Diisopropyl terephthalate

The title compound, C₁₄H₁₈O₄, comprises discrete centrosymmetric mol­ecules. The crystal structure is stabilized by inter­molecular contacts of the type C—H...O.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• R factor = 0.056
• wR factor = 0.170
• Data-to-parameter ratio = 18.1

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S1. Comment

Molecules of (I) are centrosymmetric being disposed about a centre of inversion, as is the case in the crystal structures of related compounds (Brisse & Pérez, 1976; Bailey, 1949; Hašek et al., 1982 & Ciajolo et al., 1991). Similarly, all bond lengths and angles have normal values. The C1/C2/C4/O2 dihedral angle of 161.2 (2)° indicates a deviation from planarity.

The structure comprises essentially discrete molecules, with the closest intermolecular contacts being of the type C—H···O: C3—H···O1 = 3.53 Å (-1 + x, 1/2 - y, -1/2 + z), C1—H···O1 = 3.55 Å (-1 + x, 1/2 - y, -1/2 + z), and C7—H···O1 = 3.560 Å (-2 + x, 1 - y, -3/2 + z). The molecules have an elongated shape and their orientation is almost parallel with the 2a + c vector, being inclined at an angle of 7.3°. Such a tendency for parallel arrangement is also seen in the structure of the di-p-tolyl terephtalate (Ciajolo et al., 1991) derivative, but not in the structures of dimethyl (Brisse & Pérez, 1976) and diethyl (Bailey, 1949; Hašek et al., 1982) esters.

Related literature

For related structures, see: dimethyl terephtalate (Brisse & Pérez, 1976), diethyl terephtelate (Bailey, 1949; Hašek et al., 1982) and di-p-tolyl terephtalate (Ciajolo et al., 1991).

S2. Experimental

Compound (I) was prepared unintentionally during an attempt to isolate a triketone derived from terephtalic acid. In an isooctane (20 ml) solution of sodium 2,2,6,6-tetramethylheptane-3,5-dionate (0.21 g), terephtaloyl dichloride (0.20 g) was added and the mixture heated for 15 min. The NaCl precipitate was filtered off, the filtrate evaporated to approximately 5 ml, 2-propanol (10 ml) added and the mixture left for 24 h, after which crystallized large colourless plates of (I).

S3. Refinement

All H atoms were placed geometrically and included in the refinement in the riding-model approximation, with C—H = 0.93, and with U_iso = 1.2U_eq(C).

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2003); cell refinement: CrysAlis RED (Oxford Diffraction, 2003); data reduction: CrysAlis RED (Oxford Diffraction, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); 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).

Figures

	Fig. 1. View of (I) with the atom labeling scheme. Displacement ellipsoids of are shown at 30% probability.
	Fig. 2. Crystal packing of (I) viewed along the y axis. Hydrogen atoms have been omitted for clarity.

Diisopropyl terephthalate

Crystal data

C14H18O4	F(000) = 268
Mr = 250.28	Dx = 1.174 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1344 reflections
a = 9.208 (3) Å	θ = 4.6–52.0°
b = 9.718 (3) Å	µ = 0.09 mm^−1
c = 15.844 (5) Å	T = 298 K
β = 150.03 (2)°	Prismatic, colourless
V = 708.2 (6) Å^3	0.75 × 0.49 × 0.42 mm
Z = 2

Data collection

Oxford Diffraction Xcalibur CCD diffractometer	1267 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.055
Graphite monochromator	θmax = 27.0°, θmin = 4.9°
ω scans	h = −11→11
3803 measured reflections	k = −7→12
1521 independent reflections	l = −20→19

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.056	w = 1/[σ^2(Fo^2) + (0.0956P)^2 + 0.1119P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.17	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 0.28 e Å^−3
1521 reflections	Δρmin = −0.31 e Å^−3
84 parameters

