Bis(2,5-dimethoxy-4-methylphenyl)methane and bis(2,5-dimethoxy-3,4,6-trimethylphenyl)methane.

Article abstract of DOI:10.1107/S0108270103024673

Bis(2,5-dimethoxy-4-methylphenyl)methane, C(19)H(24)O(4), (IIa), was obtained and characterized as a minor product from the reaction of toluhydroquinone dimethyl ether (1,4-dimethoxy-2-methylbenzene) with N-(hydroxymethyl)trifluoroacetamide. Similarly, bis(2,5-dimethoxy-3,4,6-trimethylphenyl)methane, C(23)H(32)O(4), (IIb), was prepared from the corresponding reaction of trimethylhydroquinone dimethyl ether (2,5-dimethoxy-1,3,4-trimethylbenzene). The molecules of (IIa) and (IIb) each lie on a twofold axis passing through the methylene group. The dihedral angle between the planar phenyl rings is 73.4 (1) degrees in (IIa) and 77.9 (1) degrees in (IIb). The external bond angles around the bridging methylene group are 116.6 (2) and 117.3 (2) degrees for (IIa) and (IIb), respectively. In (IIa), the methoxy substituents lie in the plane of the ring and are conjugated with the aromatic system, whereas in (IIb), they are almost perpendicular to the phenyl ring and are positioned on opposite sides.

Full text of DOI:10.1107/S0108270103024673

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
are known products of other reaction sequences, but their
formation via the synthetic sequence used here has not
previously been reported and was not anticipated in these
reactions. We report here the synthesis of both these bisaryl-
methane derivatives via this new reaction sequence, as well as
their full characterization by X-ray analysis.
ISSN 0108-2701
Bis(2,5-dimethoxy-4-methylphenyl)-
methane and bis(2,5-dimethoxy-
3
,4,6-trimethylphenyl)methane
David J. Wiedenfeld, Vladimir N. Nesterov,* Mark A.
Minton and David R. Glass
Department of Natural Sciences, New Mexico Highlands University, Las Vegas,
NM 87701, USA
Correspondence e-mail: vnesterov@nmhu.edu
Received 21 October 2003
Accepted 27 October 2003
Online 14 November 2003
Bis(2,5-dimethoxy-4-methylphenyl)methane, C H O , (IIa),
4
1
9
24
In the crystal structures of both compounds, (IIa) and (IIb),
the molecules lie on a twofold axis, which passes through the
methylene group, in space group C2/c (No. 15). The dihedral
was obtained and characterized as a minor product from the
reaction of toluhydroquinone dimethyl ether (1,4-dimethoxy-
2-methylbenzene) with N-(hydroxymethyl)tri¯uoroacetamide.
Similarly, bis(2,5-dimethoxy-3,4,6-trimethylphenyl)methane,
ꢀ
angle between the planar phenyl rings is 73.4 (1) in (IIa) and
ꢀ
7
ging methylene group are 116.6 (2) and 117.3 (2) , respec-
7.9 (1) in (IIb). The external bond angles around the brid-
ꢀ
C H O , (IIb), was prepared from the corresponding
4
2
3
32
reaction of trimethylhydroquinone dimethyl ether (2,5-
dimethoxy-1,3,4-trimethylbenzene). The molecules of (IIa)
and (IIb) each lie on a twofold axis passing through the
methylene group. The dihedral angle between the planar
tively, signi®cantly larger than the standard value. However,
Ê
the C1ÐC7 bond lengths [1.514 (2) and 1.522 (2) A, respec-
tively] did not increase so dramatically relative to the standard
value and are only slightly longer (Allen et al., 1987).
In (IIa), the methoxy substituents lie in the plane of the ring
and are conjugated with the aromatic system. Methoxy group
conjugation with an aromatic ring has been observed in many
systems, including arylidene dicyanovinyl derivatives (Antipin
et al., 1997), trans-1-cyano-2-(2-methoxyphenyl)-1-nitroethyl-
ene (Nesterov et al., 2000) and [(2-methoxyanilino)methyl-
ene]malononitrile (Nesterov et al., 2003). In contrast, in (IIb),
ꢀ
ꢀ
phenyl rings is 73.4 (1) in (IIa) and 77.9 (1) in (IIb). The
external bond angles around the bridging methylene group are
1
ꢀ
16.6 (2) and 117.3 (2) for (IIa) and (IIb), respectively. In
IIa), the methoxy substituents lie in the plane of the ring and
(
are conjugated with the aromatic system, whereas in (IIb),
they are almost perpendicular to the phenyl ring and are
positioned on opposite sides.
