich, chlorine-derivatized aromatic ring of the first mol­ecule lies above the electron-deficient carbonyl carbon atom of the second at a distance of 3.4600 (12) Å, suggesting the presence of electrostatic inter­actions (Fig. 2[link]). In addition to the electrostatic inter­actions, when looking into the bc-plane, between H5 on the aromatic ring and O1 from the carbonyl that is nearly co-planar with the aromatic ring, a C—H⋯O [d(C5⋯O1) = 3.23 Å; Θ(C5—H5—O1) = 159°] hydrogen bond was observed (Fig. 3[link], Table 2[link]). A one-dimensional array of symmetry-equivalent mol­ecules of 1 linked by C—H⋯O hydrogen bonds results along the b-axis direction when looking into the bc-plane (Fig. 3[link]). While there are no additional inter­actions between neighboring, co-planar one-dimensional arrays parallel to one another along c, weak C—H⋯O [d(C10⋯O3) = 3.54 Å; Θ(C10—H10B—O3) = 147°] inter­actions with a neighboring layer having the symmetry code (1 − x, −y, −z) yielded a centrosymmetric dimer (Fig. 4[link], Table 2[link]) having the R22(10) graph-set notation (Bernstein et al., 1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]).

Table 2
Experimental details

Crystal data
Chemical formula C10H8Cl2O4
Mr 263.06
Crystal system, space group Triclinic, P[\overline{1}]
Temperature (K) 173
a, b, c (Å) 7.0204 (6), 7.7661 (6), 10.5392 (8)
α, β, γ (°) 97.733 (1), 109.293 (1), 90.217 (1)
V3) 536.69 (7)
Z 2
Radiation type Mo Kα
μ (mm−1) 0.60
Crystal size (mm) 0.35 × 0.29 × 0.28
 
Data collection
Diffractometer Bruker APEX CCD area detector
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.838, 0.927
No. of measured, independent and observed [I > 2σ(I)] reflections 5934, 2582, 2417
Rint 0.031
(sin θ/λ)max−1) 0.668
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.073, 1.04
No. of reflections 2582
No. of parameters 147
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.45, −0.21
Computer programs: APEX2 and SAINT (Bruker, 2016[Bruker (2016). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014/5 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014/7 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).
[Figure 2]
Figure 2
Solid-state expansion of 1 showing the superposition of the electron-rich aromatic ring centroid and the electron-deficient carbonyl carbon atom. Anisotropic displacement ellipsoids have been set to the 50% probability level.
[Figure 3]
Figure 3
Projection of 1 within the bc-plane showing the C—H⋯O hydrogen bonding between neighboring mol­ecules along b to form one-dimensional arrays. Anisotropic displacement ellipsoids have been set to the 50% probability level. Dashed lines represent hydrogen bonds.
[Figure 4]
Figure 4
Projection of 1 within the ac-plane showing the formation of the R22(10) centrosymmetric dimer facilitated by weak C—H⋯O inter­actions between layers. Anisotropic displacement ellipsoids have been set to the 50% probability level. Dashed lines represent the C—H⋯O inter­actions.

Synthesis and crystallization

Compound 1 was synthesized by adding 4,5-di­chloro­phthalic acid (23.68 mmol, 5.566 g) to 70 ml of CH3OH in a 200 ml flask. While stirring, 1.0 ml H2SO4 (98%) was added dropwise and the mixture was allowed to reflux at 70°C overnight. The product was extracted with ethyl acetate, and washed with water, concentrated NaHCO3, 10% NaHCO3, and then a saturated solution of NaCl. After filtering through Na2SO4 to remove trace moisture, the solvent was removed in vacuo to yield a clear oil, which later crystallized into small rods. Recrystallization from the mixed solvents of isopropyl alcohol and di­chloro­methane produced X-ray quality crystals of 1 up to 2 mm.

