2-(4-Bromo­phen­yl)-2-oxoethyl 4-meth­oxy­benzoate

In the title compound, C₁₆H₁₃BrO₄, the benzene rings are almost perpendicular to each other, making a dihedral angle of 84.07 (8)°. In the crystal, the mol­ecules are linked into chains along the a axis via inter­molecular C—H...O hydrogen bonds. A C—H...π inter­action is also observed.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.027
• wR factor = 0.069
• Data-to-parameter ratio = 17.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  O3      ..       3.23 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         11
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          4
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          2

Alert level G
PLAT154_ALERT_1_G The su's on the Cell Angles are Equal  (x 10000)        100 Deg.

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   1 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Phenacyl benzoates are very useful protecting groups which can be easily removed by non-chemical reactions. The advantage of photosensitive blocking groups is that they can be removed under completely neutral and mild conditions (Sheehan & Umezaw, 1973; Ruzicka et al., 2002; Litera et al., 2006) used for identification of organic acids (Rather & Reid, 1919), synthesis of oxazoles, imidazoles (Huang et al., 1996) and benzoxazepine (Gandhi et al., 1995). Keeping this in view, we hereby report the crystal structure of 2-(4-bromophenyl)-2-oxoethyl 4-methoxybenzoate of potential commercial importance.

In the title compound (Fig. 1), the C1–C6 benzene ring [maximum deviation of 0.005 (2) Å at atom C6] is almost perpendicular with the C10–C15 benzene ring [maximum deviation of 0.014 (2) Å at atom C13] with a dihedral angle of 84.07 (8)°. Bond lengths (Allen et al., 1987) and angles are within the normal ranges.

In the crystal packing (Fig. 2), the molecules are linked into chains along the a axis via intermolecular C2—H2A···O1 hydrogen bonds (Table 1). The crystal packing is further consolidated by C—H···π interactions, involving the centroids of C1–C6 phenyl ring.

Related literature

For background to and applications of phenacyl benzoates, see: Gandhi et al. (1995); Huang et al. (1996); Litera et al. (2006); Rather & Reid (1919); Ruzicka et al. (2002); Sheehan & Umezaw (1973). For the synthesis, see: Judefind & Reid (1920). For bond-length data, see: Allen et al. (1987).

S2. Experimental

The mixture of 4-methoxy benzoic acid (1.0 g, 0.0065 mol) sodium carbonate (0.766 g, 0.0072 mol) and 2-bromo-1-(4-bromophenyl)ethanone (2.00 g, 0.0072 mol) in dimethyl formamide (10 ml) was stirred at room temperature for 2 h. On cooling, the separated colourless needle-shaped crystals of 2-(4-bromophenyl)-2-oxoethyl 4-methoxybenzoate were collected by filtration. Compound was recrystallized from ethanol. Yield: 2.1 g (91.70%), m.p.: 429–430 K (Judefind & Reid, 1920).

S3. Refinement

All the H atoms were positioned geometrically and refined with a riding model with U_iso(H) = 1.2 or 1.5U_eq(C) (C—H = 0.93 or 0.96 Å). A rotating group model was applied to the methyl groups.

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The crystal packing of the title compound, viewed along the c axis. H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity.

2-(4-Bromophenyl)-2-oxoethyl 4-methoxybenzoate

Crystal data

C16H13BrO4	Z = 2
Mr = 349.17	F(000) = 352
Triclinic, P1	Dx = 1.624 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.9700 (5) Å	Cell parameters from 4684 reflections
b = 7.9852 (5) Å	θ = 3.0–30.0°
c = 11.3185 (7) Å	µ = 2.89 mm^−1
α = 86.536 (1)°	T = 296 K
β = 83.205 (1)°	Block, colourless
γ = 89.633 (1)°	0.58 × 0.34 × 0.32 mm
V = 713.97 (8) Å^3

