2,2′-Isopropyl­idene­diphenol

The planar benzene rings in the title compound, C₁₅H₁₆O₂, are inclined at an angle of 82.61 (9)° to one another. There are two intra­molecular hydrogen bonds of types O—H...π and C—H...O. The mol­ecules are linked by strong O—H...O hydrogen bonds into a one-dimensional network, which is compared with that of related compounds.

S1. Comment

The present paper is a continuation of our structural study of compounds formed, as reaction by-products, during the industrial production of 4,4'-isopropylidenediphenol (commonly referred to as bisphenol A, BPA or p,p-BPA) by the condensation of phenol with acetone in the presence of an acid catalyst. Examples of such by-products are the isomers 2,4'-isopropylidenediphenol (o,p-BPA), the title compound 2,2'-isopropylidenediphenol [(I); o,o-BPA], and also trisphenol, polyphenols and 2,2,4-trimethyl-4-(4-hydroxyphenyl)-chromane (the so-called Dianin compound) (Kiedik et al., 1993). In a previous paper, we reported the structure of o,p-BPA [Cambridge Structural Database (Allen, 2002) refcode GALCAY (Rozycka-Sokolowska et al., 2005)]. We now compare (I) with the structures of p,p-BPA (CEGYOC02; Okada, 1996), o,p-BPA and compounds containing the 2,2`-isopropylidenediphenol skeleton, i.e. 2,2`-isopropylidene-bis(4-chloro-6-nitrophenol) (IPYCNP; Hay & Mackay, 1979) and 2,2-bis(2-hydroxy-5-methyl-3 − t-butylphenyl) propane (XMBPPR; Hardy & MacNicol, 1976).

As in the case of p,p and o,p isomers of BPA and the other above-mentioned structures, the molecule of (I) contains two planar phenyl rings, C1–C6 and C11–C16, attached to atom C8 (Fig. 1); the largest deviations from planarity are −0.009 (2) and −0.005 (2) Å for atoms C5 and C15, respectively. The dihedral angle between the planes formed by these rings is 82.61 (9)°. This angle is in close agreement with those found for the other isopropylidenediphenol isomers [84.81° for o,p-BPA, and 86.9 (2), 83.6 (2) and 79.7 (2)° for the three independent molecules of p,p-BPA], and with the values of 82.27 and 78.07° observed in XMBPPR and IPYCNP, respectively. Hydroxy atoms O7 and O17 are nearly coplanar with the C1–C6 and C11–C16 rings, with deviations from the ring planes of −0.034 (1) and 0.044 (1) Å, respectively; methyl atom C9 is 0.161 (2) Å above the plane of the C1–C6 ring and atom C10 is 0.154 (2) Å below the plane of the C11–C16 ring. The bond lengths and valence angles in (I) are within the ranges observed in the p,p and o,p isomers, and in the others compounds containing the 2,2`-isopropylidenediphenol skeleton.

There are two weak intramolecular hydrogen-bonding contacts (Table 1 and Fig. 1); the first involves hydroxy atom H17 interacting with the C1–C6 phenyl ring in a classical intramolecular O—H···π hydrogen bond (Desiraju & Steiner, 1999). The H···C distances between atom H17 and the nearest C atoms belonging to the C1–C6 phenyl ring are 2.43 (2) (for H17···C1) and 2.19 (2) Å (for H17···C6) and they are similar to the corresponding H···C distances found for 2,2-bis(2-hydroxy-5-methyl-3 − t-butylphenyl) propane, 2,6-diphenylphenol and bis(2-hydroxy-3 − t-butylphenyl) methane [XMBPPR (Hardy & MacNicol, 1976), DPPHOL (Nakatsu et al., 1978) and NISQUB (Böhmer et al., 1996), respectively]. The second C—H···O interaction between the methyl group (atom C10) and hydroxy atom O7 (Fig. 1) generates an S(6) graph-set motif (Bernstein et al., 1995). The presence of this latter weak intramolecular hydrogen bond is a common characteristic of o,p- and o,o isomers of isopropylidenediphenol and it is an important difference between them and the p,p isomer. Analysis of geometrical parameters of the intramolecular C—H···O hydrogen bonds presented here and in o,p-BPA shows a close similarity; the H···O and C···O distances and the C—H···O angle in (I) are similar to those found for the o,p-isomer [H···O = 2.51 Å, C···O = 3.100 (2) Å and C—H···O = 120° (GALCAY; Rozycka-Sokolowska et al., 2005)].

The packing structure of (I) involves one strong intermolecular hydrogen bond (Steiner, 2002) (Table 1) which links the adjacent molecules into a chain, running parallel to the [010] direction with a graph-set motif of C(8) (Bernstein et al., 1995) (Fig. 2). The two chains passing through each unit cell are antiparallel with no direction-specific interactions between the adjacent chains.

