(E)-1-(4-Bromo­phen­yl)but-2-en-1-one

Sonneck, M.; Spannenberg, A.; Wohlrab, S.; Peppel, T.

doi:10.1107/S2414314625004158

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 10| Part 5| May 2025| x250415

https://doi.org/10.1107/S2414314625004158

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(E)-1-(4-Bromophenyl)but-2-en-1-one

Marcel Sonneck,^a Anke Spannenberg,^a Sebastian Wohlrab ^a and Tim Peppel ^a ^*

^aLeibniz-Institut für Katalyse e. V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
^*Correspondence e-mail: tim.peppel@catalysis.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 30 April 2025; accepted 8 May 2025; online 13 May 2025)

The title compound, C₁₀H₉BrO, consists of a para-substituted bromophenyl core and an unsaturated carbonyl side chain. The angle between the plane through the carbon atoms of the aryl ring and the plane through the carbon atoms of the unsaturated side chain is 29.12 (16)°. The cohesion in the crystal is ensured by π–π stacking and C—H⋯O interactions.

Keywords: crystal structure; unsaturated compound; carbonyl side chain; stacking interactions.

CCDC reference: 1495201

Structure description

The structures of α,β-unsaturated carbonyl compounds are a common motif in a variety of natural products or bulk chemicals. These compounds are versatile synthetic intermediates for multiple organic transformation reactions, such as Michael addition, Diels–Alder reaction or Heck reaction (Ponec, 1997 ; Engel & Dudley, 2009 ; Desimoni et al., 2018 ). The title compound, C₁₀H₉BrO, was received in low yield in high purity in a Friedel–Crafts acylation. It can be designated as a suitable building block in the ongoing efforts to synthesize feasible new ligands for Cu-based complexes (Sonneck et al., 2015 , 2016 ).

The molecular structure of the title compound consists of a para-substituted bromophenyl core and an unsaturated carbonyl side chain (Fig. 1). The angle between the plane defined by the aryl ring (C5–C10) and the plane through the carbon atoms of the unsaturated side chain (C1–C4) is 29.12 (16)°. Carbonyl oxygen atom O1 is 0.246 (4) Å out of the latter plane. In the crystal, weak π–π stacking interactions between adjacent molecules are observed, with a centroid(C5–C10)-to-centroid(C5–C10)' distance of 3.724 (1) Å [ring slippage = 1.31 Å; symmetry code: (') 1 − x, 2 − y, 2 − z]. Additionally, weak intermolecular C—H⋯O interactions are present in the crystal packing (Table 1, Fig. 2). All bond lengths and angles are in expected ranges and the C=O bond length is 1.2278 (17) Å.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯O1ⁱ	0.95	2.56	3.5094 (18)	177
C1—H1C⋯O1ⁱⁱ	0.98	2.58	3.555 (2)	172
Symmetry codes: (i) ; (ii) .

Figure 1
Molecular structure of the title compound with atom labeling and displacement ellipsoids drawn at the 50% probability level.

Figure 2
Packing diagram (ball-and-stick representation) for the title compound in a view along [100].

Synthesis and crystallization

The title compound, C₁₀H₉BrO, was obtained as colorless crystals in low yield from the Friedel–Crafts acylation of bromobenzene and crotonyl chloride in CS₂. AlCl₃ (61.2 g, 459.2 mmol, 1.20 eq.) was added to a stirred solution of bromobenzene (81.1 g, 516.6 mmol, 1.35 eq.) in 150 ml of CS₂ at room temperature. Crotonyl chloride (40.0 g, 382.7 mmol, 1.00 eq.) was added dropwise to the thoroughly stirred suspension and afterwards the solution was heated under reflux for 24 h. The resulting red solution was poured onto a mixture of ice and concentrated hydrochloric acid (500 g: 50 g) and extracted 3× with 150 ml portions of ethyl acetate. The volume of the combined organic phases was reduced to 150 ml and extracted twice with 100 ml portions of brine. The organic phase was dried with Na₂SO₄ and the solvent was removed completely under diminished pressure. The resulting raw product was distilled under reduced pressure to give an orange-colored distillate. After storing the distillate for several days at 243 K, colorless single crystals of the product were obtained in low yield (9.5 g, 11%).