Data collection

Bruker SMART APEXII DUO CCD area-detector diffractometer	3270 independent reflections
Radiation source: fine-focus sealed tube	2767 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
φ and ω scans	θmax = 27.5°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −10→10
Tmin = 0.286, Tmax = 0.461	k = −10→10
10671 measured reflections	l = −14→14

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.069	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0314P)^2 + 0.2047P] where P = (Fo^2 + 2Fc^2)/3
3270 reflections	(Δ/σ)max = 0.001
191 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.52 e Å^−3

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
Br1	0.26530 (3)	0.93852 (3)	0.738521 (19)	0.06416 (9)
O1	1.05611 (17)	0.7434 (2)	0.48016 (14)	0.0727 (4)
O2	1.07533 (16)	0.58534 (16)	0.28028 (12)	0.0543 (3)
O3	1.07066 (18)	0.84361 (18)	0.19107 (14)	0.0628 (4)
O4	1.82176 (17)	0.60709 (18)	0.03308 (13)	0.0589 (3)
C1	0.6023 (2)	0.7176 (2)	0.48878 (16)	0.0451 (4)
H1A	0.5962	0.6522	0.4242	0.054*
C2	0.4543 (2)	0.7690 (2)	0.55394 (16)	0.0471 (4)
H2A	0.3495	0.7382	0.5337	0.057*
C3	0.4655 (2)	0.8663 (2)	0.64896 (16)	0.0458 (4)
C4	0.6205 (3)	0.9145 (2)	0.67953 (17)	0.0521 (4)
H4A	0.6261	0.9816	0.7433	0.062*
C5	0.7661 (2)	0.8622 (2)	0.61464 (17)	0.0502 (4)
H5A	0.8705	0.8939	0.6351	0.060*
C6	0.7594 (2)	0.7624 (2)	0.51864 (15)	0.0426 (4)
C7	0.9203 (2)	0.7110 (2)	0.44998 (17)	0.0483 (4)
C8	0.9105 (2)	0.6156 (3)	0.33964 (18)	0.0517 (4)
H8A	0.8535	0.5094	0.3618	0.062*
H8B	0.8449	0.6796	0.2858	0.062*
C9	1.1450 (2)	0.7150 (2)	0.21027 (16)	0.0462 (4)
C10	1.3205 (2)	0.6803 (2)	0.16089 (15)	0.0413 (4)
C11	1.4168 (2)	0.5522 (2)	0.20810 (16)	0.0443 (4)
H11A	1.3686	0.4808	0.2708	0.053*
C12	1.5823 (2)	0.5308 (2)	0.16269 (17)	0.0464 (4)
H12A	1.6453	0.4447	0.1946	0.056*
C13	1.6566 (2)	0.6365 (2)	0.06941 (16)	0.0439 (4)
