4-(Hexyl­amino)phenol

The title compound, C₁₂H₁₉NO, presents a two-dimensional hydrogen-bonding pattern, where amine and hydroxyl functionalities serve as both donors and acceptors.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.053
• wR factor = 0.170
• Data-to-parameter ratio = 9.8

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT027_ALERT_3_B _diffrn_reflns_theta_full (too) Low ............      24.99 Deg.

Alert level C
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.97 Ratio
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.30 Ratio
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          6
PLAT352_ALERT_3_C Short   N-H Bond (0.87A)   N1     -   H1B    ...       0.75 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           24.99
           From the CIF: _reflns_number_total               1327
           Count of symmetry unique reflns         1338
           Completeness (_total/calc)             99.18%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 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
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Secondary amines are ubiquitous in polymer synthesis, where they are used as monomer chain extenders and crosslinking agents (Herman et al., 1990; Choi et al., 2004). The title compound, (I), is an amphiphilic monomer belonging to this class of compounds, including an hydrophobic alkyl-chain moiety and a polar hydroxyl functionality. It was obtained by reacting 4-aminophenol with 1-bromohexane (see Experimental), demonstrating that, as expected, the amine functionality is more reactive than the hydroxy group when 4-aminophenol undergoes an S_N2 reaction with primary alkyl halides.

The asymmetric unit of (I) consists of one molecule in a general position with the expected geometry (Fig. 1 and Table 1). O—H and N—H bond lengths are short [0.72 (5) and 0.75 (5) Å, respectively] compared to those found, for example, in 4-aminophenol [0.87 and 0.90–0.96 Å, respectively; Ermer & Eling, 1994]. These groups are involved in a network of hydrogen bonds of moderate strength (Table 2); hydroxyl and amine functionalities serve both as donor and acceptor groups, forming a directed two-membered chain ···O—H···N—H···O—H··· running along the short axis [100]. The complete network has a two-dimensional pattern (Fig. 2), giving an arrangement which avoids π–π interactions; the dihedral angle between two adjacent phenol rings belonging to two hydrogen-bonded molecules is 78.99 (9)° (symmetry code: 1 − x, 1/2 + y, 1 − z). The crystal structure is based on segregated stacks of aryl groups and alkyl groups, parallel to the [100] axis (Fig. 2, inset).

S2. Experimental

To a solution of 4-aminophenol (1 g, 9 mmol) in cyclohexanone was added finely powdered K₂CO₃ (2.53 g, 18 mmol) under an argon atmosphere. The mixture was refluxed for 2 h and then 1-bromohexane (1.82 g, 11 mmol) was added in small portions. The reaction was continued under reflux for 24 h and the mixture was then cooled and filtered to remove KBr and unreacted K₂CO₃. After evaporation of the solvent, the residue was dissolved in acetone and this solution was poured into hexane in order to precipitate unreacted 4-aminophenol and the solution reduced under reduced pressure at T < 323 K. This procedure was repeated until pure (I) was isolated as brown crystals (yield 0.82 g, 70%, m.p. 348 K). Analysis found: C 74.6, H 9.7, O 8.2, N 7.3%; calculated for C₁₂H₁₉NO: C 74.6, H 9.8, O 8.2, N 7.2%. ¹H NMR (400 MHz, CDCl₃): δ 0.89 (m, J = 8.8 Hz, 3H, CH₃), 1.30 (m, J = 7.2, 6H, 3 × CH₂), 1.58 (m, J = 6.8 Hz, 2H, CH₂), 3.05 (m, J = 6.8 Hz, 2H, NCH₂), 4.01 (s, 1H, OH), 6.55 (d, J = 8.4 Hz, 2H, Ph), 6.68 (d, J = 8.4 Hz, 2H, Ph).

S3. Refinement

The H atoms bonded to heteroatoms N1 and O1 were found in a difference map and refined with free coordinates and isotropic U parameters. H atoms bonded to C atoms were placed in idealized positions and refined as riding on their parent C atom [restrained C—H distances and isotropic U_iso(H) parameters: methylene 0.97 Å and 1.2U_eq(C); methyl 0.96 Å and 1.5U_eq(C); aromatic 0.93 Å and 1.2U_eq(C)]. In the absence of significant anomalous scattering effects, Friedel pairs were merged.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1998); program(s) used to refine structure: SHELXTL-Plus; molecular graphics: SHELXTL-Plus; software used to prepare material for publication: SHELXTL-Plus.

Figures

	Fig. 1. The structure of (I), with displacement ellipsoids for non-H atoms drawn at the 30% probability level.
	Fig. 2. Part of the crystal structure of (I), showing the hydrogen-bonding scheme (dashed red lines). For clarity, H atoms bonded to C atoms have been omitted. The inset is a projection of the crystal structure along [010]. The short cell axis corresponds to the a axis and the long axis corresponds to the c axis.

