1-Acetyl-1,3-dicyclo­hexyl­urea

The title compound, C₁₅H₂₆N₂O₂, was prepared from dicyclo­hexyl­carbodiimide and acetic acid. The crystal structure is established by strong N—H...O inter­actions between the amide H atom and the acetyl O atom, producing dimeric units which are connected into infinite chains by additional C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 183 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.044
• wR factor = 0.108
• Data-to-parameter ratio = 20.2

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S1. Comment

Acylated N-aryl- and N-alkylurea derivatives have been investigated, e.g. as intermediates in the synthesis of amidines and heterocyclic compounds derived therefrom, as well as precursors for poly(amide-imide)s (Wei et al. 2006, Ramsden & Rose 1997, Khorana 1953, Smith et al. 1958, Detar & Silverstein 1966a,b, Ogawa et al. 1990, Smart et al. 1960). Although quite a number of acylated dicyclohexylurea derivatives have been structurally characterized (Ball et al. 1990, Banerjee et al. 2000, Bechtel et al. 1979, Behrens & Rehder 2006, Chérioux et al. 2002, Orea Flores et al. 2006, Gallagher et al. 1999, Goel et al. 2003, Ishida et al. 1983, Mazumdar et al. 2003, Perollier et al. 1999, Salas-Coronado et al. 2001, Toniolo et al. 1990), the structure of the most simple derivative, with an acetyl group, has not yet been reported.

The molecular structure of the title compound (Fig. 1) shows the two urea nitrogen atoms N1 and N2 having a planar geometry, with an angle of 69.00 (6)° between [C6, N1, H1N, C7] and [C7, N2, C8, C14]. The bond lengths and angles have expected values. The crystal structure is determined by hydrogen bonds. The strongest interactions are observed between the amide N1—H1N group and the acetyl oxygen atom (H···O 2.035 Å). Two of these hydrogen bonds link two molecules, forming a dimeric cyclic unit. These dimers are linked to produce infinite chains by additional C—H···O bonds from one of the cyclohexyl substituents to the carbonyl oxygen atom of the urea unit (Fig. 2, Table 1).

Related literature

For related literature, see: Ball et al. (1990); Banerjee et al. (2000); Bechtel et al. (1979); Behrens & Rehder (2006); Chérioux et al. (2002); Orea Flores et al. (2006); Gallagher et al. (1999); Goel et al. (2003); Ishida et al. (1983); Mazumdar et al. (2003); Perollier et al. (1999); Salas-Coronado et al. (2001); Toniolo et al. (1990).

For related literature, see: Detar & Silverstein (1966a, 1966b); Khorana (1953); Ogawa et al. (1990); Ramsden & Rose (1997); Smart et al. (1960); Smith et al. (1958); Wei et al. (2006).

S2. Experimental

1.96 g Dicyclohexylcarbodiimide (9.51 mmol) were stirred at room temperature for 5 h together with 5 ml glacial acetic acid and 1 mol% (110 mg) [Pd(PPh₃)₄] in 10 ml THF. On standing at -20° for three days, colorless crystals of the title compound were produced; these were identified by their melting point and ¹H NMR spectrum (Ogawa et al. 1990, Smart et al. 1960). ¹³C NMR (CDCl₃, 293 K) [p.p.m.]: 23.9 (CH₃), 24.6 (CH₂), 25.2 (CH₂), 25.4 (CH₂), 26.2 (CH₂), 30.7 (CH₂), 32.6 (CH₂), 55.6 (CH), 56,4 (CH), 153.9 (C=O), 170.9 (C=O).

S3. Refinement

Hydrogen atoms were placed in idealized positions and refined using a riding model, with distances of N—H = 0.88 Å and C—H = 0.98–1.00 Å; U_iso(H) = 1.5U_eq(C,N).

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1990); software used to prepare material for publication: XP (Siemens, 1990).

Figures

	Fig. 1. The molecular structure of the title compound, showing the labelling scheme. Displacement ellipsoids are drawn at the 40% probability level.
	Fig. 2. Crystal structure of the title compound. Dashed lines indicate hydrogen bonds.

