research communications
Crystallographic and spectroscopic characterization of (R)-O-acetylmandelic acid
aDepartment of Chemistry, Vassar College, Poughkeepsie, NY 12604, USA
*Correspondence e-mail: jotanski@vassar.edu
The title compound [systematic name: (R)-(−)-2-acetoxy-2-phenylacetic acid], C10H10O4, is a resolved chiral ester derivative of mandelic acid. The compound contains an acetate group and a carboxylic acid group, which engage in intermolecular hydrogen bonding, forming chains extending parallel to [001] with a short donor–acceptor hydrogen-bonding distance of 2.676 (2) Å.
CCDC reference: 1482445
1. Chemical context
Chiral, resolved carboxylic acids have played an important role as chiral NMR shift reagents (Lovely & Wenzel, 2008; Parker, 1991). The title compound, (R)-(−)-2-acetoxy-2-phenylacetic acid (I), commonly known as (R)-O-acetylmandelic acid, is a chiral, resolved derivative of mandelic acid. The compound may be synthesized by acetylation of the parent α-hydroxy acid with acetic anhydride in pyridine (Ornelas et al., 2013). When racemic, resolution of the compound with free amino acids has been demonstrated (Szeleczky et al., 2015). The title compound has been employed as a chiral NMR shift reagent (Parker, 1991).
2. Structural commentary
The molecular structure of the title compound (Fig. 1) shows the R confguration about carbon atom C1, and that the molecule does not engage in intramolecular or pairwise hydrogen bonding. The parameters confirm the R assignment, with Flack x = −0.01 (4) and Hooft y = −0.02 (4), calculated with PLATON (Spek, 2009).
3. Supramolecular features
The molecules pack together in the solid state via and hydrogen bonding between the carboxylic acid OH group and the carbonyl oxygen atom of the ester on a neighboring molecule, O1—H1⋯O4i [symmetry code (i) −x + , −y + 1, z − ] with a donor–acceptor distance of 2.676 (2) Å (Table 1). These interactions create zigzag hydrogen-bonded chains that extend parallel to the c axis of the (Fig. 2). Notably, there is no face-to-face or edge-to-face π-stacking.
4. Database survey
The Cambridge Structural Database (Groom et al., 2016) contains several related mandelic acid ester structures. Related structures of resolved mandelic acid that differ by the nature of the ester group include (2S)-[(2S)-2-hydroxy-2-phenylethanoyloxy]phenylacetic acid (Mughal et al., 2004) and (1R,2R,3S,4S)-2-[(R)-mandeloxycarbonyl]bicyclo(2.2.1)heptane-3-carboxylic acid (Ohtani et al., 1991). The hydrogen bonding in the former differs from (I), forming an intermolecular chain with the carboxylic acid groups further cross-linked by hydrogen bonding of the alcohol moiety with the ester, whereas the latter compound exhibits pairwise dimerization of the carboxylic acid groups. A related structure with a tert-butyl ester and substituents on the phenyl ring, (S,E)-2-[2-(3-methoxy-3-oxoprop-1-en-1-yl)-4-(trifluoromethyl)phenyl]-2-(pivaloyloxy)acetic acid (Xiao et al., 2016), exhibits a similar one-dimensional intermolecular carboxylic acid OH⋯ester carbonyl hydrogen-bonding motif to that found in the title compound.
5. Synthesis and crystallization
(R)-(−)-2-acetoxy-2-phenylacetic acid (99%) was purchased from Aldrich Chemical Company, USA, and was used as received.
6. Analytical data
1H NMR (Bruker Avance 300 MHz, CDCl3): δ 2.19 (s, 3 H, CH3), 5.93 (s, 1H, CH), 7.36–7.42 (m, 3 H, CarylH), 7.45–7.51 (m, 2H, CarylH), 11.76 (br s, 1H, OH). 13C NMR (13C{1H}, 75.5 MHz, CDCl3): δ 20.59 (CH3), 74.02 (CH), 127.62 (CarylH), 128.86 (CarylH), 129.49 (CarylH), 132.98 (Caryl), 170.38 (CO), 174.55 (CO). IR (Thermo Nicolet iS50, ATR, cm−1): 3483 (w), 3014 (v br, O—H str), 2708 (w), 2588 (w), 1752 (v s, C=O str), 1686 (v s, C=O str), 1498 (w), 1461 (w), 1412 (m), 1382 (s), 1321 (m), 1277 (s), 1259 (s), 1206 (s), 1182 (s), 1045 (s), 996 (m), 967 (m), 919 (m), 888 (m), 767 (s), 734 (s), 700 (s), 642 (m), 616 (w), 603 (w), 583 (w), 525 (s), 487 (w). GC/MS (Hewlett-Packard MS 5975/GC 7890): M-18+ = 176 (calc. exact mass 194.06 - water = 176).
