N-Acetyl-L-alanine

The crystal structure of the title compound, C₅H₉NO₃, has been investigated as part of a search for suitable materials for electron paramagnetic resonance (EPR) radiation dosimetry.

Key indicators

• Single-crystal X-ray study
• T = 105 K
• Mean [sigma](C-C) = 0.001 Å
• R factor = 0.037
• wR factor = 0.100
• Data-to-parameter ratio = 28.6

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT063_ALERT_3_A Crystal Probably too Large for Beam Size .......       1.15 mm

Author Response: This is no problem for a light atom structure, see Gorbitz, Acta Cryst. B55 (1999) 1090-98.

Alert level B
CRYSS02_ALERT_3_B  The value of _exptl_crystal_size_mid is > 0.8
   Mid crystal size given     =   1.000
CRYSS02_ALERT_3_B  The value of _exptl_crystal_size_max is > 1.0
   Maximum crystal size given =   1.150

Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
            Tmin and Tmax reported:      0.688     0.997
            Tmin' and Tmax expected:      0.884     0.997
            RR' =      0.779
            Please check that your absorption correction is appropriate.
PLAT061_ALERT_3_C Tmax/Tmin Range Test RR' too Large .............       0.78
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.36
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O3     -   C4      ..       5.04 su
PLAT480_ALERT_4_C Long H...A H-Bond Reported H21    ..  O3      ..       2.62 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H53    ..  O3      ..       2.65 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           44.76
           From the CIF: _reflns_number_total               3149
           Count of symmetry unique reflns         3178
           Completeness (_total/calc)             99.09%
           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

   1 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   7 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
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   4 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

N-acetyl-L-alanine

Crystal data

C5H9NO3	Dx = 1.265 Mg m^−3
Mr = 131.13	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P21212	Cell parameters from 10042 reflections
a = 10.3879 (2) Å	θ = 2.6–44.8°
b = 11.5449 (3) Å	µ = 0.11 mm^−1
c = 5.7426 (1) Å	T = 105 K
V = 688.69 (3) Å^3	Rod, colourless
Z = 4	1.15 × 1.00 × 0.03 mm
F(000) = 280

Data collection

Siemens SMART CCD diffractometer	3149 independent reflections
Radiation source: fine-focus sealed tube	2839 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.018
Detector resolution: 8.3 pixels mm^-1	θmax = 44.8°, θmin = 2.6°
sets of exposures each taken over 0.3° ω rotation scans	h = −19→20
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −22→22
Tmin = 0.688, Tmax = 0.997	l = −11→10
14223 measured reflections

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.100	Only H-atom coordinates refined
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0667P)^2 + 0.0041P] where P = (Fo^2 + 2Fc^2)/3
3149 reflections	(Δ/σ)max = 0.004
110 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

Special details

Refinement. Data were collected by measuring five sets of exposures with the detector set at 2θ = 29°, crystal-to-detector distance 5.00 cm. Refinement of F² against ALL reflections.