1-Acetyl-1,3-dicyclohexyurea

Crystal data

C15H26N2O2	F(000) = 584
Mr = 266.38	Dx = 1.157 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P2yn	Cell parameters from 5982 reflections
a = 10.6174 (4) Å	θ = 2.5–27.5°
b = 14.2451 (9) Å	µ = 0.08 mm^−1
c = 10.8862 (6) Å	T = 183 K
β = 111.795 (3)°	Cuboid, colourless
V = 1528.80 (14) Å^3	0.3 × 0.2 × 0.2 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	2103 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.030
Graphite monochromator	θmax = 27.5°, θmin = 2.5°
phi–scan, ω–scan	h = −13→13
5982 measured reflections	k = −16→18
3494 independent 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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.108	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0565P)^2] where P = (Fo^2 + 2Fc^2)/3
3494 reflections	(Δ/σ)max < 0.001
173 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.18 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
C1	0.06204 (15)	0.63488 (12)	0.96118 (14)	0.0552 (4)
H1A	0.1613	0.6441	0.9905	0.083*
H1B	0.0443	0.5666	0.9597	0.083*
C2	0.01037 (16)	0.68244 (14)	1.05960 (14)	0.0639 (5)
H2A	0.0525	0.6522	1.1473	0.096*
H2B	0.0376	0.7493	1.0690	0.096*
C3	−0.14216 (16)	0.67575 (12)	1.01465 (16)	0.0576 (4)
H3A	−0.1688	0.6092	1.0153	0.086*
H3B	−0.1730	0.7108	1.0769	0.086*
C4	−0.20999 (14)	0.71539 (13)	0.87715 (14)	0.0584 (4)
H4A	−0.1919	0.7837	0.8789	0.088*
H4B	−0.3093	0.7064	0.8478	0.088*
C5	−0.15866 (13)	0.66796 (12)	0.77887 (14)	0.0571 (4)
H5A	−0.1864	0.6012	0.7692	0.086*
H5B	−0.2006	0.6984	0.6913	0.086*
C6	−0.00597 (12)	0.67416 (9)	0.82379 (12)	0.0348 (3)
H6	0.0198	0.7418	0.8251	0.052*
N1	0.03787 (10)	0.62479 (8)	0.72894 (10)	0.0384 (3)
H1N	−0.0132	0.5789	0.6825	0.058*
C7	0.15079 (12)	0.64555 (9)	0.70914 (12)	0.0350 (3)
O1	0.23242 (9)	0.70596 (7)	0.76652 (9)	0.0460 (3)
N2	0.17255 (10)	0.58545 (7)	0.61161 (10)	0.0348 (3)
C8	0.28978 (12)	0.52058 (9)	0.65772 (12)	0.0345 (3)
H8	0.2645	0.4638	0.5997	0.052*
C9	0.41480 (12)	0.56302 (10)	0.64319 (14)	0.0420 (3)
H9A	0.4454	0.6183	0.7020	0.063*
H9B	0.3927	0.5840	0.5508	0.063*
C10	0.52742 (14)	0.48970 (11)	0.67961 (15)	0.0526 (4)