7. Refinement
Crystal data, data collection and structure . All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on carbon were included in calculated positions and refined using a riding model with C–H = 0.95, 0.98 and 1.00 Å and Uiso(H) = 1.2, 1.5 and 1.2 × Ueq(C) of the aryl, methyl and methine C atoms, respectively. The position of the carboxylic acid hydrogen atom was found in the difference map and the atom refined semi-freely using a distance restraint d(O—H) = 0.84 Å, and Uiso(H) = 1.2Ueq(O).
details are summarized in Table 2Supporting information
CCDC reference: 1482445
https://doi.org/10.1107/S2056989016008653/pk2580sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016008653/pk2580Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989016008653/pk2580Isup3.cml
Data collection: APEX2 (Bruker, 2013); cell
SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009), Mercury (Macrae et al., 2008) and PLATON (Spek, 2009).C10H10O4 | Dx = 1.337 Mg m−3 |
Mr = 194.18 | Cu Kα radiation, λ = 1.54178 Å |
Orthorhombic, P212121 | Cell parameters from 8300 reflections |
a = 9.1047 (10) Å | θ = 4.2–66.6° |
b = 10.0086 (11) Å | µ = 0.88 mm−1 |
c = 10.5871 (11) Å | T = 125 K |
V = 964.75 (18) Å3 | Block, colourless |
Z = 4 | 0.26 × 0.26 × 0.17 mm |
F(000) = 408 |
Bruker APEXII CCD diffractometer | 1698 independent reflections |
Radiation source: Cu IuS micro-focus source | 1693 reflections with I > 2σ(I) |
Detector resolution: 8.3333 pixels mm-1 | Rint = 0.030 |
φ and ω scans | θmax = 66.6°, θmin = 6.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2013) | h = −10→10 |
Tmin = 0.74, Tmax = 0.86 | k = −11→11 |
8953 measured reflections | l = −12→12 |
Refinement on F2 | Hydrogen site location: mixed |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.025 | w = 1/[σ2(Fo2) + (0.0336P)2 + 0.1385P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.062 | (Δ/σ)max < 0.001 |
S = 1.10 | Δρmax = 0.19 e Å−3 |
1698 reflections | Δρmin = −0.19 e Å−3 |
131 parameters | Absolute structure: Flack x determined using 691 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013); Hooft y calculated with PLATON (Spek, 2009) |
1 restraint | Absolute structure parameter: −0.01 (4) |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.42132 (13) | 0.46237 (13) | 0.08956 (12) | 0.0329 (3) | |
H1 | 0.355 (2) | 0.479 (2) | 0.035 (2) | 0.039* | |
O2 | 0.35211 (12) | 0.66275 (12) | 0.16115 (11) | 0.0286 (3) | |
O3 | 0.50941 (12) | 0.63319 (11) | 0.37499 (9) | 0.0235 (3) | |
O4 | 0.29716 (12) | 0.53107 (12) | 0.42058 (10) | 0.0273 (3) | |
C1 | 0.53382 (16) | 0.53625 (15) | 0.27588 (13) | 0.0200 (3) | |
H1A | 0.5199 | 0.4438 | 0.3097 | 0.024* | |
C2 | 0.69072 (15) | 0.55447 (14) | 0.23211 (13) | 0.0184 (3) | |
C3 | 0.79939 (18) | 0.47071 (16) | 0.27844 (16) | 0.0272 (4) | |