A similar one-dimensional hydrogen-bond network is found in 2,2'-diphenol (NUTSUQ; Byrne et al., 1998) and its derivatives, such as 2,2'-dihydroxy-5,5'-diallyl-biphenyl (CIPXII; Wang et al., 1983), 5,5'-di-t-butylbiphenyl-2,2'-diol and 5,5'-dimethylbiphenyl-2,2'-diol [MEBMIP and MEBMOV, respectively (Bocelli et al., 1999)]. By contrast, a totally different molecular arrangement is found in the o,p and p,p isomers of (I). The molecules of o,p-BPA are connected by two independent intermolecular O—H···O hydrogen bonds into a two-dimensional sheet of six-membered rings, which is parallel to (100), while the molecules of p,p-BPA are connected by a combination of six O—H···O and one C—H···O hydrogen bonds into a three-dimensional network built from many four- and six-membered rings. In summary, significant packing changes occur through hydrogen-bond networks found for these compounds, from three-dimensional for the p,p isomer, through two-dimensional for the o,p isomer, to a one-dimensional network here for the o,o isomer, all related to the moving of one (in o,p-BPA) or two (in o,o-BPA) hydroxy substituents from the para to the ortho position.

S2. Experimental

The sample of o,o-BPA was obtained from the Institute of Heavy Organic Synthesis (Kedzierzyn-Kozle, Poland). Crystals suitable for X-ray diffraction were crystallized from ethanol by slow evaporation of the solvent at a constant temperature of 293 K.

S3. Refinement

All C-bound H atoms were refined in geometrically idealized positions, with C—H distances of 0.93 Å (aromatic) and 0.96 Å (methyl groups), and with U_iso(H) values of 1.2 (aromatic) or 1.5 (CH₃) times U_eq(C). The H atoms of hydroxy groups were located from difference maps and refined isotropically. Friedel equivalent data were merged using MERG4 in SHELXL97 (Sheldrick, 1997), according to the standard procedure for X-ray measurements of chemical compounds without atoms heavier than Si.

Computing details

Data collection: KM4B8 (Gałdecki et al., 1996); cell refinement: KM4B8; data reduction: KM4B8; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek,2000) and Mercury1.4 (Bruno et al., 2002); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. The constituent molecule of (I), with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The dashed lines depict the intramolecular hydrogen bonds. H atoms are drawn as spheres of arbitrary radii. The centroid (Cg1) of the ring formed by C1–C6 atoms is denoted by small black circle.
	Fig. 2. Part of the crystal structure of (I), showing two C(8) chains of molecules lying in domains 0.05 < c < 0.45 (molecules drawn with grey lines) and 0.55 < c < 0.95 (molecules drawn with black lines) [symmetry code (i): 1 − x, −1/2 + y, 1/2 − z]. All H atoms not involved in the hydrogen bonding have been omitted for clarity.

2,2'-Isopropylidenediphenol

Crystal data

C15H16O2	F(000) = 488
Mr = 228.28	Dx = 1.216 Mg m^−3
Orthorhombic, P212121	Cu Kα radiation, λ = 1.54180 Å
Hall symbol: P 2ac 2ab	Cell parameters from 35 reflections
a = 7.032 (1) Å	θ = 6–20°
b = 10.419 (2) Å	µ = 0.63 mm^−1
c = 17.017 (3) Å	T = 288 K
V = 1246.8 (4) Å^3	Table, colourless
Z = 4	0.23 × 0.21 × 0.11 mm

Data collection

Kuma KM-4 diffractometer	Rint = 0.031
Radiation source: fine-focus sealed tube	θmax = 68.1°, θmin = 5.0°
Graphite monochromator	h = −8→8
ω–2θ scans	k = −10→12
8248 measured reflections	l = −14→20
1343 independent reflections	3 standard reflections every 100 reflections
1163 reflections with I > 2σ(I)	intensity decay: 1.9%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.025	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.071	w = 1/[σ^2(Fo^2) + (0.0439P)^2 + 0.0854P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
1343 reflections	Δρmax = 0.15 e Å^−3
165 parameters	Δρmin = −0.09 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0042 (6)