Analytical data for C₁₀H₉BrO: mp. 323 K, elemental analysis % (calculated): C 53.40 (53.36), H 3.95 (4.03); Br 35.42 (35.50). ¹H NMR (300 MHz, MeOD): δ (p.p.m.) = 8.75–8.67 (m, 2H, ArH); 8.56–8.48 (m, 2H, ArH); 8.01–7.81 (m, 2H); 2.87 (d, ³J = 6.0 Hz, 3H, –Me); ¹³C NMR (75 MHz, MeOD): δ (p.p.m.) = 191.15 (CO); 147.25 (CH); 137.84 (C); 132.98, 132.98, 141.29, 131.29 (CH), 128.78 (C), 127.97 (CH), 18.67 (CH₃).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₀H₉BrO
M_r	225.08
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	150
a, b, c (Å)	5.5734 (9), 8.1618 (13), 10.6194 (16)
α, β, γ (°)	98.577 (2), 96.441 (2), 102.546 (2)
V (Å³)	461.00 (13)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	4.41
Crystal size (mm)	0.36 × 0.23 × 0.04

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.63, 0.85
No. of measured, independent and observed [I > 2σ(I)] reflections	12194, 2232, 2077
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.661

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.051, 1.05
No. of reflections	2232
No. of parameters	110
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.27
Computer programs: APEX2 and SAINT (Bruker, 2014 ), SHELXS97 (Sheldrick, 2008 ), SHELXL (Sheldrick, 2015 ), XP in SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1495201

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314625004158/wm4228sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314625004158/wm4228Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314625004158/wm4228Isup3.cml

checkCIF report

Computing details top

(E)-1-(4-Bromophenyl)but-2-en-1-one top

Crystal data top

C₁₀H₉BrO	Z = 2
M_r = 225.08	F(000) = 224
Triclinic, P1	D_x = 1.622 Mg m⁻³
a = 5.5734 (9) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.1618 (13) Å	Cell parameters from 7348 reflections
c = 10.6194 (16) Å	θ = 2.6–28.6°
α = 98.577 (2)°	µ = 4.41 mm⁻¹
β = 96.441 (2)°	T = 150 K
γ = 102.546 (2)°	Plate, colourless
V = 461.00 (13) Å³	0.36 × 0.23 × 0.04 mm

Data collection top

Bruker APEXII CCD diffractometer	2232 independent reflections
Radiation source: fine-focus sealed tube	2077 reflections with I > 2σ(I)
Detector resolution: 8.3333 pixels mm^-1	R_int = 0.027
φ and ω scans	θ_max = 28.0°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −7→7
T_min = 0.63, T_max = 0.85	k = −10→10
12194 measured reflections	l = −14→14

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.019	H-atom parameters constrained
wR(F²) = 0.051	w = 1/[σ²(F_o²) + (0.0243P)² + 0.1552P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.002
2232 reflections	Δρ_max = 0.32 e Å⁻³
110 parameters	Δρ_min = −0.27 e Å⁻³

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.46488 (3)	1.00661 (2)	1.33348 (2)	0.03862 (7)
C1	0.1030 (3)	0.2949 (2)	0.52287 (17)	0.0397 (4)
H1A	−0.047264	0.328231	0.545930	0.060*
H1B	0.086027	0.173332	0.524923	0.060*
H1C	0.125813	0.316143	0.436060	0.060*
C2	0.3226 (3)	0.39689 (19)	0.61669 (15)	0.0308 (3)
H2	0.480779	0.377596	0.603523	0.037*
C3	0.3146 (3)	0.51246 (19)	0.71713 (14)	0.0274 (3)
H3	0.158932	0.534668	0.732273	0.033*
C4	0.5417 (3)	0.60755 (18)	0.80609 (14)	0.0253 (3)
C5	0.5149 (2)	0.70343 (17)	0.93299 (13)	0.0230 (3)
C6	0.7179 (3)	0.82873 (19)	1.00146 (15)	0.0284 (3)
H6	0.867758	0.852042	0.965647	0.034*
C7	0.7057 (3)	0.91961 (19)	1.12013 (15)	0.0304 (3)
H7	0.843908	1.006229	1.165242	0.037*
C8	0.4872 (3)	0.88158 (18)	1.17190 (13)	0.0260 (3)
C9	0.2838 (3)	0.75609 (19)	1.10791 (14)	0.0276 (3)
H9	0.136975	0.729938	1.145979	0.033*
C10	0.2970 (2)	0.66900 (18)	0.98747 (14)	0.0257 (3)
H10	0.156462	0.585051	0.941560	0.031*
O1	0.75060 (19)	0.60866 (15)	0.77924 (11)	0.0348 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.05075 (11)	0.03740 (10)	0.02638 (9)	0.01081 (7)	0.00651 (7)	0.00052 (6)
C1	0.0426 (9)	0.0367 (9)	0.0352 (8)	0.0058 (7)	0.0048 (7)	−0.0022 (7)
C2	0.0319 (7)	0.0300 (7)	0.0329 (8)	0.0098 (6)	0.0087 (6)	0.0068 (6)
C3	0.0246 (7)	0.0318 (7)	0.0276 (7)	0.0090 (6)	0.0066 (5)	0.0061 (6)
C4	0.0243 (6)	0.0268 (7)	0.0282 (7)	0.0091 (5)	0.0071 (5)	0.0086 (5)
C5	0.0212 (6)	0.0244 (6)	0.0259 (6)	0.0074 (5)	0.0045 (5)	0.0085 (5)
C6	0.0207 (6)	0.0317 (7)	0.0326 (7)	0.0035 (5)	0.0053 (5)	0.0083 (6)
C7	0.0256 (7)	0.0310 (7)	0.0302 (7)	0.0001 (6)	−0.0005 (5)	0.0044 (6)
C8	0.0310 (7)	0.0265 (7)	0.0219 (6)	0.0093 (6)	0.0032 (5)	0.0059 (5)
C9	0.0249 (6)	0.0307 (7)	0.0291 (7)	0.0063 (6)	0.0082 (5)	0.0083 (6)
C10	0.0210 (6)	0.0261 (7)	0.0287 (7)	0.0027 (5)	0.0049 (5)	0.0047 (5)
O1	0.0239 (5)	0.0467 (7)	0.0360 (6)	0.0114 (5)	0.0098 (4)	0.0063 (5)

