(1E,5E)-2,5-Di­bromo­cyclo­dodeca-1,5-dien-9-yne

Detert, H.; Schollmeyer, D.

doi:10.1107/S2414314617015504

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 2| Part 10| October 2017| x171550

https://doi.org/10.1107/S2414314617015504

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(1E,5E)-2,5-Dibromocyclododeca-1,5-dien-9-yne

Heiner Detert ^a ^* and Dieter Schollmeyer ^a

^aUniversity of Mainz, Institut of Organic Chemistry, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: detert@uni-mainz.de

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 11 September 2017; accepted 24 October 2017; online 27 October 2017)

The title compound, C₁₂H₁₄Br₂, was prepared by bromination/dehydrobromination of E,E,Z-cyclododecatriene. The crystal is composed of C₂-symmetrical molecules with an E conformation of the bromoalkene fragments and nearly linear alkyne units. The torsion angles in the ring suggest significant ring strain.

Keywords: crystal structure; organobromine compound; cycloalkyne.

CCDC reference: 1581763

Structure description

Dibromocyclododecatriene has been prepared as intermediate for the selective synthesis of (Z,Z,Z)-cyclododecatriene (Trauer & Haufe, 1988 ) and cyclotridecatrienes (Trauer & Haufe, 1990 ). The former is a valuable intermediate for the preparation of cyclododecatriyne (Barkovich & Vollhardt, 1976 ) and hexaradialene (Barkovich et al. 1980 ). Currently, strained alkynes are central coupling partners in click chemistry. Even medium-sized cycloalkynes can be highly strained (Meier et al. 1982 ; Bissinger et al. 1988 ).

The orthorhombic unit cell of the title compound (Fig. 1) is filled with four identical molecules of C₂ symmetry: the X-ray analysis gives proof for the E-conformation of the bromovinylene units. The C₂-symmetrical molecule shows a nearly perfect linearity of the alkyne unit with bond angles at the sp carbon atoms of 178.4 (4)°. Whereas the ethylene unit C1—C1ⁱ [symmetry code: (i) −x, y, −z + $[{1\over 2}]$ ] possesses quasi ideal bond and torsion angles, the bond angles at C4 [C3—C4—C5 = 112.0 (6)°] and C5 [C4—C5—C6 = 113.9 (6)°] are slightly opened. The same holds for the sp² carbon atoms [C3—C2—C1 = 128.0 (6)°]. These deformations and the torsion angles C2—C3—C4—C5 = −102.7 (8) and C3—C4—C5—C6 = 73.4 (8)° indicate geometrical ring strain even in a macrocyclic alkyne. In the crystal (Fig. 2), no directional interactions beyond normal van der Waals contacts could be identified.

Figure 1
View of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Atoms with the suffix a are generated by the symmetry operation −x, y, −z + $[{1\over 2}]$ .

Figure 2
Part of the packing diagram. View along b-axis direction.

Synthesis and crystallization

The title compound was prepared in a two-step procedure. First, 40.5 g (0.25 mol) of E,E,Z-1,5,9-cyclododecatriene in a Morton flask (2 l) containing 1 l anhydrous ether was cooled in an ice bath (CaCl₂ tube). A solution of 120.0 g, of bromine (0.75 mol) in dichloromethane in a constant addition funnel with Mariott tube (NORMAG) was added dropwise to the heavily stirred solution. When the colour vanished, 100 ml of petroleum ether was added slowly and the precipitate was collected on a Büchner funnel, yield: 132.8 g (83%) of a white powder with m.p. 471 K. Dehydrobromination of 6.4 g of the hexabromocyclododecane with sodium ethanolate in ethanol was performed according to Trauer & Haufe (1988) and yielded 2.13 g (65%) of an off-white powder with m.p. 431 K. Colourless blocks were grown via slow evaporation of a solution in chloroform and 2-propanol (1:1).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₂H₁₄Br₂
M_r	318.05
Crystal system, space group	Orthorhombic, Pbcn
Temperature (K)	120
a, b, c (Å)	16.8714 (12), 7.7191 (4), 9.1556 (5)
V (Å³)	1192.35 (12)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	6.76
Crystal size (mm)	0.27 × 0.23 × 0.22

Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Integration (X-RED32; Stoe & Cie, 2006 b)
T_min, T_max	0.190, 0.356
No. of measured, independent and observed [I > 2σ(I)] reflections	7295, 1465, 1204
R_int	0.031
(sin θ/λ)_max (Å⁻¹)	0.665

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.061, 0.193, 1.20
No. of reflections	1465
No. of parameters	64
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.54, −0.69
Computer programs: X-AREA and X-RED32 (Stoe & Cie, 2006), SHELXT2014 (Sheldrick, 2015a ) and SHELXL2017 (Sheldrick, 2015b ).

Structural data

CCDC reference: 1581763

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314617015504/hb4171sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617015504/hb4171Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314617015504/hb4171Isup3.cml

checkCIF report

Computing details top

Data collection: X-AREA (Stoe & Cie, 2006); cell refinement: X-AREA (Stoe & Cie, 2006); data reduction: X-RED32 (Stoe & Cie, 2006); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015b); molecular graphics: SHELXL2017 (Sheldrick, 2015b); software used to prepare material for publication: SHELXL2017 (Sheldrick, 2015b).