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. One reflection (0,2,0) was identified from refinement statistics as an outlier and omitted from the 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
O17	0.39327 (18)	0.26163 (12)	0.29360 (7)	0.0484 (3)
O7	0.7311 (2)	0.01843 (12)	0.18298 (7)	0.0557 (3)
C1	0.4967 (3)	0.30348 (16)	0.10850 (9)	0.0459 (4)
H1	0.5018	0.3922	0.1142	0.055*
C2	0.3666 (3)	0.25170 (19)	0.05626 (10)	0.0535 (5)
H2	0.2868	0.3049	0.0273	0.064*
C3	0.3569 (3)	0.1208 (2)	0.04771 (11)	0.0570 (5)
H3	0.2691	0.0849	0.0133	0.068*
C4	0.4774 (3)	0.04239 (18)	0.09022 (9)	0.0514 (4)
H4	0.4702	−0.0462	0.0842	0.062*
C5	0.6090 (3)	0.09462 (15)	0.14169 (9)	0.0420 (4)
C6	0.6205 (2)	0.22800 (15)	0.15306 (9)	0.0393 (4)
C8	0.7634 (2)	0.28554 (15)	0.21121 (9)	0.0420 (4)
C9	0.7402 (3)	0.43219 (17)	0.21978 (11)	0.0558 (5)
H9A	0.7649	0.4727	0.1702	0.084*
H9B	0.8285	0.4636	0.2583	0.084*
H9C	0.6128	0.4515	0.2362	0.084*
C10	0.9648 (2)	0.2627 (2)	0.17801 (12)	0.0589 (5)
H10A	0.9933	0.1726	0.1795	0.088*
H10B	1.0559	0.3086	0.2092	0.088*
H10C	0.9703	0.2926	0.1247	0.088*
C11	0.8911 (3)	0.18601 (19)	0.33816 (11)	0.0563 (5)
H11	1.0121	0.1889	0.3161	0.068*
C12	0.8705 (3)	0.1408 (2)	0.41399 (11)	0.0671 (6)
H12	0.9767	0.1138	0.4421	0.080*
C13	0.6939 (4)	0.1356 (2)	0.44797 (11)	0.0633 (6)
H13	0.6798	0.1055	0.4991	0.076*
C14	0.5374 (3)	0.17537 (18)	0.40581 (10)	0.0530 (5)
H14	0.4172	0.1723	0.4285	0.064*
C15	0.5588 (2)	0.21977 (15)	0.32982 (9)	0.0414 (4)
C16	0.7371 (2)	0.22736 (15)	0.29373 (9)	0.0411 (4)
H17	0.405 (3)	0.261 (2)	0.2435 (12)	0.071 (7)*
H7	0.688 (4)	−0.060 (3)	0.1781 (14)	0.094 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O17	0.0408 (6)	0.0561 (7)	0.0483 (7)	0.0024 (6)	0.0027 (5)	−0.0003 (6)
O7	0.0641 (8)	0.0425 (7)	0.0606 (7)	0.0081 (6)	−0.0118 (7)	0.0034 (5)
C1	0.0480 (9)	0.0465 (9)	0.0433 (9)	0.0069 (8)	0.0022 (7)	0.0064 (7)
C2	0.0510 (10)	0.0666 (12)	0.0428 (9)	0.0099 (9)	−0.0048 (8)	0.0086 (8)
C3	0.0592 (11)	0.0696 (12)	0.0421 (9)	−0.0063 (10)	−0.0091 (9)	−0.0028 (9)
C4	0.0658 (11)	0.0486 (9)	0.0398 (8)	−0.0030 (9)	−0.0012 (9)	−0.0028 (7)
C5	0.0469 (9)	0.0429 (8)	0.0362 (8)	0.0038 (7)	0.0012 (7)	0.0019 (6)
C6	0.0378 (8)	0.0437 (8)	0.0363 (8)	0.0026 (7)	0.0045 (6)	0.0035 (6)
C8	0.0389 (8)	0.0429 (8)	0.0443 (8)	−0.0016 (7)	0.0003 (7)	0.0032 (6)
C9	0.0643 (12)	0.0423 (9)	0.0609 (10)	−0.0102 (9)	−0.0008 (10)	0.0042 (8)
C10	0.0413 (9)	0.0774 (12)	0.0579 (11)	−0.0019 (9)	0.0043 (8)	0.0058 (10)
C11	0.0526 (10)	0.0650 (11)	0.0514 (10)	0.0081 (9)	−0.0082 (9)	0.0004 (9)
C12	0.0726 (13)	0.0780 (14)	0.0505 (11)	0.0123 (12)	−0.0146 (11)	0.0066 (10)
C13	0.0904 (16)	0.0601 (11)	0.0393 (9)	0.0003 (11)	−0.0055 (10)	0.0054 (9)
C14	0.0666 (12)	0.0474 (9)	0.0448 (9)	−0.0058 (9)	0.0072 (9)	−0.0022 (8)
C15	0.0475 (9)	0.0348 (7)	0.0420 (8)	−0.0003 (7)	−0.0003 (7)	−0.0026 (6)
C16	0.0440 (8)	0.0381 (7)	0.0414 (8)	0.0002 (7)	−0.0032 (7)	−0.0015 (6)

Geometric parameters (Å, º)