C14	1.5604 (2)	0.7614 (2)	0.01947 (16)	0.0492 (4)
H14A	1.6077	0.8305	−0.0448	0.059*
C15	1.3943 (2)	0.7820 (2)	0.06586 (16)	0.0487 (4)
H15A	1.3304	0.8663	0.0325	0.058*
C16	1.9073 (3)	0.7168 (3)	−0.0585 (2)	0.0675 (6)
H16A	2.0238	0.6843	−0.0727	0.101*
H16B	1.9003	0.8299	−0.0341	0.101*
H16C	1.8554	0.7100	−0.1304	0.101*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.06137 (14)	0.06633 (15)	0.05890 (14)	0.01421 (10)	0.01096 (9)	0.00724 (9)
O1	0.0370 (7)	0.1133 (13)	0.0702 (10)	−0.0055 (8)	−0.0113 (7)	−0.0132 (9)
O2	0.0440 (7)	0.0500 (7)	0.0654 (8)	0.0035 (5)	0.0050 (6)	0.0008 (6)
O3	0.0581 (8)	0.0542 (8)	0.0725 (9)	0.0160 (6)	0.0025 (7)	0.0021 (7)
O4	0.0462 (7)	0.0601 (8)	0.0664 (9)	0.0025 (6)	0.0045 (6)	0.0077 (7)
C1	0.0393 (8)	0.0515 (10)	0.0449 (9)	−0.0038 (7)	−0.0073 (7)	−0.0007 (7)
C2	0.0381 (8)	0.0516 (10)	0.0510 (10)	−0.0043 (7)	−0.0067 (7)	0.0056 (8)
C3	0.0470 (9)	0.0429 (9)	0.0442 (9)	0.0036 (7)	0.0014 (7)	0.0103 (7)
C4	0.0621 (11)	0.0497 (10)	0.0441 (10)	−0.0045 (8)	−0.0064 (8)	0.0000 (8)
C5	0.0470 (9)	0.0553 (11)	0.0489 (10)	−0.0104 (8)	−0.0114 (8)	0.0032 (8)
C6	0.0388 (8)	0.0468 (9)	0.0416 (9)	−0.0048 (7)	−0.0064 (7)	0.0069 (7)
C7	0.0370 (8)	0.0565 (11)	0.0505 (10)	−0.0035 (7)	−0.0067 (7)	0.0072 (8)
C8	0.0383 (9)	0.0569 (11)	0.0586 (11)	0.0000 (8)	−0.0005 (8)	−0.0037 (9)
C9	0.0481 (9)	0.0445 (9)	0.0462 (9)	0.0032 (7)	−0.0050 (7)	−0.0057 (7)
C10	0.0448 (9)	0.0388 (8)	0.0408 (9)	0.0015 (7)	−0.0050 (7)	−0.0058 (7)
C11	0.0463 (9)	0.0410 (9)	0.0448 (9)	−0.0028 (7)	−0.0049 (7)	0.0036 (7)
C12	0.0464 (9)	0.0416 (9)	0.0510 (10)	0.0008 (7)	−0.0091 (8)	0.0047 (7)
C13	0.0445 (9)	0.0430 (9)	0.0439 (9)	−0.0021 (7)	−0.0025 (7)	−0.0056 (7)
C14	0.0572 (11)	0.0451 (10)	0.0429 (9)	0.0013 (8)	0.0012 (8)	0.0030 (7)
C15	0.0563 (10)	0.0422 (9)	0.0465 (9)	0.0076 (8)	−0.0039 (8)	0.0018 (7)
C16	0.0556 (12)	0.0722 (14)	0.0686 (14)	−0.0042 (10)	0.0125 (10)	0.0063 (11)