(1E,5E)-2,5-Dibromocyclododeca-1,5-dien-9-yne top

Crystal data top

C₁₂H₁₄Br₂	D_x = 1.772 Mg m⁻³
M_r = 318.05	Melting point: 431 K
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
a = 16.8714 (12) Å	Cell parameters from 9463 reflections
b = 7.7191 (4) Å	θ = 2.4–28.4°
c = 9.1556 (5) Å	µ = 6.76 mm⁻¹
V = 1192.35 (12) Å³	T = 120 K
Z = 4	Block, colourless
F(000) = 624	0.27 × 0.23 × 0.22 mm

Data collection top

Stoe IPDS 2T diffractometer	1465 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	1204 reflections with I > 2σ(I)
Plane graphite monochromator	R_int = 0.031
Detector resolution: 6.67 pixels mm^-1	θ_max = 28.2°, θ_min = 2.4°
rotation method scans	h = −22→22
Absorption correction: integration (X-RED32; Stoe & Cie, 2006b)	k = −10→10
T_min = 0.190, T_max = 0.356	l = −11→12
7295 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.061	H-atom parameters constrained
wR(F²) = 0.193	w = 1/[σ²(F_o²) + (0.0757P)² + 11.4374P] where P = (F_o² + 2F_c²)/3
S = 1.20	(Δ/σ)_max < 0.001
1465 reflections	Δρ_max = 1.54 e Å⁻³
64 parameters	Δρ_min = −0.69 e Å⁻³
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. Hydrogen atoms attached to carbons were placed at calculated positions with C—H = 0.95 Å (sp²) or 0.99 Å (sp³ C-atom). All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2–1.5 times of the U_eq of the parent atom).

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

	x	y	z	U_iso*/U_eq
Br1	0.15412 (3)	0.49337 (7)	0.37567 (6)	0.0204 (3)
C1	0.0288 (3)	0.3816 (8)	0.1832 (7)	0.0243 (12)
H1A	0.010594	0.295662	0.110314	0.029*
H1B	0.028447	0.497259	0.136454	0.029*
C2	0.1119 (3)	0.3376 (8)	0.2315 (7)	0.0223 (12)
C3	0.1575 (3)	0.2044 (9)	0.1877 (8)	0.0265 (13)
H3	0.208538	0.193789	0.230594	0.032*
C4	0.1342 (4)	0.0716 (9)	0.0768 (8)	0.0300 (14)
H4A	0.179279	0.051056	0.009796	0.036*
H4B	0.089357	0.116479	0.018263	0.036*
C5	0.1100 (5)	−0.1000 (9)	0.1478 (8)	0.0339 (16)
H5A	0.109077	−0.191212	0.071789	0.041*
H5B	0.150743	−0.132693	0.220615	0.041*
C6	0.0324 (4)	−0.0948 (8)	0.2201 (8)	0.0305 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0147 (4)	0.0213 (4)	0.0251 (4)	−0.00532 (19)	−0.0026 (2)	0.00172 (19)
C1	0.017 (2)	0.026 (3)	0.031 (3)	0.001 (2)	−0.002 (3)	0.001 (3)
C2	0.020 (3)	0.025 (3)	0.022 (3)	−0.002 (2)	−0.001 (2)	0.005 (2)
C3	0.018 (3)	0.031 (3)	0.031 (3)	0.002 (2)	0.001 (2)	0.005 (3)
C4	0.025 (3)	0.039 (4)	0.025 (3)	0.005 (3)	0.002 (3)	−0.001 (3)
C5	0.033 (4)	0.027 (3)	0.042 (4)	0.009 (3)	0.004 (3)	−0.001 (3)
C6	0.038 (3)	0.025 (3)	0.029 (3)	−0.001 (3)	−0.002 (3)	0.000 (3)

Geometric parameters (Å, º) top

Br1—C2	1.922 (6)	C4—C5	1.531 (11)
C1—C2	1.509 (8)	C4—H4A	0.9900
C1—C1ⁱ	1.562 (12)	C4—H4B	0.9900
C1—H1A	0.9900	C5—C6	1.469 (10)
C1—H1B	0.9900	C5—H5A	0.9900
C2—C3	1.346 (9)	C5—H5B	0.9900
C3—C4	1.495 (10)	C6—C6ⁱ	1.222 (14)
C3—H3	0.9500

C2—C1—C1ⁱ	110.4 (6)	C3—C4—H4A	109.2
C2—C1—H1A	109.6	C5—C4—H4A	109.2
C1ⁱ—C1—H1A	109.6	C3—C4—H4B	109.2
C2—C1—H1B	109.6	C5—C4—H4B	109.2
C1ⁱ—C1—H1B	109.6	H4A—C4—H4B	107.9
H1A—C1—H1B	108.1	C6—C5—C4	113.9 (6)
C3—C2—C1	128.0 (6)	C6—C5—H5A	108.8
C3—C2—Br1	118.1 (5)	C4—C5—H5A	108.8
C1—C2—Br1	113.9 (4)	C6—C5—H5B	108.8
C2—C3—C4	125.2 (6)	C4—C5—H5B	108.8
C2—C3—H3	117.4	H5A—C5—H5B	107.7
C4—C3—H3	117.4	C6ⁱ—C6—C5	178.4 (4)
C3—C4—C5	112.0 (6)

C1ⁱ—C1—C2—C3	120.5 (6)	Br1—C2—C3—C4	−179.9 (5)
C1ⁱ—C1—C2—Br1	−58.5 (4)	C2—C3—C4—C5	−102.7 (8)
C1—C2—C3—C4	1.2 (11)	C3—C4—C5—C6	73.4 (8)

Symmetry code: (i) −x, y, −z+1/2.

References

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