O17—C15	1.387 (2)	C8—C9	1.543 (2)
O17—H17	0.86 (2)	C9—H9A	0.9600
O7—C5	1.3642 (19)	C9—H9B	0.9600
O7—H7	0.87 (3)	C9—H9C	0.9600
C1—C2	1.385 (3)	C10—H10A	0.9600
C1—C6	1.397 (2)	C10—H10B	0.9600
C1—H1	0.9300	C10—H10C	0.9600
C2—C3	1.373 (3)	C11—C12	1.381 (3)
C2—H2	0.9300	C11—C16	1.389 (2)
C3—C4	1.382 (3)	C11—H11	0.9300
C3—H3	0.9300	C12—C13	1.371 (3)
C4—C5	1.386 (2)	C12—H12	0.9300
C4—H4	0.9300	C13—C14	1.377 (3)
C5—C6	1.405 (2)	C13—H13	0.9300
C6—C8	1.533 (2)	C14—C15	1.382 (2)
C8—C16	1.541 (2)	C14—H14	0.9300
C8—C10	1.543 (2)	C15—C16	1.399 (2)
C15—O17—H17	111.0 (16)	H9A—C9—H9B	109.5
C5—O7—H7	106.1 (17)	C8—C9—H9C	109.5
C2—C1—C6	122.74 (16)	H9A—C9—H9C	109.5
C2—C1—H1	118.6	H9B—C9—H9C	109.5
C6—C1—H1	118.6	C8—C10—H10A	109.5
C3—C2—C1	119.19 (17)	C8—C10—H10B	109.5
C3—C2—H2	120.4	H10A—C10—H10B	109.5
C1—C2—H2	120.4	C8—C10—H10C	109.5
C2—C3—C4	120.10 (18)	H10A—C10—H10C	109.5
C2—C3—H3	120.0	H10B—C10—H10C	109.5
C4—C3—H3	120.0	C12—C11—C16	122.17 (19)
C3—C4—C5	120.55 (17)	C12—C11—H11	118.9
C3—C4—H4	119.7	C16—C11—H11	118.9
C5—C4—H4	119.7	C13—C12—C11	120.15 (19)
O7—C5—C4	121.16 (15)	C13—C12—H12	119.9
O7—C5—C6	117.93 (15)	C11—C12—H12	119.9
C4—C5—C6	120.91 (16)	C12—C13—C14	119.49 (17)
C1—C6—C5	116.50 (15)	C12—C13—H13	120.3
C1—C6—C8	122.61 (14)	C14—C13—H13	120.3
C5—C6—C8	120.88 (15)	C13—C14—C15	120.09 (18)
C6—C8—C16	110.85 (13)	C13—C14—H14	120.0
C6—C8—C10	107.76 (14)	C15—C14—H14	120.0
C16—C8—C10	112.53 (14)	C14—C15—O17	115.46 (16)
C6—C8—C9	112.27 (15)	C14—C15—C16	121.82 (17)
C16—C8—C9	106.90 (14)	O17—C15—C16	122.65 (14)
C10—C8—C9	106.51 (16)	C11—C16—C15	116.26 (14)
C8—C9—H9A	109.5	C11—C16—C8	121.64 (16)
C8—C9—H9B	109.5	C15—C16—C8	122.00 (14)
C6—C1—C2—C3	0.4 (3)	C16—C11—C12—C13	−0.1 (3)
C1—C2—C3—C4	−0.7 (3)	C11—C12—C13—C14	0.2 (3)
C2—C3—C4—C5	−0.1 (3)	C12—C13—C14—C15	0.1 (3)
C3—C4—C5—O7	−178.84 (16)	C13—C14—C15—O17	−177.82 (17)
C3—C4—C5—C6	1.3 (3)	C13—C14—C15—C16	−0.8 (3)
C2—C1—C6—C5	0.8 (3)	C12—C11—C16—C15	−0.5 (3)
C2—C1—C6—C8	−179.60 (16)	C12—C11—C16—C8	176.07 (18)
O7—C5—C6—C1	178.51 (14)	C14—C15—C16—C11	0.9 (2)
C4—C5—C6—C1	−1.6 (3)	O17—C15—C16—C11	177.76 (16)
O7—C5—C6—C8	−1.1 (2)	C14—C15—C16—C8	−175.65 (15)
C4—C5—C6—C8	178.79 (14)	O17—C15—C16—C8	1.2 (2)
C1—C6—C8—C16	124.83 (16)	C6—C8—C16—C11	134.19 (17)
C5—C6—C8—C16	−55.6 (2)	C10—C8—C16—C11	13.4 (2)
C1—C6—C8—C10	−111.63 (18)	C9—C8—C16—C11	−103.16 (19)
C5—C6—C8—C10	67.9 (2)	C6—C8—C16—C15	−49.4 (2)
C1—C6—C8—C9	5.3 (2)	C10—C8—C16—C15	−170.19 (15)
C5—C6—C8—C9	−175.08 (15)	C9—C8—C16—C15	73.22 (19)