Geometric parameters (Å, º) top

Br1—C8	1.8925 (14)	C5—C6	1.395 (2)
C1—C2	1.490 (2)	C5—C10	1.3951 (18)
C1—H1A	0.9800	C6—C7	1.380 (2)
C1—H1B	0.9800	C6—H6	0.9500
C1—H1C	0.9800	C7—C8	1.385 (2)
C2—C3	1.326 (2)	C7—H7	0.9500
C2—H2	0.9500	C8—C9	1.382 (2)
C3—C4	1.478 (2)	C9—C10	1.385 (2)
C3—H3	0.9500	C9—H9	0.9500
C4—O1	1.2278 (17)	C10—H10	0.9500
C4—C5	1.4940 (19)

C2—C1—H1A	109.5	C10—C5—C4	122.52 (13)
C2—C1—H1B	109.5	C7—C6—C5	121.43 (13)
H1A—C1—H1B	109.5	C7—C6—H6	119.3
C2—C1—H1C	109.5	C5—C6—H6	119.3
H1A—C1—H1C	109.5	C6—C7—C8	118.46 (14)
H1B—C1—H1C	109.5	C6—C7—H7	120.8
C3—C2—C1	125.10 (14)	C8—C7—H7	120.8
C3—C2—H2	117.4	C9—C8—C7	121.73 (13)
C1—C2—H2	117.4	C9—C8—Br1	119.11 (11)
C2—C3—C4	121.66 (13)	C7—C8—Br1	119.16 (11)
C2—C3—H3	119.2	C8—C9—C10	119.06 (13)
C4—C3—H3	119.2	C8—C9—H9	120.5
O1—C4—C3	122.00 (13)	C10—C9—H9	120.5
O1—C4—C5	119.30 (13)	C9—C10—C5	120.62 (13)
C3—C4—C5	118.69 (12)	C9—C10—H10	119.7
C6—C5—C10	118.67 (13)	C5—C10—H10	119.7
C6—C5—C4	118.78 (12)

C1—C2—C3—C4	179.68 (14)	C5—C6—C7—C8	1.2 (2)
C2—C3—C4—O1	13.9 (2)	C6—C7—C8—C9	0.0 (2)
C2—C3—C4—C5	−165.45 (14)	C6—C7—C8—Br1	−179.19 (11)
O1—C4—C5—C6	17.9 (2)	C7—C8—C9—C10	−1.6 (2)
C3—C4—C5—C6	−162.71 (13)	Br1—C8—C9—C10	177.61 (10)
O1—C4—C5—C10	−160.10 (14)	C8—C9—C10—C5	2.0 (2)
C3—C4—C5—C10	19.2 (2)	C6—C5—C10—C9	−0.8 (2)
C10—C5—C6—C7	−0.8 (2)	C4—C5—C10—C9	177.24 (13)
C4—C5—C6—C7	−178.94 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O1ⁱ	0.95	2.56	3.5094 (18)	177
C1—H1C···O1ⁱⁱ	0.98	2.58	3.555 (2)	172

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

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