7-Nitro-1,2,3,4-tetra­hydro­quinoline

In the title compound, C₉H₁₀N₂O₂, the tetra­hydro­pyridine ring adopts an envelope conformation and the mol­ecule, except for the envelope flap C and the H atoms, is essentially planar.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.035
• wR factor = 0.071
• Data-to-parameter ratio = 16.0

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    N2     -   C3      ..       8.39 su

Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O1     -   N2      ..       5.76 su
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C5     -   C6      ..       5.88 su
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1     ...          ?

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

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

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S1. Comment

7-Nitro-1,2,3,4-tetrahydroquinoline, (I), is a versatile intermediate in the preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline, which is widely used in the efficient synthesis of laser dyes of the rhodamine class (Field et al., 1994). Bond lengths and angles in the title compound agree with those reported for related structures (Jasinski & Woudenberg, 1993; Sivaraman et al., 1996; Smith et al., 2002; Sankaranarayanan et al., 2003). The tetrahydropyridine ring adopts an envelope conformation, with atom C8 deviating by 0.659 (2) Å from the mean plane through the other five atoms (Fig. 1). This mean plane is almost planar with the benzene ring, forming a dihedral angle of 0.46 (5)°. The NO₂ group is slightly twisted out of the benzene ring plane, the angle between the nitro group and the benzene ring being 16.16 (3)°. The nitro group is, therefore, not conjugated with benzene, resulting in a longer C3—N2 bond length.

S2. Experimental

The title compound was prepared according to the method reported by Kulka & Manske (1952). To sulfuric acid (75 ml, 96.6%) cooled in a salt-ice bath was added dropwise 1,2,3,4-tetrahydroquinoline (25 ml, 0.2 mol). After 30 min, concomitant addition of nitric acid (9.5 ml, 0.2 mol, 90%) in sulfuric acid (40 ml) was started, keeping the temperature at 278–283 K. The reaction mixture was stirred in the ice bath for 3 h and then poured on to 1.4 kg of ice. The solution was neutralized to pH 8 with sodium carbonate (255 g). The precipitate was then collected, washed with water and recrystallized from methanol (200 ml) to give a dark-orange solid (yield 49%, 35 g). It was recrystallized from acetonitrile, giving red crystals of (I) suitable for X-ray diffraction.

S3. Refinement

All H atoms were placed in calculated positions, with C—H = 0.93–0.96 Å and N—H = 0.86 Å, and included in the refinement in the riding-model approximation, with U_iso(H) = 1.2U_eq(carrier atom).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: CrystalStructure.

Figures

Fig. 1. View of the molecular structure of (I) and the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level.

7-Nitro-1,2,3,4-tetrahydroquinoline

Crystal data

C9H10N2O2	F(000) = 752.00
Mr = 178.19	Dx = 1.415 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71075 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 12005 reflections
a = 7.985 (2) Å	θ = 3.1–27.5°
b = 10.583 (4) Å	µ = 0.10 mm^−1
c = 19.790 (5) Å	T = 296 K
V = 1672.4 (9) Å^3	Block, red
Z = 8	0.28 × 0.15 × 0.14 mm

Data collection

Rigaku R-AXIS RAPID diffractometer	Rint = 0.036
Detector resolution: 10.00 pixels mm^-1	θmax = 27.5°
ω scans	h = −9→10
15209 measured reflections	k = −13→13
1906 independent reflections	l = −25→25
1188 reflections with F^2 > 2σ(F^2)

Refinement

Refinement on F^2	w = 1/[0.0001Fo^2 + σ(Fo^2)]/(4Fo^2)
R[F^2 > 2σ(F^2)] = 0.035	(Δ/σ)max < 0.001
wR(F^2) = 0.071	Δρmax = 0.25 e Å^−3
S = 1.01	Δρmin = −0.17 e Å^−3
1906 reflections	Extinction correction: Larson (1970)
119 parameters	Extinction coefficient: 313 (18)
H-atom parameters constrained

