2,3-Di­hydro-2-hydroxy­benzo­[b]­furan-3-one

The structure of the title compound, C₈H₆O₃, was determined in order to resolve a long-standing uncertainty as to whether this compound or its isomer, 2,3-di­hydro-3-hydroxy­benzo­[b]furan-2-one, is the solid substance with a melting point of 381 K, prepared by a variety of methods over a number of years. The mol­ecules form infinite (O—H...O) hydrogen-bonded chains, through 2₁ axes in the b direction, with an O...O distance of 2.7095 (14) Å.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.038
• wR factor = 0.106
• Data-to-parameter ratio = 14.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

As part of our continuing study of the photochemistry of diazocarbonyl compounds and how hydrolysis of these substances impacts on this work, we have recently examined the acid-catalyzed hydrolysis of 2,3-dihydro-3-diazobenzo[b]furan-2-one, (1) (Chiang et al., 2002). The product of this reaction is expected to be the hydroxylactone, 2,3-dihydro-3-hydroxybenzo[b]furan-2-one, (2) (Scheme 1). This hydroxylactone was reported by Ladenburg et al. in 1936 as the substance formed by treatment of salicylaldehyde, (3), with HCN followed by hydrolysis of the cyanohydrin thus obtained, (4) (Scheme 2); the final product was a solid with melting point of 381 K.

This work was repeated some years later and the product was shown, by mixed melting point, to be identical with a substance obtained by selenium dioxide oxidation of o-hydroxyacetophenone, (5) (Howe et al., 1967). The chemical behavior of this oxidation product as well as its method of formation suggested that it was the hemiacetal 2,3-dihydro-2-hydroxybenzo[b]furan-3-one, (7), produced by cyclization of the direct oxidation product o-hydroxyphenylglyoxal, (6) (Scheme 3). It was concluded, therefore, that the Ladenburg structural assignment was not correct.

Still later, the Landenburg synthesis was repeated again and the product was shown, once again by mixed melting point, to be identical with a substance obtained by hydrolysis of the adduct, (9), produced by treatment of ω,ω-dichloro-o-hydroxyacetophenone, (8), with morpholine (Scheme 4) (Kappe et al., 1968). It was postulated that hydrolysis of the morpholino adduct first gave the hemiacetal, (7), which then, under the acidic hydrolysis conditions, isomerized into Ladenburg's hydroxylactone. Independent evidence for such an isomerization was claimed in a subsequent publication (Sterk et al., 1968).

Because of the contradictory nature of these reports concerning the structure of this solid substance with melting point of 381 K, and because of the possibility that this substance might be the product of our hydrolysis reaction shown in Scheme 1, we carried out this X-ray diffraction analysis. The results showed unequivocally that the solid is the hemiacetal 2,3-dihydro-2-hydroxybenzo[b]furan-3-one, (7), and that this substance was produced not only by the reaction sequence of Scheme 3 but also by those of Schemes 2 and 4 as well. In the case of Scheme 2, by a rearrangement during the hydrolysis step and in the case of Scheme 4 by straightforward replacement of morpholino by hydroxyl.

S2. Refinement

H atoms were placed in calculated positions with C—H distances ranging from 0.95 to 1.00 Å and then included in the refinement in a riding-motion approximation, with U_iso = 1.2U_eq of the carrier atom. The hydroxyl H atom was refined independently.

Computing details

Data collection: COLLECT (Nonius, 1997-2001); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXTL (Sheldrick, 1999); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of (7), with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Hydrogen bonding in (7). See Table 1 for the hydrogen-bond geometry. Displacement ellipsoids are drawn at the 50% probability level. H atoms bonded to C atoms have been omitted for clarity.

2,3-Dihydro-2-hydroxybenzo[b]furan-3-one

Crystal data

C8H6O3	F(000) = 624
Mr = 150.13	Dx = 1.478 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 7696 reflections
a = 11.0278 (2) Å	θ = 2.6–27.5°
b = 7.7486 (5) Å	µ = 0.12 mm^−1
c = 15.7861 (7) Å	T = 150 K
V = 1348.92 (11) Å^3	Needle, colourless
Z = 8	0.40 × 0.20 × 0.15 mm