H10A	0.4983	0.4363	0.6173	0.079*
H10B	0.6095	0.5176	0.6717	0.079*
C11	0.56119 (15)	0.45453 (11)	0.82013 (16)	0.0591 (4)
H11A	0.6302	0.4043	0.8395	0.089*
H11B	0.6001	0.5066	0.8831	0.089*
C12	0.43630 (15)	0.41690 (10)	0.83923 (15)	0.0526 (4)
H12A	0.4601	0.4000	0.9334	0.079*
H12B	0.4056	0.3591	0.7859	0.079*
C13	0.32072 (14)	0.48780 (10)	0.79900 (13)	0.0434 (3)
H13A	0.3463	0.5423	0.8597	0.065*
H13B	0.2388	0.4586	0.8056	0.065*
C14	0.09682 (12)	0.59270 (9)	0.47971 (13)	0.0363 (3)
O2	0.11724 (8)	0.53978 (7)	0.39946 (9)	0.0435 (3)
C15	−0.00869 (13)	0.66818 (10)	0.43522 (13)	0.0449 (4)
H15A	−0.0302	0.6815	0.3413	0.067*
H15B	0.0259	0.7252	0.4871	0.067*
H15C	−0.0908	0.6472	0.4481	0.067*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0564 (9)	0.0703 (11)	0.0422 (8)	0.0220 (8)	0.0222 (7)	0.0044 (8)
C2	0.0658 (10)	0.0937 (14)	0.0366 (8)	0.0233 (9)	0.0240 (7)	0.0030 (9)
C3	0.0711 (10)	0.0585 (10)	0.0630 (10)	−0.0031 (8)	0.0478 (8)	−0.0074 (8)
C4	0.0411 (8)	0.0827 (12)	0.0558 (10)	0.0064 (8)	0.0230 (7)	−0.0156 (9)
C5	0.0386 (8)	0.0856 (12)	0.0474 (9)	0.0047 (8)	0.0163 (6)	−0.0181 (9)
C6	0.0381 (7)	0.0349 (7)	0.0358 (7)	−0.0018 (5)	0.0188 (5)	−0.0058 (6)
N1	0.0375 (6)	0.0437 (7)	0.0386 (6)	−0.0075 (5)	0.0193 (5)	−0.0128 (5)
C7	0.0366 (7)	0.0369 (7)	0.0336 (7)	0.0010 (6)	0.0154 (6)	−0.0016 (6)
O1	0.0426 (5)	0.0449 (6)	0.0549 (6)	−0.0092 (5)	0.0233 (4)	−0.0152 (5)
N2	0.0355 (6)	0.0400 (6)	0.0324 (6)	0.0020 (5)	0.0167 (5)	−0.0031 (5)
C8	0.0382 (7)	0.0341 (7)	0.0349 (7)	−0.0003 (6)	0.0176 (5)	−0.0028 (6)
C9	0.0392 (7)	0.0458 (8)	0.0449 (8)	−0.0011 (6)	0.0204 (6)	0.0014 (7)
C10	0.0389 (7)	0.0638 (10)	0.0564 (10)	0.0041 (7)	0.0193 (6)	−0.0021 (8)
C11	0.0510 (9)	0.0614 (10)	0.0542 (10)	0.0149 (8)	0.0072 (7)	−0.0017 (8)
C12	0.0707 (10)	0.0418 (8)	0.0416 (8)	0.0095 (7)	0.0165 (7)	0.0044 (7)
C13	0.0547 (8)	0.0403 (8)	0.0404 (8)	0.0008 (7)	0.0236 (6)	0.0038 (7)
C14	0.0356 (7)	0.0400 (8)	0.0365 (7)	−0.0093 (6)	0.0170 (6)	−0.0052 (6)
O2	0.0484 (6)	0.0479 (6)	0.0368 (5)	−0.0063 (4)	0.0188 (4)	−0.0102 (4)
C15	0.0392 (7)	0.0521 (9)	0.0402 (8)	0.0009 (6)	0.0111 (6)	−0.0006 (7)