Special details

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY

Refinement. Refinement using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	Uiso*/Ueq
O1	0.63457 (13)	0.46121 (12)	0.09338 (5)	0.0803 (3)
O2	0.56622 (13)	0.26946 (12)	0.11683 (4)	0.0709 (3)
N1	0.49817 (12)	0.26484 (11)	0.36674 (5)	0.0488 (3)
N2	0.60753 (12)	0.37617 (13)	0.13382 (5)	0.0533 (3)
C1	0.56791 (12)	0.34555 (12)	0.32053 (5)	0.0345 (3)
C2	0.55548 (12)	0.31988 (12)	0.25155 (6)	0.0374 (3)
C3	0.62554 (13)	0.40348 (12)	0.20609 (5)	0.0386 (3)
C4	0.70973 (14)	0.51039 (13)	0.22548 (6)	0.0449 (3)
C5	0.72221 (14)	0.53368 (12)	0.29399 (6)	0.0447 (3)
C6	0.65336 (13)	0.45445 (12)	0.34164 (5)	0.0377 (3)
C7	0.66928 (18)	0.48050 (13)	0.41660 (6)	0.0536 (4)
C8	0.66406 (16)	0.35882 (13)	0.45633 (6)	0.0530 (4)
C9	0.50867 (16)	0.28493 (13)	0.43921 (6)	0.0524 (4)
H1	0.4465	0.1991	0.3520	0.059*
H2	0.5007	0.2478	0.2363	0.044*
H4	0.7561	0.5647	0.1936	0.054*
H5	0.7789	0.6052	0.3089	0.053*
H72	0.7730	0.5235	0.4252	0.064*
H71	0.5776	0.5326	0.4310	0.064*
H82	0.7594	0.3089	0.4436	0.063*
H81	0.6682	0.3757	0.5040	0.063*
H91	0.4133	0.3330	0.4537	0.062*
H92	0.5101	0.2051	0.4622	0.063*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0978 (8)	0.0946 (10)	0.0487 (5)	0.0100 (7)	0.0028 (5)	0.0272 (5)
O2	0.0827 (7)	0.0843 (9)	0.0458 (5)	−0.0039 (7)	−0.0054 (4)	−0.0152 (5)
N1	0.0577 (6)	0.0464 (7)	0.0424 (5)	−0.0139 (5)	0.0069 (4)	−0.0031 (5)
N2	0.0472 (6)	0.0703 (10)	0.0423 (5)	0.0119 (6)	−0.0002 (5)	0.0043 (6)
C1	0.0306 (5)	0.0332 (7)	0.0396 (5)	0.0035 (5)	0.0034 (4)	0.0005 (5)
C2	0.0344 (6)	0.0342 (7)	0.0437 (5)	0.0014 (5)	−0.0007 (5)	−0.0053 (5)
C3	0.0349 (6)	0.0441 (8)	0.0369 (5)	0.0097 (5)	−0.0012 (5)	0.0017 (5)
C4	0.0417 (7)	0.0390 (8)	0.0540 (7)	0.0050 (6)	0.0033 (5)	0.0127 (6)
C5	0.0426 (6)	0.0312 (8)	0.0603 (7)	−0.0013 (6)	−0.0041 (5)	−0.0010 (6)
C6	0.0355 (5)	0.0333 (7)	0.0442 (6)	0.0043 (5)	−0.0007 (5)	−0.0031 (5)
C7	0.0570 (8)	0.0533 (10)	0.0504 (7)	−0.0017 (7)	−0.0013 (6)	−0.0151 (6)
C8	0.0526 (7)	0.0693 (11)	0.0372 (5)	0.0074 (7)	−0.0009 (5)	−0.0032 (6)
C9	0.0540 (7)	0.0627 (11)	0.0405 (6)	0.0041 (7)	0.0085 (5)	0.0019 (6)

Geometric parameters (Å, º)