H3A | 0.7744 | 0.3988 | 0.3329 | 0.033* | |
C4 | 0.94513 (18) | 0.49242 (17) | 0.2450 (2) | 0.0346 (4) | |
H4A | 1.0198 | 0.4358 | 0.2776 | 0.042* | |
C5 | 0.98206 (18) | 0.59621 (18) | 0.16417 (17) | 0.0326 (4) | |
H5A | 1.0818 | 0.6109 | 0.1418 | 0.039* | |
C6 | 0.87356 (18) | 0.67809 (18) | 0.11641 (16) | 0.0303 (4) | |
H6A | 0.8985 | 0.7482 | 0.0599 | 0.036* | |
C7 | 0.72770 (17) | 0.65833 (17) | 0.15078 (14) | 0.0242 (3) | |
H7A | 0.6534 | 0.7157 | 0.1187 | 0.029* | |
C8 | 0.42388 (15) | 0.56275 (15) | 0.16993 (14) | 0.0201 (3) | |
C9 | 0.38220 (17) | 0.62321 (16) | 0.43773 (14) | 0.0237 (3) | |
C10 | 0.3600 (2) | 0.7365 (2) | 0.52655 (17) | 0.0364 (4) | |
H10A | 0.4523 | 0.7555 | 0.5707 | 0.055* | |
H10B | 0.2842 | 0.7128 | 0.5883 | 0.055* | |
H10C | 0.329 | 0.8158 | 0.4792 | 0.055* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0273 (6) | 0.0350 (6) | 0.0363 (6) | 0.0053 (5) | −0.0144 (5) | −0.0139 (5) |
O2 | 0.0270 (6) | 0.0289 (6) | 0.0298 (6) | 0.0060 (5) | −0.0008 (5) | −0.0001 (5) |
O3 | 0.0209 (5) | 0.0298 (6) | 0.0198 (5) | −0.0061 (4) | 0.0051 (4) | −0.0055 (4) |
O4 | 0.0232 (5) | 0.0335 (6) | 0.0253 (6) | −0.0066 (5) | 0.0058 (4) | 0.0003 (5) |
C1 | 0.0197 (7) | 0.0209 (7) | 0.0193 (7) | −0.0032 (6) | 0.0012 (6) | −0.0020 (6) |
C2 | 0.0171 (7) | 0.0207 (7) | 0.0173 (7) | −0.0019 (6) | −0.0001 (5) | −0.0046 (6) |
C3 | 0.0249 (8) | 0.0232 (8) | 0.0334 (8) | 0.0001 (7) | −0.0030 (7) | 0.0014 (7) |
C4 | 0.0214 (7) | 0.0329 (9) | 0.0496 (11) | 0.0066 (7) | −0.0035 (8) | −0.0042 (8) |
C5 | 0.0184 (7) | 0.0424 (9) | 0.0370 (9) | −0.0037 (7) | 0.0061 (7) | −0.0119 (8) |
C6 | 0.0276 (8) | 0.0394 (9) | 0.0238 (8) | −0.0093 (8) | 0.0042 (7) | 0.0016 (7) |
C7 | 0.0215 (7) | 0.0301 (8) | 0.0210 (7) | −0.0005 (6) | −0.0010 (6) | 0.0037 (6) |
C8 | 0.0149 (7) | 0.0237 (7) | 0.0216 (7) | −0.0034 (6) | 0.0036 (5) | −0.0010 (6) |
C9 | 0.0213 (7) | 0.0315 (8) | 0.0184 (7) | −0.0036 (7) | 0.0033 (6) | 0.0021 (6) |
C10 | 0.0390 (10) | 0.0389 (10) | 0.0311 (9) | −0.0082 (9) | 0.0139 (8) | −0.0076 (8) |
O1—C8 | 1.3168 (19) | C3—H3A | 0.95 |
O1—H1 | 0.852 (19) | C4—C5 | 1.387 (3) |
O2—C8 | 1.1989 (19) | C4—H4A | 0.95 |
O3—C9 | 1.3389 (18) | C5—C6 | 1.380 (3) |
O3—C1 | 1.4463 (17) | C5—H5A | 0.95 |
O4—C9 | 1.218 (2) | C6—C7 | 1.391 (2) |
C1—C2 | 1.5128 (19) | C6—H6A | 0.95 |
C1—C8 | 1.527 (2) | C7—H7A | 0.95 |
C1—H1A | 1.0 | C9—C10 | 1.487 (2) |
C2—C3 | 1.386 (2) | C10—H10A | 0.98 |
C2—C7 | 1.391 (2) | C10—H10B | 0.98 |
C3—C4 | 1.391 (2) | C10—H10C | 0.98 |
C8—O1—H1 | 107.2 (15) | C4—C5—H5A | 120.1 |
C9—O3—C1 | 116.28 (11) | C5—C6—C7 | 120.22 (16) |
O3—C1—C2 | 106.65 (11) | C5—C6—H6A | 119.9 |
O3—C1—C8 | 108.41 (11) | C7—C6—H6A | 119.9 |
C2—C1—C8 | 111.91 (12) | C6—C7—C2 | 119.95 (14) |
O3—C1—H1A | 109.9 | C6—C7—H7A | 120.0 |
C2—C1—H1A | 109.9 | C2—C7—H7A | 120.0 |