Geometric parameters (Å, º)

Br1—C3	1.8925 (18)	C7—C8	1.511 (3)
O1—C7	1.207 (2)	C8—H8A	0.9700
O2—C9	1.346 (2)	C8—H8B	0.9700
O2—C8	1.429 (2)	C9—C10	1.475 (2)
O3—C9	1.203 (2)	C10—C15	1.384 (3)
O4—C13	1.356 (2)	C10—C11	1.394 (2)
O4—C16	1.428 (2)	C11—C12	1.371 (2)
C1—C2	1.389 (2)	C11—H11A	0.9300
C1—C6	1.389 (2)	C12—C13	1.389 (2)
C1—H1A	0.9300	C12—H12A	0.9300
C2—C3	1.376 (3)	C13—C14	1.387 (3)
C2—H2A	0.9300	C14—C15	1.378 (3)
C3—C4	1.385 (3)	C14—H14A	0.9300
C4—C5	1.374 (3)	C15—H15A	0.9300
C4—H4A	0.9300	C16—H16A	0.9600
C5—C6	1.392 (3)	C16—H16B	0.9600
C5—H5A	0.9300	C16—H16C	0.9600
C6—C7	1.488 (2)
C9—O2—C8	115.26 (14)	H8A—C8—H8B	108.0
C13—O4—C16	118.49 (15)	O3—C9—O2	123.12 (17)
C2—C1—C6	121.02 (17)	O3—C9—C10	124.67 (17)
C2—C1—H1A	119.5	O2—C9—C10	112.21 (14)
C6—C1—H1A	119.5	C15—C10—C11	118.55 (16)
C3—C2—C1	118.78 (16)	C15—C10—C9	118.67 (15)
C3—C2—H2A	120.6	C11—C10—C9	122.75 (16)
C1—C2—H2A	120.6	C12—C11—C10	120.37 (16)
C2—C3—C4	121.30 (17)	C12—C11—H11A	119.8
C2—C3—Br1	119.48 (14)	C10—C11—H11A	119.8
C4—C3—Br1	119.22 (14)	C11—C12—C13	120.61 (16)
C5—C4—C3	119.33 (18)	C11—C12—H12A	119.7
C5—C4—H4A	120.3	C13—C12—H12A	119.7
C3—C4—H4A	120.3	O4—C13—C14	124.61 (16)
C4—C5—C6	120.87 (17)	O4—C13—C12	115.91 (16)
C4—C5—H5A	119.6	C14—C13—C12	119.48 (16)
C6—C5—H5A	119.6	C15—C14—C13	119.44 (17)
C1—C6—C5	118.69 (17)	C15—C14—H14A	120.3
C1—C6—C7	122.38 (16)	C13—C14—H14A	120.3
C5—C6—C7	118.91 (16)	C14—C15—C10	121.49 (17)
O1—C7—C6	121.84 (18)	C14—C15—H15A	119.3
O1—C7—C8	119.99 (17)	C10—C15—H15A	119.3
C6—C7—C8	118.17 (15)	O4—C16—H16A	109.5
O2—C8—C7	111.04 (15)	O4—C16—H16B	109.5
O2—C8—H8A	109.4	H16A—C16—H16B	109.5
C7—C8—H8A	109.4	O4—C16—H16C	109.5
O2—C8—H8B	109.4	H16A—C16—H16C	109.5
C7—C8—H8B	109.4	H16B—C16—H16C	109.5
C6—C1—C2—C3	0.3 (3)	C8—O2—C9—C10	174.72 (15)
C1—C2—C3—C4	0.6 (3)	O3—C9—C10—C15	−15.5 (3)
C1—C2—C3—Br1	179.71 (13)	O2—C9—C10—C15	164.40 (16)
C2—C3—C4—C5	−0.9 (3)	O3—C9—C10—C11	162.56 (18)
Br1—C3—C4—C5	179.99 (14)	O2—C9—C10—C11	−17.5 (2)
C3—C4—C5—C6	0.3 (3)	C15—C10—C11—C12	1.5 (3)
C2—C1—C6—C5	−0.8 (3)	C9—C10—C11—C12	−176.60 (17)
C2—C1—C6—C7	−179.34 (17)	C10—C11—C12—C13	0.2 (3)
C4—C5—C6—C1	0.5 (3)	C16—O4—C13—C14	3.6 (3)
C4—C5—C6—C7	179.10 (17)	C16—O4—C13—C12	−176.97 (18)
C1—C6—C7—O1	−176.21 (19)	C11—C12—C13—O4	178.46 (17)
C5—C6—C7—O1	5.3 (3)	C11—C12—C13—C14	−2.1 (3)
C1—C6—C7—C8	3.8 (3)	O4—C13—C14—C15	−178.44 (17)
C5—C6—C7—C8	−174.72 (17)	C12—C13—C14—C15	2.2 (3)
C9—O2—C8—C7	−80.8 (2)	C13—C14—C15—C10	−0.4 (3)
O1—C7—C8—O2	−3.7 (3)	C11—C10—C15—C14	−1.4 (3)
C6—C7—C8—O2	176.31 (15)	C9—C10—C15—C14	176.76 (17)
C8—O2—C9—O3	−5.3 (3)

Hydrogen-bond geometry (Å, º)

Cg1 is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O1^i	0.93	2.48	3.386 (2)	164
C11—H11A···Cg1^ii	0.93	2.81	3.6395 (18)	149

Symmetry codes: (i) x−1, y, z; (ii) −x+2, −y+1, −z+1.