O1—N2	1.2236 (17)	C7—C8	1.5094 (19)
O2—N2	1.2236 (19)	C8—C9	1.5053 (18)
N1—C1	1.3697 (15)	N1—H1	0.860
N1—C9	1.4523 (15)	C2—H2	0.930
N2—C3	1.4662 (14)	C4—H4	0.930
C1—C2	1.3954 (15)	C5—H5	0.930
C1—C6	1.4030 (17)	C7—H72	0.960
C2—C3	1.3803 (16)	C7—H71	0.960
C3—C4	1.3709 (19)	C8—H82	0.960
C4—C5	1.3816 (16)	C8—H81	0.960
C5—C6	1.3764 (16)	C9—H91	0.960
C6—C7	1.5142 (15)	C9—H92	0.960
O1···N1^i	3.4745 (16)	H2···C4^iv	3.116
O1···C9^ii	3.5805 (17)	H2···C5^viii	3.367
O2···N1^ii	3.4648 (14)	H2···C5^iv	2.943
O2···C8^iii	3.5415 (15)	H2···H4^viii	2.870
O2···C9^iii	3.5914 (14)	H2···H4^iv	3.145
N1···O1^iv	3.4745 (16)	H2···H5^viii	2.727
N1···O2^v	3.4648 (14)	H2···H5^iv	2.838
N1···N2^v	3.3345 (14)	H4···O2^ix	3.003
N2···N1^ii	3.3345 (14)	H4···N1^i	3.168
C1···C4^v	3.4717 (16)	H4···C1^ii	3.414
C2···C4^v	3.4488 (17)	H4···C2^ix	3.297
C3···C5^v	3.5031 (16)	H4···C6^ii	3.451
C4···C1^ii	3.4717 (16)	H4···H1^i	2.336
C4···C2^ii	3.4488 (17)	H4···H2^ix	2.870
C5···C3^ii	3.5031 (16)	H4···H2^i	3.145
C8···O2^vi	3.5415 (15)	H4···H71^ii	3.576
C9···O1^v	3.5805 (17)	H5···O2^i	3.574
C9···O2^vi	3.5914 (14)	H5···N1^ix	2.708
O1···H1^i	2.816	H5···C1^ix	2.832
O1···H72^vii	3.413	H5···C2^ix	2.863
O1···H72^v	2.984	H5···C3^ii	3.509
O1···H82^v	3.480	H5···H1^ix	2.555
O1···H81^vii	2.931	H5···H2^ix	2.727
O1···H91^ii	2.769	H5···H2^i	2.838
O1···H92^iii	3.290	H5···H82^ix	3.442
O1···H92^i	3.035	H72···O1^xiii	3.413
O2···H1^ii	3.187	H72···O1^ii	2.984
O2···H4^viii	3.003	H72···N1^ix	3.347
O2···H5^iv	3.574	H72···N2^ii	3.306
O2···H71^iv	2.915	H72···C9^ix	3.282
O2···H82^v	2.758	H72···H1^ix	3.252
O2···H81^iii	2.831	H72···H82^ix	3.054
O2···H91^ii	3.176	H72···H91^x	3.203
O2···H92^iii	3.104	H72···H92^ix	2.690
N1···H4^iv	3.168	H71···O2^i	2.915
N1···H5^viii	2.708	H71···C8^x	3.164
N1···H72^viii	3.347	H71···C9^x	3.286
N2···H1^i	3.456	H71···H4^v	3.576
N2···H1^ii	3.304	H71···H71^x	3.076
N2···H72^v	3.306	H71···H82^ix	3.211
N2···H82^v	3.253	H71···H81^x	2.540
N2···H91^ii	3.029	H71···H91^x	2.689
N2···H92^iii	3.588	H71···H92^x	3.558
C1···H4^v	3.414	H82···O1^ii	3.480
C1···H5^viii	2.832	H82···O2^ii	2.758
C2···H4^viii	3.297	H82···N2^ii	3.253
C2···H5^viii	2.863	H82···C7^viii	3.563
C3···H1^i	3.382	H82···C9^xi	3.214
C3···H1^ii	3.545	H82···H5^viii	3.442
C3···H5^v	3.509	H82···H72^viii	3.054
C4···H1^i	2.810	H82···H71^viii	3.211
C4···H2^ix	3.421	H82···H91^xi	2.810
C4···H2^i	3.116	H82···H92^xi	2.739
C5···H1^ix	3.374	H81···O1^xiii	2.931
C5···H2^ix	3.367	H81···O2^vi	2.831
C5···H2^i	2.943	H81···C7^x	3.471
C6···H4^v	3.451	H81···H71^x	2.540