Comment
In the course of the syntheses of ammonium quinone deri-
vatives as potential electron acceptors for electron-transfer
studies, the amidomethylation reactions of several di-
methoxybenzene derivatives have been studied (Zaugg, 1970,
1
984; Zaugg & Martin, 1965). The methodology involves
reacting the aromatic derivative with N-(hydroxymethyl)tri-
uoroacetamide in chloroform±tri¯uoroacetic acid solution.
¯
The major products in each of the reactions we have studied
are the expected tri¯uoroacetamide adducts, (Ia) and (Ib). We
will report, in due course, our studies on the elaboration of
such adducts into ammonium quinones.
Interestingly, in the cases of trimethylhydroquinone di-
methyl ether and toluhydroquinone dimethyl ether, signi®cant
minor products were also obtained, namely the title bisaryl-
methane derivatives, (IIa) and (IIb), respectively. Such species
Figure 1
A view of the molecule of (IIa) with the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as small spheres of arbitrary radii.
o700 # 2003 International Union of Crystallography
DOI: 10.1107/S0108270103024673
Acta Cryst. (2003). C59, o700±o702

organic compounds
on silica gel with hexanes±ethyl acetate (8:1) gave two fractions, both
white crystalline solids. The diphenylmethane (0.15 g, 11%) was
1
13
obtained as the ®rst fraction; H and C NMR data are in accordance
with the literature (Rathore & Kochi, 1995). Crystallization from
hexanes±ethyl acetate (9:1) gave X-ray quality crystals of (IIa) [m.p.
4
1
13±414 K; literature range (Rathore & Kochi, 1995; Hunt & Lindsey,
962; Jacini & Bacchetti, 1950): 420±421 K]. The second fraction, (Ia),
was the expected amidomethylation product (yield 1.61 g, 68%).
1
Spectroscopic analysis of (IIa): H NMR (300 MHz, CDCl
.22 (s, 3H, Ar-CH ), 3.78 (s, 3H, OCH ), 3.83 (s, 3H, OCH ), 4.48 (d,
J = 5.9 Hz, 2H, Ar-CH ), 6.73 (s, 1H, Ar-H), 6.75 (s, 1H, Ar-H), 6.94
3
, p.p.m):
2
3
3
3
2
13
(
br s, 1H, NH); C NMR (75 MHz, CDCl
3
, p.p.m.): 16.3 (Ar-CH
), 116.0 (q, J = 287.7 Hz, CF
3
),
),
4
1
0.2 (Ar-CH
2
), 55.9, 56.0 (2 Â OCH
3
3
12.6 (Ar-C6), 113.7 (Ar-C3), 121.4 (Ar-C4), 127.8 (Ar-C1), 151.2
Figure 2
(
Ar-C2), 151.6 (Ar-C5), 156.7 (q, J = 36.7 Hz, CO). Minor peaks for
A view of the molecule of (IIb) with the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as small spheres of arbitrary radii.
the two possible regioisomers were also present in both spectra of this
fraction. For the preparation of (IIb), the above procedure was
applied to trimethylhydroquinone dimethyl ether (Rathore et al.,
1
994a,b). In this case, the diphenylmethane was obtained in 40%
1
13
the methoxy groups are almost perpendicular to the phenyl
ꢀ
yield, again as the ®rst fraction. H and C NMR spectra were in
accordance with the literature (Rathore & Kochi, 1995). Recrys-
tallization from absolute ethanol gave X-ray quality crystals of (IIb)
[m.p. 415±416 K; literature range (Rathore & Kochi, 1995): 415±
ring [C8ÐO1ÐC2ÐC1 = 93.3 (2) and C11ÐO2ÐC5ÐC4 =
ꢀ
�
93.3 (2) ] and are positioned on opposite sides of the ring.