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O2	0.6575 (2)	0.08936 (11)	0.44294 (13)	0.0556 (4)
C2	0.2478 (3)	−0.01186 (14)	0.17469 (18)	0.0427 (4)
C3	0.2212 (3)	0.09717 (15)	0.10444 (19)	0.0475 (4)
H3	0.369	0.162	0.1743	0.057*
C1	0.0255 (3)	−0.10864 (15)	0.06930 (19)	0.0485 (4)
H1	0.0429	−0.1813	0.1159	0.058*
C4	0.5081 (3)	−0.02752 (14)	0.36151 (18)	0.0458 (4)
O1	0.5706 (3)	−0.13377 (13)	0.42786 (15)	0.0704 (4)
C5	0.9128 (3)	0.09072 (19)	0.62716 (19)	0.0574 (5)
H5	0.8796	0.0288	0.6583	0.069*
C7	0.9347 (4)	0.2370 (2)	0.6695 (3)	0.0728 (6)
H7A	0.9438	0.2986	0.6268	0.109*
H7B	1.1071	0.247	0.7899	0.109*
H7C	0.7671	0.2584	0.6188	0.109*
C6	1.1736 (4)	0.0427 (3)	0.7094 (3)	0.0848 (7)
H6A	1.1394	−0.0487	0.6715	0.127*
H6B	1.3413	0.0425	0.8299	0.127*
H6C	1.2065	0.1037	0.6792	0.127*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0551 (7)	0.0525 (7)	0.0425 (6)	−0.0100 (5)	0.0399 (6)	−0.0063 (4)
C2	0.0446 (7)	0.0404 (7)	0.0419 (8)	0.0014 (5)	0.0373 (7)	0.0001 (5)
C3	0.0472 (8)	0.0431 (8)	0.0458 (8)	−0.0068 (6)	0.0393 (7)	−0.0040 (6)
C1	0.0539 (8)	0.0425 (7)	0.0474 (8)	−0.0043 (6)	0.0437 (8)	−0.0004 (6)
C4	0.0456 (7)	0.0447 (8)	0.0427 (8)	−0.0007 (6)	0.0377 (7)	−0.0006 (6)
O1	0.0657 (8)	0.0545 (7)	0.0485 (7)	−0.0020 (5)	0.0434 (7)	0.0057 (5)
C5	0.0510 (9)	0.0657 (11)	0.0421 (9)	−0.0100 (7)	0.0384 (8)	−0.0054 (7)
C7	0.0743 (12)	0.0767 (13)	0.0617 (11)	−0.0183 (10)	0.0581 (11)	−0.0197 (9)
C6	0.0573 (11)	0.0934 (16)	0.0656 (12)	0.0003 (10)	0.0478 (11)	−0.0053 (11)

Geometric parameters (Å, º)

O2—C4	1.3311 (18)	C5—C7	1.509 (3)
O2—C5	1.469 (2)	C5—H5	0.98
C2—C1	1.393 (2)	C7—H7A	0.96
C2—C3	1.396 (2)	C7—H7B	0.96
C2—C4	1.496 (2)	C7—H7C	0.96
C3—H3	0.93	C6—H6A	0.96
C1—H1	0.93	C6—H6B	0.96
C4—O1	1.2058 (19)	C6—H6C	0.96
C5—C6	1.504 (3)
C4—O2—C5	117.70 (12)	O2—C5—H5	109.5
C1—C2—C3	119.73 (14)	C6—C5—H5	109.5
C1—C2—C4	118.34 (13)	C7—C5—H5	109.5
C3—C2—C4	121.92 (13)	C5—C7—H7A	109.5
C1^i—C3—C2	119.93 (13)	C5—C7—H7B	109.5
C1^i—C3—H3	120	H7A—C7—H7B	109.5
C2—C3—H3	120	C5—C7—H7C	109.5
C3^i—C1—C2	120.34 (14)	H7A—C7—H7C	109.5
C3^i—C1—H1	119.8	H7B—C7—H7C	109.5
C2—C1—H1	119.8	C5—C6—H6A	109.5
O1—C4—O2	125.00 (15)	C5—C6—H6B	109.5
O1—C4—C2	123.28 (13)	H6A—C6—H6B	109.5
O2—C4—C2	111.72 (12)	C5—C6—H6C	109.5
O2—C5—C6	108.93 (16)	H6A—C6—H6C	109.5
O2—C5—C7	105.04 (14)	H6B—C6—H6C	109.5
C6—C5—C7	114.16 (17)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O1^ii	0.93	2.90	3.532 (4)	126
C1—H1···O1^iii	0.93	2.93	3.546 (3)	125
C7—H7B···O1^iv	0.96	2.67	3.560 (4)	153

Symmetry codes: (ii) −x+1, y+1/2, −z+1/2; (iii) x−1, −y−1/2, z−1/2; (iv) −x+2, y+1/2, −z+3/2.