C7···H82^ix	3.563	H81···H91^x	3.260
C7···H81^x	3.471	H81···H91^xi	3.067
C7···H91^x	3.304	H81···H92^xi	2.938
C8···H71^x	3.164	H91···O1^v	2.769
C8···H91^xi	3.354	H91···O2^v	3.176
C8···H92^xi	3.269	H91···N2^v	3.029
C9···H72^viii	3.282	H91···C7^x	3.304
C9···H71^x	3.286	H91···C8^xii	3.354
C9···H82^xii	3.214	H91···H72^x	3.203
C9···H81^xii	3.398	H91···H71^x	2.689
H1···O1^iv	2.816	H91···H82^xii	2.810
H1···O2^v	3.187	H91···H81^x	3.260
H1···N2^iv	3.456	H91···H81^xii	3.067
H1···N2^v	3.304	H92···O1^vi	3.290
H1···C3^iv	3.382	H92···O1^iv	3.035
H1···C3^v	3.545	H92···O2^vi	3.104
H1···C4^iv	2.810	H92···N2^vi	3.588
H1···C5^viii	3.374	H92···C8^xii	3.269
H1···H4^iv	2.336	H92···H72^viii	2.690
H1···H5^viii	2.555	H92···H71^x	3.558
H1···H72^viii	3.252	H92···H82^xii	2.739
H2···C4^viii	3.421	H92···H81^xii	2.938
C1—N1—C9	123.00 (10)	C1—C2—H2	120.8
O1—N2—O2	123.14 (10)	C3—C2—H2	120.3
O1—N2—C3	118.41 (12)	C3—C4—H4	121.0
O2—N2—C3	118.45 (11)	C5—C4—H4	121.8
N1—C1—C2	120.19 (10)	C4—C5—H5	119.4
N1—C1—C6	120.75 (9)	C6—C5—H5	118.3
C2—C1—C6	119.07 (10)	C6—C7—H72	109.4
C1—C2—C3	118.95 (11)	C6—C7—H71	109.4
N2—C3—C2	118.01 (11)	C8—C7—H72	109.6
N2—C3—C4	118.94 (10)	C8—C7—H71	108.3
C2—C3—C4	123.05 (10)	H72—C7—H71	109.5
C3—C4—C5	117.21 (11)	C7—C8—H82	108.1
C4—C5—C6	122.33 (12)	C7—C8—H81	110.6
C1—C6—C5	119.39 (9)	C9—C8—H82	108.0
C1—C6—C7	118.82 (10)	C9—C8—H81	110.3
C5—C6—C7	121.78 (11)	H82—C8—H81	109.5
C6—C7—C8	110.65 (11)	N1—C9—H91	109.1
C7—C8—C9	110.41 (10)	N1—C9—H92	109.9
N1—C9—C8	110.24 (10)	C8—C9—H91	108.1
C1—N1—H1	118.2	C8—C9—H92	109.9
C9—N1—H1	118.8	H91—C9—H92	109.5
C1—N1—C9—C8	−27.63 (16)	C6—C1—C2—C3	−0.96 (16)
C9—N1—C1—C2	179.06 (10)	C1—C2—C3—N2	−178.58 (10)
C9—N1—C1—C6	−0.59 (17)	C1—C2—C3—C4	1.06 (17)
O1—N2—C3—C2	163.85 (11)	N2—C3—C4—C5	179.20 (11)
O1—N2—C3—C4	−15.80 (17)	C2—C3—C4—C5	−0.44 (18)
O2—N2—C3—C2	−16.16 (16)	C3—C4—C5—C6	−0.27 (18)
O2—N2—C3—C4	164.19 (11)	C4—C5—C6—C1	0.33 (18)
N1—C1—C2—C3	179.38 (10)	C4—C5—C6—C7	179.45 (12)
N1—C1—C6—C5	179.95 (10)	C1—C6—C7—C8	27.19 (15)
N1—C1—C6—C7	0.80 (16)	C5—C6—C7—C8	−151.93 (11)
C2—C1—C6—C5	0.30 (16)	C6—C7—C8—C9	−54.66 (14)
C2—C1—C6—C7	−178.85 (10)	C7—C8—C9—N1	54.67 (14)

Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) x+1/2, y, −z+1/2; (iii) x, −y+1/2, z−1/2; (iv) −x+1, y−1/2, −z+1/2; (v) x−1/2, y, −z+1/2; (vi) x, −y+1/2, z+1/2; (vii) −x+3/2, −y+1, z−1/2; (viii) −x+3/2, y−1/2, z; (ix) −x+3/2, y+1/2, z; (x) −x+1, −y+1, −z+1; (xi) x+1/2, −y+1/2, −z+1; (xii) x−1/2, −y+1/2, −z+1; (xiii) −x+3/2, −y+1, z+1/2.