Geometric parameters (Å, º)

C1—C6	1.5065 (19)	N2—C8	1.4802 (15)
C1—C2	1.5311 (19)	C8—C9	1.5194 (17)
C1—H1A	0.9900	C8—C13	1.5219 (18)
C1—H1B	0.9900	C8—H8	1.0000
C2—C3	1.511 (2)	C9—C10	1.5250 (19)
C2—H2A	0.9900	C9—H9A	0.9900
C2—H2B	0.9900	C9—H9B	0.9900
C3—C4	1.509 (2)	C10—C11	1.521 (2)
C3—H3A	0.9900	C10—H10A	0.9900
C3—H3B	0.9900	C10—H10B	0.9900
C4—C5	1.5268 (19)	C11—C12	1.514 (2)
C4—H4A	0.9900	C11—H11A	0.9900
C4—H4B	0.9900	C11—H11B	0.9900
C5—C6	1.5121 (17)	C12—C13	1.5227 (18)
C5—H5A	0.9900	C12—H12A	0.9900
C5—H5B	0.9900	C12—H12B	0.9900
C6—N1	1.4608 (15)	C13—H13A	0.9900
C6—H6	1.0000	C13—H13B	0.9900
N1—C7	1.3278 (15)	C14—O2	1.2325 (15)
N1—H1N	0.8800	C14—C15	1.4977 (18)
C7—O1	1.2165 (15)	C15—H15A	0.9800
C7—N2	1.4477 (15)	C15—H15B	0.9800
N2—C14	1.3645 (16)	C15—H15C	0.9800
C6—C1—C2	111.49 (12)	N2—C8—C9	111.93 (10)
C6—C1—H1A	109.3	N2—C8—C13	111.91 (10)
C2—C1—H1A	109.3	C9—C8—C13	110.99 (11)
C6—C1—H1B	109.3	N2—C8—H8	107.2
C2—C1—H1B	109.3	C9—C8—H8	107.2
H1A—C1—H1B	108.0	C13—C8—H8	107.2
C3—C2—C1	111.40 (13)	C8—C9—C10	109.35 (12)
C3—C2—H2A	109.3	C8—C9—H9A	109.8
C1—C2—H2A	109.3	C10—C9—H9A	109.8
C3—C2—H2B	109.3	C8—C9—H9B	109.8
C1—C2—H2B	109.3	C10—C9—H9B	109.8
H2A—C2—H2B	108.0	H9A—C9—H9B	108.3
C4—C3—C2	110.92 (12)	C11—C10—C9	110.88 (12)
C4—C3—H3A	109.5	C11—C10—H10A	109.5
C2—C3—H3A	109.5	C9—C10—H10A	109.5
C4—C3—H3B	109.5	C11—C10—H10B	109.5
C2—C3—H3B	109.5	C9—C10—H10B	109.5
H3A—C3—H3B	108.0	H10A—C10—H10B	108.1
C3—C4—C5	111.49 (13)	C12—C11—C10	111.31 (12)
C3—C4—H4A	109.3	C12—C11—H11A	109.4
C5—C4—H4A	109.3	C10—C11—H11A	109.4
C3—C4—H4B	109.3	C12—C11—H11B	109.4
C5—C4—H4B	109.3	C10—C11—H11B	109.4
H4A—C4—H4B	108.0	H11A—C11—H11B	108.0
C6—C5—C4	111.49 (11)	C11—C12—C13	112.26 (12)
C6—C5—H5A	109.3	C11—C12—H12A	109.2
C4—C5—H5A	109.3	C13—C12—H12A	109.2
C6—C5—H5B	109.3	C11—C12—H12B	109.2
C4—C5—H5B	109.3	C13—C12—H12B	109.2
H5A—C5—H5B	108.0	H12A—C12—H12B	107.9
N1—C6—C1	111.22 (11)	C12—C13—C8	110.05 (11)
N1—C6—C5	109.15 (10)	C12—C13—H13A	109.7
C1—C6—C5	111.13 (11)	C8—C13—H13A	109.7
N1—C6—H6	108.4	C12—C13—H13B	109.7
C1—C6—H6	108.4	C8—C13—H13B	109.7
C5—C6—H6	108.4	H13A—C13—H13B	108.2
C7—N1—C6	123.46 (10)	O2—C14—N2	120.64 (12)
C7—N1—H1N	118.3	O2—C14—C15	121.14 (12)
C6—N1—H1N	118.3	N2—C14—C15	118.19 (11)
O1—C7—N1	126.04 (12)	C14—C15—H15A	109.5
O1—C7—N2	121.17 (11)	C14—C15—H15B	109.5
N1—C7—N2	112.76 (11)	H15A—C15—H15B	109.5
C14—N2—C7	122.34 (11)	C14—C15—H15C	109.5
C14—N2—C8	119.79 (10)	H15A—C15—H15C	109.5
C7—N2—C8	117.62 (9)	H15B—C15—H15C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O2^i	0.88	2.04	2.907 (3)	171
C12—H12B···O1^ii	0.99	2.57	3.469 (3)	151

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