The presence in (IIb) of bulky substituents in both ortho
4
16 K]. The second fraction, (Ib), was the expected amidomethyl-
positions is apparently the cause of signi®cant C ÐO
Ph
OMe
1
ation product in 49% yield. Spectroscopic analysis of (IIb): H NMR
300 MHz, CDCl , p.p.m.): 2.19 (s, 3H, Ar-CH ), 2.21 (s, 3H, Ar-CH ),
.28 (s, 3H, Ar-CH ), 3.65 (s, 3H, OCH ), 3.71 (s, 3H, OCH ), 4.56 (d,
J = 5.5 Hz, 2H, Ar-CH ), 6.67 (br s, 1H, NH); C NMR (75 MHz,
CDCl ), 36.6 (Ar-CH ), 60.2,
, p.p.m.): 12.1, 12.8, 12.9 (3 Â Ar-CH
1.0 (2 Â OCH ), 115.9 (q, J = 287.7 Hz, CF ), 125.4 (Ar-C6), 128.1
Ar-C3 or Ar-C4), 128.5 (Ar-C4 or Ar-C3), 131.8 (Ar-C1), 153.4 (Ar-
bond stretching; the C2ÐO1 and C5ÐO2 bond lengths are
Ê
.393 (2) and 1.389 (2) A, respectively. In contrast, the corre-
(
3
3
3
1
sponding bond lengths in (IIa), which does not have multiple
ortho substitutions, are shorter than in (IIb), with values of
2
3
3
3
13
2
3
3
2
Ê
.371 (2) and 1.372 (2) A, respectively, comparable with the
1
standard bond value (Allen et al., 1987).
6
3
3
(
The different orientations of the methoxy groups about the
phenyl rings in (IIa) and (IIb) account for the distortion of the
bond angles. Thus, we found an increase in the C2ÐO1ÐC8
C5 or Ar-C2), 153.6 (Ar-C2 or Ar-C5), 156.7 (q, J = 36.7 Hz, CO).
ꢀ
and C5ÐO2ÐC10 angles [118.0 (2) and 117.3 (2) , respec-
tively] and in the C3ÐC2ÐO1 and C6ÐC5ÐO2 angles
Compound (IIa)
ꢀ
Crystal data
[124.2 (2) and 124.3 (2) , respectively] in (IIa). The corre-
sponding values in (IIb) are smaller [CÐOÐC angles
�
3
C
19
H O
24 4
D
x
= 1.226 Mg m
r
M = 316.38
Mo Kꢁ radiation
ꢀ
1
approximately standard and within 1 of 120 . Such effects are
13.7 (1) and 113.7 (1) ], but the CÐCÐO values are
ꢀ
Monoclinic, C2=c
Cell parameters from 24
re¯ections
ꢀ
Ê
a = 23.282 (5) A
b = 7.7280 (15) A
Ê
ꢀ
ꢂ = 11±12
ꢃ = 0.09 mm
T = 295 (2) K
usual for compounds containing OCH groups and have been
3
Ê
c = 9.6740 (19) A
� 1
well explained previously (Gallagher et al., 2001). Other bond
lengths and angles in (IIa) and (IIb) have expected values
ꢀ
ꢀ
= 100.10 (3)
Ê
3
V = 1713.6 (6) A
Z = 4
Prism, colourless
0.45 Â 0.35 Â 0.25 mm
(
Allen et al., 1987).
There are no signi®cant intermolecular interactions in
Data collection
either (IIa) or (IIb). However, in (IIb), there are some weak
intramolecular contacts involving C9Á Á ÁO1 and C10/C12Á Á ÁO2
ꢀ
Enraf±Nonius CAD-4
diffractometer
ꢂ/2ꢂ scans
1900 measured re¯ections
ꢂmax = 27.0
h = 0 ! 29
Ê
Ê
ꢀ
(
all HÁ Á ÁO > 2.30 A, CÁ Á ÁO > 2.80 A and CÐHÁ Á ÁO ' 110 ).
k = 0 ! 9
i
l = � 12 ! 12
Two other C7/C12Á Á ÁO1 contacts involve the symmetry-
1
856 independent re¯ections
1130 re¯ections with I > 2ꢄ(I)
int = 0.044
3 standard re¯ections
every 97 re¯ections
intensity decay: 3%
3
2
related parts of (IIb) [symmetry code: (i) 1 � x, y, � z].