4-(n-Hexylamino)phenol

Crystal data

C12H19NO	Dx = 1.026 Mg m^−3
Mr = 193.28	Melting point: 348 K
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 55 reflections
a = 4.7016 (6) Å	θ = 4.8–11.9°
b = 10.1325 (14) Å	µ = 0.07 mm^−1
c = 26.273 (3) Å	T = 296 K
V = 1251.6 (3) Å^3	Prism, brown
Z = 4	0.55 × 0.28 × 0.20 mm
F(000) = 424

Data collection

Bruker P4 diffractometer	Rint = 0.048
Radiation source: fine-focus sealed tube, FN4	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = −5→5
2θ/ω scans	k = −12→12
5524 measured reflections	l = −31→31
1327 independent reflections	3 standard reflections every 97 reflections
833 reflections with I > 2σ(I)	intensity decay: 3%

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)] = 0.053	Hydrogen site location: See text
wR(F^2) = 0.170	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.1)^2] where P = (Fo^2 + 2Fc^2)/3
1327 reflections	(Δ/σ)max < 0.001
136 parameters	Δρmax = 0.11 e Å^−3
0 restraints	Δρmin = −0.17 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	0.1149 (7)	0.5685 (3)	0.32994 (10)	0.0833 (8)
H1A	−0.028 (11)	0.542 (4)	0.3307 (16)	0.098 (18)*
N1	0.3464 (8)	0.8998 (3)	0.16515 (12)	0.0754 (9)
H1B	0.495 (10)	0.925 (4)	0.1686 (15)	0.093 (15)*
C1	0.1688 (6)	0.6457 (3)	0.28791 (13)	0.0659 (9)
C2	0.0336 (7)	0.6269 (4)	0.24204 (14)	0.0756 (10)
H2A	−0.1008	0.5602	0.2387	0.091*
C3	0.0971 (7)	0.7073 (3)	0.20079 (13)	0.0768 (10)
H3A	0.0050	0.6933	0.1699	0.092*
C4	0.2953 (6)	0.8079 (3)	0.20483 (13)	0.0660 (9)
C5	0.4315 (7)	0.8240 (4)	0.25173 (13)	0.0744 (9)
H5A	0.5675	0.8899	0.2555	0.089*
C6	0.3674 (7)	0.7438 (3)	0.29239 (14)	0.0765 (9)
H6A	0.4600	0.7564	0.3233	0.092*
C7	0.3220 (9)	0.8555 (4)	0.11289 (14)	0.0878 (11)
H7A	0.1276	0.8287	0.1061	0.105*
H7B	0.4444	0.7797	0.1075	0.105*
C8	0.4068 (10)	0.9663 (4)	0.07655 (15)	0.0992 (13)
H8A	0.2828	1.0413	0.0823	0.119*
H8B	0.5995	0.9938	0.0844	0.119*
C9	0.3925 (13)	0.9294 (5)	0.02187 (16)	0.1203 (16)
H9A	0.1998	0.9026	0.0137	0.144*
H9B	0.5166	0.8545	0.0158	0.144*
C10	0.4811 (15)	1.0442 (5)	−0.01366 (18)	0.1311 (18)
H10A	0.3490	1.1168	−0.0091	0.157*
H10B	0.6683	1.0750	−0.0037	0.157*
C11	0.4880 (19)	1.0084 (6)	−0.0677 (2)	0.168 (2)
H11A	0.2979	0.9838	−0.0785	0.202*
H11B	0.6101	0.9321	−0.0721	0.202*
C12	0.593 (2)	1.1177 (7)	−0.1009 (2)	0.196 (3)
H12A	0.5281	1.1040	−0.1351	0.294*
H12B	0.7975	1.1189	−0.1004	0.294*
H12C	0.5221	1.2005	−0.0885	0.294*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0817 (19)	0.0811 (17)	0.0870 (17)	−0.0060 (15)	−0.0013 (15)	0.0114 (14)
N1	0.077 (2)	0.0712 (19)	0.078 (2)	−0.0101 (17)	0.0024 (16)	0.0022 (16)
C1	0.0611 (16)	0.0558 (18)	0.081 (2)	0.0055 (16)	0.0013 (17)	0.0081 (18)
C2	0.0687 (18)	0.063 (2)	0.095 (2)	−0.0132 (16)	−0.0019 (19)	0.002 (2)
C3	0.079 (2)	0.074 (2)	0.077 (2)	−0.0062 (19)	−0.0107 (19)	−0.005 (2)
C4	0.0651 (16)	0.0561 (17)	0.077 (2)	0.0022 (15)	0.0044 (17)	−0.0031 (19)
C5	0.0671 (17)	0.070 (2)	0.086 (2)	−0.0114 (17)	−0.005 (2)	−0.0006 (18)
C6	0.0724 (19)	0.075 (2)	0.082 (2)	−0.0036 (19)	−0.0073 (19)	−0.005 (2)
C7	0.102 (2)	0.079 (2)	0.082 (2)	−0.005 (2)	0.011 (2)	−0.007 (2)
C8	0.115 (3)	0.099 (3)	0.083 (3)	−0.010 (3)	0.006 (2)	0.002 (2)
C9	0.151 (4)	0.115 (3)	0.095 (3)	−0.004 (4)	0.016 (3)	−0.003 (3)
C10	0.163 (5)	0.135 (4)	0.095 (3)	−0.009 (4)	0.003 (3)	0.006 (3)
C11	0.226 (6)	0.150 (5)	0.127 (5)	−0.003 (6)	0.019 (4)	0.012 (4)
C12	0.259 (9)	0.187 (6)	0.143 (5)	−0.027 (7)	0.026 (6)	0.058 (5)