Refinement

Crystal data, data collection and structure refinement details for 1 are summarized in Table 2[link]. The choice of the space group P[\overline{1}] for 1 was unambiguously verified by PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]; Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Dimethyl 4,5-dichlorophthalate top
Crystal data top
C10H8Cl2O4Z = 2
Mr = 263.06F(000) = 268
Triclinic, P1Dx = 1.628 Mg m3
a = 7.0204 (6) ÅMo Kα radiation, λ = 0.71073 Å
b = 7.7661 (6) ÅCell parameters from 548 reflections
c = 10.5392 (8) Åθ = 2.4–27.7°
α = 97.733 (1)°µ = 0.60 mm1
β = 109.293 (1)°T = 173 K
γ = 90.217 (1)°Irregular, colorless
V = 536.69 (7) Å30.35 × 0.29 × 0.28 mm
Data collection top
Bruker APEX CCD area detector
diffractometer
2582 independent reflections
Radiation source: Fine-focus sealed tube2417 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.031
phi and ω scansθmax = 28.3°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
h = 99
Tmin = 0.838, Tmax = 0.927k = 1010
5934 measured reflectionsl = 1414
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.026H-atom parameters constrained
wR(F2) = 0.073 w = 1/[σ2(Fo2) + (0.0368P)2 + 0.1955P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.001
2582 reflectionsΔρmax = 0.45 e Å3
147 parametersΔρmin = 0.21 e Å3
0 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. All non-hydrogen atoms were refined anisotropically. H atoms bound to C atoms were constrained to ride on the atoms onto which they are bonded, where C—H = 0.95 (aromatic) or 0.98 Å (methyl) with Uiso(H) = 1.2Ueq(C).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.81953 (5)0.48342 (4)0.83259 (3)0.02349 (9)
Cl20.74478 (5)0.08068 (4)0.71750 (3)0.02487 (9)
O10.76916 (17)0.76700 (12)0.40055 (10)0.0310 (2)
O20.69277 (14)0.55617 (11)0.22210 (9)0.02121 (18)
O30.50933 (14)0.17388 (12)0.16137 (9)0.02470 (19)
O40.84744 (13)0.20884 (11)0.21752 (8)0.02113 (18)
C10.73795 (16)0.47447 (14)0.43804 (11)0.0158 (2)
C20.77075 (17)0.53010 (15)0.57530 (12)0.0170 (2)
H20.79040.65080.60940.020*
C30.77483 (17)0.41014 (15)0.66231 (11)0.0172 (2)
C40.74445 (17)0.23318 (15)0.61230 (12)0.0181 (2)
C50.71216 (18)0.17662 (15)0.47593 (12)0.0185 (2)
H50.69210.05580.44230.022*
C60.70903 (17)0.29623 (14)0.38820 (11)0.0159 (2)
C70.73570 (17)0.61539 (15)0.35369 (12)0.0179 (2)
C80.6829 (2)0.68909 (17)0.13612 (13)0.0247 (3)
H8A0.63900.63520.04080.037*
H8B0.81680.74730.16030.037*
H8C0.58630.77460.14910.037*
C90.67274 (18)0.22206 (14)0.24202 (12)0.0175 (2)
C100.8297 (2)0.14662 (17)0.07783 (12)0.0249 (3)
H10A0.76400.23300.02000.037*
H10B0.74850.03650.04740.037*
H10C0.96460.12830.07170.037*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.02835 (16)0.02741 (16)0.01490 (15)0.00009 (11)0.00920 (12)0.00131 (11)
Cl20.03392 (18)0.02289 (16)0.01804 (15)0.00098 (12)0.00730 (12)0.00740 (11)
O10.0505 (6)0.0152 (4)0.0266 (5)0.0004 (4)0.0124 (4)0.0022 (3)
O20.0281 (4)0.0181 (4)0.0175 (4)0.0002 (3)0.0066 (3)0.0052 (3)