C8—C1—H1A | 109.9 | O2—C8—O1 | 125.26 (14) |
C3—C2—C7 | 119.87 (14) | O2—C8—C1 | 124.01 (14) |
C3—C2—C1 | 119.51 (13) | O1—C8—C1 | 110.72 (12) |
C7—C2—C1 | 120.54 (13) | O4—C9—O3 | 122.18 (14) |
C2—C3—C4 | 119.76 (15) | O4—C9—C10 | 125.84 (14) |
C2—C3—H3A | 120.1 | O3—C9—C10 | 111.98 (13) |
C4—C3—H3A | 120.1 | C9—C10—H10A | 109.5 |
C5—C4—C3 | 120.37 (16) | C9—C10—H10B | 109.5 |
C5—C4—H4A | 119.8 | H10A—C10—H10B | 109.5 |
C3—C4—H4A | 119.8 | C9—C10—H10C | 109.5 |
C6—C5—C4 | 119.83 (15) | H10A—C10—H10C | 109.5 |
C6—C5—H5A | 120.1 | H10B—C10—H10C | 109.5 |
C9—O3—C1—C2 | −172.13 (12) | C4—C5—C6—C7 | 1.1 (3) |
C9—O3—C1—C8 | 67.21 (15) | C5—C6—C7—C2 | −1.0 (3) |
O3—C1—C2—C3 | 98.10 (15) | C3—C2—C7—C6 | −0.2 (2) |
C8—C1—C2—C3 | −143.51 (14) | C1—C2—C7—C6 | 176.71 (15) |
O3—C1—C2—C7 | −78.78 (16) | O3—C1—C8—O2 | 13.69 (19) |
C8—C1—C2—C7 | 39.62 (18) | C2—C1—C8—O2 | −103.65 (16) |
C7—C2—C3—C4 | 1.1 (2) | O3—C1—C8—O1 | −167.43 (12) |
C1—C2—C3—C4 | −175.84 (16) | C2—C1—C8—O1 | 75.23 (15) |
C2—C3—C4—C5 | −0.9 (3) | C1—O3—C9—O4 | 6.3 (2) |
C3—C4—C5—C6 | −0.2 (3) | C1—O3—C9—C10 | −173.19 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O4i | 0.85 (2) | 1.84 (2) | 2.6761 (16) | 165 (2) |
C10—H10B···O1ii | 0.98 | 2.56 | 3.312 (2) | 133 |
Symmetry codes: (i) −x+1/2, −y+1, z−1/2; (ii) −x+1/2, −y+1, z+1/2. |
Acknowledgements
This work was supported by Vassar College. X-ray facilities were provided by the US National Science Foundation (Grant Nos. 0521237 and 0911324 to JMT). We acknowledge the Salmon Fund of Vassar College for funding publication expenses.
References
Bruker (2013). SAINT, SADABS and APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CSD CrossRef IUCr Journals Google Scholar
Lovely, A. E. & Wenzel, T. J. (2008). Chirality, 20, 370–378. Web of Science CrossRef PubMed CAS Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Mughal, R. K., Pritchard, R. G. & Davey, R. J. (2004). Acta Cryst. E60, o232–o233. Web of Science CSD CrossRef IUCr Journals Google Scholar
Ohtani, M., Matsuura, T., Watanabe, F. & Narisada, M. (1991). J. Org. Chem. 56, 4120–4123. CSD CrossRef CAS Web of Science Google Scholar
Ornelas, A., Korczynska, M., Ragumani, S., Kumaran, D., Narindoshvili, T., Shoichet, B. K., Swaminathan, S. & Raushel, F. M. (2013). Biochemistry, 52, 228–238. Web of Science CrossRef CAS PubMed Google Scholar
Parker, D. (1991). Chem. Rev. 91, 1441–1457. CrossRef CAS Web of Science Google Scholar
Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Szeleczky, Z., Bagi, P., Pálovics, E. & Fogassy, E. (2015). Tetrahedron Asymmetry, 26, 377–384. Web of Science CrossRef CAS Google Scholar
Xiao, K.-J., Chu, L. & Yu, J.-Q. (2016). Angew. Chem. Int. Ed. 55, 2856–2860. Web of Science CSD CrossRef CAS Google Scholar
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