Geometric parameters (Å, º)

O1—C1	1.377 (4)	C7—H7B	0.9700
O1—H1A	0.72 (5)	C8—C9	1.486 (6)
N1—C4	1.419 (4)	C8—H8A	0.9700
N1—C7	1.449 (5)	C8—H8B	0.9700
N1—H1B	0.75 (5)	C9—C10	1.549 (7)
C1—C6	1.369 (4)	C9—H9A	0.9700
C1—C2	1.376 (5)	C9—H9B	0.9700
C2—C3	1.388 (5)	C10—C11	1.466 (8)
C2—H2A	0.9300	C10—H10A	0.9700
C3—C4	1.385 (4)	C10—H10B	0.9700
C3—H3A	0.9300	C11—C12	1.494 (8)
C4—C5	1.398 (4)	C11—H11A	0.9700
C5—C6	1.376 (4)	C11—H11B	0.9700
C5—H5A	0.9300	C12—H12A	0.9600
C6—H6A	0.9300	C12—H12B	0.9600
C7—C8	1.527 (5)	C12—H12C	0.9600
C7—H7A	0.9700
C1—O1—H1A	114 (3)	C9—C8—H8A	108.7
C4—N1—C7	118.6 (3)	C7—C8—H8A	108.7
C4—N1—H1B	107 (3)	C9—C8—H8B	108.7
C7—N1—H1B	107 (3)	C7—C8—H8B	108.7
C6—C1—C2	119.4 (3)	H8A—C8—H8B	107.6
C6—C1—O1	118.0 (3)	C8—C9—C10	112.4 (4)
C2—C1—O1	122.6 (3)	C8—C9—H9A	109.1
C1—C2—C3	120.2 (3)	C10—C9—H9A	109.1
C1—C2—H2A	119.9	C8—C9—H9B	109.1
C3—C2—H2A	119.9	C10—C9—H9B	109.1
C4—C3—C2	121.1 (3)	H9A—C9—H9B	107.9
C4—C3—H3A	119.5	C11—C10—C9	113.8 (5)
C2—C3—H3A	119.5	C11—C10—H10A	108.8
C3—C4—C5	117.5 (3)	C9—C10—H10A	108.8
C3—C4—N1	122.8 (3)	C11—C10—H10B	108.8
C5—C4—N1	119.6 (3)	C9—C10—H10B	108.8
C6—C5—C4	121.0 (3)	H10A—C10—H10B	107.7
C6—C5—H5A	119.5	C10—C11—C12	112.9 (6)
C4—C5—H5A	119.5	C10—C11—H11A	109.0
C1—C6—C5	120.8 (3)	C12—C11—H11A	109.0
C1—C6—H6A	119.6	C10—C11—H11B	109.0
C5—C6—H6A	119.6	C12—C11—H11B	109.0
N1—C7—C8	110.1 (3)	H11A—C11—H11B	107.8
N1—C7—H7A	109.6	C11—C12—H12A	109.5
C8—C7—H7A	109.6	C11—C12—H12B	109.5
N1—C7—H7B	109.6	H12A—C12—H12B	109.5
C8—C7—H7B	109.6	C11—C12—H12C	109.5
H7A—C7—H7B	108.2	H12A—C12—H12C	109.5
C9—C8—C7	114.1 (4)	H12B—C12—H12C	109.5
C6—C1—C2—C3	−0.3 (5)	C2—C1—C6—C5	0.4 (5)
O1—C1—C2—C3	−179.7 (3)	O1—C1—C6—C5	179.8 (3)
C1—C2—C3—C4	−0.3 (5)	C4—C5—C6—C1	0.2 (5)
C2—C3—C4—C5	0.9 (5)	C4—N1—C7—C8	−175.8 (3)
C2—C3—C4—N1	−173.8 (3)	N1—C7—C8—C9	179.2 (4)
C7—N1—C4—C3	−33.8 (5)	C7—C8—C9—C10	−179.8 (4)
C7—N1—C4—C5	151.5 (3)	C8—C9—C10—C11	176.1 (7)
C3—C4—C5—C6	−0.9 (5)	C9—C10—C11—C12	−176.0 (6)
N1—C4—C5—C6	174.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···N1^i	0.72 (5)	2.08 (5)	2.764 (5)	158 (5)
N1—H1B···O1^ii	0.75 (5)	2.34 (5)	3.058 (5)	161 (4)

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