Data collection

Nonius KappaCCD diffractometer	1327 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.028
Graphite monochromator	θmax = 27.5°, θmin = 2.6°
Detector resolution: 9 pixels mm^-1	h = −14→14
ϕ scans and ω scans with κ offsets	k = −10→10
7696 measured reflections	l = −20→20
1535 independent 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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.106	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0521P)^2 + 0.4437P] where P = (Fo^2 + 2Fc^2)/3
1535 reflections	(Δ/σ)max < 0.001
104 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.22 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
O1	0.66766 (9)	0.02384 (12)	0.19807 (6)	0.0315 (3)
H1O	0.598 (2)	−0.040 (3)	0.2175 (14)	0.074 (7)*
O2	0.52169 (9)	0.33077 (13)	0.24733 (6)	0.0338 (3)
O3	0.74606 (8)	0.05520 (12)	0.33464 (6)	0.0292 (3)
C1	0.69647 (11)	0.14080 (17)	0.25995 (8)	0.0261 (3)
H1A	0.7587	0.2223	0.2372	0.031*
C2	0.58810 (11)	0.24633 (16)	0.29350 (8)	0.0244 (3)
C3	0.58586 (11)	0.22090 (15)	0.38411 (8)	0.0227 (3)
C4	0.51013 (11)	0.28465 (17)	0.44799 (8)	0.0263 (3)
H4A	0.4445	0.3596	0.4350	0.032*
C5	0.53342 (12)	0.23565 (18)	0.53047 (8)	0.0286 (3)
H5A	0.4839	0.2779	0.5751	0.034*
C6	0.62978 (12)	0.12377 (17)	0.54846 (8)	0.0293 (3)
H6A	0.6442	0.0918	0.6057	0.035*
C7	0.70476 (12)	0.05800 (16)	0.48608 (8)	0.0279 (3)
H7A	0.7696	−0.0182	0.4991	0.033*
C8	0.68045 (11)	0.10892 (16)	0.40337 (7)	0.0237 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0375 (5)	0.0308 (5)	0.0263 (5)	0.0003 (4)	0.0027 (4)	−0.0050 (4)
O2	0.0400 (6)	0.0371 (6)	0.0243 (5)	0.0123 (4)	−0.0023 (4)	0.0030 (4)
O3	0.0283 (5)	0.0321 (5)	0.0273 (5)	0.0072 (4)	0.0002 (4)	−0.0014 (4)
C1	0.0283 (6)	0.0261 (6)	0.0239 (6)	0.0004 (5)	0.0018 (5)	0.0005 (5)
C2	0.0278 (6)	0.0212 (6)	0.0241 (6)	−0.0005 (5)	−0.0006 (5)	−0.0011 (5)
C3	0.0244 (6)	0.0207 (6)	0.0230 (6)	−0.0017 (4)	−0.0008 (5)	0.0003 (5)
C4	0.0260 (6)	0.0260 (6)	0.0270 (6)	0.0006 (5)	0.0005 (5)	−0.0020 (5)
C5	0.0321 (6)	0.0299 (7)	0.0236 (6)	−0.0048 (5)	0.0034 (5)	−0.0031 (5)
C6	0.0368 (7)	0.0284 (7)	0.0227 (6)	−0.0077 (5)	−0.0056 (5)	0.0023 (5)
C7	0.0291 (6)	0.0249 (6)	0.0295 (6)	−0.0009 (5)	−0.0076 (5)	0.0021 (5)
C8	0.0243 (6)	0.0226 (6)	0.0243 (6)	−0.0025 (5)	−0.0006 (5)	−0.0023 (5)

Geometric parameters (Å, º)

O1—C1	1.3699 (15)	C3—C4	1.3994 (18)
O1—H1O	0.97 (2)	C4—C5	1.3803 (18)
O2—C2	1.2230 (15)	C4—H4A	0.9500
O3—C8	1.3689 (14)	C5—C6	1.4005 (19)
O3—C1	1.4592 (15)	C5—H5A	0.9500
C1—C2	1.5419 (17)	C6—C7	1.3831 (19)
C1—H1A	1.0000	C6—H6A	0.9500
C2—C3	1.4441 (17)	C7—C8	1.3902 (17)
C3—C8	1.3905 (17)	C7—H7A	0.9500
C1—O1—H1O	107.4 (13)	C5—C4—H4A	120.9
C8—O3—C1	107.70 (9)	C3—C4—H4A	120.9
O1—C1—O3	111.25 (10)	C4—C5—C6	120.18 (12)
O1—C1—C2	114.59 (10)	C4—C5—H5A	119.9
O3—C1—C2	104.71 (9)	C6—C5—H5A	119.9
O1—C1—H1A	108.7	C7—C6—C5	122.50 (12)
O3—C1—H1A	108.7	C7—C6—H6A	118.7
C2—C1—H1A	108.7	C5—C6—H6A	118.7
O2—C2—C3	130.77 (12)	C6—C7—C8	116.67 (12)
O2—C2—C1	122.90 (11)	C6—C7—H7A	121.7
C3—C2—C1	106.33 (10)	C8—C7—H7A	121.7
C8—C3—C4	120.69 (12)	O3—C8—C7	123.79 (11)
C8—C3—C2	106.79 (11)	O3—C8—C3	114.40 (11)
C4—C3—C2	132.52 (11)	C7—C8—C3	121.81 (12)
C5—C4—C3	118.13 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O2^i	0.97 (2)	1.74 (2)	2.7095 (14)	176 (2)

Symmetry code: (i) −x+1, y−1/2, −z+1/2.