R
Re®nement
Experimental
2
2
2
o
2
Re®nement on F
2
w = 1/[ꢄ (F
+ 0.8P]
) + (0.07P)
For the preparation of (IIa), a mixture of toluhydroquinone di-
methyl ether (1.31 g, 8.6 mmol), N-(hydroxymethyl)tri¯uoroacet-
amide (1.23 g, 8.6 mmol; Zaugg & Martin, 1965), CHCl (18 ml) and
2
R[F > 2ꢄ(F )] = 0.048
wR(F ) = 0.160
S = 1.09
2
2
where P = (Fo + 2F )/3
2
c
(Á/ꢄ)max = 0.001
3
Ê
� 3
Áꢅmax = 0.19 e A
1
1
856 re¯ections
12 parameters
tri¯uoroacetic acid (9 ml) was re¯uxed with stirring for 3 d under a
Ê
drying tube ®lled with 4 A molecular sieves. The resulting brown
Áꢅmin = � 0.16 e AÊ
� 3
H atoms treated by a mixture of
independent and constrained
re®nement
solution was cooled and the volatile components removed on a rotary
evaporator, leaving a yellow±brown solid. Column chromatography
ꢁ
Acta Cryst. (2003). C59, o700±o702
David J. Wiedenfeld et al.
C H
19 24
O
4
and C23
H
O
32 4
o701

organic compounds
Table 1
Selected geometric parameters (A, ) for (IIa).
Table 2
Selected geometric parameters (A, ) for (IIb).
Ê
ꢀ
Ê
ꢀ
O1ÐC2
O1ÐC8
O2ÐC5
1.371 (2)
1.406 (2)
1.372 (2)
O2ÐC10
C1ÐC7
C4ÐC9
1.422 (2)
1.514 (2)
1.507 (3)
O1ÐC2
O1ÐC8
O2ÐC5
O2ÐC11
1.3930 (16)
1.4334 (19)
1.3892 (17)
1.434 (2)
C1ÐC7
C3ÐC9
C4ÐC10
C6ÐC12
1.5222 (16)
1.510 (2)
1.509 (2)
1.5080 (19)
C2ÐO1ÐC8
C5ÐO2ÐC10
O1ÐC2ÐC1
O1ÐC2ÐC3
117.99 (16)
117.34 (15)
115.91 (15)
123.98 (16)
C1ÐC2ÐC3
O2ÐC5ÐC4
O2ÐC5ÐC6
C4ÐC5ÐC6
120.08 (17)
115.21 (16)
124.32 (17)
120.46 (18)
C2ÐO1ÐC8
C5ÐO2ÐC11
O1ÐC2ÐC1
O1ÐC2ÐC3
113.73 (11)
113.74 (12)
118.95 (11)
118.58 (11)
C1ÐC2ÐC3
O2ÐC5ÐC4
O2ÐC5ÐC6
C4ÐC5ÐC6
122.44 (12)
118.33 (13)
119.20 (13)
122.43 (13)
i
C8ÐO1ÐC2ÐC1
C10ÐO2ÐC5ÐC4
� 178.01 (19)
� 177.51 (17)
C2ÐC1ÐC7ÐC1
67.74 (14)
i
C8ÐO1ÐC2ÐC1
C11ÐO2ÐC5ÐC4
93.33 (15)
� 93.26 (18)
C2ÐC1ÐC7ÐC1
118.12 (12)
3
Symmetry code: (i) 1 � x; y; � z.
2
3
2
Symmetry code: (i) 1 � x; y; � z.
Compound (IIb)
For both compounds, data collection: CAD-4 Software (Enraf±
Nonius, 1989); cell re®nement: CAD-4 Software; data reduction:
SHELXTL-Plus (Sheldrick, 1994); program(s) used to solve struc-
ture: SHELXS97 (Sheldrick, 1990); program(s) used to re®ne struc-
ture: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-
Plus; software used to prepare material for publication: SHELXL97.
Crystal data
�
3
C
H
23 32
O
4
D
x
= 1.190 Mg m
r
M = 372.49
Mo Kꢁ radiation
Cell parameters from 24
re¯ections
Monoclinic, C2=c
Ê
a = 24.321 (5) A
Ê
b = 6.1410 (12) A
ꢀ
ꢂ = 12±13
ꢃ = 0.08 mm
T = 298 (2) K
Ê
c = 15.042 (3) A
� 1
ꢀ
We thank the National Institutes of Health, USA (grant to
DJW, No. S06 GM008066-31), for generous ®nancial support.
