organic compounds
Ê
through the aromatic ring are 0.300 (3) and 0.180 (2) A for
Acta Crystallographica Section C
Crystal Structure
Communications
atoms C8 and O2, respectively. The main geometric para-
meters are given in Table 1. As expected, the observed
geometry of the molecule agrees well with the geometries of
similar derivatives (e.g. Elbasyouny et al., 1983; Peters et al.,
1998; Lynch & McClenaghan, 2002).
ISSN 0108-2701
A new monoclinic polymorph of
methyl p-aminobenzoate
Antonio C. Doriguetto,a* Carlos H. T. de Paula Silva,a
Daniela G. Rando,b Elizabeth I. Ferreirab and Javier
Ellenaa
a
Â
Instituto de Fõsica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, CEP
Ä
Ä
b
Â
13560-970, Sao Carlos, SP, Brazil, and Departamento de Farmacia, Faculdade de
Ä
Ã
Ã
Ciencias Farmaceuticas, Universidade de Sao Paulo, Av. Prof. Lineu Prestes 580,
Ä
Bloco 13, CEP 05508-900, Sao Paulo, SP, Brazil
Ä
Correspondence e-mail: dorigue@if.sc.usp.br
Received 2 October 2003
Accepted 28 November 2003
Online 13 December 2003
Single crystals of methyl-p-aminobenzoate (MAB), C8H9NO2,
were obtained during the synthesis of 4-amino-N0-(5-nitro-2-
thienylmethylene)benzohydrazide. A P21/c polymorph [a =
Ê
Ê
Ê
8.5969 (4) A, b = 5.6053 (2) A, c = 15.5397 (7) A and ꢀ =
96.172 (2)ꢀ] of MAB was found and the intra- and inter-
molecular geometries were compared with those of the
Ê
Longarte et al. (1999) calculated the MAB ground-state
structure and vibrational frequencies using the GAUSSIAN98
package (Frisch et al., 1998) and concluded that a sensible
molecular±electronic description requires diffuse functions
and polarizabilities in the theoretical calculations. In this
way, they found that the NH2 H atoms form a 22.38ꢀ angle
with the molecular plane, as expected (Kydd & Krueger,
1977; Hollas et al., 1983). In order to check the conclusion of
Longarte et al., the positional parameters of the two H atoms
connected to the N atoms were not constrained during the
re®nements performed here. Our experimental data show that
the dihedral angles between the NH2 groups and the aromatic
ring plane are 25 (1) and 14 (1)ꢀ for the H11ÐN1ÐC1ÐC6
and H12ÐN1ÐC1ÐC2 angles, respectively, thus con®rming
the results of Kydd & Krueger (1977) and Hollas et al. (1983).
Comparison of the Longarte et al. (1999) 6-31+G* model with
previously known C2/c structure [a = 16.242 (2) A, b =
8.113 (2) A, c = 12.724 (2) A and ꢀ = 69.17 (1)ꢀ; Xianti
(1983). Jiegou Huaxue, 2, 219±221].
Ê
Ê
Comment
Tuberculosis (TB) has re-emerged as one of the leading causes
of death, accounting for nearly three million deaths annually
(Bloom & Murray, 1992). Although there are treatment
regimens based on long-term and combined chemotherapy,
the emergence of AIDS and the decline of socio-economic
standards contribute to the disease's resurgence in indus-
trialized countries and to the emergence of multidrug-resistant
strains of Mycobacterium tuberculosis (Barnes et al., 1991).
Therefore, the search for new therapeutics against tubercu-
losis is of utmost importance.
This work reports the structure of methyl-p-aminobenzoate
(MAB), (I), an intermediate used to obtain 4-amino-N0-(5-
nitro-2-thienylmethylene)benzohydrazide, (II) (see scheme),
which has been shown to be active against tuberculosis
(Rando et al., 2002). Since MAB is part of the synthesized
benzohydrazide, a knowledge of the crystal-packing forces in
(I), in addition to its molecular geometry, could be important
in explaining some aspects of the activity of (II).
The crystal structure of (I) was determined in space group
P21/c. The molecule is almost ¯at; considering the non-H
atoms, the largest deviations from the least-squares plane
Figure 1
A view of (I), with displacement ellipsoids shown at the 50% probability
level.
Acta Cryst. (2004). C60, o69±o71
DOI: 10.1107/S0108270103027422
# 2004 International Union of Crystallography o69