O30.0253 (5)0.0269 (4)0.0174 (4)0.0058 (3)0.0021 (3)0.0010 (3)
O40.0235 (4)0.0248 (4)0.0136 (4)0.0029 (3)0.0056 (3)0.0005 (3)
C10.0142 (5)0.0158 (5)0.0169 (5)0.0010 (4)0.0045 (4)0.0026 (4)
C20.0152 (5)0.0161 (5)0.0188 (5)0.0008 (4)0.0056 (4)0.0004 (4)
C30.0156 (5)0.0217 (5)0.0139 (5)0.0011 (4)0.0052 (4)0.0000 (4)
C40.0183 (5)0.0196 (5)0.0164 (5)0.0003 (4)0.0049 (4)0.0050 (4)
C50.0216 (5)0.0155 (5)0.0171 (5)0.0003 (4)0.0048 (4)0.0019 (4)
C60.0155 (5)0.0165 (5)0.0143 (5)0.0002 (4)0.0034 (4)0.0011 (4)
C70.0168 (5)0.0167 (5)0.0204 (5)0.0019 (4)0.0059 (4)0.0036 (4)
C80.0292 (6)0.0237 (6)0.0243 (6)0.0038 (5)0.0098 (5)0.0115 (5)
C90.0242 (6)0.0125 (5)0.0150 (5)0.0009 (4)0.0049 (4)0.0030 (4)
C100.0342 (7)0.0261 (6)0.0147 (5)0.0029 (5)0.0097 (5)0.0001 (4)
Geometric parameters (Å, º) top
Cl1—C31.7305 (12)C2—C31.3865 (16)
Cl2—C41.7272 (12)C3—C41.3931 (16)
O1—C71.2042 (15)C4—C51.3871 (16)
O2—C71.3330 (15)C5—H50.9500
O2—C81.4500 (14)C5—C61.3915 (15)
O3—C91.2022 (15)C6—C91.5069 (16)
O4—C91.3359 (15)C8—H8A0.9800
O4—C101.4503 (14)C8—H8B0.9800
C1—C21.3940 (16)C8—H8C0.9800
C1—C61.4018 (15)C10—H10A0.9800
C1—C71.4969 (15)C10—H10B0.9800
C2—H20.9500C10—H10C0.9800
C7—O2—C8115.05 (9)C5—C6—C9116.26 (10)
C9—O4—C10115.31 (10)O1—C7—O2123.60 (11)
C2—C1—C6119.63 (10)O1—C7—C1123.11 (11)
C2—C1—C7115.67 (10)O2—C7—C1113.29 (9)
C6—C1—C7124.70 (10)O2—C8—H8A109.5
C1—C2—H2119.8O2—C8—H8B109.5
C3—C2—C1120.33 (10)O2—C8—H8C109.5
C3—C2—H2119.8H8A—C8—H8B109.5
C2—C3—Cl1119.14 (9)H8A—C8—H8C109.5
C2—C3—C4119.92 (10)H8B—C8—H8C109.5
C4—C3—Cl1120.94 (9)O3—C9—O4125.21 (11)
C3—C4—Cl2121.06 (9)O3—C9—C6124.09 (11)
C5—C4—Cl2118.80 (9)O4—C9—C6110.60 (10)
C5—C4—C3120.14 (10)O4—C10—H10A109.5
C4—C5—H5119.9O4—C10—H10B109.5
C4—C5—C6120.23 (10)O4—C10—H10C109.5
C6—C5—H5119.9H10A—C10—H10B109.5
C1—C6—C9124.00 (10)H10A—C10—H10C109.5
C5—C6—C1119.74 (10)H10B—C10—H10C109.5
Cl1—C3—C4—Cl21.42 (14)C4—C5—C6—C10.23 (17)
Cl1—C3—C4—C5178.93 (9)C4—C5—C6—C9179.96 (10)
Cl2—C4—C5—C6179.38 (9)C5—C6—C9—O378.67 (15)
C1—C2—C3—Cl1179.08 (9)C5—C6—C9—O497.92 (12)
C1—C2—C3—C40.50 (17)C6—C1—C2—C30.00 (17)
C1—C6—C9—O3101.05 (14)C6—C1—C7—O1176.90 (12)
C1—C6—C9—O482.36 (13)C6—C1—C7—O23.20 (16)
C2—C1—C6—C50.37 (17)C7—C1—C2—C3179.72 (10)
C2—C1—C6—C9179.92 (10)C7—C1—C6—C5179.33 (10)
C2—C1—C7—O13.39 (17)C7—C1—C6—C90.38 (18)
C2—C1—C7—O2176.51 (10)C8—O2—C7—O11.71 (17)
C2—C3—C4—Cl2179.00 (8)C8—O2—C7—C1178.18 (9)
C2—C3—C4—C50.65 (17)C10—O4—C9—O36.33 (17)
C3—C4—C5—C60.28 (18)C10—O4—C9—C6177.12 (9)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···O1i0.952.333.2327 (15)159
C10—H10B···O3ii0.982.683.5380 (16)147
Symmetry codes: (i) x, y1, z; (ii) x+1, y, z.
 

Funding information

Funding for this research was provided by: Pomona College; Harvey Mudd College.

References

First citationAnderson, D. R., Hickstein, D. D., O'Leary, D. J. & Grubbs, R. H. (2006). J. Am. Chem. Soc. 128, 8386–8387.  Web of Science CSD CrossRef PubMed CAS Google Scholar
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