ꢀ
= 112.21 (3)
Ê
3
V = 2079.9 (8) A
Z = 4
Prism, colourless
0.50 Â 0.40 Â 0.30 mm
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GG1194). Services for accessing these data are
described at the back of the journal.
Data collection
ꢀ
Enraf±Nonius CAD-4
diffractometer
ꢂ/2ꢂ scans
ꢂmax = 26.0
h = 0 ! 29
k = 0 ! 7
2
2
1
068 measured re¯ections
020 independent re¯ections
620 re¯ections with I > 2ꢄ(I)
l = � 18 ! 17
3 standard re¯ections
every 97 re¯ections
intensity decay: 3%
References
R
int = 0.023
Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor,
R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1±19.
Antipin, M. Yu., Barr, T. A., Cardelino, B. H., Clark, R. D., Moore, C. E.,
Myers, T., Penn, B., Romero, M., Sanghadasa, M. & Timofeeva, T. V. (1997).
J. Phys. Chem. B, 101, 2770±2781.
Enraf±Nonius (1989). CAD-4 Software. Version 5.0. Enraf±Nonius, Delft, The
Netherlands.
Gallagher, J. F., Hanlon, K. & Howarth, J. (2001). Acta Cryst. C57, 1410±1414.
Hunt, S. E. & Lindsey, A. S. (1962). J. Chem. Soc. pp. 4550±4557.
Jacini, G. & Bacchetti, T. (1950). Gazz. Chim. Ital. 80, 757±761.
Nesterov, V. N., Kislyi, V. P., Timofeeva, T. V., Antipin, M. Yu. & Semenov, V. V.
(2000). Acta Cryst. C56, e107±e108.
Re®nement
2
2
2
2
Re®nement on F
2
w = 1/[ꢄ (F
o
) + (0.08P)
2
R[F > 2ꢄ(F )] = 0.047
wR(F ) = 0.148
S = 1.09
+ 0.8P]
where P = (F
(Á/ꢄ)max = 0.001
Áꢅmax = 0.18 e A
Áꢅmin = � 0.19 e AÊ
2
2
2
o c
+ 2F )/3
Ê
� 3
2
1
020 re¯ections
32 parameters
� 3
H atoms treated by a mixture of
independent and constrained
re®nement
Nesterov, V. N., Viltchinskaia, E. A. & Nesterova, S. V. (2003). Acta Cryst. E59,
o625±o627.
Rathore, R., Bosch, E. & Kochi, J. K. (1994a). J. Chem. Soc. Perkin Trans. 2,
pp. 1157±1166.
Rathore, R., Bosch, E. & Kochi, J. K. (1994b). Tetrahedron, 50, 6727±6758.
Rathore, R. & Kochi, J. K. (1995). J. Org. Chem. 60, 7479±7490.
Sheldrick, G. M. (1990). Acta Cryst. A46, 467±473.
Space group C2/c was assigned from the systematic absences, with
subsequent solution and re®nement for both (IIa) and (IIb) (as
distinct from space group Cc). The H atom of the methylene group
(H7A) was found from a difference Fourier map and re®ned isotro-
Ê
Sheldrick, G. M. (1994). SHELXTL-Plus. PC Version 5.02. Siemens Analytical
X-ray Instruments Inc., Madison, Wisconsin, USA.
Sheldrick, G. M. (1997). SHELXL97. University of G oÈ ttingen, Germany.
Zaugg, H. E. (1970). Synthesis, pp. 49±73.
Zaugg, H. E. (1984). Synthesis, pp. 85±110, 181±212.
pically, with CÐH distances of 0.931 (17) and 0.960 (16) A in (IIa)
and (IIb), respectively. All other H atoms were placed in geome-
trically calculated positions and re®ned using a riding model, with
Ê
Ê
CÐH distances of 0.93 A for aromatic H atoms and 0.96 A for CH
groups.
3
Zaugg, H. E. & Martin, W. B. (1965). Org. React. 14, 252±269.
ꢁ
o702 David J. Wiedenfeld et al.
19 24
C H O
4
32
and C23H O
4
Acta Cryst. (2003). C59, o700±o702