4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman

Article abstract of DOI:10.1107/S0108270199013190

The title compound, C₂₃H₂₈O₂, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.

Full text of DOI:10.1107/S0108270199013190

organic compounds
Acta Crystallographica Section C
Crystal Structure
bisphenol-A with an excess of meta-cresol in the presence of
methanesulfonic acid (Caruso & Lee, 1997).
Communications
The molecule of (I) is chiral, as are all dissymmetric spir-
anes. In the proton NMR spectrum, the geminal protons at C3
give two doublets with coupling constants of 14 Hz. Analo-
gously, the methyl C atoms on C4 give two separated signals.
Another interesting property of (I) is its dimorphism.
According to differential scanning calorimetry (DSC)
analyses, the crystals melt at 132.9ꢀ, solidify and melt again at
138.1ꢀ. Such behaviour seems to be a common feature of
structurally related spirobichromans (Baker & Besly, 1939).
The molecule of (I) consists of two identical subunits, which
are nearly perpendicular to each other (Fig. 1). The dihedral
angle between the O1ÐC2ÐC3 and O1iÐC2ÐC3i [symmetry
ISSN 0108-2701
4,4,40,40,7,70-Hexamethyl-2,20-spirobi-
chroman
Krzysztof Ejsmont, Janusz Kyzioø, Ewa Nowakowska and
Jacek Zaleski*
Institute of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
Correspondence e-mail: zaleski@uni.opole.pl
3
1
code: (i)
x,
y, z] planes is 87.2 (1)ꢀ. The oxygen-
2
2
Received 6 October 1999
Accepted 15 October 1999
containing ring is not planar, and the C2 and C3 atoms are
displaced from the plane de®ned by the benzene ring by
Ê
0.393 (4) and 0.299 (4) A, respectively. The O1 and C4 atoms
are nearly coplanar, with deviations from the ring plane of
Ê
0.060 (3) and 0.065 (3) A, respectively. The analogous half-
chair conformation of the pyran ring was observed in (IV)
(MacNicol & Mallinson, 1983). The connection of the subunits
through the spirane carbon has no signi®cant in¯uence on the
geometry of the pyran ring. The bond lengths are the same,
The title compound, C23H28O2, was obtained from the
reaction of acetone with meta-cresol. The molecular structure
consists of two identical subunits which are nearly perpendi-
cular to each other. The oxygen-containing rings are not
planar and the molecule is chiral. The crystal structure consists
of chains of molecules of the same chirality arranged along the
[010] axis.
Ê
within 0.01 A, as those observed in (IV) (MacNicol &
Mallinson, 1983) and (V) (Dianin's compound; Flippen et al.,
1970). The non-planar conformation of the pyran ring makes
the environment of the H atoms on C3 different. The H31
atom occupies a quasi-axial position with a deviation of
Comment
Ê
4,4,40,40,7,70-Hexamethyl-2,20-spirobichroman, (I), belongs to
the large and structurally diverse family of the condensation
products of carbonyl compounds with phenols. In particular,
1.26 (2) A from the mean plane of the pyran ring. The H32
atom lies in the plane and is situated on the same side of the
ring as the O1i atom belonging to the second ring. Conse-
i
quently, the distance between H32 and O1 [2.55 (2) A]
Ê
Ê
exceeds the sum of the van der Waals radii by 0.05 A. The
difference in the chemical shifts of the methyl groups on C4 is
only 0.02 p.p.m. The C41 and C42 atoms are the same distance
from the parent aromatic ring, but their displacements from
the C3ÐC4ÐC10 plane are different [1.207 (5) versus
the acid-catalysed reaction between meta-cresol and acetone
can provide any of the compounds presented in the scheme
above. The preponderance of a particular compound in any
reaction is dependent on the reaction conditions. Compound
(I) was obtained in high yield from (IV) under the in¯uence of
boiling hydriodic acid (Baker & Besly, 1939). Another method
for its preparation involves the heating (10 h at 423 K) of
Figure 1
The molecular structure of (I). Displacement ellipsoids are shown at the
50% probability level.
ꢁ
Acta Cryst. (2000). C56, 93±94
Krzysztof Ejsmont et al. C23H28O2 93