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

	x	y	z	Uiso*/Ueq
O1	0.81329 (7)	0.09735 (6)	0.75696 (10)	0.02963 (12)
O2	0.85613 (5)	0.18877 (5)	0.41981 (10)	0.02481 (10)
H2	0.9025 (17)	0.2286 (17)	0.506 (5)	0.059 (6)*
O3	0.51974 (5)	0.16482 (4)	0.41255 (9)	0.02180 (9)
N1	0.66665 (5)	0.07061 (5)	0.19533 (9)	0.01857 (8)
H1	0.7038 (12)	0.0665 (11)	0.077 (3)	0.022*
C1	0.80154 (5)	0.10683 (5)	0.54602 (10)	0.01860 (9)
C2	0.72609 (5)	0.01901 (5)	0.40063 (11)	0.01824 (9)
H21	0.6577 (11)	−0.0100 (11)	0.507 (3)	0.022*
C3	0.81747 (7)	−0.07828 (7)	0.32424 (18)	0.02913 (14)
H31	0.7701 (17)	−0.1388 (15)	0.246 (4)	0.044*
H32	0.8605 (16)	−0.1146 (15)	0.458 (4)	0.044*
H33	0.8800 (15)	−0.0455 (15)	0.229 (4)	0.044*
C4	0.56610 (5)	0.14300 (5)	0.21649 (10)	0.01755 (8)
C5	0.51119 (8)	0.19283 (8)	−0.00456 (12)	0.02748 (13)
H51	0.4989 (16)	0.2699 (14)	0.000 (4)	0.041*
H52	0.4231 (15)	0.1525 (13)	−0.027 (4)	0.041*
H53	0.5587 (15)	0.1767 (15)	−0.132 (3)	0.041*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0314 (2)	0.0414 (3)	0.01606 (17)	−0.0084 (2)	0.00052 (17)	0.00236 (18)
O2	0.0284 (2)	0.0273 (2)	0.01877 (18)	−0.01075 (16)	−0.00013 (17)	0.00106 (16)
O3	0.02385 (18)	0.02536 (19)	0.01620 (15)	0.00601 (14)	0.00286 (15)	−0.00004 (15)
N1	0.01745 (17)	0.02254 (19)	0.01572 (16)	0.00031 (13)	0.00221 (13)	−0.00078 (15)
C1	0.01676 (18)	0.0227 (2)	0.01637 (18)	−0.00072 (15)	0.00194 (15)	0.00031 (16)
C2	0.01624 (17)	0.01919 (19)	0.01930 (19)	−0.00039 (14)	0.00133 (16)	0.00083 (16)
C3	0.0248 (3)	0.0232 (2)	0.0394 (4)	0.00538 (19)	0.0000 (3)	−0.0041 (3)
C4	0.01784 (18)	0.01914 (18)	0.01566 (17)	−0.00067 (14)	0.00107 (15)	0.00082 (15)
C5	0.0282 (3)	0.0358 (3)	0.0185 (2)	0.0044 (2)	0.0005 (2)	0.0073 (2)

Geometric parameters (Å, º)

O1—C1	1.2224 (8)	C2—H21	0.995 (14)
O2—C1	1.3197 (8)	C3—H31	0.966 (19)
O2—H2	0.83 (2)	C3—H32	0.98 (2)
O3—C4	1.2501 (7)	C3—H33	0.928 (18)
N1—C4	1.3433 (8)	C4—C5	1.5059 (9)
N1—C2	1.4581 (8)	C5—H51	0.900 (16)
N1—H1	0.783 (15)	C5—H52	1.034 (16)
C1—C2	1.5296 (8)	C5—H53	0.903 (18)
C2—C3	1.5346 (9)
C1—O2—H2	108.6 (17)	C2—C3—H32	111.7 (11)
C4—N1—C2	120.69 (5)	H31—C3—H32	106.8 (15)
C4—N1—H1	120.0 (10)	C2—C3—H33	107.5 (11)
C2—N1—H1	117.9 (10)	H31—C3—H33	112.2 (17)
O1—C1—O2	124.44 (6)	H32—C3—H33	108.4 (14)
O1—C1—C2	122.19 (6)	O3—C4—N1	120.42 (5)
O2—C1—C2	113.30 (5)	O3—C4—C5	122.43 (6)
N1—C2—C1	112.80 (5)	N1—C4—C5	117.13 (5)
N1—C2—C3	109.26 (6)	C4—C5—H51	113.9 (13)
C1—C2—C3	108.92 (5)	C4—C5—H52	105.4 (11)
N1—C2—H21	109.4 (8)	H51—C5—H52	108.8 (13)
C1—C2—H21	104.7 (8)	C4—C5—H53	113.5 (11)
C3—C2—H21	111.8 (7)	H51—C5—H53	107.9 (16)
C2—C3—H31	110.3 (10)	H52—C5—H53	106.9 (15)
O1—C1—C2—N1	149.71 (7)	O2—C1—C2—N1	−33.23 (7)
C1—C2—N1—C4	−70.77 (7)	O1—C1—C2—C3	−88.80 (9)
C2—N1—C4—O3	−1.92 (9)	O2—C1—C2—C3	88.26 (7)
C4—N1—C2—C3	167.94 (6)	C2—N1—C4—C5	179.66 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.783 (15)	2.190 (15)	2.9586 (8)	167.0 (12)
O2—H2···O3^ii	0.83 (2)	1.793 (19)	2.5831 (7)	158 (2)
C2—H21···O3^iii	0.995 (14)	2.624 (13)	3.3211 (8)	127.1 (11)
C5—H53···O3^i	0.903 (18)	2.65 (2)	3.3641 (9)	136.8 (13)

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