organic compounds
Ê
1.275 (5) A] because the C41 methyl group is directed
Re®nement
Re®nement on F2
R[F2 > 2ꢃ(F2)] = 0.046
wR(F2) = 0.131
S = 1.156
1592 re¯ections
w = 1/[ꢃ2(Fo2) + (0.0546P)2
+ 0.4667P]
outwards while the second methyl group approaches another
chroman subunit. The molecule is rigid, hence it can be
concluded that the different chemical shifts of C41 and C42
result from non-valence intramolecular interactions.
The crystals of (I) are racemic, i.e. they are built from both
enantiomers, as in (IV) and (V). In the crystal structure of the
latter, six molecules form the structural unit which consists of
three pairs of enantiomers. The molecules of the same chirality
are placed on one side of the OÐHÁ Á ÁO ring (Goldup &
Smith, 1970). In clathrates of (IV), the enantiomers are
arranged in pairs connected by hydrogen bonds with the guest
molecules (Gall et al., 1985).
where P = (Fo2 + 2Fc2)/3
(Á/ꢃ)max = 0.001
3
Ê
Áꢄmax = 0.162 e A
3
Ê
0.118 e A
170 parameters
All H-atom parameters re®ned
Áꢄmin
=
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
O1ÐC9
O1ÐC2
C2ÐC3
1.378 (2)
1.423 (2)
1.508 (2)
C3ÐC4
C4ÐC10
C9ÐC10
1.533 (3)
1.512 (3)
1.387 (3)
At the present stage of our investigations, we cannot
formulate any convincing explanation for the nature and
driving force of the transformation of (I) into its high-
temperature polymorph.
C9ÐO1ÐC2
O1ÐC2ÐO1i
O1ÐC2ÐC3
O1iÐC2ÐC3
C3ÐC2ÐC3i
117.7 (1)
108.6 (2)
110.7 (1)
106.8 (1)
113.3 (2)
C2ÐC3ÐC4
O1ÐC9ÐC8
O1ÐC9ÐC10
C8ÐC9ÐC10
C9ÐC10ÐC4
115.5 (2)
114.7 (2)
123.3 (2)
122.1 (2)
122.3 (2)
3
2
Symmetry codes: (i)
x; 12 y; z.
Experimental
A mixture of acetone (14.7 ml, 0.2 mol), meta-cresol (324 g, 3 mol)
and methanesulfonic acid (1 ml) was left for 120 h at room
temperature and then heated for 9 h to 413±423 K. The unreacted
meta-cresol was distilled off in a vacuum. The residue was dissolved in
benzene and extracted with water until neutral. The solvent was
evaporated and a brown residue containing (I), (III) and (IV) was
chromatographed using hexane as the eluent. 4,4,40,40,7,70-Hexa-
methyl-2,20-spirobichroman (5.04 g, 23%) was isolated from the last
fractions as a white powder. Crystals suitable for X-ray diffraction
studies were obtained by crystallization from methanol. MS, m/z
(integration): 336 (4), 321 (35), 281 (13), 265 (21), 174 (14), 173 (100),
149 (71), 121 (11), 105 (12); 1H NMR (DMSO-d6): 7.23 (d, 3J =
7.3 Hz, 2H) and 6.71 (d, 3J = 7.3 Hz, 2H) (aromatic protons at C5, C5i,
C6 and C6i), 6.36 (s, 2H, H8 and H8i), 2.11 (s, 6H, Ar-methyl groups),
2.07 (d, 1H) and 1.92 (d, 2J = 13.9 Hz, 1H) (methylene CH2 protons of
the pyran ring), 1.51 (s, 6H) and 1.26 (s, 6H) (methyl protons of the
isopropenyl bridge); 13C NMR (CDCl3): 150.3 (C9, C9i); 136.8 (C10,
C10i); 128.5 (C7, C7i), 126.1, 122.4 and 118.1 (remaining aromatic C
atoms); 97.7 (spirane carbon, C2); 46.8 (methylene groups, C3 and
C3i); 32.5 and 32.3 (methyl groups on C4 and C4i); 30.6 (C4, C4i); 20.8
(methyl groups at C7 and C7i).
H-atom positions were re®ned by the full-matrix least-squares
Ê
method. The CÐH distances were in the range 0.97 (2)±1.02 (3)A for
Ê
H atoms attached to phenyl rings and in the range 0.91 (5)±1.09 (3)A
range for methyl H atoms.
Data collection: Kuma Diffraction Software (Kuma, 1998); cell
re®nement: Kuma Diffraction Software; data reduction: Kuma
Diffraction Software; program(s) used to solve structure: SHELXS97
(Sheldrick, 1997a); program(s) used to re®ne structure: SHELXL97
(Sheldrick, 1997b); molecular graphics: SHELXTL (Sheldrick, 1990);
software used to prepare material for publication: SHELXL97.
KE is a holder of a grant from the Foundation for Polish Science in
1999.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GD1069). Services for accessing these data are
described at the back of the journal.
Crystal data
References
C23H28O2
Mr = 336.45
Orthorhombic, Pccn
Ê
a = 16.613 (3) A
b = 10.557 (2) A
c = 11.259 (2) A
Ê
V = 1974.6 (6) A
Mo Kꢀ radiation
Cell parameters from 21
re¯ections
Baker, W. & Besly, D. M. (1939). J. Chem. Soc. pp. 195±199.
Caruso, A. J. & Lee, J. L. (1997). J. Org. Chem. 62, 1058±1063.
Flippen, J. L., Karle, J. & Karle, I. L. (1970). J. Am. Chem. Soc. 92,
3749±3755.
Gall, J. H., MacCartney, M., MacNicol, D. D. & Mallinson, P. R. (1985). J.
Inclusion Phenom. 3, 421±435.
Goldup, A. & Smith, G. W. (1970). Sep. Sci. 6, 791±817.
Kuma (1998). Kuma Diffraction Software. Versions 8.1.0 and 8.1.1. Kuma
Diffraction, Wrocøaw, Poland.
MacNicol, D. D. & Mallinson, P. R. (1983). J. Inclusion Phenom. 1,
169±174.
Sheldrick, G. M. (1990). SHELXTL. Siemens Analytical X-ray Instruments
Inc., Madison, Wisconsin, USA.
Sheldrick, G. M. (1997a). SHELXS97. Program for the Solution of Crystal
Structures. University of Gottingen, Germany.
Sheldrick, G. M. (1997b). SHELXL97. Program for the Re®nement of Crystal
È
Structures. University of Gottingen, Germany.
ꢁ = 10±20ꢀ
1
Ê
Ê
ꢂ = 0.070 mm
T = 293 (2) K
3
Plate, colourless
0.7 Â 0.4 Â 0.3 mm
Z = 4
Dx = 1.132 Mg m
3
Data collection
Kuma KM-4 diffractometer
!±ꢁ scans
h = 18 ! 13
k = 0 ! 12
9984 measured re¯ections
1592 independent re¯ections
1175 re¯ections with I > 2ꢃ(I)
Rint = 0.021
l = 13 ! 10
2 standard re¯ections
every 50 re¯ections
intensity decay: 1.7%
È
ꢁmax = 25.06ꢀ
ꢁ
94 Krzysztof Ejsmont et al. C23H28O2
Acta Cryst. (2000). C56, 93±94